java读写锁

在多线程存取数据时，如果不加锁就会导致数据有误，线程安全问题。可是如果把写入、读取都加锁，写入还好，读取也变成一个一个的读取，就会比较慢。所以读写锁就是来解决：

写入加锁，读取的时候可以多个读取,也就是独占锁（写）、共享锁（读）

package com.quxiao.controller;
 
 
import java.util.*;
import java.util.concurrent.*;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.stream.Collectors;
 
/**
 * @program: package1
 * @author: quxiao
 * @create: 2023-09-27 15:22
 **/
public class t3 {
    public static void main(String[] args) {
        t t = new t();
        for (int i = 0; i < 30; i++) {
            final int tem = i;
            new Thread(() -> {
                t.put(tem + "", tem + "");
                t.get(tem + "");
            }).start();
        }
    }
 
    static class t {
        Map map = new HashMap<>();
        ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
 
        void put(String key, String val) {
            lock.writeLock().lock();
            try {
                System.out.println(key + "写");
                map.put(key, val);
                System.out.println(key + "写ok");
            } catch (Exception e) {
                throw new RuntimeException(e);
            } finally {
                lock.writeLock().unlock();
            }
        }
 
        void get(String key) {
            lock.readLock().lock();
            try {
                System.out.println(key + "读");
                String s = map.get(key);
                System.out.println(key + "读ok:" + s);
            } catch (Exception e) {
                throw new RuntimeException(e);
            } finally {
                lock.readLock().unlock();
            }
        }
    }
}