ANDROID_MARS学习笔记_S01原始版_009_下载文件

一、代码
1.xml
(1)main.xml

 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:orientation="vertical"
     android:layout_width="fill_parent"
     android:layout_height="fill_parent"
     >
 <Button
     android:id="@+id/downloadTxt"
     android:layout_width="fill_parent"
     android:layout_height="wrap_content"
     android:text="下载文本文件"
     />
 <Button
     android:id="@+id/downloadMp3"
     android:layout_width="fill_parent"
     android:layout_height="wrap_content"
     android:text="下载MP3文件 "
     />
 </LinearLayout>

(2)AndroidManifest.xml.xml

 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.example.s01_original_e18_download"
     android:versionCode="1"
     android:versionName="1.0" >

     <uses-sdk
         android:minSdkVersion="8"
         android:targetSdkVersion="21" />

     <application
         android:allowBackup="true"
         android:icon="@drawable/ic_launcher"
         android:label="@string/app_name"
         android:theme="@style/AppTheme" >
         <activity
             android:name=".Download"
             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>
     <uses-permission android:name="android.permission.INTERNET"/>
     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
 </manifest>

2.java
(1)Download.java

 package com.example.s01_original_e18_download;

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

 public class Download extends Activity {
     /** Called when the activity is first created. */
     private Button downloadTxtButton;
     private Button downloadMp3Button;
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.main);
         downloadTxtButton = (Button)findViewById(R.id.downloadTxt);
         downloadTxtButton.setOnClickListener(new DownloadTxtListener());
         downloadMp3Button = (Button)findViewById(R.id.downloadMp3);
         downloadMp3Button.setOnClickListener(new DownloadMp3Listener());
     }

     class DownloadTxtListener implements OnClickListener{

         @Override
         public void onClick(View v) {
             HttpDownloader httpDownloader = new HttpDownloader();
             //String lrc = httpDownloader.download("http://192.168.1.104:8080/goods/LoseYourself.lrc");
             String lrc = httpDownloader.download("http://www.runoob.com/sqlite/sqlite-intro.html");
             System.out.println(lrc);
         }

     }
     class DownloadMp3Listener implements OnClickListener{

         @Override
         public void onClick(View v) {
             // TODO Auto-generated method stub
             HttpDownloader httpDownloader = new HttpDownloader();
             int result = httpDownloader.downFile("http://192.168.1.104:8080/goods/LoseYourself.mp3", "voa/", "a1.mp3");
             System.out.println(result);
         }

     }

 }

(2)HttpDownloader.java

 package com.example.s01_original_e18_download;

 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 HttpDownloader {
     private URL url = null;

     /**
      * 根据URL下载文件，前提是这个文件当中的内容是文本，函数的返回值就是文件当中的内容
      * 1.创建一个URL对象
      * 2.通过URL对象，创建一个HttpURLConnection对象
      * 3.得到InputStram
      * 4.从InputStream当中读取数据
      * @param urlStr
      * @return
      */
     public String download(String urlStr) {
         StringBuffer sb = new StringBuffer();
         String line = null;
         BufferedReader buffer = null;
         try {
             // 创建一个URL对象
             url = new URL(urlStr);
             // 创建一个Http连接
             HttpURLConnection urlConn = (HttpURLConnection) url
                     .openConnection();
             // 使用IO流读取数据
             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();
     }

     /**
      * 该函数返回整形 -1：代表下载文件出错 0：代表下载文件成功 1：代表文件已经存在
      */
     public int downFile(String urlStr, String path, String fileName) {
         InputStream inputStream = null;
         try {
             FileUtils fileUtils = new FileUtils();

             if (fileUtils.isFileExist(path + fileName)) {
                 return 1;
             } else {
                 inputStream = getInputStreamFromUrl(urlStr);
                 File resultFile = fileUtils.write2SDFromInput(path,fileName, inputStream);
                 if (resultFile == null) {
                     return -1;
                 }
             }
         } catch (Exception e) {
             e.printStackTrace();
             return -1;
         } finally {
             try {
                 inputStream.close();
             } catch (Exception e) {
                 e.printStackTrace();
             }
         }
         return 0;
     }

     /**
      * 根据URL得到输入流
      *
      * @param urlStr
      * @return
      * @throws MalformedURLException
      * @throws IOException
      */
     public InputStream getInputStreamFromUrl(String urlStr)
             throws MalformedURLException, IOException {
         url = new URL(urlStr);
         HttpURLConnection urlConn = (HttpURLConnection) url.openConnection();
         InputStream inputStream = urlConn.getInputStream();
         return inputStream;
     }
 }

(3)FileUtils.java

 package com.example.s01_original_e18_download;

 import java.io.File;
 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 String getSDPATH() {
         return SDPATH;
     }
     public FileUtils() {
         //得到当前外部存储设备的目录
         // /SDCARD
         SDPATH = Environment.getExternalStorageDirectory() + "/";
     }
     /**
      * 在SD卡上创建文件
      *
      * @throws IOException
      */
     public File creatSDFile(String fileName) throws IOException {
         File file = new File(SDPATH + fileName);
         file.createNewFile();
         return file;
     }

     /**
      * 在SD卡上创建目录
      *
      * @param dirName
      */
     public File creatSDDir(String dirName) {
         File dir = new File(SDPATH + dirName);
         dir.mkdirs();
         return dir;
     }

     /**
      * 判断SD卡上的文件夹是否存在
      */
     public boolean isFileExist(String fileName){
         File file = new File(SDPATH + fileName);
         return file.exists();
     }

     /**
      * 将一个InputStream里面的数据写入到SD卡中
      */
     public File write2SDFromInput(String path,String fileName,InputStream input){
         File file = null;
         OutputStream output = null;
         try{
             creatSDDir(path);
             file = creatSDFile(path + fileName);
             output = new FileOutputStream(file);
             byte buffer [] = new byte[4 * 1024];
             while((input.read(buffer)) != -1){
                 output.write(buffer);
             }
             output.flush();
         }
         catch(Exception e){
             e.printStackTrace();
         }
         finally{
             try{
                 output.close();
             }
             catch(Exception e){
                 e.printStackTrace();
             }
         }
         return file;
     }

 }