Android - 向服务器发送数据(GET).

2023-08-01 08:03:10

　　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.

码农公寓

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