ThreadGroup线程组应用.doc

ThreadGroup线程组应用一、基本方法1、获取当前线程组名java view plain copy 在CODE上查看代码片派生到我的代码片Thread.currentThread().getThreadGroup().getName() 在main方法是调用输出是：main2、将线程放入到一个线程组中去java view plain copy 在CODE上查看代码片派生到我的代码片ThreadGroup threadGroup1 = new ThreadGroup(group1); ThreadGroup threadGroup2 = new ThreadGroup(group2); Thread thread1 =new Thread(threadGroup1, group1s member); Thread thread2 =new Thread(threadGroup2, group2s member); 其中Thread中和ThreadGroup相关的构造函数：java view plain copy 在CODE上查看代码片派生到我的代码片 public Thread(ThreadGroup group, Runnable target) init(group, target, Thread- + nextThreadNum(), 0); public Thread(ThreadGroup group, String name) init(group, null, name, 0); public Thread(ThreadGroup group, Runnable target, String name) init(group, target, name, 0); public Thread(ThreadGroup group, Runnable target, String name, long stackSize) init(group, target, name, stackSize); 它们最终都是调用同一个函数：java view plain copy 在CODE上查看代码片派生到我的代码片 private void init(ThreadGroup g, Runnable target, String name, long stackSize) Thread parent = currentThread(); SecurityManager security = System.getSecurityManager(); if (g = null) /安全检查 if (security != null) g = security.getThreadGroup(); /设置线程组 if (g = null) g = parent.getThreadGroup(); /检查可达性 g.checkAccess(); /是否有权限访问 if (security != null) if (isCCLOverridden(getClass() security.checkPermission(SUBCLASS_IMPLEMENTATION_PERMISSION); /往线程组添加线程但未启动 g.addUnstarted(); this.group = g; this.daemon = parent.isDaemon();/是否守护线程 this.priority = parent.getPriority();/优先级 = name.toCharArray(); if (security = null | isCCLOverridden(parent.getClass() this.contextClassLoader = parent.getContextClassLoader(); else this.contextClassLoader = parent.contextClassLoader; this.inheritedAccessControlContext = AccessController.getContext(); this.target = target; setPriority(priority); if (parent.inheritableThreadLocals != null) this.inheritableThreadLocals = ThreadLocal.createInheritedMap(parent.inheritableThreadLocals); this.stackSize = stackSize; tid = nextThreadID(); this.me = this; 3、复制线程组：java view plain copy 在CODE上查看代码片派生到我的代码片/这样可以复制group里面的thread信息 Thread threads = new ThreadthreadGroup.activeCount(); threadGroup.enumerate(threads); 这里的activeCount很明显就是取得活动的线程，注意。默认情况 下，连同其子线程组也会进行复制。4、未捕获异常处理ThreadGroup中有一个uncaughtException()方法。当线程组中某个线程发生Unchecked exception异常时，由执行环境调用此方法进行相关处理，如果有必要，可以重新定义此方法二、应用实例1、实例应用java view plain copy 在CODE上查看代码片派生到我的代码片package com.func.axc.threadgroup; import java.util.Date; import java.util.Random; import java.util.concurrent.TimeUnit; class Result private String name; public String getName() return name; public void setName(String name) = name; public class SearchTask implements Runnable public SearchTask(Result result) this.result = result; private Result result; Override public void run() String name = Thread.currentThread().getName(); System.out.println(Thread Start + name); try doTask(); result.setName(name); catch (InterruptedException e) System.out.printf(Thread %s: Interruptedn, name); return; System.out.println(Thread end + name); private void doTask() throws InterruptedException Random random = new Random(new Date().getTime(); int value = (int) (random.nextDouble() * 100); System.out.printf(Thread %s: %dn, Thread.currentThread().getName(), value); TimeUnit.SECONDS.sleep(value); public static void main(String args) System.out.println(main thread start:); /创建5个线程，并入group里面进行管理 ThreadGroup threadGroup = new ThreadGroup(Searcher); Result result = new Result(); SearchTask searchTask = new SearchTask(result); for (int i = 0; i 5; i+) Thread thred = new Thread(threadGroup, searchTask); thred.start(); try TimeUnit.SECONDS.sleep(1); catch (InterruptedException e) e.printStackTrace(); /通过这种方法可以看group里面的所有信息 System.out.printf(Number of Threads: %dn, threadGroup.activeCount(); System.out.printf(Information about the Thread Groupn); threadGroup.list(); /这样可以复制group里面的thread信息 Thread threads = new ThreadthreadGroup.activeCount(); threadG(threads); for (int i = 0; i 0) try TimeUnit.SECONDS.sleep(1); catch (InterruptedException e) e.printStackTrace(); 输出结果：2、统一异常处理实例java view plain copy 在CODE上查看代码片派生到我的代码片package com.func.axc.threadgroup; /* * 功能概要： * * author linbingwen * since 2016年6月11日 */ public class ThreadGroupDemo public static void main(String args) ThreadGroup threadGroup1 = / 这是匿名类写法 new ThreadGroup(group1) / 继承ThreadGroup并重新定义以下方法 / 在线程成员抛出unchecked exception / 会执行此方法 public void uncaughtException(Thread t, Throwable e) System.out.println(t.getName() + : + e.getMessage(); ; / 这是匿名类写法 Thread thread1 = / 这个线程是threadGroup1的一员 new Thread(threadGroup1, new Runnable() public void run() / 抛出unchecked异常 throw new RuntimeException(测试异常); ); thread1.start(); 三、源码解读首先看其包含的变量java view plain copy 在CODE上查看代码片派生到我的代码片public class ThreadGroup implements Thread.UncaughtExceptionHandler private final ThreadGroup parent;/父亲ThreadGroup String name;/ThreadGroupr 的名称 int maxPriority;/线程最大优先级 boolean destroyed;/是否被销毁 boolean daemon;/是否守护线程 boolean vmAllowSuspension;/是否可以中断 int nUnstartedThreads = 0;/还未启动的线程 int nthreads;/ThreadGroup中线程数目 Thread threads;/ThreadGroup中的线程 int ngroups;/线程组数目 ThreadGroup groups;/线程组数组 从源码中可以看出，其包含的变量并不是很多。这里需要注意(1)线程组也可以包含其他线程组。如上面的groups.(2)线程组构成一棵树，在树中，除了初始线程组外，每个线程组都有一个父线程组构造函数：java view plain copy 在CODE上查看代码片派生到我的代码片/私有构造函数 private ThreadGroup() = system; this.maxPriority = Thread.MAX_PRIORITY; this.parent = null; /默认是以当前ThreadGroup传入作为parent ThreadGroup，新线程组的父线程组是目前正在运行线程的线程组。 public ThreadGroup(String name) this(Thread.currentThread().getThreadGroup(), name); /构造函数 public ThreadGroup(ThreadGroup parent, String name) this(checkParentAccess(parent), parent, name); /私有构造函数 private ThreadGroup(Void unused, ThreadGroup parent, String name) = name; this.maxPriority = parent.maxPriority; this.daemon = parent.daemon; this.vmAllowSuspension = parent.vmAllowSuspension; this.parent = parent; parent.add(this); 其终的调用构造函数只有一个，父线程组的 checkAccess 方法在checkParentAccess中会调用：java view plain copy 在CODE上查看代码片派生到我的代码片/检查parent ThreadGroup private static Void checkParentAccess(ThreadGroup parent) parent.checkAccess(); return null; 未捕获异常设置：java view plain copy 在CODE上查看代码片派生到我的代码片public void uncaughtException(Thread t, Throwable e) if (parent != null) parent.uncaughtException(t, e);/父线程组不为空，设置到父线程组 else Thread.UncaughtExceptionHandler ueh = Thread.getDefaultUncaughtExceptionHandler(); if (ueh != null) ueh.uncaughtException(t, e); else if (!(e instanceof ThreadDeath) System.err.print(Exception in thread + t.getName() + ); e.printStackTrace(System.err); 如果父线程组存在, 则调用它的uncaughtException方法.如果父线程组不存在, 但指定了默认处理器 (下节中的As the default handler for the application), 则调用默认的处理器如果默认处理器没有设置, 则写错误日志.但如果 exception是ThreadDeath实例的话, 忽略线程组复制：java view plain copy 在CODE上查看代码片派生到我的代码片/此线程组及其子组中的所有活动线程复制到指定数组中。 public int enumerate(ThreadGroup list) checkAccess(); return enumerate(list, 0, true); /此线程组及其子组中的所有活动线程复制到指定数组中。 public int enu