重启程序后为什么DataFlavor会改变？

时间：2022-04-25 09:43:17

I wrote this method

我写了这个方法

public static void printFlavors() {
    Clipboard systemClipboard = Toolkit.getDefaultToolkit().getSystemClipboard();
    Transferable transferData = systemClipboard.getContents(null);
    for (DataFlavor dataFlavor : transferData.getTransferDataFlavors()) {
        System.out.println(dataFlavor);
    }
}

Using Java I write a string to my clipboard then I call printFlavors() and get

使用Java我将一个字符串写入剪贴板,然后调用printFlavors()并获取

java.awt.datatransfer.DataFlavor[mimetype=application/x-java-serialized-object;representationclass=java.lang.String]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=java.io.InputStream;charset=unicode]

When I first stop the program and then run a new program calling printFlavors() I get a totally different result:

当我第一次停止程序然后运行一个调用printFlavors()的新程序时,我得到一个完全不同的结果:

java.awt.datatransfer.DataFlavor[mimetype=application/x-java-text-encoding;representationclass=[B]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.Reader]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.Reader]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.Reader]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.lang.String]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.lang.String]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.lang.String]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.nio.CharBuffer]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.nio.CharBuffer]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.nio.CharBuffer]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=[C]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=[C]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=[C]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.InputStream;charset=UTF-16]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.InputStream;charset=UTF-16]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.InputStream;charset=UTF-16]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.nio.ByteBuffer;charset=UTF-16]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.nio.ByteBuffer;charset=UTF-16]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.nio.ByteBuffer;charset=UTF-16]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=[B;charset=UTF-16]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=[B;charset=UTF-16]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=[B;charset=UTF-16]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.InputStream;charset=UTF-8]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.InputStream;charset=UTF-8]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.InputStream;charset=UTF-8]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.nio.ByteBuffer;charset=UTF-8]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.nio.ByteBuffer;charset=UTF-8]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.nio.ByteBuffer;charset=UTF-8]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=[B;charset=UTF-8]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=[B;charset=UTF-8]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=[B;charset=UTF-8]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.InputStream;charset=UTF-16BE]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.InputStream;charset=UTF-16BE]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.InputStream;charset=UTF-16BE]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.nio.ByteBuffer;charset=UTF-16BE]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.nio.ByteBuffer;charset=UTF-16BE]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.nio.ByteBuffer;charset=UTF-16BE]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=[B;charset=UTF-16BE]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=[B;charset=UTF-16BE]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=[B;charset=UTF-16BE]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.InputStream;charset=UTF-16LE]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.InputStream;charset=UTF-16LE]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.InputStream;charset=UTF-16LE]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.nio.ByteBuffer;charset=UTF-16LE]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.nio.ByteBuffer;charset=UTF-16LE]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.nio.ByteBuffer;charset=UTF-16LE]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=[B;charset=UTF-16LE]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=[B;charset=UTF-16LE]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=[B;charset=UTF-16LE]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.InputStream;charset=ISO-8859-1]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.InputStream;charset=ISO-8859-1]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.InputStream;charset=ISO-8859-1]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.nio.ByteBuffer;charset=ISO-8859-1]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.nio.ByteBuffer;charset=ISO-8859-1]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.nio.ByteBuffer;charset=ISO-8859-1]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=[B;charset=ISO-8859-1]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=[B;charset=ISO-8859-1]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=[B;charset=ISO-8859-1]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.InputStream;charset=windows-1252]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.InputStream;charset=windows-1252]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.InputStream;charset=windows-1252]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.InputStream;charset=windows-1252]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.nio.ByteBuffer;charset=windows-1252]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.nio.ByteBuffer;charset=windows-1252]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.nio.ByteBuffer;charset=windows-1252]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=[B;charset=windows-1252]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=[B;charset=windows-1252]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=[B;charset=windows-1252]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.InputStream;charset=US-ASCII]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.InputStream;charset=US-ASCII]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.io.InputStream;charset=US-ASCII]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.nio.ByteBuffer;charset=US-ASCII]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.nio.ByteBuffer;charset=US-ASCII]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=java.nio.ByteBuffer;charset=US-ASCII]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=[B;charset=US-ASCII]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=[B;charset=US-ASCII]
java.awt.datatransfer.DataFlavor[mimetype=text/html;representationclass=[B;charset=US-ASCII]
java.awt.datatransfer.DataFlavor[mimetype=application/x-java-serialized-object;representationclass=java.lang.String]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=java.io.Reader]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=java.lang.String]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=java.nio.CharBuffer]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=[C]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=java.io.InputStream;charset=unicode]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=java.nio.ByteBuffer;charset=UTF-16]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=[B;charset=UTF-16]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=java.io.InputStream;charset=UTF-8]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=java.nio.ByteBuffer;charset=UTF-8]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=[B;charset=UTF-8]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=java.io.InputStream;charset=UTF-16BE]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=java.nio.ByteBuffer;charset=UTF-16BE]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=[B;charset=UTF-16BE]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=java.io.InputStream;charset=UTF-16LE]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=java.nio.ByteBuffer;charset=UTF-16LE]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=[B;charset=UTF-16LE]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=java.io.InputStream;charset=ISO-8859-1]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=java.nio.ByteBuffer;charset=ISO-8859-1]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=[B;charset=ISO-8859-1]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=java.io.InputStream;charset=windows-1252]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=java.io.InputStream;charset=windows-1252]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=java.nio.ByteBuffer;charset=windows-1252]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=[B;charset=windows-1252]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=java.io.InputStream;charset=US-ASCII]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=java.nio.ByteBuffer;charset=US-ASCII]
java.awt.datatransfer.DataFlavor[mimetype=text/plain;representationclass=[B;charset=US-ASCII]

Why does the result change?

为什么结果会改变?

1 个解决方案

#1

I assume that you added content to clipboard using something like:

我假设您使用以下内容将内容添加到剪贴板:

systemClipboard.setContents(new StringSelection("abc"), null);

Then, when you read available data flavors, I assume that Clipboard is able to exactly determine what the type of clipboard content is (it is StringSelection to which it still has a reference) and it knows exactly what type of content it is (encoding, etc).

然后,当您读取可用的数据风格时,我假设剪贴板能够准确地确定剪贴板内容的类型(它仍然是一个引用的StringSelection)并且它确切地知道它是什么类型的内容(编码,等等)。

If you pause the execution of the program (by thread-sleeping or debug break point) after you programmatically set the clipboard content, and then change the clipboard content outside of the program (by copying some text for example), you should get the same output as if you restarted the app (many more data flavors to help to convert the content to a Java representation), because the content came from the outer world (Operating System).

如果在以编程方式设置剪贴板内容后暂停执行程序(通过线程休眠或调试断点),然后在程序外部更改剪贴板内容(例如通过复制某些文本),您应该得到相同的输出就好像你重新启动了应用程序(更多的数据风格,以帮助将内容转换为Java表示),因为内容来自外部世界(操作系统)。

I worked a little bit with java Clipboard in the past and these are my assumptions; as always it is best to check the source code if you really need to know what's going on exactly.

我过去曾经使用过Java剪贴板,这些都是我的假设;一如既往,最好检查源代码,如果你真的需要知道究竟发生了什么。

EDIT

I took a look at the source code, and my assumption is correct - when the app stores StringSelection to clipboard, it keeps reference to it until the clipboard content changes and returns only data flavors supported by StringSelection:

我看了一下源代码,我的假设是正确的 - 当应用程序将StringSelection存储到剪贴板时,它会一直引用它,直到剪贴板内容发生变化,并且只返回StringSelection支持的数据风格:

private static final DataFlavor[] flavors = {
   DataFlavor.stringFlavor,
   DataFlavor.plainTextFlavor // deprecated
};

#1

I assume that you added content to clipboard using something like:

我假设您使用以下内容将内容添加到剪贴板:

systemClipboard.setContents(new StringSelection("abc"), null);

Then, when you read available data flavors, I assume that Clipboard is able to exactly determine what the type of clipboard content is (it is StringSelection to which it still has a reference) and it knows exactly what type of content it is (encoding, etc).

然后,当您读取可用的数据风格时,我假设剪贴板能够准确地确定剪贴板内容的类型(它仍然是一个引用的StringSelection)并且它确切地知道它是什么类型的内容(编码,等等)。

If you pause the execution of the program (by thread-sleeping or debug break point) after you programmatically set the clipboard content, and then change the clipboard content outside of the program (by copying some text for example), you should get the same output as if you restarted the app (many more data flavors to help to convert the content to a Java representation), because the content came from the outer world (Operating System).

如果在以编程方式设置剪贴板内容后暂停执行程序(通过线程休眠或调试断点),然后在程序外部更改剪贴板内容(例如通过复制某些文本),您应该得到相同的输出就好像你重新启动了应用程序(更多的数据风格,以帮助将内容转换为Java表示),因为内容来自外部世界(操作系统)。

I worked a little bit with java Clipboard in the past and these are my assumptions; as always it is best to check the source code if you really need to know what's going on exactly.

我过去曾经使用过Java剪贴板,这些都是我的假设;一如既往,最好检查源代码,如果你真的需要知道究竟发生了什么。

EDIT

I took a look at the source code, and my assumption is correct - when the app stores StringSelection to clipboard, it keeps reference to it until the clipboard content changes and returns only data flavors supported by StringSelection:

我看了一下源代码,我的假设是正确的 - 当应用程序将StringSelection存储到剪贴板时,它会一直引用它,直到剪贴板内容发生变化,并且只返回StringSelection支持的数据风格:

private static final DataFlavor[] flavors = {
   DataFlavor.stringFlavor,
   DataFlavor.plainTextFlavor // deprecated
};
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