Android(安卓)- 向服务器发送数据(GET).

　　在此,使用HTTP协议,通过GET请求,向服务器发送请求,这种方式适合于数据量小,数据安全性要求不高的情况下.

一,服务器端,使用Servlet.

　　在服务器端,定义一个HttpServlet的子类,以及一个Filter的子类(用于统一编码,防止出现乱码).

package spt.servlet;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * type 'http://localhost:8080/ReceiveAndroid/ServletForGETMethod?name=juk&pwd=lis' * for the browser. */@WebServlet("/ServletForGETMethod")public class ServletForGETMethod extends HttpServlet {private static final long serialVersionUID = 1L;/** * @see HttpServlet#HttpServlet() */public ServletForGETMethod() {super();}/** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse *      response) */protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {String name = request.getParameter("name");String pwd = request.getParameter("pwd");System.out.println("name:" + name + "   pwd:" + pwd);}/** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse *      response) */protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stub}}

package spt.servlet.filter;import java.io.IOException;import java.io.UnsupportedEncodingException;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.annotation.WebFilter;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletRequestWrapper;//filter all servlets.@WebFilter("/*")public class EncodingFilter  implements Filter {public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {HttpServletRequest httpReq = (HttpServletRequest) servletRequest;if ("GET".equals(httpReq.getMethod()))filterChain.doFilter(new HttpServletRequestEncodingWrapper(httpReq), servletResponse);else {httpReq.setCharacterEncoding("utf-8");filterChain.doFilter(httpReq, servletResponse);}}public void init(FilterConfig filterConfig) throws ServletException {// TODO Auto-generated method stub}/**inner class dealing for 'GET' method. * @author Administrator *2015-1-27 */private class HttpServletRequestEncodingWrapper extends HttpServletRequestWrapper {public HttpServletRequestEncodingWrapper(HttpServletRequest request) {super(request);}@Overridepublic String getParameter(String name) {//encode with 'iso', and than decode with 'utf'.String val = super.getRequest().getParameter(name);if (null != val) {try {return new String(val.getBytes("iso8859-1"), "utf-8");} catch (UnsupportedEncodingException e) {e.printStackTrace();}}return super.getParameter(name);}}public void destroy() {// TODO Auto-generated method stub}}

在主机(服务器)上,往浏览器中输入'http://localhost:8080/ReceiveAndroid/ServletForGETMethod?name=juk&pwd=lis', 若在控制台打印需要的结果,则表示服务器端的Servlet已经编写好.

二,Android的业务逻辑层类,主要是将业务逻辑独立于Android的Activity.

package spt.http.get.assist;import java.io.IOException;import java.net.HttpURLConnection;import java.net.MalformedURLException;import java.net.URL;import java.net.URLEncoder;import java.util.HashMap;import java.util.Map;import java.util.Map.Entry;import android.os.Handler;/**用户向服务器端发送数据的类. * @author Administrator * */public class SendDataToServer {private static final int TIME_OUT = 10000; // 超时时间.// 连接服务器的url.private static final String URL = "http://192.168.1.101:8080/ReceiveAndroid/ServletForGETMethod";// 标识是否连接到服务器成功.public static final int SEND_SUCCESS = 1;public static final int SEND_FAIL = 0;private Handler handler = null;public SendDataToServer(Handler handler) {this.handler = handler;}/** * 往服务器发送数据. *  * @param name * @param pwd */public void send(String name, String pwd) {// 这里params要传递到另外一个方法,加final为了防止被修改.final Map<String, String> params = new HashMap<String, String>();params.put("name", name);params.put("pwd", pwd);// 启动新的线程连接服务器.new Thread(new Runnable() {@Overridepublic void run() {// 使用get请求连接.try {if (getSend(params, URL, "utf-8"))handler.sendEmptyMessage(SEND_SUCCESS);elsehandler.sendEmptyMessage(SEND_FAIL);} catch (MalformedURLException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}}}).start();}/**发送get请求的方法. * @param params 请求参数的键-值对. * @param url * @param encoding 使用指定编码对参数值进行编码. * @return * @throws MalformedURLException * @throws IOException */private boolean getSend(Map<String, String> params, String url,String encoding) throws MalformedURLException, IOException {StringBuilder sb = new StringBuilder();// 向url中添加参数.sb.append(url).append("?");for (Entry<String, String> param : params.entrySet()) {sb.append(param.getKey()).append("=").append(URLEncoder.encode(param.getValue(), encoding)).append("&");}if (params.size() > 0)sb.deleteCharAt(sb.length() - 1); // 去掉末尾的'&'.HttpURLConnection conn = (HttpURLConnection) new URL(sb.toString()).openConnection();conn.setConnectTimeout(TIME_OUT);conn.setRequestMethod("GET"); // GET是大小写敏感的.return conn.getResponseCode() == 200; // 等于200表示发送成功.}}

三:Activity类:

package spt.http.get.activity;import java.lang.ref.WeakReference;import spt.http.get.assist.SendDataToServer;import android.app.Activity;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.view.View;import android.widget.Button;import android.widget.EditText;import android.widget.Toast;public class MainActivity extends Activity {//view.private EditText edt_name = null;private EditText edt_pwd = null;private Button btn_ok = null;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);initView();initListener();}/** * 初始化View. */private void initView() {edt_name = (EditText)findViewById(R.id.edt_name);edt_pwd = (EditText)findViewById(R.id.edt_pwd);btn_ok = (Button)findViewById(R.id.btn_ok);//test:edt_name.setText("你好");edt_pwd.setText("abc");}/**使用静态内部类,解决'This Handler class should be static or leaks might occur',以免造成内存泄露. * @author Administrator * */private static class StatusHandler extends Handler {WeakReference<MainActivity>  iMainActivity = null;public StatusHandler(MainActivity mainActivity) {iMainActivity = new WeakReference<MainActivity>(mainActivity);}@Overridepublic void handleMessage(Message msg) {switch (msg.what) {case SendDataToServer.SEND_SUCCESS://有iMainActivity.get()和iMainActivity.getClass().Toast.makeText(iMainActivity.get(), "发送成功", Toast.LENGTH_SHORT).show();break;case SendDataToServer.SEND_FAIL:Toast.makeText(iMainActivity.get(), "发送失败", Toast.LENGTH_SHORT).show();break;default:throw new RuntimeException("未知的发送结果!");}}}/** * 处理发送是否成功的状态的Handler. */private final  Handler handler = new StatusHandler(this);/** * 初始化监听器. */private void initListener() {btn_ok.setOnClickListener(new Button.OnClickListener() {@Overridepublic void onClick(View v) {String name = edt_name.getText().toString();String pwd = edt_pwd.getText().toString();if(name.isEmpty() || pwd.isEmpty()) {Toast.makeText(MainActivity.this, "用户名和密码不能为空", Toast.LENGTH_SHORT).show();return;}new SendDataToServer(handler).send(name, pwd);}});}}

稍微留意的是,Activity类中的Handler的子类定义为静态类,并保存对Activity的弱引用,防止内存泄露.简略解释在我的博文 Android - This Handler class should be static or leaks might occur. 中.

四, 添加必要权限

　　在AndroidManifest.xml中,添加

<uses-permission android:name="android.permission.INTERNET" />

以对网络的访问.

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