the Java application launcher
java - the Java application launcher[*]Synopsis
[*]Description
[*]Options
[*]See Also
SYNOPSIS
java [ options ] class [ argument ... ] java [ options ] -jar file.jar [ argument ... ]options Command-line options. class Name of the class to be invoked. file.jar Name of the jar file to be invoked. Used only with -jar. argument Argument passed to the main function.
DESCRIPTION
The java tool launches a Java application. It does this bystarting a Java runtime environment, loading aspecified class, and invoking that class's main method. Themethod declaration must look like the following: public static void main(String args[])The method must be declared public and static, it must notreturn any value, and it must accept a String array as aparameter. By default, the first non-option argument is the name of the class to be invoked. A fully-qualified class name should be used. If the -jar option is specified, the first non-option argument is the name of a JAR archive containing class and resource files for the application, with the startup class indicated by theMain-Class manifest header.The Java runtime searches for the startup class, and other classesused, in three sets of locations: the bootstrap class path, theinstalled extensions, and the user class path.
Non-option arguments after the class name or JAR file name are passedto the main function.
OPTIONS
The launcher has a set of standard options that are supported on the current runtime environment and will be supported in future releases.In addition, the current implementations of the virtual machines support a set of non-standard options options that are subject to change in future releases.
Standard Options
-client Select the Java HotSpot Client VM.This is the default.
-server Select the Java HotSpot Server VM.
-classpath classpath -cp classpathSpecify a list of directories, JAR archives, and ZIParchives to search for class files. Class path entries areseparated by colons (:). Specifying-classpath or -cp overrides any setting of theCLASSPATH environment variable.If -classpath and -cp are not used andCLASSPATH is not set, the user class path consists ofthe current directory (.).
For more information on class paths, see Setting the Class Path.
-Dproperty=valueSet a system property value. <a name="-jar" />
-jarExecute a program encapsulated in a JAR file. The firstargument is the name of a JAR file instead of a startupclass name. In order for this option to work, the manifest of the JAR file must contain a line of the form Main-Class: classname. Here, classname identifies the class having the public static void main(String[] args) method that serves as your application's starting point. See the Jar tool reference page and the Jar trail of the Java Tutorial for information about working with Jar files and Jar-file manifests. When you use this option, the JAR file is the source of all user classes, and other user class path settings are ignored.
On Solaris 8, JAR files that can be run with the "java -jar" option can have their execute permissions set so they can be run without using "java -jar".
-verbose -verbose:classDisplay information about each class loaded.
-verbose:gcReport on each garbage collection event.
-verbose:jniReport information about use of native methods and otherJava Native Interface activity.
-versionDisplay version information and exit.
-showversionDisplay version information and continue.
-? -helpDisplay usage information and exit.
-XDisplay information about non-standard options and exit.
Non-Standard Options
-Xint Operate in interpreted-only mode. Compilation to native code is disabled, and all bytecodes are executed by the interpreter. The performance benefits offered by the Java HotSpot VMs' adaptive compiler will not be present in this mode.
-Xdebug Start with the debugger enabled. Refer to jdb description for more details and an example. -Xbootclasspath:bootclasspathSpecify a colon-separated list of directories, JARarchives, and ZIP archives to search for boot class files.These are used in place of the boot class files included in theJava 2 SDK. Note: Applications that use this option for the purpose of overriding a class in rt.jar should not be deployed as doing so would contravene the Java 2 Runtime Environment binary code license. -Xbootclasspath/a:path Specify a colon-separated path of directires, JAR archives, and ZIP archives to append to the default bootstrap class path. -Xbootclasspath/p:path Specify a colon-separated path of directires, JAR archives, and ZIP archives to prepend in front of the default bootstrap class path. Note: Applications that use this option for the purpose of overriding a class in rt.jar should not be deployed as doing so would contravene the Java 2 Runtime Environment binary code license.
-Xfuture Perform strict class-file format checks. For purposes of backwards compatibility, the default format checks performed by the Java 2 SDK's virtual machine are no stricter than the checks performed by 1.1.x versions of the JDK software. The -Xfuture flag turns on stricter class-file format checks that enforce closer conformance to the class-file format specification. Developers are encouraged to use this flag when developing new code because the stricter checks will become the default in future releases of the Java application launcher.
-XnoclassgcDisable class garbage collection.
-Xincgc Enable the incremental garbage collector. The incremental garbage collector, which is off by default, will eliminate occasional garbage-collection pauses during program execution. However, it can lead to a roughly 10% decrease in overall GC performance.
-XmsnSpecify the initial size, in bytes, of the memory allocation pool. This value must bea multiple of 1024 greater than 1MB. Append the letter k or K to indicate kilobytes, or m or M to indicate megabytes. The default value is 2MB. Examples:-Xms6291456 -Xms6144k -Xms6m
-Xmxn<a name="Xms" /> Specify the maximum size, in bytes, of the memory allocation pool. This value must a multiple of 1024 greater than 2MB. Append the letter k or K to indicate kilobytes, or m or M to indicate megabytes. The default value is 64MB. The upper limit for this valuewillbeapproximately4000m on Solaris 7 and Solaris 8 SPARCplatforms and 2000m on Solaris 2.6 and x86 platforms,minusoverhead amounts. Examples:-Xmx83886080 -Xmx81920k -Xmx80m
-Xssn<a name="Xms" />Set thread stack size. Each Java thread has two stacks: one for Javacode and one for C code.This option sets the maximum stack sizethat canbe used by C code in a thread to n. Every thread that is spawned duringthe executionof the program passed to java has n as its C stack size.Thedefault unitsfor nare bytes and n must be > 1000 bytes. Tomodifythemeaningof n,append either the letter k for kilobytes or the letter mformegabytes. Thedefault stack size is 512 kilobytes (-Xss512k).
-XprofProfiles the running program, and sends profiling data to standard output. This option is provided as a utility that is useful in program development and is not intended to be be used in production systems.
-Xrunhprof[:help][:<suboption>=<value>,...]Enables cpu, heap, or monitor profiling. This option is typically followed by a list of comma-separated "<suboption>=<value>" pairs. Run the command java -Xrunhprof:help to obtain a list of suboptions and their default values.
-Xrs Reduces use of operating-system signals by the Java virtual machine (JVM). This option is available beginning with J2SE 1.3.1. In J2SE 1.3.0, the Shutdown Hooks facility was added to allow orderly shutdown of a Java application. The intent was to allow user cleanup code (such as closing database connections) to run at shutdown, even if the JVM terminates abruptly.
Sun's JVM catches signals to implement shutdown hooks for abnormal JVM termination. The JVM uses SIGHUP, SIGINT, and SIGTERM to initiate the running of shutdown hooks.
The JVM uses a similar mechanism to implement the pre-1.2 feature of dumping thread stacks for debugging purposes. Sun's JVM uses SIGQUIT to perform thread dumps.
Applications embedding the JVM frequently need to trap signals like SIGINT or SIGTERM, which can lead to interference with the JVM's own signal handlers. To address this issue, the -Xrs command-line option has been added beginning in J2SE 1.3.1. When -Xrs is used on Sun's JVM, the signal masks for SIGINT, SIGTERM, SIGHUP, and SIGQUIT are not changed by the JVM, and signal handlers for these signals are not installed.
There are two consequences of specifying -Xrs:
[*]SIGQUIT thread dumps are not available.
[*]User code is responsible for causing shutdown hooks to run, for example by calling System.exit() when the JVM is to be terminated.
WARNING: Flags -Xdebug and -Xint are mutually exclusive.No more than one of those options should be used on a java command line.
SEE ALSO
[*]javac - the Java programming language compiler
[*]jdb - Java Application Debugger
[*]javah - C Header and Stub File Generator
[*]jar - JAR Archive Tool
[*]The Java Extensions Framework
[*]Security Features.
页:
[1]