获取 Applets OutputStream 抛出异常:出什么问题了? [英] Getting Applets OutputStream throws an exception: What is wrong?

问题描述

我制作了一个小程序，我尝试使用 conn.getOutputStream(); 检索 URLConnection 对象输出流.当我尝试这样做时，我的小程序抛出异常java.net.UnknownServiceException:协议不支持输出.

I have made an applet where I attempt to retrieve a URLConnection objects output stream using conn.getOutputStream();. When I attempt to do this, my applet throws the exception java.net.UnknownServiceException: protocol doesn't support output.

出了什么问题&我怎样才能解决这个问题?这是我一直在处理的一个问题 &我真的很紧张，因为我不明白到底出了什么问题&我该如何解决.

What is going wrong & how can I fix this? This has been a problem I have been dealing with for a while & I am really stressing because I dont understand what exactly is wrong & how I can fix it.

一些重要的背景信息.我打开 &通过打开加载小程序的 HTML 文件来运行我的小程序.小程序加载成功&创建其所有 JComponent.在尝试获取输出流时，我得到了上面提到的异常.

在我的浏览器中运行时显示在我的小程序中的输出:

The Output displayed in my applet when run in my browser:

路径:文件:/C:/Users/Soribo/Desktop/Website/Test/在连接():失败:java.net.UnknownServiceException:协议不支持输出

Path: file:/C:/Users/Soribo/Desktop/Website/Test/ In connect(): Failure: java.net.UnknownServiceException: protocol doesn't support output

我的代码:

public class TestApplet extends JApplet
{
    JTextArea displayTf;

    public TestApplet()
    {

    }

    public void init() 
    {
        try 
        {
            SwingUtilities.invokeAndWait( new Runnable() {
                public void run()
                {
                    initComponents();
                    connect();
                }
            });
        } 
        catch (InterruptedException e) { e.printStackTrace(); } 
        catch (InvocationTargetException e) { e.printStackTrace(); }
    }

    public void stop() {}
    public void destroy() {}
    public void start() {}

    public void initComponents()
    {
        JPanel mainPanel = (JPanel) getContentPane();
        displayTf = new JTextArea( "" );

        mainPanel.add( displayTf );
    }

    public void connect()
    {
        try
        {
            displayTf.setText( displayTf.getText() + "\nPath: " + getCodeBase() ); // In the browser it displays 'file:/c:/.../TestApplet/bin'
            URL servletUrl = new URL( getCodeBase(), "TestApplet" );               // My applet's class file name is TestApplet.class
            URLConnection conn = servletUrl.openConnection();

            conn.setDoInput( true );
            conn.setDoOutput( true );
            conn.setUseCaches( false );
            conn.setDefaultUseCaches (false);
            conn.setRequestProperty ("Content-Type", "application/octet-stream"); // Set the content type to indicate that we're sending binary data

            OutputStream out = conn.getOutputStream();  // EXCEPTION thrown here java.net.UnknownServiceException: protocol doesn't support output

            // Some tests I have done
            // conn.setRequestProperty( "Content-Type", "application/x-java-serialized-object" );
            // conn.setRequestProperty("Authorization", "Basic " + encode("uidPassword"));
            // System.setProperty("http.proxyHost", "proxy.example.com"); 
            // System.setProperty("http.proxyPort", "8080"); 

        }
        catch ( IOException e )
        {
            displayTf.setText( displayTf.getText() + "\nIn connect(): Failure: " + e );
        }
    }

推荐答案

file: URL 不支持写入.

file: URLs don't support writing to them.

当您的小程序页面位于网络服务器上时，您将拥有一个 http: URL，该 URL 支持写入 - 但只有在服务器端有人接受请求时才有效(可能是 POST 或 PUT，不知道).

When your applet page is on a webserver, you'll have an http: URL, which supports writing - but it'll only work if someone on the server-side is there accepting the request (likely POST or PUT, don't know).

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