java - 如何使用外部库在 java 上正确工作但在 Android Activity 上不工作

Question

在我的 Android 应用程序中，我需要使用外部库向 WordPress 博客发表评论。我使用的库是: http://code.google.com/p/wordpress-java/

当我在通用 java 程序中使用它时，它工作得很好，但是当我在 Android Activity 中使用它时，我遇到了异常。

这是我的 LogCat:

06-21 15:23:24.820: I/dalvikvm(15546): Total arena pages for JIT: 21
06-21 15:23:24.820: I/dalvikvm(15546): Total arena pages for JIT: 22
06-21 15:23:24.825: I/dalvikvm(15546): Total arena pages for JIT: 23
06-21 15:23:24.825: I/dalvikvm(15546): Total arena pages for JIT: 24
06-21 15:23:24.825: I/dalvikvm(15546): Total arena pages for JIT: 25
06-21 15:23:24.825: I/dalvikvm(15546): Total arena pages for JIT: 26
06-21 15:23:24.825: I/dalvikvm(15546): Total arena pages for JIT: 27
06-21 15:23:24.825: I/dalvikvm(15546): Total arena pages for JIT: 28
06-21 15:23:24.825: I/dalvikvm(15546): Total arena pages for JIT: 29
06-21 15:23:24.825: I/dalvikvm(15546): Total arena pages for JIT: 30
06-21 15:23:24.825: I/dalvikvm(15546): Total arena pages for JIT: 31
06-21 15:23:24.825: I/dalvikvm(15546): Total arena pages for JIT: 32
06-21 15:23:24.825: I/dalvikvm(15546): Total arena pages for JIT: 33
06-21 15:23:24.825: I/dalvikvm(15546): Total arena pages for JIT: 34
06-21 15:23:24.825: I/dalvikvm(15546): Total arena pages for JIT: 35
06-21 15:23:24.825: I/dalvikvm(15546): Total arena pages for JIT: 36
06-21 15:23:24.825: I/dalvikvm(15546): Total arena pages for JIT: 37
06-21 15:23:24.825: I/dalvikvm(15546): Total arena pages for JIT: 38
06-21 15:23:24.825: I/dalvikvm(15546): Total arena pages for JIT: 39
06-21 15:23:24.825: I/dalvikvm(15546): Total arena pages for JIT: 40
06-21 15:23:24.930: D/dalvikvm(15546): GC_CONCURRENT freed 390K, 8% free  12443K/13447K, paused 12ms+12ms, total 34ms
06-21 15:23:25.065: D/dalvikvm(15546): GC_CONCURRENT freed 481K, 8% free 12448 K/13511K, paused 12ms+11ms, total 42ms
06-21 15:23:25.205: D/dalvikvm(15546): GC_CONCURRENT freed 444K, 8% free  12482K/13511K, paused 1ms+1ms, total 18ms
06-21 15:23:25.320: D/dalvikvm(15546): GC_CONCURRENT freed 474K, 8% free  12491K/13575K, paused 2ms+11ms, total 33ms
06-21 15:23:25.455: D/dalvikvm(15546): GC_CONCURRENT freed 490K, 8% free 12504K/13575K, paused 12ms+12ms, total 44ms
06-21 15:23:25.590: D/dalvikvm(15546): GC_CONCURRENT freed 458K, 9% free 12542K/13639K, paused 2ms+11ms, total 30ms
06-21 15:23:25.725: D/dalvikvm(15546): GC_CONCURRENT freed 483K, 8% free 12561K/13639K, paused 1ms+16ms, total 47ms
06-21 15:23:25.910: D/dalvikvm(15546): GC_CONCURRENT freed 549K, 9% free   12578K/13703K, paused 4ms+1ms, total 37ms
06-21 15:23:25.910: D/dalvikvm(15546): WAIT_FOR_CONCURRENT_GC blocked 5ms
06-21 15:23:26.070: D/dalvikvm(15546): GC_CONCURRENT freed 454K, 9% free 12600K/13703K, paused 12ms+11ms, total 49ms
06-21 15:23:26.345: D/dalvikvm(15546): GC_CONCURRENT freed 330K, 8% free  12683K/13703K, paused 13ms+12ms, total 42ms
06-21 15:23:26.590: D/dalvikvm(15546): GC_FOR_ALLOC freed 242K, 7% free 12815K/13767K, paused 25ms, total 25ms
06-21 15:23:27.810: I/Choreographer(15546): Skipped 77 frames!  The application may be doing too much work on its main thread.
06-21 15:23:31.345: D/dalvikvm(15546): GC_FOR_ALLOC freed 338K, 8% free 12934K/13959K, paused 18ms, total 18ms
06-21 15:23:31.375: D/dalvikvm(15546): GC_CONCURRENT freed 2K, 8% free 12947K/13959K, paused 12ms+2ms, total 27ms
06-21 15:23:31.595: D/dalvikvm(15546): GC_FOR_ALLOC freed <1K, 8% free 12947K/13959K, paused 44ms, total 44ms
06-21 15:23:31.600: I/dalvikvm-heap(15546): Grow heap (frag case) to 14.134MB for 977464-byte allocation
06-21 15:23:31.635: D/dalvikvm(15546): GC_CONCURRENT freed 0K, 7% free 13901K/14919K, paused 12ms+2ms, total 35ms
06-21 15:23:31.635: D/dalvikvm(15546): WAIT_FOR_CONCURRENT_GC blocked 22ms
06-21 15:23:32.400: E/SpannableStringBuilder(15546): SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length
06-21 15:23:32.400: E/SpannableStringBuilder(15546): SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length
06-21 15:23:35.755: I/dalvikvm(15546): Could not find method java.beans.Introspector.getBeanInfo, referenced from method redstone.xmlrpc.serializers.IntrospectingSerializer.serialize
06-21 15:23:35.755: W/dalvikvm(15546): VFY: unable to resolve static method 6817: Ljava/beans/Introspector;.getBeanInfo (Ljava/lang/Class;Ljava/lang/Class;)Ljava/beans/BeanInfo;
06-21 15:23:35.755: D/dalvikvm(15546): VFY: replacing opcode 0x71 at 0x0015
06-21 15:23:35.955: D/dalvikvm(15546): GC_CONCURRENT freed 417K, 7% free 14015K/15047K, paused 12ms+3ms, total 29ms
06-21 15:23:36.770: D/AndroidRuntime(15546): Shutting down VM
06-21 15:23:36.770: W/dalvikvm(15546): threadid=1: thread exiting with uncaught exception (group=0x40ed42a0)
06-21 15:23:36.790: E/AndroidRuntime(15546): FATAL EXCEPTION: main
06-21 15:23:36.790: E/AndroidRuntime(15546): java.lang.RuntimeException: Unable to start activity ComponentInfo{rss.activity/rss.activity.CommentaArticolo}: redstone.xmlrpc.XmlRpcException: The response could not be parsed.
06-21 15:23:36.790: E/AndroidRuntime(15546):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2100)
06-21 15:23:36.790: E/AndroidRuntime(15546):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2125)
06-21 15:23:36.790: E/AndroidRuntime(15546):    at android.app.ActivityThread.access$600(ActivityThread.java:140)
06-21 15:23:36.790: E/AndroidRuntime(15546):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1227)
06-21 15:23:36.790: E/AndroidRuntime(15546):    at android.os.Handler.dispatchMessage(Handler.java:99)
06-21 15:23:36.790: E/AndroidRuntime(15546):    at android.os.Looper.loop(Looper.java:137)
06-21 15:23:36.790: E/AndroidRuntime(15546):    at android.app.ActivityThread.main(ActivityThread.java:4898)
06-21 15:23:36.790: E/AndroidRuntime(15546):    at java.lang.reflect.Method.invokeNative(Native Method)
06-21 15:23:36.790: E/AndroidRuntime(15546):    at java.lang.reflect.Method.invoke(Method.java:511)
06-21 15:23:36.790: E/AndroidRuntime(15546):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1006)
06-21 15:23:36.790: E/AndroidRuntime(15546):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:773)
06-21 15:23:36.790: E/AndroidRuntime(15546):    at dalvik.system.NativeStart.main(Native Method)
06-21 15:23:36.790: E/AndroidRuntime(15546): Caused by: redstone.xmlrpc.XmlRpcException: The response could not be parsed.
06-21 15:23:36.790: E/AndroidRuntime(15546):    at redstone.xmlrpc.XmlRpcClient.handleResponse(Unknown Source)
06-21 15:23:36.790: E/AndroidRuntime(15546):    at redstone.xmlrpc.XmlRpcClient.endCall(Unknown Source)
06-21 15:23:36.790: E/AndroidRuntime(15546):    at redstone.xmlrpc.XmlRpcClient.invoke(Unknown Source)
06-21 15:23:36.790: E/AndroidRuntime(15546):    at redstone.xmlrpc.XmlRpcProxy.invoke(Unknown Source)
06-21 15:23:36.790: E/AndroidRuntime(15546):    at net.bican.wordpress.$Proxy1.getRecentPosts(Native Method)
06-21 15:23:36.790: E/AndroidRuntime(15546):    at net.bican.wordpress.Wordpress.getRecentPosts(Wordpress.java:497)
06-21 15:23:36.790: E/AndroidRuntime(15546):    at rss.util.MyWordpress.getPostIDFromURL(MyWordpress.java:33)
06-21 15:23:36.790: E/AndroidRuntime(15546):    at rss.activity.CommentaArticolo.onCreate(CommentaArticolo.java:38)
06-21 15:23:36.790: E/AndroidRuntime(15546):    at   android.app.Activity.performCreate(Activity.java:5206)
06-21 15:23:36.790: E/AndroidRuntime(15546):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1083)
06-21 15:23:36.790: E/AndroidRuntime(15546):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2064)
06-21 15:23:36.790: E/AndroidRuntime(15546):    ... 11 more
06-21 15:23:36.790: E/AndroidRuntime(15546): Caused by: redstone.xmlrpc.XmlRpcException: Could not instantiate XMLReader parser
06-21 15:23:36.790: E/AndroidRuntime(15546):    at redstone.xmlrpc.XmlRpcParser.parse(Unknown Source)
06-21 15:23:36.790: E/AndroidRuntime(15546):    ... 22 more
06-21 15:23:36.790: E/AndroidRuntime(15546): Caused by: org.xml.sax.SAXException: Can't create default XMLReader; is system property org.xml.sax.driver set?
06-21 15:23:36.790: E/AndroidRuntime(15546):    at org.xml.sax.helpers.XMLReaderFactory.createXMLReader(XMLReaderFactory.java:156)
06-21 15:23:36.790: E/AndroidRuntime(15546):    ... 23 more

Answer 1

该堆栈跟踪的底部异常看起来是问题的根源。看起来 Wordpress 库正在使用 redstone-xmlrpc，并且它似乎正在尝试使用 XMLReader，或者至少您必须使用一个。

Caused by: org.xml.sax.SAXException: Can't create default XMLReader; is system property org.xml.sax.driver set?

此链接可能会对您有所帮助，这是一个与将代码从 Java 移植到 Android 相关的问题，但他也遇到了同样的错误。

porting to Android: why am I getting "Can't create default XMLReader; is system property org.xml.sax.driver set?"?

尽管如此，代码的 XML 部分似乎内置于 Wordpress 库中，这可能意味着您无法修复它以与 Android 一起使用。但您永远不知道，可能有一个构造函数允许您传递自定义 XMLReader 以与库一起使用。

联系 WordPress 并了解他们对于将代码移植到 Android 的看法可能是值得的，开发人员与像您这样的人合作来完成他们无法完成的任务并不是闻所未闻的继续工作，或者不继续工作。

此外，检查源代码，也许您可​​以跟踪它并修改库，以便它满足您的需求(但根据许可，您可能不想这样做)。