前言

Java 读取Json文件的内容。

pom 依赖

 <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>fastjson</artifactId>
        <version>1.2.47</version>
 </dependency>
 
<dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.6</version>
        </dependency>

程序

• Json文件

{
  "station":[
    {
      "dbm":-83,
      "lac":0,
      "mcc":"460",
      "mnc":"11",
      "psc":0,
      "sid":0,
      "type":"Lte"
    }
  ],
  "mac":[
    {
      "id":"enyouh",
      "mac":"b8:80:35:e6:68:51",
      "str":"-89"
    }
  ]
}

• 程序

package study.nian.project01;

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

import java.io.File;
import java.io.IOException;
import org.apache.commons.io.FileUtils;

public class QueryJson {

    public static void main(String[] args) {
        
        JSONObject jsonObject = new JSONObject();
        jsonObject.put("stationList", "[{\"cid\":125702705, \"dbm\":-83, \"lac\":0, \"mcc\":\"460\", \"mnc\":\"11\", \"psc\":0, \"sid\":0, \"type\":\"Lte\" }]");
        jsonObject.put("macList", "[{\"id\":\"enyouhuayi-5G\",\"mac\":\"b8:80:35:e6:68:51\",\"str\":\"-89\"}]");
        System.out.println("jsonObject的K：stationList，V：" + jsonObject.getString("stationList"));
        System.out.println("jsonObject的K：macList，V：" + jsonObject.getString("macList"));

        try {
            File file = new File("./src/main/java/study/nian/project01/entity/ea.json") ;
            String content = FileUtils.readFileToString(file,"UTF-8");
            JSONObject jsonObj = JSON.parseObject(content);

            System.out.println("K：stationList，V：" + jsonObj.getString("station"));
            System.out.println("K：macList，V：" + jsonObj.getString("mac"));

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}

结果展示

jsonObject的K：stationList，V：[{"cid":125702705, "dbm":-83, "lac":0, "mcc":"460", "mnc":"11", "psc":0, "sid":0, "type":"Lte" }]
jsonObject的K：macList，V：[{"id":"enyouhuayi-5G","mac":"b8:80:35:e6:68:51","str":"-89"}]
K：stationList，V：[{"psc":0,"mnc":"11","mcc":"460","type":"Lte","dbm":-83,"lac":0,"sid":0}]
K：macList，V：[{"str":"-89","id":"enyouh","mac":"b8:80:35:e6:68:51"}]

总结

• 文件的话，FileUtils的使用，pom文件加载
• Json文件K-V存储，加入数据用put（）方法

需要添加fastjson依赖
pom依赖

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

读取json工具类

/**
     * 读取json文件，返回json串
     * @param fileName
     * @return
     */
    public static String readJsonFile(String fileName) {
        String jsonStr = "";
        try {
            File jsonFile = new File(fileName);
            FileReader fileReader = new FileReader(jsonFile);

            Reader reader = new InputStreamReader(new FileInputStream(jsonFile),"utf-8");
            int ch = 0;
            StringBuffer sb = new StringBuffer();
            while ((ch = reader.read()) != -1) {
                sb.append((char) ch);
            }
            fileReader.close();
            reader.close();
            jsonStr = sb.toString();
            return jsonStr;
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
    }

public class Hello {
 public static void main(String[] args) throws  Exception{
        String path = Hello.class.getClassLoader().getResource("test.json").getPath();
        String s = ReadUtils.readJsonFile(path);
        JSONObject jobj = JSON.parseObject(s);
        System.out.println("name"+jobj.get("name"));
        JSONObject address1 = jobj.getJSONObject("address");
        String street = (String) address1.get("street");
        String city = (String) address1.get("city");
        String country = (String) address1.get("country");

        System.out.println("street :" + street);
        System.out.println("city :" + city);
        System.out.println("country :" + country);

        JSONArray links = jobj.getJSONArray("links");

        for (int i = 0 ; i < links.size();i++){
            JSONObject key1 = (JSONObject)links.get(i);
            String name = (String)key1.get("name");
            String url = (String)key1.get("url");
            System.out.println(name);
            System.out.println(url);
        }
    }
}