訪問Internet和保存文件到SDCard上，首先要在mainifest.xml文件中加上下面的權限。

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

gettextfilestring(String url)獲取文本文件內：

public String gettextfilestring(String url){ 
                InputStream input =getinputStream(url); 
                StringBuffer sb = new StringBuffer(""); 
                BufferedReader bfr = new BufferedReader(new InputStreamReader(input)); 
                String line = ""; 
                try { 
                        while((line=bfr.readLine())!=null){ 
                                sb.append(line); 
                        } 
                        
                } catch (IOException e) { 
                        toasterror("流文件讀寫錯誤"); 
                        e.printStackTrace(); 
                }finally{ 
                        try { 
                                bfr.close(); 
                        } catch (IOException e) { 
                                toasterror("流文件未能正常關閉"); 
                                e.printStackTrace(); 
                        } 
                } 
                return sb.toString(); 
} 

downFiletoDecive(String url,String filename)方法下載文件到設備內存，下載的文件在應用的路徑file下：

public void downFiletoDecive(String url,String filename){ 
                    if((url!=null&&!"".equals(url))&&(filename!=null&&!"".equals(filename))){ 
                            InputStream input = getinputStream(url); 
                            FileOutputStream outStream = null; 
                            try { 
                                    outStream = c.openFileOutput(filename, Context.MODE_WORLD_READABLE|Context.MODE_WORLD_WRITEABLE); 
                                    int temp = 0; 
                                    byte[] data = new byte[1024]; 
                                    while((temp = input.read(data))!=-1){ 
                                            outStream.write(data, 0, temp); 
                                    } 
                            } catch (FileNotFoundException e) { 
                                    toasterror("請傳入正確的上下文"); 
                                    e.printStackTrace(); 
                            } catch (IOException e) { 
                                    toastemessage("讀寫錯誤"); 
                                    e.printStackTrace(); 
                            }finally{ 
                                    try { 
                                            outStream.flush(); 
                                            outStream.close(); 
                                    } catch (IOException e) { 
                                            toasterror("流文件未能正常關閉"); 
                                            e.printStackTrace(); 
                                    } 
                                    
                            } 
                    } 
                    toastemessage("下載成功"); 
            } 

downFiletoSDCard(String url,String path,String filename)下載文件到SDCard中，自定義保存路：

public void downFiletoSDCard(String url,String path,String filename){ 
                
                if((url!=null&&!"".equals(url))&&(path!=null)&&(filename!=null&&!"".equals(filename))){ 
                                
                                InputStream input = getinputStream(url); 
                                downloader(input, path, filename); 
                        
                }else{ 
                                /* 
                                 * 對不合發的參數做處理 
                                 */ 
                                if(url==null||"".equals(url)){ 
                                        toasterror("url不能為空或為“”"); 
                                } 
                                if(path==null){ 
                                        toasterror("path不能為空"); 
                                } 
                                if(filename==null||"".equals(filename)){ 
                                        toasterror("filename不能為空"); 
                                } 
                } 
                
        }