java对象转json

学会了在j2ee中使用ajax后,有时候从服务器返回客户端的数据是对象，自己手动拼凑
json字符串容易出错，通过谷歌知道了json-lib这个类库，方便的支持java中对象到json字符串的转化。 
    看source-forge的json-lib介绍说，需要 
jakarta commons-lang 2.4 
jakarta commons-beanutils 1.7.0 
jakarta commons-collections 3.2 
jakarta commons-logging 1.1.1 
ezmorph 1.0.6 

jar包下载:java2json.jar 

  这些jar包的支持，下载下来试了一把，挺好用的，写出来，与大家分享。 
代码如下：

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

import net.sf.json.JSONArray;
import net.sf.json.JSONObject;


public class Test {
public static void main(String[] args) {
//当是对象的时候
Student student = new Student();
student.setAge(18);
student.setName("zhangsan");
student.setSex("male");
JSONObject jsonObject = JSONObject.fromObject(student);
System.out.println(jsonObject);//输出{"age":18,"name":"zhangsan","sex":"male"}
//当是数组或list的时候
Student[] stus = new Student[5];
List<Student> stuList = new ArrayList<Student>();
for (int i = 0; i < stus.length; i++) {
stus[i] = new Student();
stus[i].setAge(i*10+8);
stus[i].setName("zhang"+i);
stus[i].setSex("male");
//添加到list,一会儿用
stuList.add(stus[i]);
}
JSONArray jsonArray = JSONArray.fromObject(stus);
System.out.println(jsonArray);//和下面打印的结果相同
// 结果：[{"age":8,"name":"zhang0","sex":"male"}, {"age":18,"name":"zhang1","sex":"male"},{"age":28,"name":"zhang2","sex":"male"},{"age":38,"name":"zhang3","sex":"male"},{"age":48,"name":"zhang4","sex":"male"}]
JSONArray jsonArrayFromList = JSONArray.fromObject(stuList);
System.out.println(jsonArrayFromList);//和上面打印的结果相同
//当既有对象又有数组的时候
Map<String,Object> map = new HashMap<String,Object>();
Teacher teacher = new Teacher();
teacher.setAge(30);
teacher.setName("laoshi");
teacher.setSex("male");
map.put("teacher", teacher);
map.put("student", stuList);
JSONObject jsonObjectFromMap = JSONObject.fromObject(map);
System.out.println(jsonObjectFromMap);
//结果：
//{"student":[{"age":8,"name":"zhang0","sex":"male"},{"age":18,"name":"zhang1","sex":"male"},{"age":28,"name":"zhang2","sex":"male"},{"age":38,"name":"zhang3","sex":"male"},{"age":48,"name":"zhang4","sex":"male"}],"teacher":{"age":30,"name":"laoshi","sex":"male"}}
}
}