多线程下的单例（静态类单例）

定义一个单例model； 

package com.shirt.test;
/**
 * @author xiaxt
 * @date 2018/12/21.
 */
public class RunModel {

    private boolean isRunning;  //执行状态
    private String message; //执行信息
    private   data;    //执行数据

    private RunModel(boolean b) {
        this.isRunning = b;
    }
    private RunModel setIsRunning(boolean b){
        this.isRunning = b;
        return this;
    }
    private RunModel setMessage(String msg){
        this.message = msg;
        return this;
    }
    private RunModel setData(  data){
        this.data = data;
        return this;
    }
    private static class Running {
        private static RunModel instance = new RunModel(false);
    }

    /**
     * 线程运行结束
     * @return
     */
    public static RunModel runOver(){
        return getInstance().setIsRunning(false).setMessage(null).setData(null);
    }

    /**
     * 线程开始运行
     * @return
     */
    public static RunModel running(){
        return getInstance().setIsRunning(true);
    }
    public static RunModel running(String msg){
        return getInstance().setIsRunning(true).setMessage(msg);
    }
    public static RunModel running(String msg,   o){
        return getInstance().setIsRunning(true).setMessage(msg).setData(o);
    }

    /**
     * 获取定时任务执行状态isRunning
     * @return
     */
    public static boolean isRunning() {
        return getInstance().isRunning;
    }
    /**
     * 获取定时任务执行信息message
     * @return
     */
    public static String getMessage() {
        return getInstance().message;
    }
    /**
     * 获取定时任务执行数据data
     * @return
     */
    public static   getData() {
        return getInstance().data;
    }

    /**
     * 获取实例化对象
     * @return
     */
    public static RunModel getInstance() {
        return Running.instance;
    }
}

main函数调用测试 

package com.shirt.test;

/**
 * @author xiaxt
 * @date 2018/8/9.
 */
public class MainTest {
    public static void main(String[] args){
     
            new Thread(new ThreadA()).start();
            new Thread(new ThreadB()).start();
            new Thread(new ThreadC()).start();
            try {
                Thread.sleep(50);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
    }
}
class ThreadA implements Runnable{//继承Thread类
    //重写run方法
    public void run(){
        if (RunModel.isRunning()){
            System.out.println(RunModel.getMessage()+\"，线程A跳出！\");
            return;
        }
        RunModel.running(\"线程A执行中\");
        System.out.println(\"线程A开始执行\");
        try {
            Thread.sleep(100);
            System.out.println(\"线程A睡眠0.1秒\");

        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        RunModel.runOver();
        System.out.println(\"线程A执行结束\");
    }
}
class ThreadB implements Runnable{//继承Thread类
    //重写run方法
    public void run(){
        if (RunModel.isRunning()){
            System.out.println(RunModel.getMessage()+\"，线程B跳出！\");
            return;
        }
        RunModel.running(\"线程B执行中\");
        System.out.println(\"线程B开始执行\");
        try {
            Thread.sleep(100);
            System.out.println(\"线程B睡眠0.1秒\");

        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        RunModel.runOver();
        System.out.println(\"线程B执行结束\");
    }
}
class ThreadC implements Runnable{//继承Thread类
    //重写run方法
    public void run(){
        if (RunModel.isRunning()){
            System.out.println(RunModel.getMessage()+\"，线程C跳出！\");
            return;
        }
        RunModel.running(\"线程C执行中\");
        System.out.println(\"线程C开始执行\");
        try {
            Thread.sleep(100);
            System.out.println(\"线程C睡眠0.1秒\");

        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        RunModel.runOver();
        System.out.println(\"线程C执行结束\");
    }
}