java组装json和提取一个json的例子

package jsonparsed;
import net.sf.json.JSONException;
import net.sf.json.JSONObject;
import net.sf.json.JSONArray;
public class jsonparsed {
    // 创建JSONObject对象
    private static JSONObject createJSONObject() {
        JSONObject jsonObject = new JSONObject();
        jsonObject.put("ret", new Integer());
        jsonObject.put("msg", "query");
        JSONObject dataelem1=new JSONObject();
        //{"deviceid":"SH01H20130002","latitude":"32.140","longitude":"118.640","speed":"","orientation":""}
        dataelem1.put("deviceid", "SH01H20130002");
        dataelem1.put("latitude", "32.140");
        dataelem1.put("longitude", "118.640");

        JSONObject dataelem2=new JSONObject();
        //{"deviceid":"SH01H20130002","latitude":"32.140","longitude":"118.640","speed":"","orientation":""}
        dataelem2.put("deviceid", "SH01H20130002");
        dataelem2.put("latitude", "32.140");
        dataelem2.put("longitude", "118.640");

     // 返回一个JSONArray对象
        JSONArray jsonArray = new JSONArray();

        jsonArray.add(, dataelem1);
        jsonArray.add(, dataelem2);
        jsonObject.element("data", jsonArray);

        return jsonObject;
    }
public static void main(String [] args){
    JSONObject jsonObject = jsonparsed.createJSONObject();//静待  方法，直接通过类名+方法调用
    // 输出jsonobject对象
    System.out.println("jsonObject：" + jsonObject);
    // 添加JSONArray后的值

    // 根据key返回一个字符串
    String username = jsonObject.getString("ret");
    System.out.println("username==>" + username);
}
}