06_Jedis完成MySQL的条件查询案例

【概述】

　　假设现在有一个User表，其中有id,name,age,sex等字段，完成如下要求的SQL语句为：

1.查找所有age=18 的User

select  * from user where age=18 ;

2.查找所有sex="M"（"M"代表男性）的User

select * from user where sex="M" ;

3.查找所有sex="M" and age=18 的User

select * from user where age=18 and sex="M" ;

在MySQL关系型数据库中，这些操作是非常轻松的，但是在Redis这种非关系型数据库中，我们需要经过设计才能完成上述的功能。

【工程截图】



【redis.properties 配置文件】

ip=127.0.0.1
port=6379
maxActive=100
maxIdle=5
maxWait=100
isTestOnBorrow=true

【RedisUtils.java】

package com.higgin.util;

import java.io.InputStream;
import java.util.Properties;

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

public class RedisUtils {

private static String ip;
private static int port;
private static int maxActive;  //最大连接数
private static int maxIdle;
private static long  maxWait;
private static boolean isTestOnBorrow;

private static JedisPool jedisPool;
private static JedisPoolConfig config;
private static Jedis jedis;

static{   //静态代码块中完成解析redis.properties各种配置的工作
try{
InputStream in=RedisUtils.class.getClassLoader().getResourceAsStream("redis.properties");
Properties prop =new Properties();
prop.load(in);

ip=prop.getProperty("ip");
port=Integer.parseInt(prop.getProperty("port"));
maxActive=Integer.parseInt(prop.getProperty("maxActive"));
maxIdle=Integer.parseInt(prop.getProperty("maxIdle"));
maxWait=Long.parseLong(prop.getProperty("maxWait"));
isTestOnBorrow=Boolean.parseBoolean(prop.getProperty("isTestOnBorrow"));

config=new JedisPoolConfig();  //实例化一个Jedis连接池配置 的对象实例
config.setMaxActive(maxActive);  //控制一个pool可以分配多少个jedis实例，通过JedisPool.getResource()获取
config.setMaxIdle(maxIdle); //控制一个pool最多有多少个状态为idle(空闲)的jedis实例
config.setMaxWait(1000*maxWait); //当borrow(引入)一个jedis实例时，最大的等待时间，如果超过等待时间，直接抛出JedisConnectionException
config.setTestOnBorrow(isTestOnBorrow);

jedisPool=new JedisPool(config,ip,port);

}catch(Exception e){
e.printStackTrace();
}
}

/**
* 从连接池中得到一个jedis实例
* @return
*/
public static Jedis getJedis(){
jedis=jedisPool.getResource();
return jedis;
}

/**
* 将jedis返还到连接池
*/
public static void returnResource(Jedis jedis){
if(jedis!=null){
jedisPool.returnResource(jedis);
}
}

}

【JsonUtils.java】

package com.higgin.util;

import com.alibaba.fastjson.JSON;

public class JsonUtils {
/**
* 对象obj转成Json字符串
*/
public static String getJsonString(Object obj){
return JSON.toJSONString(obj);
}

/**
* json字符串转成 Object对象
*/
public static<T> T getObjectFromJsonString(String json,Class<T> clazz){
return JSON.parseObject(json,clazz);
}
}

【User.java】

package com.higgin.domain;

public class User {

final public static String USER_KEY = "user_key";
final public static String USER_AGE_KEY_18 = "user_age_key18";
final public static String USER_SEX_KEY_M ="user_sex_key_m";
final public static String USER_SEX_KEY_W ="user_sex_key_w";

private String id;
private String name;
private int age;
private String sex;

//注意：要想被FastJson的JsonString-->Object，对应的Object必须有构造方法
public User(){
}

public User(String id, String name, int age, String sex) {
this.id = id;
this.name = name;
this.age = age;
this.sex = sex;
}

public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
@Override
public String toString() {
return "User [id=" + id + ", name=" + name + ", age=" + age + ", sex="
+ sex + "]";
}
}

【UserRedisDao.java 接口】

package com.higgin.dao;

import java.util.List;
import com.higgin.domain.User;

public interface UserRedisDao {

public void setUserObject(String key,String id,User user);

public void setUserJsonStr(String key,String id, String userJsonStr);

public void setKeyId(String key,String id);

public User getUser(String key,String id);

public List<String> getIds(String key);

public List<String> getIdsInter(String key1,String key2);  //取出两个key所在的集合的交集

public List<String> getUsersByFields(String key,String[] fields);  //返回对应的key中，满足fiedls数组的所有value
}

【UserRedisDaoImpl.java】

package com.higgin.dao.impl;

import java.util.ArrayList;
import java.util.List;
import java.util.Set;

import redis.clients.jedis.Jedis;

import com.higgin.dao.UserRedisDao;
import com.higgin.domain.User;
import com.higgin.util.JsonUtils;
import com.higgin.util.RedisUtils;

public class UserRedisDaoImpl implements UserRedisDao{

Jedis jedis=RedisUtils.getJedis();

@Override
public void setUserObject(String key, String id, User user) {
setUserJsonStr(key,id,JsonUtils.getJsonString(user));
}

@Override
public void setUserJsonStr(String key,String id, String userJsonStr) {
jedis.hset(key, id, userJsonStr);
}

@Override
public User getUser(String key,String userId) {
String userJsonStr=jedis.hget(key, userId);
return JsonUtils.getObjectFromJsonString(userJsonStr, User.class);
}

@Override
public List<String> getIds(String key) {
Set<String> ids= jedis.smembers(key);
List<String> idsList=new ArrayList<String>(ids);
return idsList;
}

@Override
public void setKeyId(String key, String id) {
jedis.sadd(key, id);
}

@Override
public List<String> getIdsInter(String key1, String key2) {
Set<String> ids=jedis.sinter(key1,key2);  //得到两个id集合的交集
List<String> idsList=new ArrayList<String>(ids);
return idsList;
}

@Override
public List<String> getUsersByFields(String key, String[] fields) {
return jedis.hmget(key, fields);
}

}

【TestUserRedisDao.java】

package com.higgin.dao;

import java.util.List;
import redis.clients.jedis.Jedis;

import com.higgin.dao.impl.UserRedisDaoImpl;
import com.higgin.domain.User;
import com.higgin.util.RedisUtils;

public class TestUserRedisDao {
public static void main(String[] args) {
Jedis jedis=RedisUtils.getJedis();

User u1 =new User("10001", "zhangsan", 18, "M");
User u2 =new User("10002", "lisi",     20, "W");
User u3 =new User("10003", "wangwu",   18, "W");
User u4 =new User("10004", "maliu",    30, "W");
User u5 =new User("10005", "zhengqi",  18, "M");
User u6 =new User("10006", "songba",   35, "M");

UserRedisDao userDao=new UserRedisDaoImpl();
userDao.setUserObject(User.USER_KEY, u1.getId(), u1);
userDao.setUserObject(User.USER_KEY, u2.getId(), u2);
userDao.setUserObject(User.USER_KEY, u3.getId(), u3);
userDao.setUserObject(User.USER_KEY, u4.getId(), u4);
userDao.setUserObject(User.USER_KEY, u5.getId(), u5);
userDao.setUserObject(User.USER_KEY, u6.getId(), u6);

userDao.setKeyId(User.USER_AGE_KEY_18, u1.getId());
userDao.setKeyId(User.USER_AGE_KEY_18, u3.getId());
userDao.setKeyId(User.USER_AGE_KEY_18, u5.getId());

userDao.setKeyId(User.USER_SEX_KEY_M, u1.getId());
userDao.setKeyId(User.USER_SEX_KEY_M, u5.getId());
userDao.setKeyId(User.USER_SEX_KEY_M, u6.getId());

//完成select * from user where age=18
List<String> ageIdsList=userDao.getIds(User.USER_AGE_KEY_18);
System.out.println(ageIdsList);
String[] ageIdsArray =(String[]) ageIdsList.toArray(new String[ageIdsList.size()]);  //id的List --> 数组
List<String> userJsonList1=userDao.getUsersByFields(User.USER_KEY,ageIdsArray);    //从user的hash类型中获取多个filed的value,传入的field可以为字符串数组
System.out.println(userJsonList1);   //打印出所有的满足条件的user

System.out.println("------------------------------------------------------");

//完成select * from user where sex="M"
List<String> sexManList=userDao.getIds(User.USER_SEX_KEY_M);
System.out.println(sexManList);
String[] sexManArray=sexManList.toArray(new String[sexManList.size()]);
List<String> userJsonList2=userDao.getUsersByFields(User.USER_KEY, sexManArray);
System.out.println(userJsonList2);

System.out.println("------------------------------------------------------");

//完成select * from user where age=18 and sex="M"
List<String> ageAndSexIdsList=userDao.getIdsInter(User.USER_AGE_KEY_18, User.USER_SEX_KEY_M); //取交集
System.out.println(ageAndSexIdsList);
String[] ageAndSexArray=(String[])ageAndSexIdsList.toArray(new String[ageAndSexIdsList.size()]);
List<String> userJsonList3=userDao.getUsersByFields(User.USER_KEY, ageAndSexArray);
System.out.println(userJsonList3);

jedis.quit();
}
}

【运行结果】