Android網路檔案下載模組整理

標籤：

一、知識基礎

　　tomcat伺服器配置

　　理解http協議

　　理解javaIO操作相關知識

      SDcard操作知識

　　Android 許可權配置

二、實現步驟

　　1、從網上擷取資源

 1 public String download(String urlStr) { 2         StringBuffer sb = new StringBuffer(); 3         String line = null; 4         BufferedReader buffer = null; 5         try { 6             // 建立一個URL對象 7             url = new URL(urlStr); 8             // 建立一個Http串連 9             HttpURLConnection urlConn = (HttpURLConnection) url10                     .openConnection();11             // 使用IO流讀取資料12             buffer = new BufferedReader(new InputStreamReader(urlConn13                     .getInputStream()));14             while ((line = buffer.readLine()) != null) {15                 sb.append(line);16             }17         } catch (Exception e) {18             e.printStackTrace();19         } finally {20             try {21                 buffer.close();22             } catch (Exception e) {23                 e.printStackTrace();24             }25         }26         return sb.toString();27     }28 29     /**30      * 該函數返回整形 -1：代表下載檔案出錯 0：代表下載檔案成功 1：代表檔案已經存在31      */32     public int downFile(String urlStr, String path, String fileName) {33         InputStream inputStream = null;34         try {35             FileUtils fileUtils = new FileUtils();36             37             if (fileUtils.isFileExist(path + fileName)) {38                 return 1;39             } else {40                 inputStream = getInputStreamFromUrl(urlStr);41                 File resultFile = fileUtils.write2SDFromInput(path,fileName, inputStream);42                 if (resultFile == null) {43                     return -1;44                 }45             }46         } catch (Exception e) {47             e.printStackTrace();48             return -1;49         } finally {50             try {51                 inputStream.close();52             } catch (Exception e) {53                 e.printStackTrace();54             }55         }56         return 0;57     }58 59     /**60      * 根據URL得到輸入資料流61      * 62      * @param urlStr63      * @return64      * @throws MalformedURLException65      * @throws IOException66      */67     public InputStream getInputStreamFromUrl(String urlStr)68             throws MalformedURLException, IOException {69         url = new URL(urlStr);70         HttpURLConnection urlConn = (HttpURLConnection) url.openConnection();71         InputStream inputStream = urlConn.getInputStream();72         return inputStream;73     }74 }

從網路下載檔案

 

　　2、將資源寫入SDcard

public class FileUtils {    private String SDPATH;    public String getSDPATH() {        return SDPATH;    }    public FileUtils() {        //得到當前外部存放裝置的目錄        // /SDCARD        SDPATH = Environment.getExternalStorageDirectory() + "/";    }    /**     * 在SD卡上建立檔案     *      * @throws IOException     */    public File creatSDFile(String fileName) throws IOException {        File file = new File(SDPATH + fileName);        file.createNewFile();        return file;    }        /**     * 在SD卡上建立目錄     *      * @param dirName     */    public File creatSDDir(String dirName) {        File dir = new File(SDPATH + dirName);        dir.mkdirs();        return dir;    }    /**     * 判斷SD卡上的檔案夾是否存在     */    public boolean isFileExist(String fileName){        File file = new File(SDPATH + fileName);        return file.exists();    }        /**     * 將一個InputStream裡面的資料寫入到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);//寫入資料            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;    }}

SDCard 讀寫操作

三、版本說明

　　程式源碼來源Mars老師，表示感謝

 

Android網路檔案下載模組整理