解组期间 XML 字符无效

2022-01-19 00:00:00 java jaxb unmarshalling xml-serialization

我正在使用编码UTF-8"将对象编组为 XML 文件.它成功生成文件.但是当我尝试将其解组时，出现错误:

I am marshalling objects to XML file using encoding "UTF-8". It generates file successfully. But when I try to unmarshal it back, there is an error:

无效的 XML 字符(Unicode:0x{2}) 的值中发现属性{1}"且元素为0"

An invalid XML character (Unicode: 0x{2}) was found in the value of attribute "{1}" and element is "0"

字符为 0x1A 或 u001a，在 UTF-8 中有效但在 XML 中非法.JAXB 中的 Marshaller 允许将此字符写入 XML 文件，但 Unmarshaller 无法将其解析回来.我尝试使用另一种编码(UTF-16、ASCII 等)但仍然出错.

The character is 0x1A or u001a, which is valid in UTF-8 but illegal in XML. Marshaller in JAXB allows writing this character into XML file, but Unmarshaller cannot parse it back. I tried to use another encoding (UTF-16, ASCII, etc) but still error.

常见的解决方案是在 XML 解析之前删除/替换这个无效字符.但是如果我们需要这个字符，解组后如何得到原来的字符呢?

The common solution is to remove/replace this invalid character before XML parsing. But if we need this character back, how to get the original character after unmarshalling?

在寻找此解决方案时，我想在解组之前用替代字符(例如点 =.")替换无效字符.

While looking for this solution, I want to replace the invalid characters with a substitute character (for example dot = ".") before unmarshalling.

我已经创建了这个类:

public class InvalidXMLCharacterFilterReader extends FilterReader {

    public static final char substitute = '.'; 

    public InvalidXMLCharacterFilterReader(Reader in) {
        super(in);
    }

    @Override
    public int read(char[] cbuf, int off, int len) throws IOException {

        int read = super.read(cbuf, off, len);

        if (read == -1)
            return -1;

        for (int readPos = off; readPos < off + read; readPos++) {
            if(!isValid(cbuf[readPos])) {
                   cbuf[readPos] = substitute;
            }
        }

        return readPos - off + 1; 
    }

    public boolean isValid(char c) {
        if((c == 0x9)
                || (c == 0xA) 
                || (c == 0xD) 
                || ((c >= 0x20) && (c <= 0xD7FF)) 
                || ((c >= 0xE000) && (c <= 0xFFFD)) 
                || ((c >= 0x10000) && (c <= 0x10FFFF)))
        {
            return true;
        } else
            return false;
    }
 }

这就是我读取和解组文件的方式:

Then this is how I read and unmarshall the file:

FileReader fileReader = new FileReader(this.getFile());
Reader reader = new InvalidXMLCharacterFilterReader(fileReader);
Object o = (Object)um.unmarshal(reader);

不知何故，读者不会用我想要的字符替换无效字符.它会导致无法解组的错误 XML 数据.我的 InvalidXMLCharacterFilterReader 类有问题吗?

Somehow the reader does not replace invalid characters with the character I want. It results a wrong XML data which can't be unmarshalled. Is there something wrong with my InvalidXMLCharacterFilterReader class?

推荐答案

Unicode 字符 U+001A 是 在 XML 1.0 中是非法的:

The Unicode character U+001A is illegal in XML 1.0:

在这种情况下，用于表示它的编码无关紧要，在 XML 内容中根本不允许.

The encoding used to represent it does not matter in this case, it's simply not allowed in XML content.

XML 1.1 允许某些受限字符(包括 U+001A)被包括在内，但它们必须以数字字符引用的形式出现 (&#x1a;)

XML 1.1 allows some of the restricted characters (including U+001A) to be included, but they must be present as numeric character references (&#x1a;)

维基百科有一个很好的情况总结.

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