java组装json字符串 java创建json字符串

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response.setContentType(   "application/json" );   //服务器响应的类型
               String jsonString =   request.getParameter(   "testJsonString"   );  //获取传过来的json字符串

          JSONObject jsonobj = JSONObject.   fromObject (jsonString); //把 json格式的字符串转化为json对象

          System. out .println( "name:"   +jsonobj.getString( "name" )+   ",age:" +jsonobj.getInt( "age"   ));

              输入结果： name:james,age:29
       (2)把json数组形式的字符串转化为json数组，再解析出来

              // [{"name":"olay","age":21},{"name":"james","age":22},{"name":"kobe","age":34}]

             response.setContentType( "application/json" );   //服务器响应的类型

            String jsondata = request.getParameter(   "testJsonArray" );  //获取传过来的json字符串

            System.   out .println(jsondata);    // [{"name":"olay","age":21},{"name":"james","age":22},{"name":"kobe","age":34}]

            JSONArray jsonArray = JSONArray.   fromObject (jsondata); //转化为json数组

                    for ( int   i=0;i<jsonArray.size();i++){   //遍历json数组

                         JSONObject obj = JSONObject.   fromObject (jsonArray.get(i)); //转化为json对象

                         System. out .println( "name:"   +obj.getString( "name" )+   ",age:" +obj.getInt( "age"   ));

                  }

   2.java中创建json
       (1)java字符串转为为json对象

             String jsonString =  "{\"name\":\"olay\",\"age\":100}"   ;

             JSONObject j = JSONObject. fromObject (jsonString); // java字符串转为为json对象

            System.   out .println(j);   // {"name":"olay","age":100}
       (2)java对象转化为json对象

             User user1 =   new   User();

            user1.setName(   "james" );

            user1.setAge(29);

             JSONObject obj =JSONObject . fromObject (user1);  // 转化为json对象

            System.   out .println(obj);   // {"age":29,"name":"james"}
       (3)java中lst集合转为为json数组

             User user1 =   new   User();

            user1.setName(   "james" );

            user1.setAge(29);

            User user2 =   new   User();

            user2.setName(   "olay" );

            user2.setAge(22);


             List   list =   new   ArrayList ();

             list.add(user1) ;

             list.add(user2) ;

             JSONArray arr = JSONArray. fromObject (list);  // lst集合转为为json数组

            System.   out .println(arr);    // [{"age":29,"name":"james"},{"age":22,"name":"olay"}]
       (4)java中Map集合转化为json二位数组

           Student student =   new   Student();

          student.setName(   "张三" );

          student.setAge(15);

          student.setSex(   "男" );


          Teacher teacher =   new   Teacher();

          teacher.setName(   "梨花" );

          teacher.setAge(29);

          teacher.setSex(   "女" );

           Map   map =   new   HashMap ();

           map.put( "student" , student) ;

            map.put( "teacher" , teacher) ;

           JSONArray arrMap = JSONArray. fromObject (map);  // Map集合转化为json二位数组

          System.   out .println(arrMap);  // [{"student":{"age":15,"name":"张三","sex":"男"},"teacher":{"age":29,"name":"梨花","sex":"女"}}]