Today I want to port an automatic check-in applet using HttpClient to Android. Fortunately, the Android SDK comes with the HttpClient package. When looking through the Android documentation, I found that the official also provides an AndroidHttpClient that implements the HttpClient interface. I searched online and found no articles about AndroidHttpClient. Of course, you can continue to use DefaultHttpClient, but it is naturally better to use AndroidHttpClient customized for Android.
Below are 2 HttpServlets for testing :
Copy the code code as follows:
public class LogIn extends HttpServlet {
/**
* Processes requests for both HTTP
* <code>GET</code> and
* <code>POST</code> methods.
*
* @param request servlet request
* @param response servlet response
* @throws ServletException if a servlet-specific error occurs
* @throws IOException if an I/O error occurs
*/
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
request.setCharacterEncoding("utf-8");
PrintWriter out = response.getWriter();
HttpSession session=request.getSession();
String info=request.getParameter("info");
session.setAttribute("info", info);
try {
/* TODO output your page here. You may use following sample code. */
out.println("OK");
} finally {
out.close();
}
}
// <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
/**
* Handles the HTTP
* <code>GET</code> method.
*
* @param request servlet request
* @param response servlet response
* @throws ServletException if a servlet-specific error occurs
* @throws IOException if an I/O error occurs
*/
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
/**
* Handles the HTTP
* <code>POST</code> method.
*
* @param request servlet request
* @param response servlet response
* @throws ServletException if a servlet-specific error occurs
* @throws IOException if an I/O error occurs
*/
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
/**
* Returns a short description of the servlet.
*
* @return a String containing servlet description
*/
@Override
public String getServletInfo() {
return "Short description";
}// </editor-fold>
}
Copy the code code as follows:
public class Info extends HttpServlet {
/**
* Processes requests for both HTTP
* <code>GET</code> and
* <code>POST</code> methods.
*
* @param request servlet request
* @param response servlet response
* @throws ServletException if a servlet-specific error occurs
* @throws IOException if an I/O error occurs
*/
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
HttpSession session=request.getSession();
String info=(String)session.getAttribute("info");
try {
/* TODO output your page here. You may use following sample code. */
if(info==null)
out.print("null");
else
out.print(info);
} finally {
out.close();
}
}
// <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
/**
* Handles the HTTP
* <code>GET</code> method.
*
* @param request servlet request
* @param response servlet response
* @throws ServletException if a servlet-specific error occurs
* @throws IOException if an I/O error occurs
*/
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
/**
* Handles the HTTP
* <code>POST</code> method.
*
* @param request servlet request
* @param response servlet response
* @throws ServletException if a servlet-specific error occurs
* @throws IOException if an I/O error occurs
*/
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
/**
* Returns a short description of the servlet.
*
* @return a String containing servlet description
*/
@Override
public String getServletInfo() {
return "Short description";
}// </editor-fold>
}
The main code is in processRequest, you don’t need to look at the others.
When accessing LogIn, pass a value named info. At this time, the browser will get a cookie used to locate the server session. Then visit Info. If there is a cookie, the server can find the value you just passed and return it to you. If there is no cookie, it cannot be found.
Android side code:
Copy the code code as follows:
public class MainActivity extends Activity {
private AndroidHttpClient mHttpclient=AndroidHttpClient.newInstance("");
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
findViewById(R.id.button1).setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
new Thread(rTest).start();
}
});
}
private String toString(InputStream is) throws IOException{
String ret="";
InputStreamReader isr=new InputStreamReader(is);
BufferedReader br=new BufferedReader(isr);
String tmp=br.readLine();
while(tmp!=null){
ret+=tmp;
tmp=br.readLine();
}
br.close();
return ret;
}
private Runnable rTest=new Runnable() {
@Override
public void run() {
// TODO Auto-generated method stub
try {
BasicHttpContext context=new BasicHttpContext();
context.setAttribute(ClientContext.COOKIE_STORE,new BasicCookieStore());
HttpPost httppost = new HttpPost("http://10.226.233.48:8080/WebApplication1/LogIn");
List <NameValuePair> nvps = new ArrayList <NameValuePair>();
nvps.add(new BasicNameValuePair("info", "Hello world!!"));
httppost.setEntity(new UrlEncodedFormEntity(nvps,"utf-8"));
HttpResponse response=mHttpclient.execute(httppost,context);
HttpEntity entity = response.getEntity();
Log.i("kagami", MainActivity.this.toString(entity.getContent()));
entity.consumeContent();
HttpGet httpget2 = new HttpGet("http://10.226.233.48:8080/WebApplication1/Info");
HttpResponse response2=mHttpclient.execute(httpget2,context);
HttpEntity entity2 = response2.getEntity();
Log.i("kagami", MainActivity.this.toString(entity2.getContent()));
entity2.consumeContent();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
};
｝
The difference between AndroidHttpClient and DefaultHttpClient :
AndroidHttpClient cannot be executed in the main thread and will throw an exception. AndroidHttpClient obtains the instance through the static method newInstance. The parameter is the proxy. If no proxy is used, fill in "". DefaultHttpClient enables cookies by default. AndroidHttpClient does not enable cookies by default. To use it, add an HttpContext parameter and add CookieStore each time you execute. Don't forget to close after use, otherwise you won't be able to create a new instance.
