本实例达到的效果是：首先创建一个网页来显示系统当前的时间，然后在Android程序中每隔5秒钟刷新一次视图，已达到实时更新的效果。
首先，创建一个显示系统当前时间的jsp网页文件，代码如下：
<html>
<head>
<title>My JSP 'index.jsp' starting page</title>
</head>
<body>
<%
String type = request.getParameter("par");
String result = new String(type.getBytes("iso-8859-1"),"gb2312");
out.println("<h1>parameters:"+result+"</h1>");
%>
</body>
</html>
下面通过Http连接来读取网页，每隔5秒钟，程序自己刷新。要实时的从网页获取数据，其实就是吧获取网络数据的代码写到线程中，不停的进行更新。需要说明一点：android中更新视图不能直接在线程中进行，所以这里需要使用handler来实现更新，具体代码如下：
package com.android;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends Activity {
private final String TAG = "MainActivity" ;
private TextView textView;
private Button button;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.http);
textView = (TextView)findViewById(R.id.text);
button = (Button)findViewById(R.id.button);
button.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
refresh();
}
});
new Thread(mRunnable).start();
}
//刷新网页显示
private void refresh(){
String httpUrl = "http://127.0.0.1:8080/test/currentDate.jsp";
String result = "";
URL url = null;
try{
//构造一个URL对象
url = new URL(httpUrl);
}catch (MalformedURLException e) {
Log.e(TAG, "MalformedURLException");
e.printStackTrace();
}
if(url != null){
try{
//使用httpURLConnection打开连接
HttpURLConnection urlConnection = (HttpURLConnection)url.openConnection();
//得到读取的内容
InputStreamReader inReader = new InputStreamReader(urlConnection.getInputStream());
//为输出创建BufferedReader
BufferedReader bufferedReader = new BufferedReader(inReader);
String line = null;
//使用循环来读取获得的数据
while((line=bufferedReader.readLine())!=null){
result += line +"\n";
}
//关闭InputStreamReader
inReader.close();
//关闭Http连接
urlConnection.disconnect();
if(result.equals("")){
textView.setText("读取的内容为null");
}else{
textView.setText(result);
}
}catch (IOException e) {
// TODO: handle exception
Log.e(TAG, "IOException");
e.printStackTrace();
}
}else{
Log.e(TAG, "url null");
}
}
private Runnable mRunnable = new Runnable() {
@Override
public void run() {
while(true){
try{
Thread.sleep(5 * 1000);
//发送消息
handler.sendMessage(handler.obtainMessage());
}catch (InterruptedException e) {
// TODO: handle exception
Log.e(TAG, "InterruptedException");
e.printStackTrace();
}
}
}
};
Handler handler = new Handler(){
public void handleMessage(Message msg){
super.handleMessage(msg);
refresh();
}
};
}
注意：代码中的url地址中的ip：127.0.0.1需要修改成自己所需要的地址