Android - 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);
}
@Override
public 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() {
@Override
public void run() {
// 使用get请求连接.
try {
if (getSend(params, URL, "utf-8"))
handler.sendEmptyMessage(SEND_SUCCESS);
else
handler.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;
@Override
protected 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);
}
@Override
public 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() {
@Override
public 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.
