Android下载文本文件和mp3文件

布局文件main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <Button 
        android:id="@+id/downloadTxt"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="Download text"/>
    <Button 
        android:id="@+id/downloadMp3"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="Download MP3"/>
</LinearLayout>

Activity文件DownloadFileToSDKCardActivity.java

package paul.Activity;

import paul.utils.HttpDownloadUtil;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

//创建一个HttpURLConnection对象
//HttpURLConnection urlConn=(HttpURLConnection)url.openConnection();
//获取一个InputStream对象
//InputStream is=urlConn.getInputStream();
//访问网络权限
//android.permission.INTERNET
//得到当前设备SD卡的目录
//Environment.getExternalStorageDirectory()
//访问SD卡的权限
//android.permission.WEITE_EXTERNAL_STORAGE
public class DownloadFileToSDKCardActivity extends Activity {
    /** Called when the activity is first created. */
    HttpDownloadUtil httpDownloadUtil;
    private Button downloadTxt;
    private Button downloadMp3;
    public DownloadFileToSDKCardActivity(){
        httpDownloadUtil=new HttpDownloadUtil();
    }
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        downloadTxt=(Button) this.findViewById(R.id.downloadTxt);
        downloadTxt.setOnClickListener(new DownloadTxt());
        downloadMp3=(Button) this.findViewById(R.id.downloadMp3);
        downloadMp3.setOnClickListener(new DownloadMp3());
    }
    
    
    class DownloadTxt implements OnClickListener{

        @Override
        public void onClick(View arg0) {
            String url="http://www.baidu.com";
            System.out.println(httpDownloadUtil.downFile(url));
        }
        
    }
    
    class DownloadMp3 implements OnClickListener{

        @Override
        public void onClick(View arg0) {
            String url="http://media.ringring.vn/ringtone/realtone/0/0/161/165346.mp3";
            //int index=url.lastIndexOf("/");
//String fileName=url.substring(index+1);
            int result=httpDownloadUtil.downFile(url, "music", "aa.mp3");
            System.out.println(result);
        }
        
    }
}

文件下载类HttpDownloadUtil.java

package paul.utils;

import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

public class HttpDownloadUtil {
    
    /**
     * 根据URL下载文件，前提是这个文件当中的内容是文本，函数返回值是文件当中的文本内容
     * @param urlstr
     * @return
*/
    public String downFile(String urlstr){
        StringBuffer sb=new StringBuffer();
        BufferedReader buffer=null;
        URL url=null;
        String line=null;
        try {
            //创建一个URL对象
            url=new URL(urlstr);
            //根据URL对象创建一个Http连接
            HttpURLConnection urlConn=(HttpURLConnection) url.openConnection();
            //使用IO读取下载的文件数据
            buffer=new BufferedReader(new InputStreamReader(urlConn.getInputStream()));
            while((line=buffer.readLine())!=null){
                sb.append(line);
            }
        } catch (MalformedURLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally{
            try {
                buffer.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return sb.toString();
    }
    
    /**
     * 该函数返回整形    -1：代表下载文件错误0 ：下载文件成功1：文件已经存在 
     * @param urlstr
     * @param path
     * @param fileName
     * @return
*/
    public int downFile(String urlstr,String path,String fileName){
        InputStream inputStream=null;
        FileUtils fileUtils=new FileUtils();
        
        if(fileUtils.isFileExist(path+fileName)){
            return 1;
        }else{
            inputStream=getInputStreamFormUrl(urlstr);
            File resultFile=fileUtils.writeToSDfromInput(path, fileName, inputStream);
            if(resultFile==null){
                return -1;
            }
        }
        return 0;
    }
    
    /**
     * 根据URL得到输入流
     * @param urlstr
     * @return
*/
    public InputStream getInputStreamFormUrl(String urlstr){
        InputStream inputStream=null;
        try {
            URL url=new URL(urlstr);
            HttpURLConnection urlConn=(HttpURLConnection) url.openConnection();
            inputStream=urlConn.getInputStream();
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return inputStream;
    }
}

保存文件到SD卡通用工具类FileUtils.java

package paul.utils;

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

import android.os.Environment;

public class FileUtils {
    private String SDPath;
    
    public FileUtils(){
        //得到当前外部存储设备的目录
        SDPath=Environment.getExternalStorageDirectory().getAbsolutePath()+"/";
    }
    
    /**
     * 在SD卡上创建文件
     * @param fileName
     * @return
*/
    public File createSDFile(String fileName){
        File file=new File(SDPath+fileName);
        try {
            file.createNewFile();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return file;
    }
    
    /**
     * 在SD卡上创建目录
     * @param dirName
     * @return
*/
    public File createSDDir(String dirName){
        File file=new File(SDPath+dirName);
        file.mkdir();
        return file;
    }
    
    /**
     * 判断SD卡上文件是否存在
     * @param fileName
     * @return
*/
    public boolean isFileExist(String fileName){
        File file=new File(SDPath+fileName);
        return file.exists();
    }
    /**
     * 将一个inputStream里面的数据写到SD卡中
     * @param path
     * @param fileName
     * @param inputStream
     * @return
*/
    public File writeToSDfromInput(String path,String fileName,InputStream inputStream){
        //createSDDir(path);
        File file=createSDFile(path+fileName);
        OutputStream outStream=null;
        try {
            outStream=new FileOutputStream(file);
            byte[] buffer=new byte[4*1024];
            while(inputStream.read(buffer)!=-1){
                outStream.write(buffer);
            }
            outStream.flush();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }finally{
            try {
                outStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return file;
    }
}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="paul.Activity"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk android:minSdkVersion="10" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:name=".DownloadFileToSDKCardActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
</manifest>