多线程之间按顺序调用，实现A->B->C三个线程启动（使用Lock锁）

迈不过友情╰ 2022-01-30 01:04 193阅读 0赞

题目：多线程之间按顺序调用，实现A->B->C三个线程启动，要求如下：

*  AA打印5次，BB打印10次，CC打印15次
 *  …来十轮

思路：使用Lock锁的多个Condition实现精准唤醒。

package com.bestqiang.thread.Queue;
    
    /** * @author BestQiang */
    
    import java.util.concurrent.locks.Condition;
    import java.util.concurrent.locks.Lock;
    import java.util.concurrent.locks.ReentrantLock;
    
    /** * 题目：多线程之间按顺序调用，实现A->B->C三个线程启动，要求如下： * AA打印5次，BB打印10次，CC打印15次 * 然后 * AA打印5次，BB打印10次，CC打印15次 * ...来十轮 */
    public class SyncAndReentrantLockDemo { 
        public static void main(String[] args) { 
            ShareResource shareResource = new ShareResource();
            new Thread(() -> { 
                for (int i = 0; i < 10; i++) { 
                    shareResource.print5();
                }
            }, "线程1：").start();
            new Thread(() -> { 
                for (int i = 0; i < 10; i++) { 
                    shareResource.print10();
                }
            }, "线程2：").start();
            new Thread(() -> { 
                for (int i = 0; i < 10; i++) { 
                    shareResource.print15();
                }
            }, "线程3：").start();
        }
    
    }
    
    class ShareResource { 
        private int number = 1; // A:1 B:2 C:3
        private Lock lock = new ReentrantLock();
        Condition c1 = lock.newCondition();
        Condition c2 = lock.newCondition();
        Condition c3 = lock.newCondition();
    
        public void print5() { 
            try { 
                lock.lock();
                while (number != 1) { 
                    c1.await();
                }
                for (int i = 0; i < 5; i++) { 
                    System.out.println("AA");
                }
                number = 2;
                c2.signal();
            } catch (Exception e) { 
                e.printStackTrace();
            } finally { 
                lock.unlock();
            }
        }
    
        public void print10() { 
            try { 
                lock.lock();
                while (number != 2) { 
                    c2.await();
                }
                for (int i = 0; i < 10; i++) { 
                    System.out.println("BB");
                }
                number = 3;
                c3.signal();
            } catch (Exception e) { 
                e.printStackTrace();
            } finally { 
                lock.unlock();
            }
        }
    
        public void print15() { 
            try { 
                lock.lock();
                while (number != 3) { 
                    c3.await();
                }
                for (int i = 0; i < 15; i++) { 
                    System.out.println("CC");
                }
                number = 1;
                c1.signal();
            } catch (Exception e) { 
                e.printStackTrace();
            } finally { 
                lock.unlock();
            }
        }
    }