fastjson 进行json的解析和拼装和用ObjectMapper序列化和反序列化

ゝ一世哀愁。 2023-05-29 03:40 38阅读 0赞

### fastjson 进行json的解析和拼装和用ObjectMapper序列化和反序列化 ###

*   *  1. 使用 fastjson 进行json的解析和拼装
     *  2. 用ObjectMapper序列化和反序列化

## 1. 使用 fastjson 进行json的解析和拼装 ##

fastjson依赖：

<dependency>
                <groupId>com.alibaba</groupId>
                <artifactId>fastjson</artifactId>
                <version>1.2.58</version>
    </dependency>

1.解析json字符串

@org.junit.Test
        public void JsonToString() { 
            String jsonString = "{\n" +
                    " \"student\":[{\n" +
                    " \"name\":\"韩信\",\n" +
                    " \"age\":\"18\"\n" +
                    " },\n" +
                    " {\n" +
                    " \"name\":\"阿离\",\n" +
                    " \"age\":\"22\"\n" +
                    " },\n" +
                    " {\n" +
                    " \"name\":\"立华奏\",\n" +
                    " \"age\":\"21\"\n" +
                    " }]\n" +
                    "}";
    
            JSONObject jsonObject = new JSONObject();
            //将json字符串转换为jsonObject
            jsonObject = jsonObject.parseObject(jsonString);
            //获取json
            JSONArray jsonArray = jsonObject.getJSONArray("student");
            for (Object object : jsonArray) { 
                JSONObject object1 = (JSONObject)object;
                String name = object1.getString("name");
                String url = object1.getString("age");
                System.out.println(name + url);
            }
    
        }

输出结果为：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0RyZWFtYm95X3c_size_16_color_FFFFFF_t_70]

2.组装json数据

@org.junit.Test
    public void stringTOJson() { 
        JSONObject jsonObject = new JSONObject();
        //构建json数组
        JSONArray jsonArray = new JSONArray();
        JSONObject stObject = new JSONObject();
        stObject.put("name","韩信");
        stObject.put("age", "11");
        JSONObject stObject1 = new JSONObject();
        stObject1.put("name","阿离");
        stObject1.put("age", "22");
        jsonArray.add(stObject1);
        jsonObject.put("student", jsonArray);
        System.out.println(jsonObject.toJSONString());
    
    }

输出结果为：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0RyZWFtYm95X3c_size_16_color_FFFFFF_t_70 1]

**案例：**

实现如下的json拼接：

{ 
    	"code": 0,
    	"msg": "",
    	"count": 1000,
    	"data": [
    		{ 
    		  "id": 110,
    		  "saplingsId":1,
    		  "saplingsName": 1,
    		  "age": 1,
    		  "baseName": 1,
    		  "fieldsName": 1,
    		  "coordinate": 1
    		}
    	]
    }

实现代码：

package com.test.controller;
    
    import java.util.List;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.ResponseBody;
    
    import com.alibaba.fastjson.JSONArray;
    import com.alibaba.fastjson.JSONObject;
    import com.test.entity.Saplings;
    import com.test.service.SaplingsService;
    
    
    /** * 草木管理 * @author wuhao * */
    @Controller
    @RequestMapping("/saplings")
    public class SaplingsController { 
    	
    	@Autowired
    	private SaplingsService saplingsService;
    	
    	@ResponseBody
    	@RequestMapping("/queryforall")
    	public String queryforall(){ 
    		
    		List<Saplings> saplingslist= saplingsService.queryAll();
    		//System.out.println(saplingslist.toString());
    		
    		JSONObject jsonObject = new JSONObject();
    		JSONArray jsonArray = new JSONArray();
    		
    		for (Saplings saplings : saplingslist) { 
    			jsonArray.add(saplings);
    		}
    		jsonObject.put("code", 0);
    		jsonObject.put("code", "");
    		jsonObject.put("count", 1000);
    		jsonObject.put("data", jsonArray);
    		
    		//System.out.println(jsonObject.toJSONString());
    		return jsonObject.toJSONString();
    	}
    	
    }

## 2. 用ObjectMapper序列化和反序列化 ##

1.  序列化

**a) writeValueAsString(对象)**

将User对象转为json字符串

ObjectMapper mapper = new ObjectMapper();
    String jsonstring = mapper.writeValueAsString(User.class);

**b) writeValue（参数，对象）：**

参数：
    
    	File： 将对象转为json字符串，保存到指定的文件中
    	
    	Writer： 将对象转为json字符串，并将json数据填充到字符输出流中
    	
    	outputStream： 将对象转为json字符串，并将json数据填充到字节输出流中

通过ObjectMapper类的 writeValue()方法序列化java对象至json字符串

ObjectMapper objectMapper = new ObjectMapper();
    Car car = new Car("yellow", "renault");
    objectMapper.writeValue(new File("target/car.json"), car);

输出：

{ "color":"yellow","type":"renault"}

1.  反序列化：

**c) readValue**

将json字符串转成User对象输出

ObjectMapper mapper = new ObjectMapper();
    User user = String mapper.readValue(jsonstring,User.class);

--------------------

**参考链接：**  
[https://blog.csdn.net/qq\_42651904/article/details/102759877][https_blog.csdn.net_qq_42651904_article_details_102759877]  
[https://blog.csdn.net/neweastsun/article/details/87940257][https_blog.csdn.net_qq_42651904_article_details_102759877]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0RyZWFtYm95X3c_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20191210141555179.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0RyZWFtYm95X3c=,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0RyZWFtYm95X3c_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20191210141553109.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0RyZWFtYm95X3c=,size_16,color_FFFFFF,t_70
[https_blog.csdn.net_qq_42651904_article_details_102759877]: https://blog.csdn.net/qq_42651904/article/details/102759877