java线程之间的通信

Posted 2020-11-07 CodeZLei

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1.常用的方法
　　sleep()该线程进入等待状态,不释放锁
　　wait() 该线程进入等待状态,释放锁
　　notify() 随机唤醒一个线程
　　notifyAll() 唤醒全部线程

2.线程之间的通信

　　a.两个线程之间的通信

public class ThreadExchange {

	@Test
	public void test2Thread() {
		MyPrint myPrint = new MyPrint();
		new Thread(new Runnable() {
			@Override
			public void run() {
				while (true) {
					try {
						myPrint.printA();
					} catch (InterruptedException e) {
						e.printStackTrace();
					}
				}
			}
		}).start();
		new Thread(new Runnable() {
			@Override
			public void run() {
				while (true) {
					try {
						myPrint.printB();
					} catch (InterruptedException e) {
						e.printStackTrace();
					}
				}
			}
		}).start();
	}
}

class MyPrint {
	private Integer flag = 0;

	public synchronized void printA() throws InterruptedException {
		if (flag != 0) {
			this.wait();
		}
		System.out.print("a");
		System.out.print("a");
		System.out.print("a");
		System.out.print("a");
		System.out.println("a");
		flag = 1;
		this.notify();
	}
	public synchronized void printB() throws InterruptedException {
		if (flag != 1) {
			this.wait();
		}
		System.out.print("b");
		System.out.print("b");
		System.out.print("b");
		System.out.print("b");
		System.out.println("b");
		flag = 0;
		this.notify();
	}
}

　　b.三个以上的线程之间的通信

　　　方式一

public class ThreadExchange {

    @Test
    public void test2Thread() {
        MyPrint myPrint = new MyPrint();
        new Thread(new Runnable() {
            @Override
            public void run() {
                while (true) {
                    try {
                        myPrint.printA();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }).start();
        new Thread(new Runnable() {
            @Override
            public void run() {
                while (true) {
                    try {
                        myPrint.printB();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }).start();
    }
}

class MyPrint {
    private Integer flag = 0;

    public synchronized void printA() throws InterruptedException {
        if (flag != 0) {
            this.wait();
        }
        System.out.print("a");
        System.out.print("a");
        System.out.print("a");
        System.out.print("a");
        System.out.println("a");
        flag = 1;
        this.notify();
    }
    public synchronized void printB() throws InterruptedException {
        if (flag != 1) {
            this.wait();
        }
        System.out.print("b");
        System.out.print("b");
        System.out.print("b");
        System.out.print("b");
        System.out.println("b");
        flag = 0;
        this.notify();
    }
}

    
    
    2.三个以上的线程之间的通信

public class ThreadExchange {

    @Test
    public void test2Thread() {
        final MyPrint p = new MyPrint();
        new Thread() {
            public void run() {
                while (true) {
                    try {
                        p.print1();
                    } catch (InterruptedException e) {

                        e.printStackTrace();
                    }
                }
            }
        }.start();

        new Thread() {
            public void run() {
                while (true) {
                    try {
                        p.print2();
                    } catch (InterruptedException e) {

                        e.printStackTrace();
                    }
                }
            }
        }.start();

        new Thread() {
            public void run() {
                while (true) {
                    try {
                        p.print3();
                    } catch (InterruptedException e) {

                        e.printStackTrace();
                    }
                }
            }
        }.start();
    }

}

class MyPrint {
    private int flag = 1;

    public void print1() throws InterruptedException {                            
        synchronized(this) {
            while(flag != 1) {
                this.wait();                    
            }
            System.out.print("a");
            System.out.print("a");
            System.out.print("a");
            System.out.print("a");
            System.out.println("a");
            flag = 2;
            this.notifyAll();
        }
    }

    public void print2() throws InterruptedException {
        synchronized (this) {
            while (flag != 2) {
                this.wait();
            }
            System.out.print("b");
            System.out.print("b");
            System.out.print("b");
            System.out.print("b");
            System.out.println("b");
            flag = 3;
            this.notifyAll();
        }
    }

    public void print3() throws InterruptedException {
        synchronized (this) {
            while (flag != 3) {
                this.wait();
            }
            System.out.print("c");
            System.out.print("c");
            System.out.print("c");
            System.out.print("c");
            System.out.println("c");
            flag = 1;
            this.notifyAll();
        }
    }
}

　　方式二

    
public class ThreadExchange {

    @Test
    public void test3Thread() {
        final MyPrint p = new MyPrint();

        new Thread() {
            public void run() {
                while (true) {
                    try {
                        p.print1();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }.start();

        new Thread() {
            public void run() {
                while (true) {
                    try {
                        p.print2();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }.start();

        new Thread() {
            public void run() {
                while (true) {
                    try {
                        p.print3();
                    } catch (InterruptedException e) {

                        e.printStackTrace();
                    }
                }
            }
        }.start();
    }

}

class MyPrint {
    private ReentrantLock r = new ReentrantLock();
    private Condition c1 = r.newCondition();
    private Condition c2 = r.newCondition();
    private Condition c3 = r.newCondition();

    private int flag = 1;

    public void print1() throws InterruptedException {
        r.lock(); // 获取锁
        if (flag != 1) {
            c1.await();
        }
        System.out.print("a");
        System.out.print("a");
        System.out.print("a");
        System.out.print("a");
        System.out.println("a");
        flag = 2;
        c2.signal();
        r.unlock(); // 释放锁
    }

    public void print2() throws InterruptedException {
        r.lock();
        if (flag != 2) {
            c2.await();
        }
        System.out.print("b");
        System.out.print("b");
        System.out.print("b");
        System.out.print("b");
        System.out.println("b");
        flag = 3;
        c3.signal();
        r.unlock();
    }

    public void print3() throws InterruptedException {
        r.lock();
        if (flag != 3) {
            c3.await();
        }
        System.out.print("c");
        System.out.print("c");
        System.out.print("c");
        System.out.print("c");
        System.out.println("c");
        flag = 1;
        c1.signal();
        r.unlock();
    }
}

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