13--redis基础代码

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       /* //1.调用service查询
        ProvinceService service = new ProvinceServiceImpl();
        List<Province> list = service.findAll();
        //2.序列化list为json
        ObjectMapper mapper = new ObjectMapper();
        String json = mapper.writeValueAsString(list);*/

        //1.调用service查询
        ProvinceService service = new ProvinceServiceImpl();
        String json = service.findAllJson();

        System.out.println(json);
        //3.响应结果
        response.setContentType("application/json;charset=utf-8");
        response.getWriter().write(json);

}

public class JDBCUtils {

private static DataSource ds ;

static {

        try {
            //1.加载配置文件
            Properties pro = new Properties();
            //使用ClassLoader加载配置文件，获取字节输入流
            InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
            pro.load(is);

//2.初始化连接池对象
ds = DruidDataSourceFactory.createDataSource(pro);

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

    /**
     * 获取连接池对象
     */
    public static DataSource getDataSource(){
        return ds;
    }

    /**
     * 获取连接Connection对象
     */
    public static Connection getConnection() throws SQLException {
        return ds.getConnection();
    }
}

public String findAllJson() {
        //1.先从redis中查询数据
        //1.1获取redis客户端连接
        Jedis jedis = JedisPoolUtils.getJedis();
        String province_json = jedis.get("province");

        //2判断 province_json 数据是否为null
        if(province_json == null || province_json.length() == 0){
            //redis中没有数据
            System.out.println("redis中没数据，查询数据库...");
            //2.1从数据中查询
            List<Province> ps = dao.findAll();
            //2.2将list序列化为json
            ObjectMapper mapper = new ObjectMapper();
            try {
                province_json = mapper.writeValueAsString(ps);
            } catch (JsonProcessingException e) {
                e.printStackTrace();
            }

            //2.3 将json数据存入redis
            jedis.set("province",province_json);
            //归还连接
            jedis.close();

        }else{
            System.out.println("redis中有数据，查询缓存...");
        }

return province_json;
}

private static JedisPool jedisPool;

    static{
        //读取配置文件
        InputStream is = JedisPoolUtils.class.getClassLoader().getResourceAsStream("jedis.properties");
        //创建Properties对象
        Properties pro = new Properties();
        //关联文件
        try {
            pro.load(is);
        } catch (IOException e) {
            e.printStackTrace();
        }
        //获取数据，设置到JedisPoolConfig中
        JedisPoolConfig config = new JedisPoolConfig();
        config.setMaxTotal(Integer.parseInt(pro.getProperty("maxTotal")));
        config.setMaxIdle(Integer.parseInt(pro.getProperty("maxIdle")));

//初始化JedisPool
jedisPool = new JedisPool(config,pro.getProperty("host"),Integer.parseInt(pro.getProperty("port")));

}

    /**
     * 获取连接方法
     */
    public static Jedis getJedis(){
        return jedisPool.getResource();
    }

public class JedisTest {

    /**
     * 快速入门
     */
    @Test
    public void test1(){
        //1. 获取连接
        Jedis jedis = new Jedis("localhost",6379);
        //2. 操作
        jedis.set("username","zhangsan");