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;
    }

我写了这段代码来阅读RSS源。一切正常但是当解析器找到像这个这样的字符时它会中断。这是因为它无法找到其结束标记，因为xml被转义。

我不知道如何在代码中修复它。任何人都可以帮我解决这个问题吗？

Answer 1

问题是特殊字符是换行符，因此您的开始和结束标记会在不同的行上结束。因此，如果您逐行阅读，则无法使用您拥有的代码。

您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();
    }
}

鉴于此示例输入：

<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>

tempList的{{1}}中的完整行变为：

title

对于<title>another 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 another line in between title 5</title>：

desc

您应该在完整的RSS Feed上测试此方法的性能。另请注意，特殊字符不会被转义。

如何在Java中将转义字符作为文本读取？

1 个答案: