java - 如何在 Java 中将转义字符读取为文本？

Question

public List<String> readRSS(String feedUrl, String openTag, String closeTag)
            throws IOException, MalformedURLException {

        URL url = new URL(feedUrl);
        BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream()));

        String currentLine;
        List<String> tempList = new ArrayList<String>();
        while ((currentLine = reader.readLine()) != null) {
            Integer tagEndIndex = 0;
            Integer tagStartIndex = 0;
            while (tagStartIndex >= 0) {
                tagStartIndex = currentLine.indexOf(openTag, tagEndIndex);
                if (tagStartIndex >= 0) {
                    tagEndIndex = currentLine.indexOf(closeTag, tagStartIndex);
                    tempList.add(currentLine.substring(tagStartIndex + openTag.length(), tagEndIndex) + "\n");
                }
            }
        }
        if (tempList.size() > 0) {
            if(openTag.contains("title")){
                tempList.remove(0);
                tempList.remove(0);
            }
            else if(openTag.contains("desc")){
                tempList.remove(0);
            }
        }
        return tempList;
    }

我编写这段代码是为了阅读 RSS 提要。一切正常，但是当解析器找到像这样的字符时 它会中断。这是因为它找不到它的结束标签，因为 xml 被转义了。

我不知道如何在我的代码中修复它。谁能帮我解决这个问题？

Answer 1

问题是特殊字符 是一个换行符，因此您的开始和结束标记会出现在不同的行上。因此，如果您逐行阅读，它将无法使用您拥有的代码。

你可以尝试这样的事情:

StringBuffer fullLine = new StringBuffer();

while ((currentLine = reader.readLine()) != null) {
    int tagStartIndex = currentLine.indexOf(openTag, 0);
    int tagEndIndex = currentLine.indexOf(closeTag, tagStartIndex);

    // both tags on the same line
    if (tagStartIndex != -1 && tagEndIndex != -1) {
        // process the whole line
        tempList.add(currentLine);
        fullLine = new StringBuffer();
    // no tags on this line but the buffer has been started
    } else if (tagStartIndex == -1 && tagEndIndex == -1 && fullLine.length() > 0) {
        /*
         * add the current line to the buffer; it is part 
         * of a larger line
         */
        fullLine.append(currentLine);
    // start tag is on this line
    } else if (tagStartIndex != -1 && tagEndIndex == -1) {
        /*
         *  line started but did not have an end tag; add it to 
         *  a new buffer
         */
        fullLine = new StringBuffer(currentLine);
        // end tag is on this line
    } else if (tagEndIndex != -1 && tagStartIndex == -1) {
        /*
         *  line ended but did not have a start tag; add it to 
         *  the current buffer and then process the buffer
         */
        fullLine.append(currentLine);
        tempList.add(fullLine.toString());
        fullLine = new StringBuffer();
    }
}

给定这个样本输入:

<title>another &#xD;
title 0</title>
<title>another title 1</title>
<title>another title 2</title>
<title>another title 3</title>
<desc>description 0</desc>
<desc>another &#xD;
description 1</desc>
<title>another title 4</title>
<title>another &#xD;
another line in between &#xD;
title 5</title>

title 的 tempList 中的完整行变为:

<title>another &#xD;title 0</title>
<title>another title 1</title>
<title>another title 2</title>
<title>another title 3</title>
<title>another title 4</title>
<title>another &#xD;another line in between &#xD;title 5</title>

对于desc:

<desc>description 0</desc>
<desc>another &#xD;description 1</desc>

您应该在完整的 RSS 提要上测试此方法的性能。还要注意特殊字符不会被转义。