public class Outputter {        private Lock lock = new ReentrantLock();    public void output(String name){        lock.lock();    //得到锁        try{            for(int i = 0; i < name.length();i++){                System.out.print(name.charAt(i));            }        }catch(Exception e){            e.printStackTrace();        }finally{            lock.unlock();    //释放锁        }    }    }

public class LockTest {    public static void main(String[] args) {        final Outputter outputter = new Outputter();        new Thread(){            public void run(){                outputter.output("Chinaese ");            }        }.start();        new Thread(){            public void run(){                outputter.output("Chinaese ");            }        }.start();        new Thread(){            public void run(){                outputter.output("Chinaese ");            }        }.start();    }    }

上述代码可以解决线程安全问题，效果和synchronized一样。不同的是，synchronized修饰的方法或者代码块执行完后自动释放锁，而lock需要手动释放锁。

对于数据区的内容，我们要做到  读写互斥  写写互斥 读读不互斥(这里先考虑读读互斥)

/** * 显然不满足我们的需求 * 我们需要实现的是：读写互斥   写写互斥  读读不互斥 * @author hp * */public class ReadWriteLockTest {    public static void main(String[] args) {        final Data data = new Data();        for(int i = 0;i<3;i++){            new Thread(new Runnable(){                public void run() {                    for(int i = 0; i< 5;i++){                        data.set(new Random().nextInt(30));                    }                }            }).start();        }                for(int i = 0;i  < 3;i++){            new Thread(new Runnable(){                public void run() {                    for(int i = 0;i< 5;i++){                        data.get();                    }                }            }).start();        }    }        /*static class Data{        private int data;                public void set(int data){            System.out.println(Thread.currentThread().getName()+"准备写数据");            try {                Thread.sleep(1000);            } catch (InterruptedException e) {                e.printStackTrace();            }            this.data = data;            System.out.println(Thread.currentThread().getName()+"写入数据"+data);        }                public void get(){            System.out.println(Thread.currentThread().getName()+"准备读取数据");            try {                Thread.sleep(1000);            } catch (InterruptedException e) {                e.printStackTrace();            }            System.out.println(Thread.currentThread().getName()+"读取"+this.data);        }            }*/            static class Data{        private int data;        private ReadWriteLock rwl = new ReentrantReadWriteLock();        public void set(int data){            rwl.writeLock().lock();            try {                System.out.println(Thread.currentThread().getName()+"准备写数据");                Thread.sleep(20);                this.data = data;                System.out.println(Thread.currentThread().getName()+"写入数据"+data);            } catch (InterruptedException e) {                e.printStackTrace();            }finally{                rwl.writeLock().unlock();            }        }                public void get(){            rwl.readLock().lock();            try {                System.out.println(Thread.currentThread().getName()+"准备读取数据");                Thread.sleep(20);                System.out.println(Thread.currentThread().getName()+"读取"+this.data);            } catch (InterruptedException e) {                e.printStackTrace();            }finally{                rwl.readLock().unlock();            }        }            }    }