无法从tomcat下载文件

laoliang123a 2013-04-12 06:54:35

按照mars的视频连接tomcat下载xml文件，为甚么总是不成功啊，权限也配置了，也没报什么错，就是不下载啊
这是源码主activity



package liang.mp3player02;



import liang.download.HttpDownloader;



import com.example.mp3player02.R;



import android.os.Bundle;

import android.app.Activity;

import android.view.Menu;

import android.view.MenuItem;



public class MainActivity extends Activity {

	

	

	private static final int UPDATE=1;

	private static final int ABOUT=2;



	@Override

	protected void onCreate(Bundle savedInstanceState) {

		super.onCreate(savedInstanceState);

		setContentView(R.layout.activity_main);

	}



	@Override

	public boolean onCreateOptionsMenu(Menu menu) {

		

		menu.add(0, UPDATE, 1, R.string.mp3list_update);

		menu.add(0,ABOUT,2,R.string.mp3list_about);

		// Inflate the menu; this adds items to the action bar if it is present.

		getMenuInflater().inflate(R.menu.main, menu);

		return true;

	}

	@Override

	public boolean onOptionsItemSelected(MenuItem item) {

		

		// TODO Auto-generated method stub

		System.out.println(item.getItemId());

		if(item.getItemId()==UPDATE)

		{

		   String xml=donwloadXML("http://10.0.2.2:8080/mp3/1.txt");

		  System.out.println(xml);

		}

		else if(item.getItemId()==ABOUT)

		{

			

		}

		return super.onOptionsItemSelected(item);

	}



    private String donwloadXML(String urlStr){

    	

    	HttpDownloader httpDownloader=new HttpDownloader();

    	String result =httpDownloader.download(urlStr);

    	return result;

    

    }



}

下载类



package liang.download;



import java.io.BufferedReader;

import java.io.InputStreamReader;

import java.net.HttpURLConnection;

import java.net.URL;



public class HttpDownloader {

	public String download(String urlStr)

	{

	    StringBuffer sb=new StringBuffer();

	    String line=null;

	    BufferedReader buffer=null;

	    try{

		    URL url=new URL(urlStr);

		    HttpURLConnection urlConn=(HttpURLConnection) url.openConnection();

	        buffer=new BufferedReader(new InputStreamReader(urlConn.getInputStream()));

	        while((line=buffer.readLine())!=null){

	        	sb.append(line);

	        }

	    }	

	    catch(Exception e){

	    	e.printStackTrace();

	    }

	    finally{

	    	try{

	    		buffer.close();

	    	}catch(Exception e){

	    		e.printStackTrace();

	    	}

	    }

	    return sb.toString();

	}

	



}