1、先在AndroidManifest.xml中注册加入访问因特网服务的权限:
<uses-permission android:name="android.permission.INTERNET" />
(若不加入,则会出现permission denied异常)
2、代码如下:
package vip.test.HttpGet;import java.io.BufferedInputStream;import java.io.InputStream;import java.net.URL;import java.net.URLConnection;import org.apache.http.util.ByteArrayBuffer;import org.apache.http.util.EncodingUtils;import vip.test.HttpGet.R;import android.app.Activity;import android.os.Bundle;import android.widget.TextView;public class HttpGet extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); TextView tv = new TextView(this); String myString = null; try { // 定义获取文件内容的URL URL myURL = new URL( "HTTP://www.baidu.com/hello.txt""); // 打开URL链接 URLConnection ucon = myURL.openConnection(); // 使用InputStream,从URLConnection读取数据 InputStream is = ucon.getInputStream(); BufferedInputStream bis = new BufferedInputStream(is); // 用ByteArrayBuffer缓存 ByteArrayBuffer baf = new ByteArrayBuffer(50); int current = 0; while ((current = bis.read()) != -1) { baf.append((byte) current); } // 将缓存的内容转化为String,用UTF-8编码 myString = EncodingUtils.getString(baf.toByteArray(), "UTF-8"); } catch (Exception e) { myString = e.getMessage(); } // 设置屏幕显示 tv.setText(myString); this.setContentView(tv); }}
3、代码解释:
1)实例URL类:myURL,表示要获取内容的网址:
URL myURL=new URL(HTTP://www.baidu.com/hello.txt);
2)实例URLConnection类,表示一个打开的网络连接ucon:
URLConnection ucon=myURL.openConnection();
3)用字节流的形式表示从网络上读到的数据:
InputStream is=ucon.getInputStream();
为避免频繁读取字节流,提高读取效率,用BufferedInputStream缓存读到的字节流
InputStream is=ucon.getInputStream();
BufferedInputStream bis=new BufferedInputStream(is);
4)用read方法读入网络数据:
ByteArrayBuffer baf=new ByteArrayBuffer(50);
int current=0;
while((current=bis.read())!=-1)
{
baf.append((byte)current);
}
5)由于读到的数据只是字节流,无法直接显示到屏幕上,所以得在显示之前将字节流转换为可读取的字符串:
myString=EncodingUtils.getString(baf.toByteArray(),"UTF-8");
(如果读取的是.txt等文件是UTF-8格式的,就需要对数据进行专门的转换)