JSON数据转换

关于JSON数据转换已经是很老的话题了，这里我们将又一次讨论JSON数据与Java对象的转换。

在http://www.json.org/上你可以发现一长串关于Java JSON的数据转换库：

org.json.

org.json.me.

Jackson JSONProcessor.

Json-lib.

JSONTools.

Stringtree.

SOJO.

Jettison.

json-taglib.

XStream.

Flexjson.

JONtools.

Argo.

jsonij.

fastjson.

mjson.

jjson.

json-simple.

json-io.

JsonMarshaller.

google-gson.

Json-smart.

FOSS NovaJSON.

这里先从最简单的org.json开始,如果是Maven项目，引入jar包非常容易，详情请参考： http://mvnrepository.com/artifact/org.json/json/20090211 当然你也可以在该站点上直接下载。

写一个简单的例子：关于JSON字符串转成Java最常见的List和Map的两个方法

package com.test.json;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

public class JSONUtil {

 public static List<</span>Map<</span>String, Object>> fromJSONStr2List(String jsonStr) throws JSONException {
  JSONArray jsonArr = new JSONArray(jsonStr);
        List<</span>Map<</span>String, Object>> list = new ArrayList<</span>Map<</span>String,Object>>();
        for (int i=0; i<</span>jsonArr.length(); i++) {
         JSONObject json2 = jsonArr.getJSONObject(i);
         list.add(fromJSONStr2Map(json2.toString()));
        }
        return list;
 }
 
 public static Map<</span>String, Object> fromJSONStr2Map(String jsonStr) throws JSONException {
    Map<</span>String, Object> map = new HashMap<</span>String, Object>();

       JSONObject json = new JSONObject(jsonStr);
       Iterator<</span>String> it = json.keys();
       while (it.hasNext()){
        String key = it.next();
        Object value = json.get(key);
        if (value instanceof JSONArray) {
         List<</span>Map<</span>String, Object>> list = new ArrayList<</span>Map<</span>String,Object>>();
         JSONArray jsonArr2 = ((JSONArray)value);
         for (int i=0; i<</span>jsonArr2.length(); i++) {
          JSONObject json2 = jsonArr2.getJSONObject(i);
          list.add(fromJSONStr2Map(json2.toString()));
            }
               map.put(key.toString(), list);
        } else {
         map.put(key.toString(), value);
        }
       } 
       return map;
 }
 
 public static void main(String[] args) throws Exception {
  List<</span>Map<</span>String, Object>> list = JSONUtil.fromJSONStr2List("[{\"name\":\"Richard\",\"age\":7},{\"name\":\"Susan\",\"age\":4}]");
  System.out.println(list.get(0).get("name"));
  Map<</span>String, Object> map = JSONUtil.fromJSONStr2Map("{\"name\":\"Richard\",\"age\":7}");
  System.out.println(map.get("name"));
 }

}

测试结果：

Richard
Richard