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     * GET and     * POST 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();        }    }    // 
        
             /**     * Handles the HTTP     * 
         GET 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     * 
         POST 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";    }// 
        }

public class Info extends HttpServlet {    /**     * Processes requests for both HTTP     * GET and     * POST 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();        }    }    // 
        
             /**     * Handles the HTTP     * 
         GET 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     * 
         POST 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";    }// 
        }

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 
        
          nvps = new ArrayList 
         
          ();                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。