android中的网络通信(二) HTTP网络编程

上一篇是关于网络底层Socket编程的网络通信，这篇是之上的高级的网络编程协议HTTP协议，也是运用的比较广泛的互联网协议，通常所说的B/S的结构程序就是基于此协议的。

android中基于HTTP的网络通信的有两种分别是：HttpURLConnection和ApacheHTTP。这篇主要是HttpURLConnection通信。HttpURLConnection通过基于http的url来访问资源进行请求和响应。本篇以一个简单的登陆界面来展示HttpURLConnection。

首先在建立android客户端，布局文件分别是输入用户名和密码，传给服务器进行判断，如输入正确则返回成功。布局文件如下

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:background="#ffffff" android:layout_height="match_parent">
<TableLayout android:layout_width="fill_parent" android:id="@+id/table"
android:stretchColumns="1" android:layout_height="wrap_content">
<TableRow android:layout_width="fill_parent"
android:layout_height="wrap_content">
<TextView android:text="name:" android:textColor="#000000"
android:textSize="20dp" android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<EditText android:layout_width="fill_parent"
android:layout_height="wrap_content" android:id="@+id/name" />
</TableRow>
<TableRow android:layout_width="fill_parent"
android:layout_height="wrap_content">
<TextView android:text="password:" android:textColor="#000000"
android:textSize="20dp" android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<EditText android:layout_width="fill_parent"
android:layout_height="wrap_content" android:id="@+id/password" />
</TableRow>

</TableLayout>
<Button android:layout_below="@id/table" android:layout_width="fill_parent"
android:layout_height="wrap_content" android:id="@+id/submit"
android:text="submit" />
</RelativeLayout>

java文件通过url来访问服务器的LoginServlet通过LoginServlet来进行判断

/**
*
*/
package com.test;

import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;

/**
* @author liguiwu
*
*/
public class login extends Activity {

private EditText name;
private EditText password;
private Button submit;

public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.login);

name = (EditText) findViewById(R.id.name);
password = (EditText) findViewById(R.id.password);
submit = (Button) findViewById(R.id.submit);

submit.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
String getName = name.getText().toString();
String getPassword = password.getText().toString();

login(getName, getPassword);

}
});
}

public void login(String name, String password) {
String urlStr = "http://192.168.1.101:8080/MyServer/servlet/LoginServlet?";
String queryString = "name=" + name + "&password=" + password;
urlStr = urlStr + queryString;

try {
URL url = new URL(urlStr);
// 获得http连接的实例
HttpURLConnection conne = (HttpURLConnection) url.openConnection();
// 判断是否请求成功
if (conne.getResponseCode() == HttpURLConnection.HTTP_OK) {
InputStream in = conne.getInputStream();
byte[] b = new byte[in.available()];
// 将b读到缓冲区
in.read(b);
String msg = new String(b);
AlertDialog.Builder build = new AlertDialog.Builder(this);
build.setMessage(msg).setPositiveButton("确定",
new DialogInterface.OnClickListener() {

@Override
public void onClick(DialogInterface dialog,
int which) {
// TODO Auto-generated method stub

}
});
AlertDialog alert = build.create();
alert.show();
}

} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}

}

}

在Myeclipse新建LoginServlet的servlet类来进行判断，通过apache作为服务器，运行的时候先配置apache，我测试的时候由于忘了配置纠结了好久，测试的时候可以再浏览器中输入客户端的url看是否服务端正常启动。

package com.test;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LoginServlet extends HttpServlet {

/**
* Constructor of the object.
*/
public LoginServlet() {
super();
}

public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String name = request.getParameter("name");
String password = request.getParameter("password");
response.setContentType("text/html");
response.setCharacterEncoding("utf-8");
PrintWriter out = response.getWriter();
String msg = null;
if (name.equals("admin") && password.equals("admin")) {
msg = "successful";
} else {
msg = "fail";
}
// 传信息给客户端
out.print(msg);
// 刷新输出流
out.flush();
out.close();
}

public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);

}

}

运行结果，返回“successful”