14

在将 HTML 从 Firefox 粘贴到 Linux 上的 Java6 应用程序（仅限！）时，我遇到了一个奇怪的问题。这是一个最小的例子：

import java.awt.Toolkit;
import java.awt.datatransfer.Clipboard;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.io.Reader;
import java.nio.ByteBuffer;

class ClipboardPrinter {
    public static void main( String args[] ) throws Exception
    {
        Clipboard systemClipboard = Toolkit.getDefaultToolkit()
                .getSystemClipboard();
        Transferable transferData = systemClipboard.getContents(null);
        if (transferData == null) {
            System.out.println("no content");
            return;
        }

//      final DataFlavor htmlFlavorString = new DataFlavor("text/html;class=java.lang.String");
//      String html = (String)transferData.getTransferData(htmlFlavorString);
//      System.out.println("html = '" + html + "'");

        final DataFlavor htmlFlavor = new DataFlavor("text/html;class=java.nio.ByteBuffer;charset=US-ASCII");
        if (!transferData.isDataFlavorSupported(htmlFlavor)) {
            System.out.println("no text/html reader content");
            return;
        }

        ByteBuffer bb = (ByteBuffer)transferData.getTransferData(htmlFlavor);
        byte[] bytes = bb.array();
        for (byte b: bytes)
        {
            System.out.format("%02x", b);
        }
        System.out.println();
        final int cutoff = 2;
        byte[] bytes2 = new byte[bytes.length - cutoff];
        for (int i = cutoff; i < bytes.length; i++)
            bytes2[i-cutoff] = bytes[i];
        final String htmlContent = new String(bytes2, "UTF-16LE");


        System.out.println("htmlContent = '" + htmlContent + "'");
    }
}

首先我尝试使用new DataFlavor("text/html;class=java.lang.String"), （代码在上面的代码片段中注释掉），但这会导致一个不可用的字符串，其中包含 2 个字符，开头的值为 65533（并且它无助于切断这两个字符）。

接下来我使用了 ByteBuffer 数据风格charset=US-ASCII（我故意使用 ASCII！）：（charset=UTF-16LE或 UTF-16 或 UTF-16BE）根本不起作用。使用上述charset=US-ASCII解决方案（连同new String(bytes2, "UTF-16LE")），7 位字符可以工作（但例如变音符号不起作用，而是打印一个“？”）。

我切断了两个字节，因为开头似乎有两个 bom（不确定，可能是别的）？

我得到了一个类似的结果，数据风格为charset=UTF-8and cutoff=6（两个三字节的“替换字符” 0xEFBFBD 在开头，变音符号编码为两个错误的字符）。在这两种情况下，我都使用了new String(bytes2, "UTF-16LE").

您对如何：

  • 在此解决方案中支持非 ASCII 字符（或找到更好的解决方案）？
  • 确定是 UTF-16LE 还是 UTF-16BE？

谢谢！任何提示表示赞赏！

顺便说一句：这是我的（Linux）系统上支持的数据风格（来自transferable.getTransferDataFlavors()）：

[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.nio.CharBuffer]
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.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=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=[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.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=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=[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.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=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=[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=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]
java.awt.datatransfer.DataFlavor[mimetype=text/x-moz-url-priv;representationclass=java.io.InputStream]
java.awt.datatransfer.DataFlavor[mimetype=text/_moz_htmlinfo;representationclass=java.io.InputStream]
java.awt.datatransfer.DataFlavor[mimetype=text/_moz_htmlcontext;representationclass=java.io.InputStream]
java.awt.datatransfer.DataFlavor[mimetype=text/x-moz-url-priv;representationclass=java.nio.ByteBuffer]
java.awt.datatransfer.DataFlavor[mimetype=text/_moz_htmlinfo;representationclass=java.nio.ByteBuffer]
java.awt.datatransfer.DataFlavor[mimetype=text/_moz_htmlcontext;representationclass=java.nio.ByteBuffer]
java.awt.datatransfer.DataFlavor[mimetype=text/x-moz-url-priv;representationclass=[B]
java.awt.datatransfer.DataFlavor[mimetype=text/_moz_htmlinfo;representationclass=[B]
java.awt.datatransfer.DataFlavor[mimetype=text/_moz_htmlcontext;representationclass=[B]]
4

2 回答 2

1

我相信这个问题与他有关read from clipboard as US-ASCII，然后转换为 unicode 并期望保持德语变音符号完好无损。由于 US-ASCII 是 7 位字符集，因此不包括德语变音符号，并且在将剪贴板读取为 US-ASCII 后已经丢失。

public class CharsetDemo {
    public static void main(String[] args) throws Exception {
        byte[] bytes;

        // convert the German umlaut to bytes in US-ASCII charset
        bytes = "ö".getBytes("US-ASCII");
        System.out.println("US-ASCII");
        System.out.println("bytes : " + asHexString(bytes));
        System.out.println("string: " + new String(bytes, "US-ASCII"));
        System.out.println();

        // create a unicode string from the US-ASCII bytes
        String utf8String = new String(bytes, "UTF-8");
        bytes = utf8String.getBytes("UTF-8");
        System.out.println("UTF-8");
        System.out.println("bytes : " + asHexString(bytes));
        System.out.println("string: " + utf8String);
        System.out.println();

        // convert the German umlaut to bytes in ISO-8859-1 charset
        bytes = "ö".getBytes("ISO-8859-1");
        System.out.println("ISO 8859-1");
        System.out.println("bytes : " + asHexString(bytes));
        System.out.println("string: " + new String(bytes, "ISO-8859-1"));
        System.out.println();

        // create a unicode string from the ISO-8859-1 bytes
        utf8String = new String(bytes, "UTF-8");
        bytes = utf8String.getBytes("UTF-8");
        System.out.println("UTF-8");
        System.out.println("bytes : " + asHexString(bytes));
        System.out.println("string: " + utf8String);
        System.out.println();

        // bytes of the "REPLACEMET CHARACTER"
        System.out.println("replacement character bytes: " 
            + asHexString("\uFFFD".getBytes("UTF-8")));

    }

    static String asHexString(byte[] bytes) {
        StringBuilder sb = new StringBuilder();
        for (byte b : bytes) {
            sb.append(String.format("%X ", b));
        }
        return sb.toString();
    }
}

输出

US-ASCII
bytes : 3F 
string: ?  <--- the question mark represents here the "REPLACEMENT CHARACTER"

UTF-8
bytes : 3F 
string: ?

ISO 8859-1
bytes : F6 
string: ö

UTF-8
bytes : EF BF BD  <-- the "REPLACEMENT CHARACTER", as "F6" is not a valid UTF-8 codepoint
string: �

replacement character bytes: EF BF BD
于 2015-05-18T06:49:04.283 回答
0

不再支持 Java 6。所以，问题已经过时了。

于 2015-05-18T02:20:22.577 回答