管理线程共享数据

方法1:

将共享数据封装在一个类的对象中,然后将这个对象传递给各个 Runnable对象

每个线程对共享数据的操作方法也分配到相应的对象身上去完成

示例代码:

public class Test {
    private static ThreadLocal<MyThreadScopeData> myThreadScopeData = new ThreadLocal<MyThreadScopeData>();
    public static void main(String[] args) {
        for(int i=0;i<2;i++){
            new Thread(
                    new Runnable(){
                    @Override
                    public void run(){
                        int data = new Random().nextInt();
                        System.out.println(Thread.currentThread().getName()
                                + " has put data :" + data);
                        MyThreadScopeData myData = new MyThreadScopeData();//在静态方法中创建一个封装共享数据的对象(内部类的实例)
                        myData.setName("name " + data);
                        myData.setAge(data);
                        myThreadScopeData.set(myData);
                        new A().get();
                        new B().get();
                }
            }).start();
        }
    }
    
    static class A{
        public void get(){
            MyThreadScopeData myData = myThreadScopeData.get();
            System.out.println("A from " + Thread.currentThread().getName()
                    + " getMyData :" + myData.getName() + "," +
                    myData.getAge());
        }
    }
    static class B{
        public void get(){
            MyThreadScopeData myData = myThreadScopeData.get();
            System.out.println("B from " + Thread.currentThread().getName()
                    + " getMyData :" + myData.getName() + "," +
                    myData.getAge());
        }
    }
    //封装共享数据的对象
    static class MyThreadScopeData{
        private MyThreadScopeData(){}
        private String name;
        private int age;
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
        public int getAge() {
            return age;
        }
        public void setAge(int age) {
            this.age = age;
        }
    }
}

运行结果如下:

Thread-0 has put data :1065945080
Thread-1 has put data :1729981827
A from Thread-1 getMyData :name 1729981827,1729981827
A from Thread-0 getMyData :name 1065945080,1065945080
B from Thread-0 getMyData :name 1065945080,1065945080
B from Thread-1 getMyData :name 1729981827,1729981827

 从运行结果可以看出,A方法和B方法在同一线程中取到的是同一份数据,实现了线程的数据共享

 

方法2:

将 Runnable对象作为某一个类中的内部类
共享数据作为这个外部类中的成员变量,每个线程对共享数据的操作方法也分配给外部类
作为内部类的各个 Runnable对象调用外部类的操作方法

示例代码:

public class Test {
    private static Map<Thread, Integer> threadData = new HashMap<Thread, Integer>();
    public static void main(String[] args) {
        for(int i=0;i<2;i++){
            new Thread(
                    new Runnable(){
                        @Override
                        public void run(){
                            int data = new Random().nextInt();//共享数据
                            System.out.println(Thread.currentThread().getName()
                                    + " has put data :" + data);
                            threadData.put(Thread.currentThread(),data);
                            new A().get();
                            new B().get();
                        }
            }).start();
        }
    }
    //操作方法A
    static class A{
        public void get(){
            int data = threadData.get(Thread.currentThread());
            System.out.println("A from " + Thread.currentThread().getName()
                    + " get data :" + data);
        }
    }
    //操作方法B
    static class B{
        public void get(){
            int data = threadData.get(Thread.currentThread());
            System.out.println("B from " + Thread.currentThread().getName()
                    + " get data :" + data);
        }
    }
}

运行结果如下:

Thread-0 has put data :733399446
Thread-1 has put data :605369538
A from Thread-1 get data :605369538
A from Thread-0 get data :733399446
B from Thread-0 get data :733399446
B from Thread-1 get data :605369538

 从运行结果也可以看出,A方法和B方法在同一线程中取到的是同一份数据

方法3:

如有需要,也可以将方法1和方法2组合起来使用,这里就不介绍了,还没试~~~