Android 一个简单的json格式的封装与解析

[]http://www.cnblogs.com/xiaoluo501395377/p/3446605.html]

Android客户端解析服务器端的json数据

@WebServlet("/CityServlet")
public class CityServlet extends HttpServlet
{
private static final long serialVersionUID = 1L;

public CityServlet()
{
super();
}

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

protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException
{
response.setContentType("text/html;charset=utf-8");
request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");
PrintWriter writer = response.getWriter();

String type = request.getParameter("type");
if("json".equals(type))
{
List<String> cities = new ArrayList<String>();
cities.add("广州");
cities.add("上海");
cities.add("北京");
cities.add("湖南");
Map<String, List<String>> map = new HashMap<String, List<String>>();
map.put("cities", cities);
String citiesString = JSON.toJSONString(map);
writer.println(citiesString);
}

writer.flush();
writer.close();
}

}

如果客户端请求的参数是type=json，则响应给客户端一个json数据格式

接着来看看客户端的代码，首先看看客户端的布局文件，其实就是一个按钮和一个Spinner控件，当点击按钮后，通过http协议请求服务器端的数据，然后在接收到后再更新我们的Spinner控件的数据

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent" >

<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginLeft="64dp"
android:layout_marginTop="64dp"
android:textSize="20sp"
android:text="城市" />

<Spinner
android:id="@+id/spinner"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignTop="@id/textView1"
android:layout_toRightOf="@id/textView1"/>

<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/textView1"
android:layout_below="@+id/spinner"
android:layout_marginLeft="22dp"
android:layout_marginTop="130dp"
android:text="加载数据" />

</RelativeLayout>

Android客户端写一个解析json数据格式的类：

public class JsonUtils
{
/**
* @param citiesString    从服务器端得到的JSON字符串数据
* @return    解析JSON字符串数据，放入List当中
*/
public static List<String> parseCities(String citiesString)
{
List<String> cities = new ArrayList<String>();

try
{
JSONObject jsonObject = new JSONObject(citiesString);
JSONArray jsonArray = jsonObject.getJSONArray("cities");
for(int i = 0; i < jsonArray.length(); i++)
{
cities.add(jsonArray.getString(i));
}
}
catch (Exception e)
{
e.printStackTrace();
}

return cities;
}
}

HttpUtils类网络请求类

public class HttpUtils
{
/**
* @param path    请求的服务器URL地址
* @param encode    编码格式
* @return    将服务器端返回的数据转换成String
*/
public static String sendPostMessage(String path, String encode)
{
String result = "";
HttpClient httpClient = new DefaultHttpClient();
try
{
HttpPost httpPost = new HttpPost(path);
HttpResponse httpResponse = httpClient.execute(httpPost);
if(httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK)
{
HttpEntity httpEntity = httpResponse.getEntity();
if(httpEntity != null)
{
result = EntityUtils.toString(httpEntity, encode);
}
}
}
catch (Exception e)
{
e.printStackTrace();
}
finally
{
httpClient.getConnectionManager().shutdown();
}

return result;
}
}

MainActivity类：

public class MainActivity extends Activity
{
private Spinner spinner;
private Button button;
private ArrayAdapter<String> adapter;
private ProgressDialog dialog;
private final String CITY_PATH_JSON = "http://172.25.152.34:8080/httptest/CityServlet?type=json";
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

spinner = (Spinner)findViewById(R.id.spinner);
button = (Button)findViewById(R.id.button);
dialog = new ProgressDialog(MainActivity.this);
button.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View v)
{
dialog.setTitle("提示信息");
dialog.setMessage("loading......");
dialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
dialog.setCancelable(false);

new MyAsyncTask().execute(CITY_PATH_JSON);
}
});
}

public class MyAsyncTask extends AsyncTask<String, Void, List<String>>
{
@Override
protected void onPreExecute()
{
dialog.show();
}
@Override
protected List<String> doInBackground(String... params)
{
List<String> cities = new ArrayList<String>();
String citiesString = HttpUtils.sendPostMessage(params[0], "utf-8");
//    解析服务器端的json数据
cities = JsonUtils.parseCities(citiesString);return cities;
}
@Override
protected void onPostExecute(List<String> result)
{
adapter = new ArrayAdapter<String>(MainActivity.this, android.R.layout.simple_spinner_item, result);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(adapter);
dialog.dismiss();
}
}

@Override
public boolean onCreateOptionsMenu(Menu menu)
{
getMenuInflater().inflate(R.menu.main, menu);
return true;
}

}

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