Java:JSON和Map相互转换

Posted 2022-10-03 276815076

Java：JSON与Map相互转换

需要jar包：jackson-core-2.6.0.jar，jackson-databind-2.6.0.jar，jackson-annotations-2.6.0.jar

1. JSON String to Map

package com.inspur.trc.util;

import java.util.HashMap;
import java.util.Map;

import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;

public class Json2Map
    public static void main(String[] args)
        String json = "\"name\":\"zitong\", \"age\":\"26\"";
        Map<String, String> map = new HashMap<String, String>();
        ObjectMapper mapper = new ObjectMapper();

        try
            map = mapper.readValue(json, new TypeReference<HashMap<String,String>>());
            System.out.println(map);
        catch(Exception e)
            e.printStackTrace();
       
   

运行结果：
age=26, name=zitong
2. Map to JSON String

package com.inspur.trc.util;

import java.util.HashMap;
import java.util.Map;

import com.fasterxml.jackson.databind.ObjectMapper;

public class Map2Json
    public static void main(String[] args)
        try
            ObjectMapper mapper = new ObjectMapper();
            String json = "";

            Map<String, String> map = new HashMap<String,String>();
            map.put("name", "zitong");
            map.put("age", "26");

            json = mapper.writeValueAsString(map);

            System.out.println(json);
        catch(Exception e)
            e.printStackTrace();
       
   

运行结果：
"age":"26","name":"zitong"
3. Map to JSON File

package com.inspur.trc.util;

import java.io.File;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.fasterxml.jackson.databind.ObjectMapper;

public class Map2JsonFile
    public static void main(String[] args)
        ObjectMapper mapper = new ObjectMapper();
        Map<String, Object> map = new HashMap<String, Object>();
        map.put("name", "zitong");
        map.put("age", 29);

        List<Object> list = new ArrayList<Object>();
        list.add("music");
        list.add("football");

        map.put("hobby", list);

        try
            mapper.writeValue(new File("F:/user.json"), map);
        catch (Exception e)
            e.printStackTrace();
       
   

运行结果：F:/user.json
"age":29,"name":"zitong","hobby":["music","football"]
4. JSON File To Map

package com.inspur.trc.util;

import java.io.File;
import java.util.List;
import java.util.Map;

import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;

public class JsonFile2Map
    public static void main(String[] args)
        try
            ObjectMapper mapper = new ObjectMapper();

            Map<String, Object> map = mapper.readValue(new File("F:/user.json"),new TypeReference<Map<String, Object>>());

            System.out.println("name: " + map.get("name"));
            System.out.println("age: " + map.get("age"));

            @SuppressWarnings("unchecked")
            List<String> list = (List<String>)map.get("hobby");
            System.out.print("hobby: ");
            for(String str : list)
                System.out.print(str+ " ");
           

        catch(Exception e)
            e.printStackTrace();
       
   

运行结果：
name: zitong
age: 29
hobby: music football

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