HttpDownloader.java

 

1 package mars.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 13 public class HttpDownloader {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InputStram21      * 4.从InputStream当中读取数据22      * @param urlStr23      * @return24      */25     public String download(String urlStr) {26         StringBuffer sb = new StringBuffer();27         String line = null;28         BufferedReader buffer = null;29         try {30             // 创建一个URL对象31             url = new URL(urlStr);32             // 创建一个Http连接33             HttpURLConnection urlConn = (HttpURLConnection) url34                     .openConnection();35             // 使用IO流读取数据36             buffer = new BufferedReader(new InputStreamReader(urlConn37                     .getInputStream()));38             while ((line = buffer.readLine()) != null) {39                 sb.append(line);40             }41         } catch (Exception e) {42             e.printStackTrace();43         } finally {44             try {45                 buffer.close();46             } catch (Exception e) {47                 e.printStackTrace();48             }49         }50         return sb.toString();51     }52 53     /**54      * 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55      */56     public int downFile(String urlStr, String path, String fileName) {57         InputStream inputStream = null;58         try {59             FileUtils fileUtils = new FileUtils();60             61             if (fileUtils.isFileExist(path + fileName)) {62                 return 1;63             } else {64                 inputStream = getInputStreamFromUrl(urlStr);65                 File resultFile = fileUtils.write2SDFromInput(path,fileName, inputStream);66                 if (resultFile == null) {67                     return -1;68                 }69             }70         } catch (Exception e) {71             e.printStackTrace();72             return -1;73         } finally {74             try {75                 inputStream.close();76             } catch (Exception e) {77                 e.printStackTrace();78             }79         }80         return 0;81     }82 83     /**84      * 根据URL得到输入流85      * 86      * @param urlStr87      * @return88      * @throws MalformedURLException89      * @throws IOException90      */91     public InputStream getInputStreamFromUrl(String urlStr)92             throws MalformedURLException, IOException {93         url = new URL(urlStr);94         HttpURLConnection urlConn = (HttpURLConnection) url.openConnection();95         InputStream inputStream = urlConn.getInputStream();96         return inputStream;97     }98 }

FileUtils.java

 

1 package mars.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     private String SDPATH;13 14     public String getSDPATH() {15         return SDPATH;16     }17     public FileUtils() {18         //得到当前外部存储设备的目录19         // /SDCARD20         SDPATH = Environment.getExternalStorageDirectory() + "/";21     }22     /**23      * 在SD卡上创建文件24      * 25      * @throws IOException26      */27     public File creatSDFile(String fileName) throws IOException {28         File file = new File(SDPATH + fileName);29         file.createNewFile();30         return file;31     }32     33     /**34      * 在SD卡上创建目录35      * 36      * @param dirName37      */38     public File creatSDDir(String dirName) {39         File dir = new File(SDPATH + dirName);40         dir.mkdirs();41         return dir;42     }43 44     /**45      * 判断SD卡上的文件夹是否存在46      */47     public boolean isFileExist(String fileName){48         File file = new File(SDPATH + fileName);49         return file.exists();50     }51     52     /**53      * 将一个InputStream里面的数据写入到SD卡中54      */55     public File write2SDFromInput(String path,String fileName,InputStream input){56         File file = null;57         OutputStream output = null;58         try{59             creatSDDir(path);60             file = creatSDFile(path + fileName);61             output = new FileOutputStream(file);62             byte buffer [] = new byte[4 * 1024];63             while((input.read(buffer)) != -1){64                 output.write(buffer);65             }66             output.flush();67         }68         catch(Exception e){69             e.printStackTrace();70         }71         finally{72             try{73                 output.close();74             }75             catch(Exception e){76                 e.printStackTrace();77             }78         }79         return file;80     }81 82 }

AndroidManifest.xml

 

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