使用Tread创建线程

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package com.wsx.test;

import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class ThreadTest {
    @Test
    public void test1() {
        final Logger logger = LoggerFactory.getLogger(ThreadTest.class);
        Thread thread = new Thread() {
            @Override
            public void run() {
                logger.debug("running");
            }
        };
        thread.setName("t1");
        thread.start();
        logger.debug("running");
    }
}

得到输出

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13:23:33.225 [t1] DEBUG com.wsx.test.ThreadTest - running
13:23:33.225 [main] DEBUG com.wsx.test.ThreadTest - running

使用Runnable

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@Test
public void test2(){
    final Logger logger = LoggerFactory.getLogger(ThreadTest.class);
    Runnable runnable = new Runnable() {
        public void run() {
            logger.debug("runing");
        }
    };
    Thread thread = new Thread(runnable,"t2");
    thread.start();
    logger.debug("running");
}
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13:29:08.503 [t2] DEBUG com.wsx.test.ThreadTest - runing
13:29:08.503 [main] DEBUG com.wsx.test.ThreadTest - running

lambda表达式

注意到Runnable源码中有注解@FunctionalInterface,那么他就可以被lambda表达式简化，因为只有一个方法

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@Test
public void test3() {
    final Logger logger = LoggerFactory.getLogger(ThreadTest.class);
    Runnable runnable = () -> {
        logger.debug("runing");
    };
    Thread thread = new Thread(runnable, "t3");
    thread.start();
    logger.debug("running");
}

Thread和Runnable

Thread在用Runnable构造的时候，把他赋值给了一个target变量，然后run

FutureTask和Callable

下面的代码会阻塞

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@Test
public void test4() throws ExecutionException, InterruptedException {
    final Logger logger = LoggerFactory.getLogger(ThreadTest.class);
    FutureTask<Integer> task = new FutureTask<>(new Callable<Integer>() {
        @Override
        public Integer call() throws Exception {
            logger.debug("runing...");
            Thread.sleep(1000);
            return 100;
        }
    });
    Thread thread = new Thread(task, "t2");
    thread.start();
    logger.debug("running");

    // 阻塞
    logger.debug("{}", task.get());
}
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13:48:00.930 [main] DEBUG com.wsx.test.ThreadTest - running
13:48:00.930 [t2] DEBUG com.wsx.test.ThreadTest - runing...
13:48:01.937 [main] DEBUG com.wsx.test.ThreadTest - 100

jps

可以查看java程序的pid
jstack <pid> 查看某个java进程的所有线程状态,非动态
jconsole可以查看java进程中线程的图形界面

他还可以远程连接，注意需要在运行java程序的时候要加入一些参数，而且注意关闭防火墙

ps

script
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ps | grep java

, ps 看进程，grep筛选
kill + PID杀死进程

top

他用表格来显示，还是动态的
-H 表示查看线程，-p表示pid

script
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top -H -p 3456