map转换成JSON的方法

 json-lib

<dependency>
            <groupId>net.sf.json-lib</groupId>
            <artifactId>json-lib</artifactId>
            <version>2.4</version>
             <classifier>jdk15</classifier>
        </dependency>

 

import java.util.HashMap;
import java.util.Map;
 
import net.sf.json.JSONObject;
 
public class aaa {
	  public static void main(String[] args) {
	        Map map = new HashMap();
	        map.put("msg", "yes");//map里面装有yes
	        JSONObject jsonObject = JSONObject.fromObject(map);
	        System.out.println("输出的结果是：" + jsonObject);
	        //3、将json对象转化为json字符串
	        String result = jsonObject.toString();
	        System.out.println(result);
	    }
}

json-lib是一个比较老的解决方案，近几年都没有升级过，它的适用环境是JDK1.5，使用JDK1.6就有可能会报错。所以配置上加入classifier-jdk15来解决这个问题。JAR下载链接

Map map = new HashMap();
        map.put("success", "true");
        map.put("photoList", photoList);
        map.put("currentUser", "zhang");
        
        //net.sf.json.JSONObject 将Map转换为JSON方法
        JSONObject json = JSONObject.fromObject(map);

        //org.json.JSONObject 将Map转换为JSON方法
        JSONObject json =new JSONObject(map);

2alibaba

JSONUtils.toJSONString(requestMap);    com.alibaba.fastjson.JSON

maven坐标

<!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.41</version>
</dependency>

3  google

new Gson().toJson(param);         com.google.gson.2.2.2.jar       JAR包下载

maven坐标

<!-- https://mvnrepository.com/artifact/com.google.code.gson/gson -->
<dependency>
    <groupId>com.google.code.gson</groupId>
    <artifactId>gson</artifactId>
    <version>2.3.1</version>
</dependency>

//Map转换成JSON

Map<String,String> map = new HashMap<String,String>(); 
map.put("a","aaa"); 
map.put("b","bbb"); 
map.put("c","ccc"); 
String json=JSON.toJSONString(map); 
System.out.println(json);//输出{"a":"aaa","b":"bbb","c":"ccc"}

//JSON转换成Map

Map map1 = JSON.parseObject(json);
System.out.println(map1.get("a"));
for (Object mapData : map.entrySet()) {
Map.Entry<String,String> entry = (Map.Entry<String,String>)mapData;
System.out.println(entry.getKey()+"--->"+entry.getValue());
}
/*输出
b--->bbb
c--->ccc
a--->aaa
*/

map中含有对象Map -> JSON

//Map -> JSON
Map<String,Bar> map = new HashMap<String, Bar>(); 
map.put("a",new Bar()); 
map.put("b",new Bar()); 
map.put("c",new Bar()); 
String json = JSON.toJSONString(map,true); 
System.out.println(json); 
/*
输出{
	"a":{
		"barAge":383687382,
		"barDate":1494945882018,
		"barName":"name_1689176802"
	},
	"b":{
		"barAge":-100528778,
		"barDate":1494945882018,
		"barName":"name_-878176366"
	},
	"c":{
		"barAge":-344075192,
		"barDate":1494945882018,
		"barName":"name_-1710740534"
	}
}
*/

//JSON -> Map

Map<String,Bar> map1 = (Map<String,Bar>)JSON.parse(json); 
for (String key : map1.keySet()) { 
System.out.println(key+":"+map1.get(key)); 
} 
/*输出
b:{"barAge":-100528778,"barDate":1494945882018,"barName":"name_-878176366"}
c:{"barAge":-344075192,"barDate":1494945882018,"barName":"name_-1710740534"}
a:{"barAge":383687382,"barDate":1494945882018,"barName":"name_1689176802"}
*/

--------------------===-------------------------附--MAP的ASCII排序-----------------------===------------------------

StringBuilder sb = new StringBuilder();
	List<String> keys = new ArrayList<String>(map.keySet());
	Collections.sort(keys);//排序。
	for(String k : keys){
		String v = params.get(k);
		if(StringUtils.isNotEmpty(v)){
			sb.append(v);
		}
	}
	//return MD5.toMD5(sb+key, "UTF-8");这个就不用看了~~~