Android根據URL下載文件保存到SD卡

 //下載具體操作  

    private void download() {  

        try {  

            URL url = new URL(downloadUrl);  

            //打開連接  

            URLConnection conn = url.openConnection();  

            //打開輸入流  

            InputStream is = conn.getInputStream();  

            //獲得長度  

            int contentLength = conn.getContentLength();  

            Log.e(TAG, "contentLength = " + contentLength);  

            //創建文件夾 MyDownLoad，在存儲卡下  

            String dirName = Environment.getExternalStorageDirectory() + "/MyDownLoad/";  

            File file = new File(dirName);  

            //不存在創建  

            if (!file.exists()) {  

                file.mkdir();  

            }  

            //下載后的文件名  

            String fileName = dirName + "xiaomibianqian.apk";  

            File file1 = new File(fileName);  

            if (file1.exists()) {  

                file1.delete();  

            }  

            //創建字節流  

            byte[] bs = new byte[1024];  

            int len;  

            OutputStream os = new FileOutputStream(fileName);  

            //寫數據  

            while ((len = is.read(bs)) != -1) {  

                os.write(bs, 0, len);  

            }  

            //完成后關閉流  

            Log.e(TAG, "download-finish");  

            os.close();  

            is.close();  

        } catch (Exception e) {  

            e.printStackTrace();  

        }  

    }  

}  

    String dirName = Environment.getExternalStorageDirectory() + "/MyDownLoad/";  

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/> <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>