今天想把一个用使用了HttpClient的自动签到小程序移植到Android上，还好Android的SDK自带了HttpClient的包。翻Android的文档时发现官方还提供了一个实现了HttpClient接口的AndroidHttpClient，上网搜了下没发现关于AndroidHttpClient的文章。当然也可以继续使用DefaultHttpClient，但用为Android定制的AndroidHttpClient自然更好。
下面是2个测试用的HttpServlet：
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> }
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> }
主要代码在processRequest里，其他可以不用看。
访问LogIn时传一个name为info的值，这时浏览器会得到一个用于定位服务端session的cookie。然后访问Info，如果有cookie的话服务端能找到刚才你传的值并返回给你，没带cookie的话就不能找到。
Android端代码：
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", "你好 世界！！")); 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(); } } }; ｝
AndroidHttpClient和DefaultHttpClient的区别：
AndroidHttpClient不能在主线程中execute，会抛出异常。AndroidHttpClient通过静态方法newInstance获得实例，参数是代理，不用代理的话填“”。DefaultHttpClient默认是启用Cookie的，AndroidHttpClient默认不启用Cookie，要使用的话每次execute时要加一个HttpContext参数，并且添加CookieStore。用完后别忘了close不然不能创建新实例。