Json处理

FastJSON

1. 引入依赖或者Jar包

   <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>fastjson</artifactId>
        <version>1.1.23</version>
    </dependency>
   

2. 将Map转成JSON

   Map<String, Object> map = new HashMap<String, Object>();
   	map.put("key1", "value1");
   	map.put("key2", "value2");
   	String mapJson = JSON.toJSONString(map);
   	System.out.println(mapJson);
   	//输出{"key1":"value1","key2":"value2"}
   
   	//TODO 泛型的反序列化（使用TypeReference传入类型信息）
   	Map<String, Object> map2 = JSON.parseObject(mapJson, new TypeReference<Map<String, Object>>(){});
   	System.out.println(map2);
   

3. 将List<Map转成JSON

   List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
   		Map<String, Object> map1 = new HashMap<String, Object>();
   		map1.put("key1", "value1");
   		map1.put("key2", "value2");
   
   		Map<String, Object> map2 = new HashMap<String, Object>();
   		map2.put("key1", "value3");
   		map2.put("key2", "value4");
   		list.add(map1);
   		list.add(map2);
   
   		String jsonstr = JSON.toJSONString(list);
   		System.out.println(jsonstr);
   		System.out.println("==========================================");
   
   		//输出 [{"key1":"value1","key2":"value2"},{"key1":"value3","key2":"value4"}]
   		// TODO String objJson = JSON.toJSONString(Object object, boolean prettyFormat)
   		//TODO 传入一个对象和一个布尔类型（是否格式化），将对象转成格式化后的JSON字符串。
   		String listJson1 = JSONArray.toJSONString(list, true);
   		System.out.println(listJson1);
   		System.out.println("==========================================");
   		String listJson2 = JSONArray.toJSONString(list, false);
   		System.out.println(listJson2);
   		System.out.println("==========================================");
   
   		//TODO 使用单引号
   		String listJson = JSON.toJSONString(list, SerializerFeature.UseSingleQuotes);
   		//输出 [{'key1':'value1','key2':'value2'},{'key1':'value3','key2':'value4'}]
   		System.out.println(listJson);
   		System.out.println("==========================================");
   
   		//TODO	集合反序列化
   		List<Map> list1 = JSON.parseArray(listJson, Map.class);
   		for(Map<String, Object> map : list1){
   			System.out.println(map.get("key1"));
   			System.out.println(map.get("key2"));
   		}
   		//输出 value1 value2 value3 value4

4. Java bean

   UserDO userDO = new UserDO();
   		userDO.setId(1);
   		userDO.setName("乐乐");
   		userDO.setAge(12);
   		String userJson = JSON.toJSONString(userDO);
   		System.out.println(userJson);
   		//输出 {"age":12,"id":1,"username":"乐乐"}
   
   		//TODO 普通序列化
   		UserDO user1 = (UserDO) JSON.parse(userJson);
   		System.out.println(user1.getAge());
   		//输出 12
   
   		//TODO 指定Class信息反序列化
   		UserDO user2 = JSON.parseObject(userJson,UserDO.class);
   		System.out.println(user2.getName());
   		//输出 乐乐
   

5. 时间

   //TODO （1）FastJSON将java.util.Date转成long。
   		String dateJson1 = JSON.toJSONString(new Date());
   		System.out.println(dateJson1);
   		System.out.println("==========================================");
   
   		//输出 1547900848449
   		//TODO（2）使用SerializerFeature特性格式化日期。
   		String dateJson2 = JSON.toJSONString(new Date(), SerializerFeature.WriteDateUseDateFormat);
   		System.out.println(dateJson2);
   		System.out.println("==========================================");
   
   		//输出 "2019-01-19 20:29:24"
   		//TODO（3）指定输出日期格式
   		String dateJson3 = JSON.toJSONStringWithDateFormat(new Date(), "yyyy-MM-dd HH:mm:ss");
   		System.out.println(dateJson3);
   		System.out.println("==========================================");
   		//输出"2019-01-19 20:32:34"