android之download

有三个java类

Download.java

View Code

 1 package tk.download;

 2 

 3 

 4 import tk.utils.HttpDownloader;

 5 import android.os.Bundle;

 6 import android.R.integer;

 7 import android.app.Activity;

 8 import android.view.Menu;

 9 import android.view.View;

10 import android.view.View.OnClickListener;

11 import android.widget.Button;

12 

13 public class Download extends Activity {

14     

15     /**

16      *创建一个HttpURLConnection对象

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

18      *获得一个InputStream对象

19      *urlConn.getInputStream()

20      *访问网络的权限(在mainfest中声明)

21      *android.permission.INTERNET 

22      * 

23      *访问SDCARD

24      *得到当前设备SD卡的目录

25      *Environment.getExternalStorageDirectory()

26      *访问SD卡的权限

27      *android.permission.WRITE_EXTERNAL_STORAGE

28      * 

29      * /

30     /**Called when the activity is first created.*/

31     

32     private Button downloadTxtButton;

33     private Button downloadMp3Button;

34 

35     

36     @Override

37     public void onCreate(Bundle savedInstanceState) {

38         super.onCreate(savedInstanceState);

39         setContentView(R.layout.main);

40         downloadMp3Button=(Button)findViewById(R.id.downloadMp3);

41         downloadMp3Button.setOnClickListener(new DownloadMp3Listener());

42         downloadTxtButton=(Button)findViewById(R.id.downloadTxt);

43         downloadTxtButton.setOnClickListener(new DownloadTxtListener());

44         

45         

46     }

47     

48     class DownloadTxtListener implements OnClickListener{

49 

50         @Override

51         public void onClick(View v) {

52             HttpDownloader httpDownloader=new HttpDownloader();

53             System.out.println("begin");

54             String lrc = httpDownloader.download("http://125.222.201.90/home/download4.asp?FileName=hello.txt");

55             System.out.println(lrc);

56             System.out.println("end");

57             

58             

59         }

60         

61         

62     }

63     

64     class DownloadMp3Listener implements OnClickListener{

65 

66         @Override

67         public void onClick(View v) {

68             HttpDownloader httpDownloader=new HttpDownloader();

69             System.out.println("begin");

70             int result = httpDownloader.downFile("http://125.222.201.90/home/download4.asp?FileName=Layout_04.apk", "tk/", "test.apk");

71             System.out.println(result);

72             

73         }

74 

75     }

76     

77     

78 

79     @Override

80     public boolean onCreateOptionsMenu(Menu menu) {

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

82         return true;

83     }

84 }

FileUtils.java

View Code

 1 package tk.utils;

 2 

 3 import java.io.File;

 4 import java.io.FileOutputStream;

 5 import java.io.IOException;

 6 import java.io.InputStream;

 7 import java.io.OutputStream;

 8 

 9 import android.os.Environment;

10 

11 public class FileUtils {

12     

13     private String SDPATH;

14     

15     public String getSDPATH() {

16         return SDPATH;

17     }

18 

19     public FileUtils() {

20         //得到当前外部存储设备的目录  /SDCARD

21         SDPATH = Environment.getExternalStorageDirectory() + "/";

22         //SDPATH ="/";

23     }

24 

25 /**

26 * 在SD卡上创建目录

27 * 

28 * @param dirName

29 */

30 

31     public File creatSDDir(String dirName) {

32         File file = new File(SDPATH + dirName);

33         file.mkdirs();

34         return file;

35     }

36 

37 /**

38 * 在SD卡上创建文件

39 * 

40 * @throws IOException

41 */

42 

43     public File creatSDFile(String fileName) throws IOException {

44         File file = new File(SDPATH + fileName);

45         file.createNewFile();

46         return file;

47     }

48 

49  

50 

51 /**

52 * 判断SD卡上的文件夹是否存在

53 */

54 

55     public boolean isFileExist(String fileName){

56         File file = new File(SDPATH + fileName);

57         return file.exists();

58     }

59 

60 /**

61 * 将一个InputStream里面的数据写入到SD卡中

62 */

63 

64     public File write2SDFromInput(String path,String fileName,InputStream inputStream){

65     

66         File file = null;

67         OutputStream outputStream = null;

68         

69         try{

70             creatSDDir(path);

71             file = creatSDFile(path + fileName);

72             outputStream = new FileOutputStream(file);

73             byte buffer [] = new byte[4 * 1024];

74             while((inputStream.read(buffer)) != -1){

75                 

76                 outputStream.write(buffer);

77                 

78             }

79             outputStream.flush();

80             

81         }catch(Exception e){

82             

83             e.printStackTrace();

84             

85         }finally{

86             

87             try{

88                 outputStream.close();

89             }catch(Exception e){

90                 e.printStackTrace();

91             }

92             

93         }

94         

95         return file;

96     

97     }

98 

99 }

HttpDownloader.java

View Code

  1 package tk.utils;

  2 

  3 import java.io.BufferedReader;

  4 import java.io.File;

  5 import java.io.IOException;

  6 import java.io.InputStream;

  7 import java.io.InputStreamReader;

  8 import java.net.HttpURLConnection;

  9 import java.net.MalformedURLException;

 10 import java.net.URL;

 11 

 12 public class HttpDownloader {

 13 

 14     private URL url = null;

 15     

 16     /**

 17      * 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

 18      * 1.创建一个URL对象

 19      * 2.通过URL对象，创建一个HttpURLConnection对象

 20      * 3.得到Inputstream

 21      * 4.从InputStream当中读取数据

 22      * @param urlStr

 23      * @return

 24      */

 25     public String download(String urlStr){

 26         StringBuffer sb = new StringBuffer();

 27         String line = null;

 28         

 29         BufferedReader buffer = null;

 30         

 31         try{

 32             //创建一个Http对象

 33             url = new URL(urlStr);

 34             //创建一个Http连接

 35             HttpURLConnection urlconn = (HttpURLConnection)url.openConnection();

 36             //使用IO流读取数据

 37             buffer = new BufferedReader(new InputStreamReader(urlconn.getInputStream()));

 38             

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

 40                 sb.append(line);

 41             }

 42         }catch(Exception e){

 43             e.printStackTrace();            

 44         }finally{

 45             try{

 46                 buffer.close();

 47             }catch(Exception e){

 48                 e.printStackTrace();

 49             }

 50         }

 51         

 52         return sb.toString();

 53     }

 54     /**

 55      *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 代表文件已存在

 56      */

 57     public int downFile(String urlStr, String path, String fileName) {

 58     

 59         InputStream inputStream = null;

 60         

 61         try {

 62             FileUtils fileUtils = new FileUtils(); 

 63             if (fileUtils.isFileExist(path + fileName)) {

 64                 return 1; //文件已经存在

 65             } else {

 66                 inputStream =getInputStreamFromUrl(urlStr);

 67                 if(inputStream==null)return 2;

 68                 File resultFile =fileUtils.write2SDFromInput(path,fileName,inputStream);  

 69                 if (resultFile == null){

 70                     return -1;  //下载文件出错

 71                 }

 72             }

 73         } catch (Exception e) {

 74             e.printStackTrace();

 75             return -1;

 76         } finally {

 77             try {

 78                 inputStream.close();

 79             } catch (Exception e) {

 80                 e.printStackTrace();

 81             }

 82         }

 83     return 0;

 84     }

 85     

 86      

 87     

 88     public InputStream getInputStreamFromUrl(String urlStr) throws MalformedURLException, IOException {

 89     

 90         InputStream inputStream=null;

 91         

 92         try{

 93             // 创建一个URL对象

 94            url = new URL(urlStr);

 95            // 创建一个Http连接

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

 97            // 使用IO流读取数据

 98            inputStream = urlConn.getInputStream();

 99            return inputStream;

100         }catch (Exception e) {

101             e.printStackTrace();

102             return null;

103         }finally {

104            inputStream.close();

105         }

106     }

107 

108 }

androidmainfest.xml

View Code

main.xml

View Code

 1 <?xml version= "1.0" encoding ="utf-8"?>

 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

 3     android:orientation= "vertical"

 4     android:layout_width= "fill_parent"

 5     android:layout_height= "fill_parent"

 6     >

 7     

 8     <Button 

 9         android:id="@+id/downloadTxt"

10         android:layout_width="fill_parent"

11         android:layout_height="wrap_content"

12         android:text="downloadtxt"

13         />

14     

15      <Button 

16         android:id="@+id/downloadMp3"

17         android:layout_width="fill_parent"

18         android:layout_height="wrap_content"

19         android:text="downloadMP3"

20         />

21 </LinearLayout>