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使用java代码操作Redis

一、在 pom.xml 里添加依赖

      <dependency>
        <groupId>redis.clients</groupId>
        <artifactId>jedis</artifactId>
        <version>2.9.0</version>
      </dependency>

 

二、连接 Redis

Jedis jedis =new Jedis("192.168.124.129",6379);
        jedis.auth("123456");
        //测试连接（打印 pong 就算连接成功）
        System.out.println(jedis.ping());

 

三、操作数据

 

//操作字符串
        //插入数据
//        jedis.set("aaa", "zs");
        //获取数据
//        System.out.println(jedis.get("aaa"));

 </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">操作哈希
    </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">插入数据



//        jedis.hset("user1","uname","ls");
//        jedis.hset("useq r1","sex","女");
//获取数据
//        System.out.println(jedis.hget("user1", "sex"));
//        System.out.println(jedis.hgetAll("user1"));


</span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">操作列表(堆栈结构)</span>
 jedis.lpush(<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">hobby</span><span style="color: rgba(128, 0, 0, 1)">"</span>,<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">a</span><span style="color: rgba(128, 0, 0, 1)">"</span>,<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">b</span><span style="color: rgba(128, 0, 0, 1)">"</span>,<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">c</span><span style="color: rgba(128, 0, 0, 1)">"</span>,<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">d</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">);
 </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">从栈顶开始取值</span>
    System.<span style="color: rgba(0, 0, 255, 1)">out</span>.println(jedis.lpop(<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">hobby</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">));
 </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">从栈底开始取值</span>
    System.<span style="color: rgba(0, 0, 255, 1)">out</span>.println(jedis.rpop(<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">hobby</span><span style="color: rgba(128, 0, 0, 1)">"</span>));</span></pre>

 

四、运用

 

@Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

    </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">首页第一次是读取数据库，后面读取缓存（在没有增删改的情况下）</span>
    Jedis jedis =<span style="color: rgba(0, 0, 255, 1)">new</span> Jedis(<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">192.168.124.129</span><span style="color: rgba(128, 0, 0, 1)">"</span>,<span style="color: rgba(128, 0, 128, 1)">6379</span><span style="color: rgba(0, 0, 0, 1)">);
    jedis.auth(</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">123456</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">);
    </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">从缓存中获取当前登录的用户信息</span>
    Map&lt;String,String&gt; currentUser =jedis.hgetAll(<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">currentUser</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">);
    </span><span style="color: rgba(0, 0, 255, 1)">if</span> (currentUser !=<span style="color: rgba(0, 0, 255, 1)">null</span> &amp;&amp; currentUser.size()&gt;<span style="color: rgba(128, 0, 128, 1)">0</span><span style="color: rgba(0, 0, 0, 1)">){
        req.setAttribute(</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">msg</span><span style="color: rgba(128, 0, 0, 1)">"</span>,<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">从缓存中获取数据</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">);
        req.setAttribute(</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">currentUser</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">,currentUser);
    }
    </span><span style="color: rgba(0, 0, 255, 1)">else</span><span style="color: rgba(0, 0, 0, 1)"> {
        </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">第一次登录，第一次访问首页数据</span>
        req.setAttribute(<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">msg</span><span style="color: rgba(128, 0, 0, 1)">"</span>,<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">从数据库中获取数据</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">);
        String uname </span>=<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">tianqi</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">;
        String upass </span>=<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">123456</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">;
        </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">接下来把数据中的对应对象存储到缓存中</span>
        jedis.hset(<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">currentUser</span><span style="color: rgba(128, 0, 0, 1)">"</span>,<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">uname</span><span style="color: rgba(128, 0, 0, 1)">"</span>,<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">tianqi</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">);
        jedis.hset(</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">currentUser</span><span style="color: rgba(128, 0, 0, 1)">"</span>,<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">upass</span><span style="color: rgba(128, 0, 0, 1)">"</span>,<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">123456</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">);
        </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">此时能获取到值，原因是上面已经将数据存储到缓存中</span>
        currentUser = jedis.hgetAll(<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">currentUser</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">);
        req.setAttribute(</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">currentUser</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">,currentUser);

    }
    req.getRequestDispatcher(</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">/home.jsp</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">).forward(req,resp);
}</span></span></pre>

 

五、实战

  1. 首页第一次是读取数据库，后面读取缓存（在没有增删改的情况）：

 

 // 从 Redis 中获取数据
    String bolgListALL =jedis.get("blogList");
                if(bolgListALL != null && bolgListALL.length()>0) {
        System.out.println("使用 Redis 查询");
        request.setAttribute("blogList", JSON.parse(bolgListALL));
    }else {
// 从数据库中查询数据
        List<Map<String, Object>> blogList = this.blogDao.freemarker_list(title, null);
// 放入缓存
        jedis.set("blogList", JSON.toJSONString(blogList));
        //传到 jsp 页面
        request.setAttribute("blogList", blogList);
        System.out.println("从缓存中拿数据");

 

  2. 增删改的时候，要顺带更新缓存，下一次再次访问首页要保证 redis 中数据跟 mysql 数据是一致：

 

public String add() {
        HttpServletRequest request = ServletActionContext.getRequest();
        Map parameterMap = request.getParameterMap();
        try {
            // 将博客添加到数据库中 
            this.blogDao.add(parameterMap);
            //清除 Redis 缓存
            jedis.del("blogList");
            // 获取当前博客的 id
            int maxId = (int) this.blogDao.maxId();
            // 添加到 lucene 中
            addIndex(maxId + "", parameterMap);
            // 进行网页静态化
            addStaticPage(maxId + "", parameterMap);} catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();}
        return "blogList";
    }