| /* System.java -- useful methods to interface with the system |
| Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2007, 2012 |
| Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2, or (at your option) |
| any later version. |
| |
| GNU Classpath is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package java.lang; |
| |
| import gnu.classpath.SystemProperties; |
| import gnu.classpath.VMStackWalker; |
| |
| import java.io.IOException; |
| import java.io.InputStream; |
| import java.io.PrintStream; |
| import java.io.Console; |
| import java.nio.channels.Channel; |
| import java.nio.channels.spi.SelectorProvider; |
| import java.util.AbstractCollection; |
| import java.util.Collection; |
| import java.util.Collections; |
| import java.util.HashMap; |
| import java.util.Iterator; |
| import java.util.List; |
| import java.util.Map; |
| import java.util.Set; |
| import java.util.Properties; |
| import java.util.PropertyPermission; |
| |
| /** |
| * System represents system-wide resources; things that represent the |
| * general environment. As such, all methods are static. |
| * |
| * @author John Keiser |
| * @author Eric Blake (ebb9@email.byu.edu) |
| * @since 1.0 |
| * @status still missing 1.4 functionality |
| */ |
| public final class System |
| { |
| // WARNING: System is a CORE class in the bootstrap cycle. See the comments |
| // in vm/reference/java/lang/Runtime for implications of this fact. |
| |
| /** |
| * The standard InputStream. This is assigned at startup and starts its |
| * life perfectly valid. Although it is marked final, you can change it |
| * using {@link #setIn(InputStream)} through some hefty VM magic. |
| * |
| * <p>This corresponds to the C stdin and C++ cin variables, which |
| * typically input from the keyboard, but may be used to pipe input from |
| * other processes or files. That should all be transparent to you, |
| * however. |
| */ |
| public static final InputStream in = VMSystem.makeStandardInputStream(); |
| |
| /** |
| * The standard output PrintStream. This is assigned at startup and |
| * starts its life perfectly valid. Although it is marked final, you can |
| * change it using {@link #setOut(PrintStream)} through some hefty VM magic. |
| * |
| * <p>This corresponds to the C stdout and C++ cout variables, which |
| * typically output normal messages to the screen, but may be used to pipe |
| * output to other processes or files. That should all be transparent to |
| * you, however. |
| */ |
| public static final PrintStream out = VMSystem.makeStandardOutputStream(); |
| |
| private static final String LINE_SEPARATOR = SystemProperties.getProperty("line.separator"); |
| |
| /** |
| * The standard output PrintStream. This is assigned at startup and |
| * starts its life perfectly valid. Although it is marked final, you can |
| * change it using {@link #setErr(PrintStream)} through some hefty VM magic. |
| * |
| * <p>This corresponds to the C stderr and C++ cerr variables, which |
| * typically output error messages to the screen, but may be used to pipe |
| * output to other processes or files. That should all be transparent to |
| * you, however. |
| */ |
| public static final PrintStream err = VMSystem.makeStandardErrorStream(); |
| |
| /** |
| * A cached copy of the environment variable map. |
| */ |
| private static Map<String,String> environmentMap; |
| |
| /** |
| * This class is uninstantiable. |
| */ |
| private System() |
| { |
| } |
| |
| /** |
| * Set {@link #in} to a new InputStream. This uses some VM magic to change |
| * a "final" variable, so naturally there is a security check, |
| * <code>RuntimePermission("setIO")</code>. |
| * |
| * @param in the new InputStream |
| * @throws SecurityException if permission is denied |
| * @since 1.1 |
| */ |
| public static void setIn(InputStream in) |
| { |
| SecurityManager sm = SecurityManager.current; // Be thread-safe. |
| if (sm != null) |
| sm.checkPermission(new RuntimePermission("setIO")); |
| |
| VMSystem.setIn(in); |
| } |
| |
| /** |
| * Set {@link #out} to a new PrintStream. This uses some VM magic to change |
| * a "final" variable, so naturally there is a security check, |
| * <code>RuntimePermission("setIO")</code>. |
| * |
| * @param out the new PrintStream |
| * @throws SecurityException if permission is denied |
| * @since 1.1 |
| */ |
| public static void setOut(PrintStream out) |
| { |
| SecurityManager sm = SecurityManager.current; // Be thread-safe. |
| if (sm != null) |
| sm.checkPermission(new RuntimePermission("setIO")); |
| VMSystem.setOut(out); |
| } |
| |
| /** |
| * Set {@link #err} to a new PrintStream. This uses some VM magic to change |
| * a "final" variable, so naturally there is a security check, |
| * <code>RuntimePermission("setIO")</code>. |
| * |
| * @param err the new PrintStream |
| * @throws SecurityException if permission is denied |
| * @since 1.1 |
| */ |
| public static void setErr(PrintStream err) |
| { |
| SecurityManager sm = SecurityManager.current; // Be thread-safe. |
| if (sm != null) |
| sm.checkPermission(new RuntimePermission("setIO")); |
| VMSystem.setErr(err); |
| } |
| |
| /** |
| * Set the current SecurityManager. If a security manager already exists, |
| * then <code>RuntimePermission("setSecurityManager")</code> is checked |
| * first. Since this permission is denied by the default security manager, |
| * setting the security manager is often an irreversible action. |
| * |
| * <STRONG>Spec Note:</STRONG> Don't ask me, I didn't write it. It looks |
| * pretty vulnerable; whoever gets to the gate first gets to set the policy. |
| * There is probably some way to set the original security manager as a |
| * command line argument to the VM, but I don't know it. |
| * |
| * @param sm the new SecurityManager |
| * @throws SecurityException if permission is denied |
| */ |
| public static synchronized void setSecurityManager(SecurityManager sm) |
| { |
| // Implementation note: the field lives in SecurityManager because of |
| // bootstrap initialization issues. This method is synchronized so that |
| // no other thread changes it to null before this thread makes the change. |
| if (SecurityManager.current != null) |
| SecurityManager.current.checkPermission |
| (new RuntimePermission("setSecurityManager")); |
| |
| // java.security.Security's class initialiser loads and parses the |
| // policy files. If it hasn't been run already it will be run |
| // during the first permission check. That initialisation will |
| // fail if a very restrictive security manager is in force, so we |
| // preload it here. |
| if (SecurityManager.current == null) |
| { |
| try |
| { |
| Class.forName("java.security.Security"); |
| } |
| catch (ClassNotFoundException e) |
| { |
| } |
| } |
| |
| SecurityManager.current = sm; |
| } |
| |
| /** |
| * Get the current SecurityManager. If the SecurityManager has not been |
| * set yet, then this method returns null. |
| * |
| * @return the current SecurityManager, or null |
| */ |
| public static SecurityManager getSecurityManager() |
| { |
| return SecurityManager.current; |
| } |
| |
| /** |
| * Get the current time, measured in the number of milliseconds from the |
| * beginning of Jan. 1, 1970. This is gathered from the system clock, with |
| * any attendant incorrectness (it may be timezone dependent). |
| * |
| * @return the current time |
| * @see java.util.Date |
| */ |
| public static long currentTimeMillis() |
| { |
| return VMSystem.currentTimeMillis(); |
| } |
| |
| /** |
| * <p> |
| * Returns the current value of a nanosecond-precise system timer. |
| * The value of the timer is an offset relative to some arbitrary fixed |
| * time, which may be in the future (making the value negative). This |
| * method is useful for timing events where nanosecond precision is |
| * required. This is achieved by calling this method before and after the |
| * event, and taking the difference betweent the two times: |
| * </p> |
| * <p> |
| * <code>long startTime = System.nanoTime();</code><br /> |
| * <code>... <emph>event code</emph> ...</code><br /> |
| * <code>long endTime = System.nanoTime();</code><br /> |
| * <code>long duration = endTime - startTime;</code><br /> |
| * </p> |
| * <p> |
| * Note that the value is only nanosecond-precise, and not accurate; there |
| * is no guarantee that the difference between two values is really a |
| * nanosecond. Also, the value is prone to overflow if the offset |
| * exceeds 2^63. |
| * </p> |
| * |
| * @return the time of a system timer in nanoseconds. |
| * @since 1.5 |
| */ |
| public static long nanoTime() |
| { |
| return VMSystem.nanoTime(); |
| } |
| |
| /** |
| * Copy one array onto another from <code>src[srcStart]</code> ... |
| * <code>src[srcStart+len-1]</code> to <code>dest[destStart]</code> ... |
| * <code>dest[destStart+len-1]</code>. First, the arguments are validated: |
| * neither array may be null, they must be of compatible types, and the |
| * start and length must fit within both arrays. Then the copying starts, |
| * and proceeds through increasing slots. If src and dest are the same |
| * array, this will appear to copy the data to a temporary location first. |
| * An ArrayStoreException in the middle of copying will leave earlier |
| * elements copied, but later elements unchanged. |
| * |
| * @param src the array to copy elements from |
| * @param srcStart the starting position in src |
| * @param dest the array to copy elements to |
| * @param destStart the starting position in dest |
| * @param len the number of elements to copy |
| * @throws NullPointerException if src or dest is null |
| * @throws ArrayStoreException if src or dest is not an array, if they are |
| * not compatible array types, or if an incompatible runtime type |
| * is stored in dest |
| * @throws IndexOutOfBoundsException if len is negative, or if the start or |
| * end copy position in either array is out of bounds |
| */ |
| public static void arraycopy(Object src, int srcStart, |
| Object dest, int destStart, int len) |
| { |
| VMSystem.arraycopy(src, srcStart, dest, destStart, len); |
| } |
| |
| /** |
| * Get a hash code computed by the VM for the Object. This hash code will |
| * be the same as Object's hashCode() method. It is usually some |
| * convolution of the pointer to the Object internal to the VM. It |
| * follows standard hash code rules, in that it will remain the same for a |
| * given Object for the lifetime of that Object. |
| * |
| * @param o the Object to get the hash code for |
| * @return the VM-dependent hash code for this Object |
| * @since 1.1 |
| */ |
| public static int identityHashCode(Object o) |
| { |
| return VMSystem.identityHashCode(o); |
| } |
| |
| /** |
| * Get all the system properties at once. A security check may be performed, |
| * <code>checkPropertiesAccess</code>. Note that a security manager may |
| * allow getting a single property, but not the entire group. |
| * |
| * <p>The required properties include: |
| * <dl> |
| * <dt>java.version</dt> <dd>Java version number</dd> |
| * <dt>java.vendor</dt> <dd>Java vendor specific string</dd> |
| * <dt>java.vendor.url</dt> <dd>Java vendor URL</dd> |
| * <dt>java.home</dt> <dd>Java installation directory</dd> |
| * <dt>java.vm.specification.version</dt> <dd>VM Spec version</dd> |
| * <dt>java.vm.specification.vendor</dt> <dd>VM Spec vendor</dd> |
| * <dt>java.vm.specification.name</dt> <dd>VM Spec name</dd> |
| * <dt>java.vm.version</dt> <dd>VM implementation version</dd> |
| * <dt>java.vm.vendor</dt> <dd>VM implementation vendor</dd> |
| * <dt>java.vm.name</dt> <dd>VM implementation name</dd> |
| * <dt>java.specification.version</dt> <dd>Java Runtime Environment version</dd> |
| * <dt>java.specification.vendor</dt> <dd>Java Runtime Environment vendor</dd> |
| * <dt>java.specification.name</dt> <dd>Java Runtime Environment name</dd> |
| * <dt>java.class.version</dt> <dd>Java class version number</dd> |
| * <dt>java.class.path</dt> <dd>Java classpath</dd> |
| * <dt>java.library.path</dt> <dd>Path for finding Java libraries</dd> |
| * <dt>java.io.tmpdir</dt> <dd>Default temp file path</dd> |
| * <dt>java.compiler</dt> <dd>Name of JIT to use</dd> |
| * <dt>java.ext.dirs</dt> <dd>Java extension path</dd> |
| * <dt>os.name</dt> <dd>Operating System Name</dd> |
| * <dt>os.arch</dt> <dd>Operating System Architecture</dd> |
| * <dt>os.version</dt> <dd>Operating System Version</dd> |
| * <dt>file.separator</dt> <dd>File separator ("/" on Unix)</dd> |
| * <dt>path.separator</dt> <dd>Path separator (":" on Unix)</dd> |
| * <dt>line.separator</dt> <dd>Line separator ("\n" on Unix)</dd> |
| * <dt>user.name</dt> <dd>User account name</dd> |
| * <dt>user.home</dt> <dd>User home directory</dd> |
| * <dt>user.dir</dt> <dd>User's current working directory</dd> |
| * </dl> |
| * |
| * In addition, gnu defines several other properties, where ? stands for |
| * each character in '0' through '9': |
| * <dl> |
| * <dt>gnu.classpath.home</dt> <dd>Path to the classpath libraries.</dd> |
| * <dt>gnu.classpath.version</dt> <dd>Version of the classpath libraries.</dd> |
| * <dt>gnu.classpath.vm.shortname</dt> <dd>Succinct version of the VM name; |
| * used for finding property files in file system</dd> |
| * <dt>gnu.classpath.home.url</dt> <dd> Base URL; used for finding |
| * property files in file system</dd> |
| * <dt>gnu.cpu.endian</dt> <dd>big or little</dd> |
| * <dt>gnu.java.io.encoding_scheme_alias.iso-8859-?</dt> <dd>8859_?</dd> |
| * <dt>gnu.java.io.encoding_scheme_alias.iso8859_?</dt> <dd>8859_?</dd> |
| * <dt>gnu.java.io.encoding_scheme_alias.iso-latin-_?</dt> <dd>8859_?</dd> |
| * <dt>gnu.java.io.encoding_scheme_alias.latin?</dt> <dd>8859_?</dd> |
| * <dt>gnu.java.io.encoding_scheme_alias.utf-8</dt> <dd>UTF8</dd> |
| * <dt>gnu.java.util.zoneinfo.dir</dt> <dd>Root of zoneinfo tree</dd> |
| * <dt>gnu.javax.print.server</dt> <dd>Hostname of external CUPS server.</dd> |
| * </dl> |
| * |
| * @return the system properties, will never be null |
| * @throws SecurityException if permission is denied |
| */ |
| public static Properties getProperties() |
| { |
| SecurityManager sm = SecurityManager.current; // Be thread-safe. |
| if (sm != null) |
| sm.checkPropertiesAccess(); |
| return SystemProperties.getProperties(); |
| } |
| |
| /** |
| * Set all the system properties at once. A security check may be performed, |
| * <code>checkPropertiesAccess</code>. Note that a security manager may |
| * allow setting a single property, but not the entire group. An argument |
| * of null resets the properties to the startup default. |
| * |
| * @param properties the new set of system properties |
| * @throws SecurityException if permission is denied |
| */ |
| public static void setProperties(Properties properties) |
| { |
| SecurityManager sm = SecurityManager.current; // Be thread-safe. |
| if (sm != null) |
| sm.checkPropertiesAccess(); |
| SystemProperties.setProperties(properties); |
| } |
| |
| /** |
| * Get a single system property by name. A security check may be performed, |
| * <code>checkPropertyAccess(key)</code>. |
| * |
| * @param key the name of the system property to get |
| * @return the property, or null if not found |
| * @throws SecurityException if permission is denied |
| * @throws NullPointerException if key is null |
| * @throws IllegalArgumentException if key is "" |
| */ |
| public static String getProperty(String key) |
| { |
| SecurityManager sm = SecurityManager.current; // Be thread-safe. |
| if (sm != null) |
| sm.checkPropertyAccess(key); |
| if (key.length() == 0) |
| throw new IllegalArgumentException("key can't be empty"); |
| return SystemProperties.getProperty(key); |
| } |
| |
| /** |
| * Get a single system property by name. A security check may be performed, |
| * <code>checkPropertyAccess(key)</code>. |
| * |
| * @param key the name of the system property to get |
| * @param def the default |
| * @return the property, or def if not found |
| * @throws SecurityException if permission is denied |
| * @throws NullPointerException if key is null |
| * @throws IllegalArgumentException if key is "" |
| */ |
| public static String getProperty(String key, String def) |
| { |
| SecurityManager sm = SecurityManager.current; // Be thread-safe. |
| if (sm != null) |
| sm.checkPropertyAccess(key); |
| // This handles both the null pointer exception and the illegal |
| // argument exception. |
| if (key.length() == 0) |
| throw new IllegalArgumentException("key can't be empty"); |
| return SystemProperties.getProperty(key, def); |
| } |
| |
| /** |
| * Set a single system property by name. A security check may be performed, |
| * <code>checkPropertyAccess(key, "write")</code>. |
| * |
| * @param key the name of the system property to set |
| * @param value the new value |
| * @return the previous value, or null |
| * @throws SecurityException if permission is denied |
| * @throws NullPointerException if key is null |
| * @throws IllegalArgumentException if key is "" |
| * @since 1.2 |
| */ |
| public static String setProperty(String key, String value) |
| { |
| SecurityManager sm = SecurityManager.current; // Be thread-safe. |
| if (sm != null) |
| sm.checkPermission(new PropertyPermission(key, "write")); |
| // This handles both the null pointer exception and the illegal |
| // argument exception. |
| if (key.length() == 0) |
| throw new IllegalArgumentException("key can't be empty"); |
| return SystemProperties.setProperty(key, value); |
| } |
| |
| /** |
| * Remove a single system property by name. A security check may be |
| * performed, <code>checkPropertyAccess(key, "write")</code>. |
| * |
| * @param key the name of the system property to remove |
| * @return the previous value, or null |
| * @throws SecurityException if permission is denied |
| * @throws NullPointerException if key is null |
| * @throws IllegalArgumentException if key is "" |
| * @since 1.5 |
| */ |
| public static String clearProperty(String key) |
| { |
| SecurityManager sm = SecurityManager.current; // Be thread-safe. |
| if (sm != null) |
| sm.checkPermission(new PropertyPermission(key, "write")); |
| // This handles both the null pointer exception and the illegal |
| // argument exception. |
| if (key.length() == 0) |
| throw new IllegalArgumentException("key can't be empty"); |
| return SystemProperties.remove(key); |
| } |
| |
| /** |
| * Gets the value of an environment variable. |
| * |
| * @param name the name of the environment variable |
| * @return the string value of the variable or null when the |
| * environment variable is not defined. |
| * @throws NullPointerException |
| * @throws SecurityException if permission is denied |
| * @since 1.5 |
| * @specnote This method was deprecated in some JDK releases, but |
| * was restored in 1.5. |
| */ |
| public static String getenv(String name) |
| { |
| if (name == null) |
| throw new NullPointerException(); |
| SecurityManager sm = SecurityManager.current; // Be thread-safe. |
| if (sm != null) |
| sm.checkPermission(new RuntimePermission("getenv." + name)); |
| return VMSystem.getenv(name); |
| } |
| |
| /** |
| * <p> |
| * Returns an unmodifiable view of the system environment variables. |
| * If the underlying system does not support environment variables, |
| * an empty map is returned. |
| * </p> |
| * <p> |
| * The returned map is read-only and does not accept queries using |
| * null keys or values, or those of a type other than <code>String</code>. |
| * Attempts to modify the map will throw an |
| * <code>UnsupportedOperationException</code>, while attempts |
| * to pass in a null value will throw a |
| * <code>NullPointerException</code>. Types other than <code>String</code> |
| * throw a <code>ClassCastException</code>. |
| * </p> |
| * <p> |
| * As the returned map is generated using data from the underlying |
| * platform, it may not comply with the <code>equals()</code> |
| * and <code>hashCode()</code> contracts. It is also likely that |
| * the keys of this map will be case-sensitive. |
| * </p> |
| * <p> |
| * Use of this method may require a security check for the |
| * RuntimePermission "getenv.*". |
| * </p> |
| * |
| * @return a map of the system environment variables. |
| * @throws SecurityException if the checkPermission method of |
| * an installed security manager prevents access to |
| * the system environment variables. |
| * @since 1.5 |
| */ |
| public static Map<String, String> getenv() |
| { |
| SecurityManager sm = SecurityManager.current; // Be thread-safe. |
| if (sm != null) |
| sm.checkPermission(new RuntimePermission("getenv.*")); |
| |
| if (environmentMap == null) |
| { |
| Map<String,String> variables = new EnvironmentMap(); |
| List<String> environ = (List<String>)VMSystem.environ(); |
| for (String envEntry : environ) |
| { |
| // avoid broken and null entries |
| if (envEntry != null && !envEntry.endsWith("=")) |
| { |
| // it's perfectly legal that some entries may be in the form |
| // key=value=value=value |
| int equalSignIndex = envEntry.indexOf('='); |
| String key = envEntry.substring(0, equalSignIndex); |
| String value = envEntry.substring(equalSignIndex + 1); |
| variables.put(key, value); |
| } |
| } |
| |
| environmentMap = Collections.unmodifiableMap(variables); |
| } |
| |
| return environmentMap; |
| } |
| |
| /** |
| * Terminate the Virtual Machine. This just calls |
| * <code>Runtime.getRuntime().exit(status)</code>, and never returns. |
| * Obviously, a security check is in order, <code>checkExit</code>. |
| * |
| * @param status the exit status; by convention non-zero is abnormal |
| * @throws SecurityException if permission is denied |
| * @see Runtime#exit(int) |
| */ |
| public static void exit(int status) |
| { |
| Runtime.getRuntime().exit(status); |
| } |
| |
| /** |
| * Calls the garbage collector. This is only a hint, and it is up to the |
| * implementation what this hint suggests, but it usually causes a |
| * best-effort attempt to reclaim unused memory from discarded objects. |
| * This calls <code>Runtime.getRuntime().gc()</code>. |
| * |
| * @see Runtime#gc() |
| */ |
| public static void gc() |
| { |
| Runtime.getRuntime().gc(); |
| } |
| |
| /** |
| * Runs object finalization on pending objects. This is only a hint, and |
| * it is up to the implementation what this hint suggests, but it usually |
| * causes a best-effort attempt to run finalizers on all objects ready |
| * to be reclaimed. This calls |
| * <code>Runtime.getRuntime().runFinalization()</code>. |
| * |
| * @see Runtime#runFinalization() |
| */ |
| public static void runFinalization() |
| { |
| Runtime.getRuntime().runFinalization(); |
| } |
| |
| /** |
| * Tell the Runtime whether to run finalization before exiting the |
| * JVM. This is inherently unsafe in multi-threaded applications, |
| * since it can force initialization on objects which are still in use |
| * by live threads, leading to deadlock; therefore this is disabled by |
| * default. There may be a security check, <code>checkExit(0)</code>. This |
| * calls <code>Runtime.runFinalizersOnExit()</code>. |
| * |
| * @param finalizeOnExit whether to run finalizers on exit |
| * @throws SecurityException if permission is denied |
| * @see Runtime#runFinalizersOnExit(boolean) |
| * @since 1.1 |
| * @deprecated never rely on finalizers to do a clean, thread-safe, |
| * mop-up from your code |
| */ |
| public static void runFinalizersOnExit(boolean finalizeOnExit) |
| { |
| Runtime.runFinalizersOnExit(finalizeOnExit); |
| } |
| |
| /** |
| * Load a code file using its explicit system-dependent filename. A security |
| * check may be performed, <code>checkLink</code>. This just calls |
| * <code>Runtime.getRuntime().load(filename)</code>. |
| * |
| * <p> |
| * The library is loaded using the class loader associated with the |
| * class associated with the invoking method. |
| * |
| * @param filename the code file to load |
| * @throws SecurityException if permission is denied |
| * @throws UnsatisfiedLinkError if the file cannot be loaded |
| * @see Runtime#load(String) |
| */ |
| public static void load(String filename) |
| { |
| Runtime.getRuntime().load(filename, VMStackWalker.getCallingClassLoader()); |
| } |
| |
| /** |
| * Load a library using its explicit system-dependent filename. A security |
| * check may be performed, <code>checkLink</code>. This just calls |
| * <code>Runtime.getRuntime().load(filename)</code>. |
| * |
| * <p> |
| * The library is loaded using the class loader associated with the |
| * class associated with the invoking method. |
| * |
| * @param libname the library file to load |
| * @throws SecurityException if permission is denied |
| * @throws UnsatisfiedLinkError if the file cannot be loaded |
| * @see Runtime#load(String) |
| */ |
| public static void loadLibrary(String libname) |
| { |
| Runtime.getRuntime().loadLibrary(libname, |
| VMStackWalker.getCallingClassLoader()); |
| } |
| |
| /** |
| * Convert a library name to its platform-specific variant. |
| * |
| * @param libname the library name, as used in <code>loadLibrary</code> |
| * @return the platform-specific mangling of the name |
| * @since 1.2 |
| */ |
| public static String mapLibraryName(String libname) |
| { |
| return VMRuntime.mapLibraryName(libname); |
| } |
| |
| /** |
| * Returns the inherited channel of the VM. |
| * |
| * This wraps the inheritedChannel() call of the system's default |
| * {@link SelectorProvider}. |
| * |
| * @return the inherited channel of the VM |
| * |
| * @throws IOException If an I/O error occurs |
| * @throws SecurityException If an installed security manager denies access |
| * to RuntimePermission("inheritedChannel") |
| * |
| * @since 1.5 |
| */ |
| public static Channel inheritedChannel() |
| throws IOException |
| { |
| return SelectorProvider.provider().inheritedChannel(); |
| } |
| |
| /* |
| * @since 1.6 |
| */ |
| public static Console console() |
| { |
| return Console.console(); |
| } |
| |
| /** |
| * Returns the system-dependent line separator. |
| * |
| * @return the system-dependent line separator. |
| */ |
| public static String lineSeparator() |
| { |
| return LINE_SEPARATOR; |
| } |
| |
| /** |
| * This is a specialised <code>Collection</code>, providing |
| * the necessary provisions for the collections used by the |
| * environment variable map. Namely, it prevents |
| * querying anything but <code>String</code>s. |
| * |
| * @author Andrew John Hughes (gnu_andrew@member.fsf.org) |
| */ |
| private static class EnvironmentCollection |
| extends AbstractCollection<String> |
| { |
| |
| /** |
| * The wrapped collection. |
| */ |
| protected Collection<String> c; |
| |
| /** |
| * Constructs a new environment collection, which |
| * wraps the elements of the supplied collection. |
| * |
| * @param coll the collection to use as a base for |
| * this collection. |
| */ |
| public EnvironmentCollection(Collection<String> coll) |
| { |
| c = coll; |
| } |
| |
| /** |
| * Blocks queries containing a null object or an object which |
| * isn't of type <code>String</code>. All other queries |
| * are forwarded to the underlying collection. |
| * |
| * @param obj the object to look for. |
| * @return true if the object exists in the collection. |
| * @throws NullPointerException if the specified object is null. |
| * @throws ClassCastException if the specified object is not a String. |
| */ |
| public boolean contains(Object obj) |
| { |
| if (obj == null) |
| throw new |
| NullPointerException("This collection does not support " + |
| "null values."); |
| if (!(obj instanceof String)) |
| throw new |
| ClassCastException("This collection only supports Strings."); |
| return c.contains(obj); |
| } |
| |
| /** |
| * Blocks queries where the collection contains a null object or |
| * an object which isn't of type <code>String</code>. All other |
| * queries are forwarded to the underlying collection. |
| * |
| * @param coll the collection of objects to look for. |
| * @return true if the collection contains all elements in the collection. |
| * @throws NullPointerException if the collection is null. |
| * @throws NullPointerException if any collection entry is null. |
| * @throws ClassCastException if any collection entry is not a String. |
| */ |
| public boolean containsAll(Collection<?> coll) |
| { |
| for (Object o: coll) |
| { |
| if (o == null) |
| throw new |
| NullPointerException("This collection does not support " + |
| "null values."); |
| if (!(o instanceof String)) |
| throw new |
| ClassCastException("This collection only supports Strings."); |
| } |
| return c.containsAll(coll); |
| } |
| |
| /** |
| * This returns an iterator over the map elements, with the |
| * same provisions as for the collection and underlying map. |
| * |
| * @return an iterator over the map elements. |
| */ |
| public Iterator<String> iterator() |
| { |
| return c.iterator(); |
| } |
| |
| /** |
| * Blocks the removal of elements from the collection. |
| * |
| * @return true if the removal was sucessful. |
| * @throws NullPointerException if the collection is null. |
| * @throws NullPointerException if any collection entry is null. |
| * @throws ClassCastException if any collection entry is not a String. |
| */ |
| public boolean remove(Object key) |
| { |
| if (key == null) |
| throw new |
| NullPointerException("This collection does not support " + |
| "null values."); |
| if (!(key instanceof String)) |
| throw new |
| ClassCastException("This collection only supports Strings."); |
| return c.contains(key); |
| } |
| |
| /** |
| * Blocks the removal of all elements in the specified |
| * collection from the collection. |
| * |
| * @param coll the collection of elements to remove. |
| * @return true if the elements were removed. |
| * @throws NullPointerException if the collection is null. |
| * @throws NullPointerException if any collection entry is null. |
| * @throws ClassCastException if any collection entry is not a String. |
| */ |
| public boolean removeAll(Collection<?> coll) |
| { |
| for (Object o: coll) |
| { |
| if (o == null) |
| throw new |
| NullPointerException("This collection does not support " + |
| "null values."); |
| if (!(o instanceof String)) |
| throw new |
| ClassCastException("This collection only supports Strings."); |
| } |
| return c.removeAll(coll); |
| } |
| |
| /** |
| * Blocks the retention of all elements in the specified |
| * collection from the collection. |
| * |
| * @param coll the collection of elements to retain. |
| * @return true if the other elements were removed. |
| * @throws NullPointerException if the collection is null. |
| * @throws NullPointerException if any collection entry is null. |
| * @throws ClassCastException if any collection entry is not a String. |
| */ |
| public boolean retainAll(Collection<?> coll) |
| { |
| for (Object o: coll) |
| { |
| if (o == null) |
| throw new |
| NullPointerException("This collection does not support " + |
| "null values."); |
| if (!(o instanceof String)) |
| throw new |
| ClassCastException("This collection only supports Strings."); |
| } |
| return c.containsAll(coll); |
| } |
| |
| /** |
| * This simply calls the same method on the wrapped |
| * collection. |
| * |
| * @return the size of the underlying collection. |
| */ |
| public int size() |
| { |
| return c.size(); |
| } |
| |
| } // class EnvironmentCollection<String> |
| |
| /** |
| * This is a specialised <code>HashMap</code>, which |
| * prevents the addition or querying of anything other than |
| * <code>String</code> objects. |
| * |
| * @author Andrew John Hughes (gnu_andrew@member.fsf.org) |
| */ |
| static class EnvironmentMap |
| extends HashMap<String,String> |
| { |
| |
| /** |
| * Cache the entry set. |
| */ |
| private transient Set<Map.Entry<String,String>> entries; |
| |
| /** |
| * Cache the key set. |
| */ |
| private transient Set<String> keys; |
| |
| /** |
| * Cache the value collection. |
| */ |
| private transient Collection<String> values; |
| |
| /** |
| * Constructs a new empty <code>EnvironmentMap</code>. |
| */ |
| EnvironmentMap() |
| { |
| super(); |
| } |
| |
| /** |
| * Constructs a new <code>EnvironmentMap</code> containing |
| * the contents of the specified map. |
| * |
| * @param m the map to be added to this. |
| * @throws NullPointerException if a key or value is null. |
| * @throws ClassCastException if a key or value is not a String. |
| */ |
| EnvironmentMap(Map<String,String> m) |
| { |
| super(m); |
| } |
| |
| /** |
| * Blocks queries containing a null key or one which is not |
| * of type <code>String</code>. All other queries |
| * are forwarded to the superclass. |
| * |
| * @param key the key to look for in the map. |
| * @return true if the key exists in the map. |
| * @throws NullPointerException if the specified key is null. |
| */ |
| public boolean containsKey(Object key) |
| { |
| if (key == null) |
| throw new |
| NullPointerException("This map does not support null keys."); |
| if (!(key instanceof String)) |
| throw new |
| ClassCastException("This map only allows queries using Strings."); |
| return super.containsKey(key); |
| } |
| |
| /** |
| * Blocks queries using a null or non-<code>String</code> value. |
| * All other queries are forwarded to the superclass. |
| * |
| * @param value the value to look for in the map. |
| * @return true if the value exists in the map. |
| * @throws NullPointerException if the specified value is null. |
| */ |
| public boolean containsValue(Object value) |
| { |
| if (value == null) |
| throw new |
| NullPointerException("This map does not support null values."); |
| if (!(value instanceof String)) |
| throw new |
| ClassCastException("This map only allows queries using Strings."); |
| return super.containsValue(value); |
| } |
| |
| /** |
| * Returns a set view of the map entries, with the same |
| * provisions as for the underlying map. |
| * |
| * @return a set containing the map entries. |
| */ |
| public Set<Map.Entry<String,String>> entrySet() |
| { |
| if (entries == null) |
| entries = super.entrySet(); |
| return entries; |
| } |
| |
| /** |
| * Blocks queries containing a null or non-<code>String</code> key. |
| * All other queries are passed on to the superclass. |
| * |
| * @param key the key to retrieve the value for. |
| * @return the value associated with the given key. |
| * @throws NullPointerException if the specified key is null. |
| * @throws ClassCastException if the specified key is not a String. |
| */ |
| public String get(Object key) |
| { |
| if (key == null) |
| throw new |
| NullPointerException("This map does not support null keys."); |
| if (!(key instanceof String)) |
| throw new |
| ClassCastException("This map only allows queries using Strings."); |
| return super.get(key); |
| } |
| |
| /** |
| * Returns a set view of the keys, with the same |
| * provisions as for the underlying map. |
| * |
| * @return a set containing the keys. |
| */ |
| public Set<String> keySet() |
| { |
| if (keys == null) |
| keys = new EnvironmentSet(super.keySet()); |
| return keys; |
| } |
| |
| /** |
| * Associates the given key to the given value. If the |
| * map already contains the key, its value is replaced. |
| * The map does not accept null keys or values, or keys |
| * and values not of type {@link String}. |
| * |
| * @param key the key to map. |
| * @param value the value to be mapped. |
| * @return the previous value of the key, or null if there was no mapping |
| * @throws NullPointerException if a key or value is null. |
| * @throws ClassCastException if a key or value is not a String. |
| */ |
| public String put(String key, String value) |
| { |
| if (key == null) |
| throw new NullPointerException("A new key is null."); |
| if (value == null) |
| throw new NullPointerException("A new value is null."); |
| if (!(key instanceof String)) |
| throw new ClassCastException("A new key is not a String."); |
| if (!(value instanceof String)) |
| throw new ClassCastException("A new value is not a String."); |
| return super.put(key, value); |
| } |
| |
| /** |
| * Removes a key-value pair from the map. The queried key may not |
| * be null or of a type other than a <code>String</code>. |
| * |
| * @param key the key of the entry to remove. |
| * @return the removed value. |
| * @throws NullPointerException if the specified key is null. |
| * @throws ClassCastException if the specified key is not a String. |
| */ |
| public String remove(Object key) |
| { |
| if (key == null) |
| throw new |
| NullPointerException("This map does not support null keys."); |
| if (!(key instanceof String)) |
| throw new |
| ClassCastException("This map only allows queries using Strings."); |
| return super.remove(key); |
| } |
| |
| /** |
| * Returns a collection view of the values, with the same |
| * provisions as for the underlying map. |
| * |
| * @return a collection containing the values. |
| */ |
| public Collection<String> values() |
| { |
| if (values == null) |
| values = new EnvironmentCollection(super.values()); |
| return values; |
| } |
| |
| } |
| |
| /** |
| * This is a specialised <code>Set</code>, providing |
| * the necessary provisions for the collections used by the |
| * environment variable map. Namely, it prevents |
| * modifications and the use of queries with null |
| * or non-<code>String</code> values. |
| * |
| * @author Andrew John Hughes (gnu_andrew@member.fsf.org) |
| */ |
| private static class EnvironmentSet |
| extends EnvironmentCollection |
| implements Set<String> |
| { |
| |
| /** |
| * Constructs a new environment set, which |
| * wraps the elements of the supplied set. |
| * |
| * @param set the set to use as a base for |
| * this set. |
| */ |
| public EnvironmentSet(Set<String> set) |
| { |
| super(set); |
| } |
| |
| /** |
| * This simply calls the same method on the wrapped |
| * collection. |
| * |
| * @param obj the object to compare with. |
| * @return true if the two objects are equal. |
| */ |
| public boolean equals(Object obj) |
| { |
| return c.equals(obj); |
| } |
| |
| /** |
| * This simply calls the same method on the wrapped |
| * collection. |
| * |
| * @return the hashcode of the collection. |
| */ |
| public int hashCode() |
| { |
| return c.hashCode(); |
| } |
| |
| } // class EnvironmentSet<String> |
| |
| } // class System |