java 线程组作用_Java线程组（ThreadGroup）使用

JDK 对线程组类注释：

A thread group represents a set of threads. In addition, a thread group can also include other thread groups. The thread groups form a tree in which every thread group except the initial thread group has a parent.

A thread is allowed to access information about its own thread group, but not to access information about its thread group's parent thread group or any other thread groups.

可以把线程归属到某一个线程组中，线程组中可以有线程对象，也可以有线程组，组中还可以有线程，这样的组织结构有点类似于树的形式，如图所示.

线程组的作用是：可以批量管理线程或线程组对象，有效地对线程或线程组对象进行组织

１．线程组示例：

展示线程组结构代码实例如下：

/**

* 类功能描述：

*

* @author WangXueXing create at 18-12-27 下午3:25

* @version 1.0.0

*/

public class ThreadGroupTest implements Runnable {

@Override

public void run() {

try {

while (!Thread.currentThread().isInterrupted()) {

Thread currentThread = Thread.currentThread();

System.out.println("current thread:" + currentThread.getName()

+" thread group:"+currentThread.getThreadGroup().getName()

+" parent thread group:"+currentThread.getThreadGroup().getParent().getName());

Thread.sleep(3000);

}

} catch (InterruptedException e) {

e.printStackTrace();

}

}

public static void main(String[] args) {

ThreadGroup rootThreadGroup = new ThreadGroup("root线程组1");

Thread t0 = new Thread(rootThreadGroup, new ThreadGroupTest(), "Thread 0");

t0.start();

ThreadGroup tg = new ThreadGroup(rootThreadGroup,"线程组1");

ThreadGroup tg2 = new ThreadGroup(rootThreadGroup,"线程组2");

Thread t1 = new Thread(tg, new ThreadGroupTest(), "Thread 1");

Thread t2 = new Thread(tg, new ThreadGroupTest(), "Thread 2");

t1.start();

t2.start();

Thread t3 = new Thread(tg2, new ThreadGroupTest(), "Thread 3");

Thread t4 = new Thread(tg2, new ThreadGroupTest(), "Thread 4");

t3.start();

t4.start();

}

}

打印结果如下：

current thread:Thread 0 thread group:root线程组1 parent thread group:main

current thread:Thread 2 thread group:线程组1 parent thread group:root线程组1

current thread:Thread 1 thread group:线程组1 parent thread group:root线程组1

current thread:Thread 3 thread group:线程组2 parent thread group:root线程组1

current thread:Thread 4 thread group:线程组2 parent thread group:root线程组1

current thread:Thread 1 thread group:线程组1 parent thread group:root线程组1

current thread:Thread 0 thread group:root线程组1 parent thread group:main

current thread:Thread 2 thread group:线程组1 parent thread group:root线程组1

current thread:Thread 3 thread group:线程组2 parent thread group:root线程组1

......

２．线程组项目中应用(线程组内的线程异常统一管理)：

最近有个需求，生成复杂报表－从很多表数据中分析统计到一个报表。

实现思路：

多个线程分别到不同表中查数据并统计分析，任何一个线程失败整体报表生成失败，记录日志并立即中断其他线程。全部线程成功，报表生成成功。

废话少说以下利用Java线程组结合CountDownLatch实现代码如下：

/**

* 多线程获取报表数据

* @param reportId 报表ID

* @return

*/

def getReportData(reportId: Long, supplierDetailMap: ConcurrentHashMap[Integer, Supplier]):

ConcurrentHashMap[Integer, AnyRef] = {

val dataMap = new ConcurrentHashMap[Integer, AnyRef]()

//多线程同步器

val conutDownLatch = new CountDownLatch(3)

//实例化线程组

val genThreadGroup = new GenThreadGroup(request.reportInfo.reportType.name, reportId)

//获取当月已开返利

new Thread(genThreadGroup, new Runnable {

override def run(): Unit = {

dataMap.put(OPENED_REBATE_CODE, SupplierAccountDetailQuerySql.getTaxDiscountByMonth(request))

conutDownLatch.countDown()

}

}, "获取当月已开返利").start()

//获取当月累计解押款

new Thread(genThreadGroup, new Runnable {

override def run(): Unit = {

dataMap.put(DEPOSIT_BY_MONTH, SupplierAccountDetailQuerySql.getDepositAmountByMonth(request))

conutDownLatch.countDown()

}

}, "获取当月累计解押款").start()

//结算单的含税金额

new Thread(genThreadGroup, new Runnable {

override def run(): Unit = {

dataMap.put(ACCOUNT_PAYABLE_AMOUNT, SupplierAccountDetailQuerySql.getAccountPayableAmount(request))

conutDownLatch.countDown()

}

}, "获取结算单的含税金额").start()

//所有线程都执行完成

conutDownLatch.await()

dataMap

}

统一捕获异常的线程组定义如下：

/**

* 定义报表生成线程组

*

* @author BarryWang create at 2018/5/21 11:04

* @version 0.0.1

*/

class GenThreadGroup(groupName: String, reportId: Long) extends ThreadGroup(groupName){

val logger: Logger = LoggerFactory.getLogger(classOf[GenThreadGroup])

/**

* 定义线程组中任意一个线程异常处理

* @param thread 当前线程

* @param exception 异常

*/

override def uncaughtException(thread: Thread, exception: Throwable): Unit = {

logger.error(s"报表(ID：${reportId})生成异常, 线程组：${groupName}; 线程：${thread.getName} 失败", exception)

thread.getThreadGroup.interrupt()

}

}