Redis的Java客户端Jedis

时间:2021-06-19 17:27:59

Redis 的 Java 客户端 Jedis

一、Jedis 所需要的 jar 包

<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-pool2</artifactId>
<version>2.4.2</version>
</dependency>
<dependency>
<groupId>redis.clients</groupId>
<artifactId>jedis</artifactId>
<version>2.9.0</version>
</dependency>

二、Jedis 常用操作

2.1、测试连通性

public class Demo01 {
public static void main(String[] args) {
//连接本地的 Redis 服务
Jedis jedis = new Jedis("127.0.0.1",6379);
//查看服务是否运行,打出pong表示OK
System.out.println("connection is OK==========>: "+jedis.ping());
}
}

控制台输出

PONG

2.2、5+1

一个 key ,五大数据类型

package test;

import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import redis.clients.jedis.Jedis;

public class TestAPI {
public static void main(String[] args) {
Jedis jedis = new Jedis("127.0.0.1", 6379);

//key
Set<String> sets = jedis.keys("*");
for(Iterator iterator = sets.iterator();iterator.hasNext();){
String key = (String) iterator.next();
System.out.println(key);
}
System.out.println("jedis.exists====>"+jedis.exists("k2"));
System.out.println(jedis.ttl("k1"));

//String
System.out.println(jedis.get("k1"));
jedis.set("k4", "v4");
System.out.println("----------------------------------");
jedis.mset("str1","v1","str2","v2","str3","v3");
System.out.println(jedis.mget("str1","str2","str3"));

//list
System.out.println("----------------------------------");
jedis.lpush("mylist", "v1","v2","v3","v4","v5");
List<String> list = jedis.lrange("mylist", 0, -1);
for(String element:list){
System.out.println(element);
}

//set
System.out.println("----------------------------------");
jedis.sadd("orders", "jd001");
jedis.sadd("orders", "jd002");
jedis.sadd("orders", "jd003");
Set<String> set1 = jedis.smembers("orders");
for(Iterator iterator = set1.iterator();iterator.hasNext();){
String string = (String) iterator.next();
System.out.println(string);
}
jedis.srem("orders", "jd002");
System.out.println(jedis.smembers("orders").size());

//hash
System.out.println("----------------------------------");
jedis.hset("hash1", "userName", "lisi");
System.out.println(jedis.hget("hash1", "userName"));
Map<String, String> map = new HashMap<String, String>();
map.put("telphone", "13811814763");
map.put("address", "atguigu");
map.put("email", "abc@163.com");
jedis.hmset("hash2", map);
List<String> result =jedis.hmget("hash2", "telphone","email");
for(String element : result){
System.out.println(element);
}

//zset
System.out.println("----------------------------------");
jedis.zadd("zset01", 60d,"v1");
jedis.zadd("zset01", 70d,"v2");
jedis.zadd("zset01", 80d,"v3");
jedis.zadd("zset01", 90d,"v4");
Set<String> s1 = jedis.zrange("zset01", 0, -1);
for(Iterator iterator = s1.iterator();iterator.hasNext();){
String string = (String) iterator.next();
System.out.println(string);
}
}
}

2.3、事务提交

日常

package test;

import com.sun.prism.impl.Disposer.Target;

import redis.clients.jedis.Jedis;
import redis.clients.jedis.Transaction;

public class TestTx {
public static void main(String[] args) {
Jedis jedis = new Jedis("127.0.0.1", 6379);

Transaction transaction = jedis.multi();

transaction.set("k44", "v44");
transaction.set("k55", "v55");

//transaction.exec();
transaction.discard();
}
}

加锁

import com.sun.prism.impl.Disposer.Target;

import redis.clients.jedis.Jedis;
import redis.clients.jedis.Transaction;

public class TestTx {

public boolean transMethod(){
Jedis jedis = new Jedis("127.0.0.1", 6379);
int balance;// 可用余额
int debt;// 欠额
int amtToSubtract = 10;// 实刷额度

jedis.watch("balance");
//jedis.set("balance","5");//此句不该出现,讲课方便。模拟其他程序已经修改了该条目
balance = Integer.parseInt(jedis.get("balance"));
if (balance < amtToSubtract) {
jedis.unwatch();
System.out.println("modify");
return false;
} else {
System.out.println("***********transaction");
Transaction transaction = jedis.multi();
transaction.decrBy("balance", amtToSubtract);
transaction.incrBy("debt", amtToSubtract);
transaction.exec();
balance = Integer.parseInt(jedis.get("balance"));
debt = Integer.parseInt(jedis.get("debt"));


System.out.println("*******" + balance);
System.out.println("*******" + debt);
return true;
}
}

/**
* 通俗点讲,watch命令就是标记一个键,如果标记了一个键, 在提交事务前如果该键被别人修改过,那事务就会失败,这种情况通常可以在程序中
* 重新再尝试一次。
* 首先标记了键balance,然后检查余额是否足够,不足就取消标记,并不做扣减; 足够的话,就启动事务进行更新操作,
* 如果在此期间键balance被其它人修改, 那在提交事务(执行exec)时就会报错, 程序中通常可以捕获这类错误再重新执行一次,直到成功。
* @throws InterruptedException
*/

public static void main(String[] args){
TestTx test = new TestTx();
boolean retValue = test.transMethod();
System.out.println("main retValue-------: " + retValue);
}
}

2.4、主从复制

  • 6379,6380启动,先各自先独立
  • 主写
  • 从读
package test;

import redis.clients.jedis.Jedis;

public class TestMS {
public static void main(String[] args) {
Jedis jedis_M = new Jedis("127.0.0.1", 6379);
Jedis jedis_S = new Jedis("127.0.0.1", 6380);

jedis_S.slaveof("127.0.0.1", 6379);

jedis_M.set("class", "1122vv");

String result = jedis_S.get("class");
System.out.println(result);
}
}

三、JedisPool

  • Jedis 实例需要从 JedisPool 中获取
  • 用完 Jedis 实例需要返还给 JedisPool
  • 如果 Jedis 在使用过程中出错,则也需要还给 JedisPool

案例

JedisPoolUtil.java

package test;

import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;
import redis.clients.jedis.JedisPoolConfig;

public class JedisPoolUtil {

private static volatile JedisPool jedisPool = null;

private JedisPoolUtil(){}

public static JedisPool getJedisPoolInstance(){
if(null == jedisPool){
synchronized (JedisPoolUtil.class) {
if(null == jedisPool){
JedisPoolConfig poolConfig = new JedisPoolConfig();
poolConfig.setMaxTotal(1000);
poolConfig.setMaxIdle(32);
poolConfig.setMaxWaitMillis(100*1000);
poolConfig.setTestOnBorrow(true);

jedisPool = new JedisPool(poolConfig,"127.0.0.1",6379);
}
}
}
return jedisPool;
}

public static void release(JedisPool jedisPool,Jedis jedis){
if(null != jedis){
jedisPool.returnResourceObject(jedis);
}
}
}

TestPool.java

package test;

import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;

public class TestPool {
public static void main(String[] args) {

JedisPool jedisPool = JedisPoolUtil.getJedisPoolInstance();

Jedis jedis = null;

try {
jedis = jedisPool.getResource();
jedis.set("aa", "bb");
} catch (Exception e) {
e.printStackTrace();
}finally{
JedisPoolUtil.release(jedisPool, jedis);
}
}
}

配置总结

JedisPool的配置参数大部分是由JedisPoolConfig的对应项来赋值的。

  • maxActive:控制一个pool可分配多少个jedis实例,通过pool.getResource()来获取;如果赋值为-1,则表示不限制;如果pool已经分配了maxActive个jedis实例,则此时pool的状态为exhausted。
  • maxIdle:控制一个pool最多有多少个状态为idle(空闲)的jedis实例;
  • whenExhaustedAction:表示当pool中的jedis实例都被allocated完时,pool要采取的操作;默认有三种。
    • WHEN_EXHAUSTED_FAIL –> 表示无jedis实例时,直接抛出NoSuchElementException;
    • WHEN_EXHAUSTED_BLOCK –> 则表示阻塞住,或者达到maxWait时抛出JedisConnectionException;
    • WHEN_EXHAUSTED_GROW –> 则表示新建一个jedis实例,也就说设置的maxActive无用;
  • maxWait:表示当borrow一个jedis实例时,最大的等待时间,如果超过等待时间,则直接抛JedisConnectionException;
  • testOnBorrow:获得一个jedis实例的时候是否检查连接可用性(ping());如果为true,则得到的jedis实例均是可用的;
  • testOnReturn:return 一个jedis实例给pool时,是否检查连接可用性(ping());
  • testWhileIdle:如果为true,表示有一个idle object evitor线程对idle object进行扫描,如果validate失败,此object会被从pool中drop掉;这一项只有在timeBetweenEvictionRunsMillis大于0时才有意义;
  • timeBetweenEvictionRunsMillis:表示idle object evitor两次扫描之间要sleep的毫秒数;
  • numTestsPerEvictionRun:表示idle object evitor每次扫描的最多的对象数;
  • minEvictableIdleTimeMillis:表示一个对象至少停留在idle状态的最短时间,然后才能被idle object evitor扫描并驱逐;这一项只有在timeBetweenEvictionRunsMillis大于0时才有意义;
  • softMinEvictableIdleTimeMillis:在minEvictableIdleTimeMillis基础上,加入了至少minIdle个对象已经在pool里面了。如果为-1,evicted不会根据idle time驱逐任何对象。如果minEvictableIdleTimeMillis>0,则此项设置无意义,且只有在timeBetweenEvictionRunsMillis大于0时才有意义;
  • lifo:borrowObject返回对象时,是采用DEFAULT_LIFO(last in first out,即类似cache的最频繁使用队列),如果为False,则表示FIFO队列;

\==================================================================================================================
其中JedisPoolConfig对一些参数的默认设置如下:

testWhileIdle=true
minEvictableIdleTimeMills=60000
timeBetweenEvictionRunsMillis=30000
numTestsPerEvictionRun=-1