Java 连接MySQL，返回Json数据

1，连接数据库的简单操作，

    //这是链接数据库的

    Class.forName("com.mysql.jdbc.Driver");

    String path ="jdbc:mysql://127.0.0.1:3306/MyServletDB";

    Connectioncon =DriverManager.getConnection(path,"root","root");

    PreparedStatementps = (PreparedStatement)con.createStatement();

    ResultSet set =ps.executeQuery("select * from tb_user");

    while(set.next()){

        System.out.println("result = "+set.getInt(1));

    }

2，这里需要一些jar包，就是将对象，或者是数组转换为JSON的jar包。自行百度吧，我也忘记叫啥了，哈哈

    //内部类的调用，先实例化外部类

    TestJson.User u1 =new TestJson().new User("liyang", 25);

    TestJson.User u2 =new TestJson().new User("shuyang", 22);

    //User u2 = new User("shuayng", 22);

    ArrayList l = new ArrayList();

    l.add(u1);

    l.add(u2);

    System.out.println("-----"+u1.getAge());

    // Json 转数组需要用到set get 方法，在类需要实现该方法

    JSONObject obj = JSONObject.fromObject(u1);

    System.out.println(obj);

    // 数组转

    JSONArray array = JSONArray.fromObject(l);

    System.out.println(array);

    // Map转json

    Map map = new HashMap();

    map.put("one",u1);

    map.put("two",u2);

    map.put("three",l);

    JSONArray mArr= JSONArray.fromObject(map);

    System.out.println(mArr);

// 输出

{"age":25,"name":"liyang"}

[{"age":25,"name":"liyang"},{"age":22,"name":"shuyang"}]

[{"one":{"age":25,"name":"liyang"},"two":{"age":22,"name":"shuyang"},"three":[{"age":25,"name":"liyang"},{"age":22,"name":"shuyang"}]}]