Read-Write lock 看可以，不过看的时候不能写

来源：互联网发布：淘宝商城分销平台编辑：程序博客网时间：2024/04/20 14:58

当线程“读取”实例的状态时，实例的状态不会改变，只有线程对实例“写入”操作时才会改变。read-write lock 模式将读取和写入分开来处理，在读取数据前获取读锁定，而写入之前，必须获取写锁定。

public class ReadWriteThreadTest {    public static void main(String[] args) {        Data data = new Data(5);        new ReaderThread(data).start();        new ReaderThread(data).start();        new ReaderThread(data).start();        new ReaderThread(data).start();                new WriterThread(data, "asdfghjk").start();    }}class Data {    private final char[] buffer;    private final ReadWriteLock lock = new ReentrantReadWriteLock();    Lock read = lock.readLock();    Lock write = lock.writeLock();    public Data(int size) {        this.buffer = new char[size];        for (int i = 0; i < buffer.length; i++) {            buffer[i] = '*';        }    }    public char[] read() {        read.lock();        try {            return doRead();        } finally {            read.unlock();        }    }    public void write(char c) {        write.lock();        try {            doWrite(c);        } finally {            write.unlock();        }    }    private void doWrite(char c) {        for (int i = 0; i < buffer.length; i++) {            buffer[i] = c;            try {                Thread.sleep(50);            } catch (InterruptedException e) {                e.printStackTrace();            }        }    }    private char[] doRead() {        char[] newbuf = new char[buffer.length];        for (int i = 0; i < buffer.length; i++) {            newbuf[i] = buffer[i];        }        try {            Thread.sleep(50);        } catch (InterruptedException e) {            e.printStackTrace();        }        return newbuf;    }}class WriterThread extends Thread {    private static final Random random = new Random();    private final Data data;    private final String filter;    private int index;    public WriterThread(Data data, String filter) {        this.index = 0;        this.data = data;        this.filter = filter;    }    @Override    public void run() {        try {            while (true) {                char c = nextchar();                data.write(c);                Thread.sleep(random.nextInt(3000));            }        } catch (InterruptedException e) {            e.printStackTrace();        }    }    private char nextchar() {        char c = filter.charAt(index);        index++;        if (index >= filter.length()) {            index = 0;        }        return c;    }}class ReaderThread extends Thread{    private final Data data;        public ReaderThread(Data data) {        this.data=data;    }    @Override    public void run() {        while(true){            char[] readbuf = data.read();            System.out.println(Thread.currentThread().getName() + " reads " + String.valueOf(readbuf));        }    }}

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