JsonObject和Gson详解

参考文件：http://www.cnblogs.com/xwdreamer/archive/2011/12/16/2296904.html
一、JsonObject

1.JAR包简介

要使程序可以运行必须引入JSON-lib包，JSON-lib包同时依赖于以下的JAR包：

1. commons-lang.jar
2. commons-beanutils.jar
3. commons-collections.jar
4. commons-logging.jar 
5. ezmorph.jar
6. json-lib-2.4-jdk15.jar
7. json-lib-2.4-jdk15-javadoc.jar
8. json-lib-2.4-jdk15-sources.jar

2.JSONObject对象使用

JSON-lib包是一个beans,collections,maps,java arrays 和XML和JSON互相转换的包。在本例中，我们将使用JSONObject类创建JSONObject对象，然后我们打印这些对象的值。为了使用JSONObject对象，我们要引入"net.sf.json"包。为了给对象添加元素，我们要使用put()方法。

public static User getUserFromJson(String json) {
        User user = new User();
        try {
            JSONObject obj = JSONObject.fromObject(json);
            user.setUserId(obj.getInt(Tables.User.Fields.USERID));
            user.setAccount(obj.getString(Tables.User.Fields.ACCOUNT));
            user.setPassword(obj.getString(Tables.User.Fields.PASSWORD));
            user.setGender(obj.getInt(Tables.User.Fields.GENDER));
            user.setPermission(obj.getInt(Tables.User.Fields.PERMISSION));
            user.setName(obj.getString(Tables.User.Fields.NAME));
            user.setRemark(obj.getString(Tables.User.Fields.REMARK));
            user.setContact(obj.getString(Tables.User.Fields.CONTACT));

            return user;
        } catch (Exception ex) {
            ex.printStackTrace();
        }

        return null;
    }

二、Gson处理Json格式数据

1.Object to json格式

public String getAllVideosByJson() throws Exception {
        List<Video> videos = service.getAllVideos();
        StringBuilder sb = new StringBuilder();
        //Gson gson = new Gson();
        Gson gson = new Gson();
        String result = gson.toJson(videos);

        return result;
    }

2.json格式的字符串变为Video对象

public static List<Video> getJSONAllVideos_2() throws Exception {

        String path = "http://192.168.2.107:8080/VideoWeb/VideoServlet?format=json&type=get";
        URL url = new URL(path);
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setReadTimeout(5 * 1000);
        conn.setRequestMethod("GET");
        InputStream inStream = conn.getInputStream();
        byte[] data = StreamTool.readInputStream(inStream);
        String json = new String(data);
        Type typeList = new TypeToken<ArrayList<Video>>() {
        }.getType();
        Gson gson = new Gson();
        ArrayList<Video> videos = gson.fromJson(json, typeList);
        return videos;
    }