关于java:Java解析Json字符串

Json 是一种轻量级的数据交换格局, 其语法格局非常简单

对象：{key : value, key: value…}
数组：[元素 1, 元素 2 …]

在平时的开发中，咱们都须要应用 Json 在前后端之间进行数据交换，这里咱们次要来看一下 Java 最方便快捷的解析 Json 的形式

1. 谷歌 Gson
   将对象转为 Json
   String toJson(Object src)

   将 json 转为对象
   <T> T fromJson(String json, Class<T> classOfT)

   将 json 转为汇合
   <T> T fromJson(String json, Type typeOfT)

   代码示例：

   /**
     * 将对象转换为 json
     * @param o
     * @return
     */
    public static String getJsonString(Object o){return new Gson().toJson(o);
    }

    /**
     * 将 json 转为对象
     * @param jsonString
     * @param clazz
     * @return
     */
    public static Object getObjectFromJson(String jsonString, Class<?> clazz){return new Gson().fromJson(jsonString, clazz);
    }

    /**
     * 将 json 转为汇合
     * @param jsonString
     * @param type
     * @return
     */
    public static Object getObjectFromJson(String jsonString, Type type){return new Gson().fromJson(jsonString, type);
    }

    public static void main(String[] args) {
          // 对象转 json
        String objectJson = getJsonString(new Student(18, "jason"));
         // 后果：{"age":18,"name":"jason"}
        System.out.println(objectJson);  
      
        // json 转对象
          Student student = (Student) getObjectFromJson("{\"age\":18,\"name\":\"jason\"}", Student.class);
          // 后果：Student{age=18, name='jason'}
        System.out.println(student);  
      
        // List
          List<Student> list = new ArrayList<>();
        list.add(new Student(18, "jason"));
        list.add(new Student(19, "lee"));

          // 汇合转 json
        String listJson = getJsonString(list);
         // 后果：[{"age":18,"name":"jason"},    {"age":19,"name":"lee"}]
        System.out.println(listJson);  
        

          // Json 转 List
        Type type = new TypeToken<ArrayList<Student>>() {}.getType();
        ArrayList<Student> arrayList = (ArrayList<Student>) getObjectFromJson(listJson,           type);
          // 后果：[Student{age=18, name='jason'}, Student{age=19, name='lee'}]
        System.out.println(arrayList.toString());  
          
          // HashMap
          HashMap<String, String> hashMap = new HashMap<>();
        hashMap.put("name", "jason");
        hashMap.put("age", "18");
      
          // HashMap 转 json
        String mapJson = getJsonString(hashMap);
        // 后果：{"name":"jason","age":"18"}
        System.out.println(mapJson);

        // json 转 HashMap
        Type mapType = new TypeToken<HashMap<String, String>>() {}.getType();
        HashMap<String, String> map = (HashMap<String, String>) getObjectFromJson(mapJson, mapType);
          
        /**
         * 后果
         * key:name, value:jason
         * key:age, value:18
         */
        for (Map.Entry<String, String> entry : map.entrySet()){System.out.println("key:" + entry.getKey() + ", value:" + entry.getValue());
        }
    }

1. 阿里 FastJson
   对象转 json
   static String toJSONString(Object object)

   json 转对象
   static <T> T parseObject(String text, Class<T> clazz)

   json 转 List
   static <T> List<T> parseArray(String text, Class<T> clazz)

   json 转 Map
   static <T> T parseObject(String text, TypeReference<T> type, Feature... features)

   代码示例：

/**
 * 对象转 json
 * @param o
 * @return
 */
public static String getJsonString(Object o){return JSON.toJSONString(o);
}

/**
 * json 转对象
 * @param jsonString
 * @param clazz
 * @return
 */
public static Object getObjectFromJson(String jsonString, Class<?> clazz){return JSON.parseObject(jsonString, clazz);
}

/**
 * json 转 list
 * @param jsonString
 * @param clazz
 * @return
 */
public static Object getArrayFromJson(String jsonString, Class<?> clazz){return JSON.parseArray(jsonString, clazz);
}

/**
 * json 转 map
 * @param jsonString
 * @param typeReference
 * @return
 */
public static Object getMapFromJson(String jsonString, TypeReference<?> typeReference){return JSON.parseObject(jsonString, typeReference);
}

public static void main(String[] args) {
        // 对象转 json
        String objectJson = getJsonString(new Student(18, "jason"));
        // 后果：{"age":18,"name":"jason"}
        System.out.println(objectJson);

        // json 转对象
        Student student = (Student) getObjectFromJson(objectJson, Student.class);
        // 后果：Student{age=18, name='jason'}
        System.out.println(student);

        // List
        List<Student> list = new ArrayList<>();
        list.add(new Student(18, "jason"));
        list.add(new Student(19, "lee"));

        // List 转 json
        String listJson = getJsonString(list);
        // 后果：[{"age":18,"name":"jason"},{"age":19,"name":"lee"}]
        System.out.println(listJson);

        // json 转 List
        List<Student> students = (List<Student>) getArrayFromJson(listJson, Student.class);
        // 后果：[Student{age=18, name='jason'}, Student{age=19, name='lee'}]
        System.out.println(students.toString());
      
        // Map
        HashMap<String, String> hashMap = new HashMap<>();
        hashMap.put("name", "jason");
        hashMap.put("age", "18");

        // Map 转 json
        String mapJson = getJsonString(hashMap);
        // 后果：{"name":"jason","age":"18"}
        System.out.println(mapJson);

        // json 转 HashMap
        TypeReference<HashMap<String, String>> typeReference = new TypeReference<HashMap<String, String>>() {};
        HashMap<String, String> map = (HashMap<String, String>) getMapFromJson(mapJson, typeReference);

        /**
         * 后果
         * key:name, value:jason
         * key:age, value:18
         */
        for (Map.Entry<String, String> entry : map.entrySet()){System.out.println("key:" + entry.getKey() + ", value:" + entry.getValue());
        }
}