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java - 使用 XmlPullParserFactory 解析 XML 在 while 语句中崩溃

转载 作者：行者123 更新时间：2023-12-01 14:09:57 26 4
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我正在使用 XmlPullParserFactory 对象来解析我从服务器收到的一些 XML。由于某种原因，它在 while 语句处崩溃，我不明白为什么会发生这种情况。

XML:

<?xml version="1.0" encoding="UTF-8"?>
<body>
<item>
  <id>115240</id>
  <title>
    <![CDATA[Student Evangelism Team Leaves for Fiji]]>
  </title>
  <created>20130821-15:50</created>
  <author>
    <![CDATA[Staff Writer]]>
  </author>
  <summary>
    <![CDATA[On August 21, Service, Justice, and Missions Coordinator Fabio Maia and ten
      Pacific Union College students left for an eighteen-day evangelism mission in
      Fiji with ShareHim and Quiet Hour Ministries.]]>
  </summary>
  <body_text>
    <![CDATA[<p>On August 21, Service, Justice, and Missions Coordinator
      Fabio Maia and ten Pacific Union College students left for an eighteen-day
      evangelism mission in Fiji with ShareHim and Quiet Hour Ministries. Each
      student will be placed in a specific community where they will present the
      story of Christ’s love and sacrifice each evening. Many of the students are
      active in the college’s praise and worship teams and brought their instruments
      so they can share God’s love through music.</p>
      <p>Before the group departed, the students gathered in
      President Heather J. Knight’s office for a special blessing prayer led by
      Pastor Mark Witas, the lead pastor of the PUC Church. Pastor Witas included
      special prayer that God lead the group in doing good in His name. <a></a>The group also
      bonded by sharing a meal together before heading to the airport for their
      flight to Fiji.</p>
      <p>For many PUC students, summer is the perfect opportunity to
      devote time to ministry and service. While some students work at summer camps
      or serve as literature evangelists, other groups get the experience of a
      lifetime by sharing the gospel and serving local communities in places around
      the world. The PUC community is invited to join in prayer for the team travelling
      to Fiji as well as other student groups currently on short-term mission trips
      to Nicaragua and Brazil.</p>]]>
  </body_text>
  <url>http://www.puc.edu/news/archives/2013/student-evangelism-team-leaves-for-fiji</url>
  <images>
    <image url="http://www.puc.edu/__data/assets/image/0014/115241/fiji.jpg" url_2x="http://www.puc.edu/__data/assets/image/0014/115241/varieties/2x.jpg" thumb_small="http://www.puc.edu/__data/assets/image/0014/115241/varieties/thumb.jpg" thumb_medium="http://www.puc.edu/__data/assets/image/0014/115241/varieties/thumb_large.jpg" thumb_large="http://www.puc.edu/__data/assets/image/0014/115241/varieties/thumb_large.jpg" />
  </images>
  </item>
... lots more item nodes
</body>

Java:

class PUCNewsItem
{

    public String title;
    public String summary;
    public String body;
    public String url;
    public String imageUrl;

}

public class PUCDatasource extends Activity {

    public static ArrayList<PUCNewsItem> getPUCNews() throws IOException {

            String url = "http://api.mysite.com/list";
            InputStream is = downloadUrl(url);
            XmlPullParserFactory pullParserFactory;

            try {
                pullParserFactory = XmlPullParserFactory.newInstance();
                XmlPullParser parser = pullParserFactory.newPullParser();
                parser.setInput(is, null);

                ArrayList<PUCNewsItem> items = null;
                int eventType = parser.getEventType();
                PUCNewsItem item = null;
                Log.d("Debug: ", "Start");
                while (eventType != XmlPullParser.END_DOCUMENT){
                    String name = null;
                    switch (eventType){
                        case XmlPullParser.START_DOCUMENT:
                            Log.d("Debug: ", "Start doc");
                            items = new ArrayList<PUCNewsItem>();
                            break;
                        case XmlPullParser.START_TAG:
                            name = parser.getName();
                            if (name == "item"){
                                item = new PUCNewsItem();
                            } else if (item != null){
                                if (name == "title"){
                                    item.title = parser.nextText();
                                } else if (name == "summary"){
                                    item.summary = parser.nextText();
                                } else if (name == "body_text"){
                                    item.body = parser.nextText();
                                }  
                            }
                            break;
                        case XmlPullParser.END_TAG:
                            name = parser.getName();
                            if (name.equalsIgnoreCase("item") && item != null) {
                                items.add(item);
                            }
                            break;
                    }//end switch

                    eventType = parser.next();

                }//end while

                return items;

            } catch (XmlPullParserException e) {
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

            return null;

        }//end

}//end class

错误:

09-03 16:31:50.100: W/System.err(16727): Invalid stream or encoding: java.io.IOException: Stream is closed (position:START_DOCUMENT null@1:1) caused by: java.io.IOException: Stream is closed; nested exception is:
09-03 16:31:50.108: W/System.err(16727): java.io.IOException: Stream is closed
09-03 16:31:50.108: W/System.err(16727):    at java.util.zip.GZIPInputStream.read(GZIPInputStream.java:158)
09-03 16:31:50.108: W/System.err(16727):    at libcore.io.Streams.readSingleByte(Streams.java:41)
09-03 16:31:50.108: W/System.err(16727):    at java.util.zip.InflaterInputStream.read(InflaterInputStream.java:128)
09-03 16:31:50.108: W/System.err(16727):    at org.kxml2.io.KXmlParser.setInput(KXmlParser.java:1623)
09-03 16:31:50.108: W/System.err(16727):    at com.puc.mobile.PUCDatasource.getPUCNews(PUCDatasource.java:40)
09-03 16:31:50.108: W/System.err(16727):    at com.puc.mobile.MainActivity$DownloadPUCNews.doInBackground(MainActivity.java:94)
09-03 16:31:50.108: W/System.err(16727):    at com.puc.mobile.MainActivity$DownloadPUCNews.doInBackground(MainActivity.java:1)
09-03 16:31:50.108: W/System.err(16727):    at android.os.AsyncTask$2.call(AsyncTask.java:264)
09-03 16:31:50.108: W/System.err(16727):    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
09-03 16:31:50.108: W/System.err(16727):    at java.util.concurrent.FutureTask.run(FutureTask.java:137)
09-03 16:31:50.108: W/System.err(16727):    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)
09-03 16:31:50.108: W/System.err(16727):    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
09-03 16:31:50.108: W/System.err(16727):    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
09-03 16:31:50.108: W/System.err(16727):    at java.lang.Thread.run(Thread.java:856)
09-03 16:31:50.108: D/AndroidRuntime(16727): Shutting down VM
09-03 16:31:50.108: W/dalvikvm(16727): threadid=1: thread exiting with uncaught exception (group=0x40aba210)
09-03 16:31:50.108: E/AndroidRuntime(16727): FATAL EXCEPTION: main
09-03 16:31:50.108: E/AndroidRuntime(16727): java.lang.NullPointerException
09-03 16:31:50.108: E/AndroidRuntime(16727):    at com.puc.mobile.MainActivity$DownloadPUCNews.onPostExecute(MainActivity.java:103)
09-03 16:31:50.108: E/AndroidRuntime(16727):    at com.puc.mobile.MainActivity$DownloadPUCNews.onPostExecute(MainActivity.java:1)
09-03 16:31:50.108: E/AndroidRuntime(16727):    at android.os.AsyncTask.finish(AsyncTask.java:602)
09-03 16:31:50.108: E/AndroidRuntime(16727):    at android.os.AsyncTask.access$600(AsyncTask.java:156)
09-03 16:31:50.108: E/AndroidRuntime(16727):    at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:615)
09-03 16:31:50.108: E/AndroidRuntime(16727):    at android.os.Handler.dispatchMessage(Handler.java:99)
09-03 16:31:50.108: E/AndroidRuntime(16727):    at android.os.Looper.loop(Looper.java:137)
09-03 16:31:50.108: E/AndroidRuntime(16727):    at android.app.ActivityThread.main(ActivityThread.java:4697)
09-03 16:31:50.108: E/AndroidRuntime(16727):    at java.lang.reflect.Method.invokeNative(Native Method)
09-03 16:31:50.108: E/AndroidRuntime(16727):    at java.lang.reflect.Method.invoke(Method.java:511)
09-03 16:31:50.108: E/AndroidRuntime(16727):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:787)
09-03 16:31:50.108: E/AndroidRuntime(16727):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:554)
09-03 16:31:50.108: E/AndroidRuntime(16727):    at dalvik.system.NativeStart.main(Native Method)

关于崩溃发生的原因有什么想法吗？我应该以某种方式指定我的 roote 节点的名称吗？

最佳答案

根据堆栈跟踪，问题似乎不是 while 循环。

09-03 16:31:50.108: W/System.err(16727): java.io.IOException: Stream is closed
09-03 16:31:50.108: W/System.err(16727):    at java.util.zip.GZIPInputStream.read(GZIPInputStream.java:158)
09-03 16:31:50.108: W/System.err(16727):    at libcore.io.Streams.readSingleByte(Streams.java:41)
09-03 16:31:50.108: W/System.err(16727):    at java.util.zip.InflaterInputStream.read(InflaterInputStream.java:128)
09-03 16:31:50.108: W/System.err(16727):    at org.kxml2.io.KXmlParser.setInput(KXmlParser.java:1623)

它在代码中的 while 循环之前的 setInput() 处引发异常。

这里的根本原因可能有很多。我首先查看 downloadUrl() 代码，看看是否有任何原因可能会返回已关闭的流。

关于java - 使用 XmlPullParserFactory 解析 XML 在 while 语句中崩溃，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/18602900/

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