Java读取并修改保存JSON文件

Posted 2023-02-16 JOSON.

文章目录

• POM依赖
• 读取JSON文件
• 解析JSON
• 生成新JSON文件

JSON文件存放在项目的resources资源目录下，内容如下：

test.json

  "core": 123,
  "channel":"ok",
  "parameter":[
    "aaa","bbb","ccc"
  ],
  "content": [
    
      "reader":"xiaoming",
      "writer":"lisi"
    
  ]

POM依赖

<dependency>
	<groupId>com.alibaba</groupId>
	<artifactId>fastjson</artifactId>
	<version>1.2.47</version>
</dependency>

读取JSON文件

private String readJsonFile() 
    String jsonStr = "";
    try 
        InputStream in = getClass().getClassLoader().getResourceAsStream("test.json");
        Reader reader = new InputStreamReader(in,"utf-8");
        int ch = 0;
        StringBuffer sb = new StringBuffer();
        while ((ch = reader.read()) != -1) 
            sb.append((char) ch);
        

        reader.close();
        jsonStr = sb.toString();
        return jsonStr;
     catch (IOException e) 
        e.printStackTrace();
        return null;
    

解析JSON

JSONObject jobj = JSON.parseObject(readJsonFile());
System.out.println("=======节点元素=======");
System.out.println(jobj.get("core"));
System.out.println(jobj.get("channel"));
System.out.println("=======列表元素=======");
System.out.println(jobj.getJSONArray("parameter").get(1));
JSONObject contentObj =  (JSONObject) jobj.getJSONArray("content").get(0);
System.out.println(contentObj.get("writer"));

//修改元素方法与操作map类似，通过put(key,value)完成
jobj.put("core","333")

输出结果：

=节点元素=
123
ok
=列表元素=
bbb
lisi

生成新JSON文件

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.serializer.SerializerFeature;


private void writeJsonFile(JSONObject jobj)
    String content = JSON.toJSONString(jobj, SerializerFeature.PrettyFormat, SerializerFeature.WriteMapNullValue,
            SerializerFeature.WriteDateUseDateFormat);
    try 
        File file = new File(System.getProperty("user.dir")+ File.separator+ "New.json");
        if (file.exists()) 
            file.delete();
        
        file.createNewFile();
        // 写入文件
        Writer write = new OutputStreamWriter(new FileOutputStream(file), StandardCharsets.UTF_8);
        write.write(content);
        write.flush();
        write.close();
     catch (Exception e) 
        e.printStackTrace();