Android数据转化为Json形式给客户端及客户端使用json数据

（1）首先创建生成原始数据的service，VideoNewsServiceBean，这是一个接口的实现类，接口的功能如下：

public interface VideoNewsService {
/**
* 获取最新的视频资讯
* @return
*/
public List<News> getLastNews();

}

News类

public class News {
private Integer id;
private String title;
private Integer timelength;

public News(Integer id, String title, Integer timelength) {
this.id = id;
this.title = title;
this.timelength = timelength;
}
//get/set方法
}

接口的实现类：生成一些假数据

public class VideoNewsServiceBean implements VideoNewsService {

public List<News> getLastNews(){
List<News> newes = new ArrayList<News>();
newes.add(new News(90, "喜羊羊与灰太狼全集", 78));
newes.add(new News(10, "实拍舰载直升东海救援演习", 28));
newes.add(new News(56, "喀麦隆VS荷兰", 70));
return newes;
}
}

（2）通过servlet将数据返回给客户端：ListServlet.java

public class ListServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
private VideoNewsService service = new VideoNewsServiceBean();

protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}

protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
List<News> videos = service.getLastNews();

// [{id:56,title:"xxxxx",timelength:90},{id:16,title:"xbbx",timelength:20}]
StringBuilder builder = new StringBuilder();
//对数据进行追加为json格式
builder.append('[');
for (News news : videos) {
builder.append('{');
builder.append("id:").append(news.getId()).append(',');
builder.append("title:\"").append(news.getTitle())
.append("\",");
builder.append("timelength:").append(news.getTimelength());
builder.append("},");
}
//删除最后一个多的字符
builder.deleteCharAt(builder.length() - 1);
builder.append(']');
//将数据设置在request域中,进行跳转，当客户端请求该servlet的时候跳转到该jsp页面，实际请求的为jsp页面
request.setAttribute("json", builder.toString());
request.getRequestDispatcher("/WEB-INF/page/jsonvideonews.jsp")
.forward(request, response);
}

}

（3）当客户端通过servlet请求的时候就经过跳转可以返回jsp页面数据（使用的是el表达式，因为json数据为String类型所以 contentType=”text/plain; charset=UTF-8”）

<%@ page language="java" contentType="text/plain; charset=UTF-8" pageEncoding="UTF-8"%>${json}

（4）在客户端取出数据

同样的第一步仍是创建一个News的类，这里省略

创建一个获取Json的service，VideoNewsService.java

public class VideoNewsService {
/**
* 获取最新的视频资讯
* @return
* @throws Exception
*/
public static List<News> getJSONLastNews() throws Exception{
String path = "服务器请求servlet的地址";
URL url = new URL(path);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setConnectTimeout(5000);
conn.setRequestMethod("GET");
if(conn.getResponseCode() == 200){
InputStream inStream = conn.getInputStream();
return parseJSON(inStream);
}
return null;
}
/**
* 解析JSON数据
* @param inStream
* @return
*/
private static List<News> parseJSON(InputStream inStream) throws Exception{
List<News> newses = new ArrayList<News>();
byte[] data = StreamTool.read(inStream);
String json = new String(data);
//因为数据是类似于数组的形式重复的使用JSONArray
JSONArray array = new JSONArray(json);
for(int i = 0 ; i < array.length() ; i++){
JSONObject jsonObject = array.getJSONObject(i);
News news = new News(jsonObject.getInt("id"), jsonObject.getString("title"), jsonObject.getInt("timelength"));
newses.add(news);
}
return newses;
}
}

这里边使用了一个工具类StreamTool.java，将输入流转化为byte数据返回

public class StreamTool {
/**
* 读取输入流数据
*/
public static byte[] read(InputStream inStream) throws Exception {
ByteArrayOutputStream outStream = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len = 0;
while ((len = inStream.read(buffer)) != -1) {
outStream.write(buffer, 0, len);
}
inStream.close();
return outStream.toByteArray();
}

然后皆可以在具体的界面中进行数据的使用：（这里为一个listview设置值）

MainActivity.java

public class MainActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

ListView listView = (ListView) this.findViewById(R.id.listView);
try {
List<News> videos = VideoNewsService.getJSONLastNews();//需修改成你本机的Http请求路径
//这里使用的List<HashMap<String, Object>>可以将数据放入hashmap之后再放入list集合中
List<HashMap<String, Object>> data = new ArrayList<HashMap<String,Object>>();
for(News news : videos){
HashMap<String, Object> item = new HashMap<String, Object>();
item.put("id", news.getId());
item.put("title", news.getTitle());
item.put("timelength", getResources().getString(R.string.timelength)
+ news.getTimelength()+ getResources().getString(R.string.min));
data.add(item);
}
//为listview设置适配器
SimpleAdapter adapter = new SimpleAdapter(this, data, R.layout.item,
new String[]{"title", "timelength"}, new int[]{R.id.title, R.id.timelength});
listView.setAdapter(adapter);
} catch (Exception e) {
e.printStackTrace();
}
}
}

到此json数据的生成客客户端使用json数据操作已经完成！