通過命令行執行WGET下載會更快，而通過Java代碼執行時會更慢

Question

我正在使用WGET通過java代碼下載文件，這需要大約10分鐘才能下載20 MB文件。但是通過命令行執行wget下載，同樣的文件以10MbPs的速度在7秒內下載。有人知道爲什麼嗎？我該如何改進我的Java代碼？

下面是我用來使用WGET下載文件的代碼。大約需要10分鐘才能下載20 MB的文件。但是當我通過命令行運行wget命令時，它發生在幾秒鐘內！

import java.io.BufferedReader; 
    import java.io.File; 
    import java.io.FileOutputStream; 
    import java.io.IOException; 
    import java.io.InputStreamReader; 
    import java.net.MalformedURLException; 
    import java.net.URL; 
    import java.net.URLConnection; 



public class WGETServer 
{ 



public File download(URL sourceurl, String username, String password, String fileName) 
{ 
    //System.out.println("WGET download() is starting ..."); 

    File file = null; 
    URLConnection urlConnection = null; 
    BufferedReader reader = null; 
    FileOutputStream outputStream = null; 
    try { 

     urlConnection = sourceurl.openConnection(); 

      String userNameAndPassword = username +":"+ password; 
      String encoding = new sun.misc.BASE64Encoder().encode (userNameAndPassword.getBytes()); 
      //The line which is supposed to add authorization data 
      urlConnection.setRequestProperty ("Authorization", "Basic " + encoding); 

     reader = new BufferedReader(new InputStreamReader(urlConnection.getInputStream())); 
    } 
    catch (IOException e) { 
     System.err.println("Internet connection failure or invalid Username/Password."); 
     return null; 
    } 
    try { 
     file = new File("file path"); 
     outputStream = new FileOutputStream(file); 
     int character; 
     while((character = reader.read()) != -1) 
     { 
      outputStream.write(character); 
     } 
     outputStream.flush(); 
     outputStream.close(); 
     reader.close(); 
    } catch (IOException e) { 
     System.err.println(e.getMessage()); 
     return null; 
    } 
    System.out.println("downloading completed"); 
    return file; 

} 



public static void main(String args[]) throws MalformedURLException 
{ 
    URL sourceurl = new URL("https:blablabla"); 
    String username = "username"; 
    String password = "password"; 
    String filename = "filename"; 
    WGETServer WGETdownload = new WGETServer(); 
    WGETdownload.download(sourceurl, username, password, filename); 
} 

}

Answer 1

您已經閱讀器緩存（好），但是你寫的字符內容字符到磁盤（BAD）。這會殺死你的表現。這不是閱讀，而是寫作。

Answer 2

用BufferedOutputStream包裝FileOutputStream。

new BufferedOutputStream(new FileOutputStream(...))

否則，寫入每一個字符由底層操作系統這是一個耗時的過程同步到磁盤。這就是緩衝如此重要的原因。