Java多线程

• 1.如何创建一个线程？
• • 1.1继承Thread类
  • 1.2实现Runnable接口
  • 1.3实现Callable接口
  • 1.4使用线程池
• 2.线程有几种状态？

1.如何创建一个线程？

Java提供多种方式创建线程

• 继承Thread类，重新写run方法
• 实现Runnable接口，重新run方法
• 实现Callable接口，重新call方法
• 使用线程池

1.1继承Thread类

import lombok.extern.slf4j.Slf4j;
import org.junit.Test;@Slf4j
public class MyTest {@Testpublic void test() {MyThread myThread=new MyThread();myThread.start();}
}@Slf4j
class MyThread extends Thread {@Overridepublic void run() {log.info("自定义线程");}
}

1.2实现Runnable接口

import lombok.extern.slf4j.Slf4j;
import org.junit.Test;@Slf4j
public class MyTest {@Testpublic void test() {MyThread myThread = new MyThread();Thread thread = new Thread(myThread);thread.start();}
}@Slf4j
class MyThread implements Runnable {@Overridepublic void run() {log.info("自定义线程");}
}

或

import lombok.extern.slf4j.Slf4j;
import org.junit.Test;@Slf4j
public class MyTest {@Testpublic void test() {Thread thread = new Thread(new Runnable() {@Overridepublic void run() {log.info("自定义线程");}});thread.start();}
}

或

import lombok.extern.slf4j.Slf4j;
import org.junit.Test;@Slf4j
public class MyTest {@Testpublic void test() {Thread thread = new Thread(() -> log.info("自定义线程"));thread.start();}
}

1.3实现Callable接口

import lombok.extern.slf4j.Slf4j;
import org.junit.Test;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.FutureTask;@Slf4j
public class MyTest {@Testpublic void test() {try {MyThread myThread = new MyThread();FutureTask futureTask = new FutureTask<>(myThread);Thread thread = new Thread(futureTask);//启动线程thread.start();//获取线程返回值String s = futureTask.get();log.info(s);} catch (InterruptedException | ExecutionException e) {e.printStackTrace();Thread.currentThread().interrupt();}}
}@Slf4j
class MyThread implements Callable {@Overridepublic String call() throws Exception {log.info("自定义线程");return "自定义线程执行完毕";}
}

1.4使用线程池

import lombok.extern.slf4j.Slf4j;
import org.junit.Test;
import java.util.concurrent.*;@Slf4j
public class MyTest {@Testpublic void test() {ExecutorService executorService = Executors.newSingleThreadExecutor();MyThread myThread=new MyThread();executorService.execute(myThread);}
}@Slf4j
class MyThread implements Runnable {@Overridepublic void run() {log.info("自定义线程");}
}

2.线程有几种状态？

线程主要包括以下几个状态：

• new：创建成功，但还没有调用start方法
• runnable：包括就绪状态和运行状态（线程拿到时间片就处于运行状态；没有拿到时间片就处于就绪状态）
• blocked：阻塞状态
• waiting：等待状态
• timed-waiting：限时等待状态
• terminated：终止状态