Android学习13-----网络通信(1) 与WEB服务器交换数据
与Web服务器交互：
如果手机要想与 web 容器交互的话，那么就必须依靠 Http 协议完成。
一、通过地址重新访问动态 Web
首先我们需要建立一个 Web 程序，现在为了说明问题，我们简单见一个 Servlet ，然后返回 true or false 即可
服务器端： AndroidServlet.java
package com.iflytek.demo;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class AndroidServlet
*/
public class AndroidServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* Default constructor.
*/
public AndroidServlet() {
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
//http://IP:8080/09AndroidWeb/AndroidServlet?name=xdwang&password=1111
String name = request.getParameter("name");
String password = request.getParameter("password");
if ("xdwang".equals(name) && "1111".equals(password)) {
response.getWriter().println("true");
} else {
response.getWriter().println("false");
}
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}
}
客户端：
Web01_Activity.java
package com.iflytek.demo;
import java.net.HttpURLConnection;
import java.net.URL;
import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.widget.TextView;
public class Web01_Activity extends Activity {
private TextView infoTxt;
public Handler handler = new Handler() {
@Override
public void handleMessage(android.os.Message msg) {
super.handleMessage(msg);
switch (msg.what) {
case 1:
infoTxt.setText(msg.obj.toString());
break;
default:
break;
}
}
};
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
infoTxt = (TextView) super.findViewById(R.id.info);
this.HttpHelper();
}
private void HttpHelper() {
final AsyncTask<Void, Void, String> task = new AsyncTask<Void, Void, String>() {
@Override
protected void onPostExecute(String result) {
final String temp = result;
Thread thread = new Thread(new Runnable() {
@Override
public void run() {
Message msg = new Message();
msg.what = 1;
msg.obj = temp;
handler.sendMessage(msg);
}
});
thread.start();
}
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected String doInBackground(Void... arg0) {
boolean flag = false; // 成功与否的标记
try {
URL url = new URL("http", "IP", 8080,
"/09AndroidWeb/AndroidServlet?name=xdwang&password=1111");
HttpURLConnection conn = (HttpURLConnection) url
.openConnection();
byte data[] = new byte[512];// 开辟一个空间
int len = conn.getInputStream().read(data); // 输入流读取
if (len > 0) { // 已经读取到内容
String temp = new String(data, 0, len).trim();
flag = Boolean.parseBoolean(temp); // 取出里面的boolean型数据
}
conn.getInputStream().close();
} catch (Exception e) {
return "WEB服务器连接失败！";
}
if (flag) {
return "用户登录成功！";
} else {
return "用户登录失败！";
}
}
};
task.execute();
}
}
AndroidManifest.xml需要添加网络访问权限
<uses-permission android:name="android.permission.INTERNET" />
总结，这种方式是地址重写的方式完成，但是我们知道地址重写是 Get 请求方式，从上面的 Servlet 类的处理也可以看出是 Get 请求，但是这种方式会收到地址传输的限制，所以这时候我们也可以使用 post 请求方式提交。
二、 POST 请求
Get 请求与 Post 请求最大的区别在于一个地址显示，一个不显示，具体可以看我写的 GET 与 POST 请求 。 可是如何在 Android 中实现 post 请求呢？严格来说，之前的程序并不标准，地址重写问题较多。
使用 POST 提交访问动态 WEB 所需要的操作类：
由于 WEB 连接采用的是 HTTP 操作协议进行的，所以用户想要发送请求（ POST 、 GET ）则可以使用 org.apache.http.client.methods.HttpPost 类或者是 org.apache.http.client.methods.HttpGet 类进行。
当用户成功的向 Web Server 端发送请求后，所有返回的数据将使用 org.apache.http.HttpResponse 接口保存。
当用户使用 HttpResponse 的 getEntity() 方法接受所有返回数据之后，可以使用 EntityUtils 类进行处理，而且由于 HttpResponse 是一个接口，所以要想实例化此接口，就要使用 org.apache.http.impl.client.DefaultHttpClient 类完成。
由于在 Web Server 上所提供的方法需要参数的传递，所以所有的参数都要使用 org.apache.http.message.BasicName.ValuePair 类进行封装。
除了处理好参数之外，还需要处理请求时的所需要的编码，通用的编码为 UTF-8 ，而要想指定此编码则必须使用 org.apache.http.client.entry.UrlEncodedFormEntity 类完成。
此时把服务器端的 doPost 中再去调用 doGet 方法：
客户端 Web02_Activity.java
package com.iflytek.demo;
import java.util.ArrayList;
import java.util.List;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.protocol.HTTP;
import org.apache.http.util.EntityUtils;
import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.widget.TextView;
public class Web02_Activity extends Activity {
private TextView infoTxt = null;
private static final String URL = "http://IP:8080/09AndroidWeb/AndroidServlet"; // 请求地址
public Handler handler = new Handler() {
@Override
public void handleMessage(android.os.Message msg) {
super.handleMessage(msg);
switch (msg.what) {
case 1:
infoTxt.setText(msg.obj.toString());
break;
default:
break;
}
}
};
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
this.infoTxt = (TextView) super.findViewById(R.id.info);
this.HttpHelper();
}
private void HttpHelper() {
final AsyncTask<Void, Void, String> task = new AsyncTask<Void, Void, String>() {
@Override
protected void onPostExecute(String result) {
final String temp = result;
Thread thread = new Thread(new Runnable() {
@Override
public void run() {
Message msg = new Message();
msg.what = 1;
msg.obj = temp;
handler.sendMessage(msg);
}
});
thread.start();
}
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected String doInBackground(Void... arg0) {
boolean flag = false; // 成功与否的标记
try {
HttpPost request = new HttpPost(URL);
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("name", "xdwang"));
params.add(new BasicNameValuePair("password", "1111"));
request.setEntity(new UrlEncodedFormEntity(params,
HTTP.UTF_8));
HttpResponse response = new DefaultHttpClient()
.execute(request);
if (response.getStatusLine().getStatusCode() != 404) { // 现在已经发现了数据了
flag = Boolean.parseBoolean(EntityUtils.toString(
response.getEntity()).trim());
}
} catch (Exception e) {
return "WEB服务器连接失败！";
}
if (flag) {
return "用户登录成功！";
} else {
return "用户登录失败！";
}
}
};
task.execute();
}
}
三、网络读取图片
服务器端：
先设计一个返回图片流的工具类
ImageUtil.java
package com.iflytek.util;
import java.awt.image.BufferedImage;
import java.io.FileInputStream;
import java.io.IOException;
import java.text.MessageFormat;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
public class ImageUtil {
/**
* @descrption
* @author xdwang
* @create 2012-11-16下午8:35:36
* @param response
* @param path
* 文件路径
* @param type
* 图片类型
*/
public static void showImage(HttpServletResponse response, String path,
String type) {
try {
ServletOutputStream outStream = response.getOutputStream();// 得到向客户端输出二进制数据的对象
FileInputStream fis = new FileInputStream(path); // 以byte流的方式打开文件
// 读数据
byte data[] = new byte[1000];
while (fis.read(data) > 0) {
outStream.write(data);
}
fis.close();
response.setContentType(MessageFormat.format("image/{0}", type)); // 设置返回的文件类型
outStream.write(data); // 输出数据
outStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* @descrption
* @author xdwang
* @create 2012-11-16下午8:35:48
* @param response
* @param data
* byte数组
* @param type
* 图片类型
*/
public static void showImage(HttpServletResponse response, byte[] data,
String type) {
try {
ServletOutputStream outStream = response.getOutputStream();// 得到向客户端输出二进制数据的对象
// 读数据
outStream.write(data);
response.setContentType(MessageFormat.format("image/{0}", type)); // 设置返回的文件类型
outStream.write(data); // 输出数据
outStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
AndroidServlet.java
package com.iflytek.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.iflytek.util.ImageUtil;
/**
* Servlet implementation class AndroidServlet
*/
public class AndroidServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* Default constructor.
*/
public AndroidServlet() {
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
ImageUtil.showImage(response,
getServletContext().getRealPath("Java.jpg"), "jpeg");
}
}
Android客户端：
Web03_Activity.java
package com.iflytek.demo;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.widget.ImageView;
public class Web03_Activity extends Activity {
private ImageView iamgeView = null;
private static final String PATH = "http://IP:8080/09AndroidWeb/Java.jpg"; // 请求地址
private Bitmap bitmap;
public Handler handler = new Handler() {
@Override
public void handleMessage(android.os.Message msg) {
super.handleMessage(msg);
switch (msg.what) {
case 1:
try {
iamgeView.setImageBitmap(bitmap);
} catch (Exception e) {
}
break;
default:
break;
}
}
};
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
this.iamgeView = (ImageView) super.findViewById(R.id.img);
this.HttpHelper();
}
private void HttpHelper() {
final AsyncTask<Void, Void, String> task = new AsyncTask<Void, Void, String>() {
@Override
protected void onPostExecute(String result) {
Thread thread = new Thread(new Runnable() {
@Override
public void run() {
Message msg = new Message();
msg.what = 1;
handler.sendMessage(msg);
}
});
thread.start();
}
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected String doInBackground(Void... arg0) {
ByteArrayOutputStream bos = null; // 内存操作流完成
try {
URL url = new URL(PATH);
HttpURLConnection conn = (HttpURLConnection) url
.openConnection();
conn.connect();
InputStream input = conn.getInputStream();
bitmap = BitmapFactory.decodeStream(input);
// bos = new ByteArrayOutputStream();
// byte data[] = new byte[1024];
// int len = 0;
// while ((len = input.read(data)) != -1) {
// bos.write(data, 0, len);
// }
// byte resultData[] = bos.toByteArray();
// bitmap = BitmapFactory.decodeByteArray(resultData, 0,
// resultData.length); // 把二进制变为图片
} catch (Exception e) {
} finally {
if (bos != null) {
try {
bos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return null;
}
};
task.execute();
}
}