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= ;

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= 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=
maxActive=
maxIdle=
maxWait=
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(*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("", "zhangsan", , "M");
        User u2 =new User("", "lisi",     , "W");
        User u3 =new User("", "wangwu",   , "W");
        User u4 =new User("", "maliu",    , "W");
        User u5 =new User("", "zhengqi",  , "M");
        User u6 =new User("", "songba",   , "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】