Question

我试图从我的XML（包含重复的子元素）中获取顶级元素的列表

示例XML

<feed>
   <folder name="subfolder1">
       <file name="subfile1" />
       <file name="subfile2" />
       <folder name="subsubfolder1">
            <file name="subsubfile1" />
            <file name="subsubfile2" />
        </folder>
   </folder>
   <folder name="subfolder2">
       <file name="subfile1" />
       <file name="subfile2" />
       <folder name="subsubfolder1">
            <file name="subsubfile1" />
            <file name="subsubfile2" />
        </folder>
   </folder>
   <file name="file1"/>
</feed>

我试图获取顶级元素的所有名称列表，例如

.subfolder1
.subfolder2

这是我的FeedReader ....

private List<Entry> readFeed(XmlPullParser parser) throws XmlPullParserException, IOException {
        List<Entry> entries = new ArrayList<Entry>();

        Log.v("ab", "reed feed started");

        parser.require(XmlPullParser.START_TAG, ns, "feed");
        while (parser.next() != XmlPullParser.END_TAG) {

            if (parser.getEventType() != XmlPullParser.START_TAG) {
                continue;
            }
            String sectionName = parser.getName();

            if(sectionName.equals("folder")) {
                readFolder(parser);
            } 
        }

        return entries;
    }

private void readFolder (XmlPullParser parser) throws XmlPullParserException, IOException  {
        parser.require(XmlPullParser.START_TAG, ns, "folder");
        Log.v("ab", parser.getAttributeValue(null, "name"));
        parser.require(XmlPullParser.END_TAG, ns, "folder");
    }

这是我的LogCat ....

09-02 13:40:22.537  31736-31753/? V/ab reed feed started
09-02 13:40:22.537  31736-31753/? V/ab﹕ subfolder1

在找到文件夹元素的第一个实例后，任何人都可以帮助解决这个问题吗？

Answer 1

您的上一个parser.require行看起来有问题：

parser.require(XmlPullParser.END_TAG, ns, "folder");

documentation你在这里做的是检查是否满足这些条件，如果没有，则抛出异常。因此，您目前处于刚刚阅读的“文件夹”开始标记中，并且您正在检查您是否位于“文件夹”结束标记中。由于您不在'folder'结束标记，因此parser.require将抛出异常。

如果删除该行，则应该让while循环继续运行，直到下一个文件夹开始标记。

编辑：这是一个完整的解决方案

我们需要一直持续到文档结尾，直到任何END_TAG，所以我将while循环修改为while (parser.next() != XmlPullParser.END_DOCUMENT)，然后在readFolder方法调用之后添加一些额外的代码。如果我理解正确，您只能在名为“子文件夹”的文件夹之后跳过'子文件夹'。所以我已经包含了一个应该跳过这些的循环。我也删除了parser.require行，因为我没有亲自看到需要，但这只是一种方法。

private List<Entry> readFeed(XmlPullParser parser) throws XmlPullParserException, IOException {
    List<Entry> entries = new ArrayList<Entry>();

    Log.v("ab", "reed feed started");

    while (parser.next() != XmlPullParser.END_DOCUMENT) {

        if (parser.getEventType() != XmlPullParser.START_TAG) {
            continue;
        }
        String sectionName = parser.getName();

        if(sectionName.equals("folder")) {
            readFolder(parser);

            //these booleans will be used to help us skip the subfolders
            boolean finishedTopLevelElement = false;
            boolean unwantedSubFolderFound = false;

            //this will loop until we are at a "folder" tag and have 
            //confirmed we have finished with the top level folder
            while (!(("folder".equals(parser.getName())) && finishedTopLevelElement)){
                parser.next();

                //we only care about 'folder' tags, for anything else
                //we keep looping
                if ("folder".equals(parser.getName())){

                    if (parser.getEventType() == XmlPullParser.START_TAG){

                        //if we hit a folder start tag, we're at a sub-folder
                        unwantedSubFolderFound = true;

                    } else if (parser.getEventType() == XmlPullParser.END_TAG && !unwantedSubFolderFound){

                        //if we hit a 'folder' end tag and we've not got an unwanted subfolder then
                        //we're done, it's the end tag of the top-level folder
                        finishedTopLevelElement = true;
                        unwantedSubFolderFound = false;

                    } else {

                        //if it's a folder end tag and we HAVE previously found an unwanted sub folder start tag
                        //then we've successfully skipped that sub-folder and can keep looking
                        unwantedSubFolderFound = false;
                    }
                }


            }
        } 
    }

    return entries;
}

private void readFolder (XmlPullParser parser) throws XmlPullParserException, IOException  {
    Log.v("ab", parser.getAttributeValue(null, "name"));
}

XmlPullParser处理多维重复元素

1 个答案: