Android 从服务器下载文件

首先在电脑上配置tomcat，webapps目录下新建mp3文件夹，

截图

首先我们通过SAX解析resources.xml 获取歌曲信息。

启动 Tomcat访问一下服务器地址http://210.**.**.**:8080/mp3/resources.xml

210.**.**.**是我的IP，把这里改成自己的IP

本来下载是一个耗时的东西，需要另外开启一个线程或则service去下载，由于这里就在本人的电脑上测试

就在主线程中下载了

Info.java

package rw.down;

public class Info {
  int id;
  String nameString;
/**
 * @return the id
 */
public int getId() {
	return id;
}
/**
 * @param id the id to set
 */
public void setId(int id) {
	this.id = id;
}
/**
 * @return the nameString
 */
public String getNameString() {
	return nameString;
}
/**
 * @param nameString the nameString to set
 */
public void setNameString(String nameString) {
	this.nameString = nameString;
}
/* (non-Javadoc)
 * @see java.lang.Object#toString()
 */
@Override
public String toString() {
	return "info [id=" + id + ", nameString=" + nameString + "]";
}
}

infoHandle.java

package rw.down;

import java.util.List;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

import android.util.Log;



public class infoHandle extends DefaultHandler {

	private Info Mp3_info;
    private List<Info> List_Mp3_Infos;
    private String preString;

	public infoHandle() {
		super();
	}


	public infoHandle(List<Info> list_Mp3_Infos) {
		super();
		List_Mp3_Infos = list_Mp3_Infos;
	}


	@Override
	public void startDocument() throws SAXException {
		// TODO Auto-generated method stub
		super.startDocument();
	}


	@Override
	public void startElement(String uri, String localName, String qName,
			Attributes attributes) throws SAXException {
		// TODO Auto-generated method stub
		preString=localName;
		if (preString.equals("resource")) {
			Mp3_info=new Info();
		}
		super.startElement(uri, localName, qName, attributes);
	}


	public void endElement(String uri, String localName, String qName)
			throws SAXException {
		// TODO Auto-generated method stub
		preString=" ";
		Log.i("endElement_localName-------->", localName);
		if (localName.equals("resource")) {
			List_Mp3_Infos.add(Mp3_info);
		}
		super.endElement(uri, localName, qName);
	}



	@Override
	public void characters(char[] ch, int start, int length)
			throws SAXException {
		// TODO Auto-generated method stub
		String dateString;
		dateString=new String(ch, start, length);
		if (preString.equals("id")) {
			Mp3_info.setId(Integer.parseInt(dateString));
			Log.i("id--------->", dateString);
		}else if (preString.equals("mp3.name")) {
			Mp3_info.setNameString(dateString);
			Log.i("mp3.name--------->", dateString);
		}
		
		super.characters(ch, start, length);
	}
   

	
	@Override
	public void endDocument() throws SAXException {
		// TODO Auto-generated method stub
		super.endDocument();
	}
	

}

DonwnFileActivity.java

package rw.down;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;


import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import org.apache.http.HttpConnection;
import org.apache.http.message.BufferedHeader;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;
import org.xmlpull.v1.XmlPullParserFactory;

import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.content.res.AssetManager.AssetInputStream;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import android.widget.Toast;

public class DownFileActivity extends Activity {
    /** Called when the activity is first created. */
	private Button button;
	private ListView listView;
	private List<String> list=new ArrayList<String>();
	private ArrayAdapter<String> adapter1;
	private List<String> musicnameList;
    private Intent service;
	@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        service=new Intent(this,DownService.class);
        button=(Button) findViewById(R.id.button1);
        listView=(ListView) findViewById(R.id.listView1);
        button.setOnClickListener(new Mybutton());
    }
    class Mybutton implements OnClickListener{

		@Override
		public void onClick(View v) {
		
			// TODO Auto-generated method stub
		 button.setText("刷新列表");
		  musicnameList=new ArrayList<String>();
		  List<Info> lInfos=parseXML();
		  list.clear();
		  adapter1 =new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_list_item_1, list);
		  listView.setAdapter(adapter1);
		for (Iterator iterator = lInfos.iterator(); iterator.hasNext();) {
			Info info = (Info) iterator.next();
			musicnameList.add(info.getNameString());
		    list.add(info.getId()+"  "+info.getNameString());
		}
		 adapter1 =new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_list_item_1, list);
		 listView.setAdapter(adapter1);
		 listView.setOnItemClickListener(new ItemLitener());
		}
    	
    }
    private List<Info> parseXML()
    {
    List<Info> infos=null;
    
    SAXParserFactory factory=SAXParserFactory.newInstance();
    try {
    	
    	URL url=new URL("http://210.30.12.34:8080/mp3/resources.xml");
        
    	HttpURLConnection connection=(HttpURLConnection) url.openConnection();
    	if (connection.getReadTimeout()==4) {
    		
			Toast.makeText(getApplicationContext(), "请求超时", Toast.LENGTH_LONG).show();
			return null;
		}
    	InputStream inputStream2=connection.getInputStream();
		SAXParser parser=factory.newSAXParser();
		XMLReader reader=parser.getXMLReader();
		infos=new ArrayList<Info>();
		reader.setContentHandler(new infoHandle(infos));
		reader.parse(new InputSource(inputStream2));
	
	} catch (ParserConfigurationException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	} catch (SAXException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	} catch (MalformedURLException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	} catch (IOException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	} 
    return infos;
    }
   private class ItemLitener implements OnItemClickListener{

	@Override
	public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
		// TODO Auto-generated method stub
		
	     Toast.makeText( getApplicationContext(), musicnameList.get(arg2).toString(), Toast.LENGTH_LONG).show();
	     String downUrlString="http://210.30.12.34:8080/mp3/"+musicnameList.get(arg2).toString();
	     String sdcardSave="DownFile";
	     String filename=musicnameList.get(arg2).toString(); 
	     OutputStream outputStream=null;
	     HttpURLConnection connection;
	                      /* 
	                      * 1.在AndroidMainfest.xml中进行权限配置 
	                      * <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> 
	                      * 取得写入SDCard的权限 
	                      * 2.取得SDCard的路径： Environment.getExternalStorageDirectory() 
	                      * 3.检查要保存的文件上是否已经存在 
	                      * 4.不存在，新建文件夹，新建文件 
	                      * 5.将input流中的信息写入SDCard 
	                      * 6.关闭流 
	                      */  
        String SDcardPath=Environment.getExternalStorageDirectory()+"";
        String pathString=SDcardPath+"/"+sdcardSave+"/"+filename;
        File file=new File(pathString);
        
   	    startService(service);
        try {
        	connection = (HttpURLConnection) new URL(downUrlString).openConnection();
			InputStream inputStream=connection.getInputStream();
			 if (!file.exists()) {
				   new File(SDcardPath+"/"+sdcardSave).mkdir();
				}
			 File[] filelist=new File(SDcardPath+"/"+sdcardSave).listFiles();
			 for (int i = 0; i < filelist.length; i++) {
				if (filelist[i].getName().equals(filename)) {
					Toast.makeText(getApplicationContext(), filename+"已经存在", Toast.LENGTH_LONG).show();
					return ;
				}
			}
			 file.createNewFile();
			 System.err.println("开始下载");
		
			 outputStream=new FileOutputStream(file);
			 byte[] buffer=new byte[4*1024];
			 while ((inputStream.read(buffer))!=-1) {
				outputStream.write(buffer);
			}
			 outputStream.flush();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally{
			try {
				outputStream.close();
				Toast.makeText(getApplicationContext(), "下载成功", Toast.LENGTH_LONG).show();
				System.err.println("下载完成");
				//progressDialog.dismiss();
			} catch (Exception e2) {
				// TODO: handle exception	
				Toast.makeText(getApplicationContext(), "下载失败", Toast.LENGTH_LONG).show();
				//progressDialog.cancel();
			}
			
		}      
	}
	   
   }
}

DownService.java

package rw.down;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.widget.Toast;


public class DownService extends Service {

	@Override
	public IBinder onBind(Intent arg0) {
		// TODO Auto-generated method stub
		return null;
	}

	
	public void onCreate() {
		// TODO Auto-generated method stub
		super.onCreate();
	}

	
	public void onDestroy() {
		// TODO Auto-generated method stub
		super.onDestroy();
	}

	
	public void onStart(Intent intent, int startId) {
		// TODO Auto-generated method stub
		Toast.makeText(getApplicationContext(), "服务开始", Toast.LENGTH_LONG).show();
		super.onStart(intent, startId);
	}
   
}

在AndroidManifest.xml中添加两个权限

 <uses-permission android:name="android.permission.INTERNET"></uses-permission>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>

和一个服务

<service android:name="DownService"></service>

效果，因为我已经运行过了，因为我已经运行过了，所以DownFile这个文件已经存在，第一次运行是回创建这个文件夹

通过ls命令 我们看见 现在文件夹里面什么也没有

点击我们要下载的歌曲，我现在点击Beyond.mo3

如果下载成功

如果没有找到这个歌曲，会提示下载失败

现在我们再来看看DownFile这个文件夹下面