框架版本：1.4.3
平台：Java 1.8.0_74、Ubuntu 16.04、64位
详细信息：
正在尝试将播放版本从1.2.7升级到1.4.3。不得不为1.4.3升级一些模块/lib。
通过播放运行启动应用程序，导致以下异常：
@722hc68nl
Error during the 500 response generation
Oops: UnexpectedException
Unexpected error : While applying play.CorePlugin@1de5f259 on controllers.Application, caused by exception UnexpectedException: While applying class play.classloading.enhancers.LocalvariablesNamesEnhancer on controllers.Application
play.exceptions.UnexpectedException: While applying play.CorePlugin@1de5f259 on controllers.Application
at play.plugins.PluginCollection.enhance(PluginCollection.java:656)
at play.classloading.ApplicationClasses$ApplicationClass.enhance(ApplicationClasses.java:242)
at play.classloading.ApplicationClassloader.loadApplicationClass(ApplicationClassloader.java:165)
at play.classloading.ApplicationClassloader.loadClass(ApplicationClassloader.java:83)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:760)
at play.classloading.ApplicationClassloader.loadApplicationClass(ApplicationClassloader.java:166)
at play.classloading.ApplicationClassloader.getAllClasses(ApplicationClassloader.java:425)
at play.classloading.ApplicationClassloader.getAssignableClasses(ApplicationClassloader.java:466)
at play.templates.GroovyTemplateCompiler.endTag(GroovyTemplateCompiler.java:363)
at play.templates.TemplateCompiler.generate(TemplateCompiler.java:93)
at play.templates.TemplateCompiler.compile(TemplateCompiler.java:15)
at play.templates.GroovyTemplateCompiler.compile(GroovyTemplateCompiler.java:40)
at play.templates.TemplateCompiler.compile(TemplateCompiler.java:28)
at play.templates.TemplateLoader.load(TemplateLoader.java:81)
at play.templates.TemplateLoader.load(TemplateLoader.java:176)
at play.server.PlayHandler.serve500(PlayHandler.java:836)
at Invocation.HTTP Request(Play!)
Caused by: play.exceptions.UnexpectedException: While applying class play.classloading.enhancers.LocalvariablesNamesEnhancer on controllers.Application
at play.CorePlugin.enhance(CorePlugin.java:311)
at play.plugins.PluginCollection.enhance(PluginCollection.java:651)
... 18 more
Caused by: javassist.CannotCompileException: by javassist.bytecode.BadBytecode: renderDelegate ()V in controllers.Application: conflict: *top* and java.lang.Object
at javassist.CtBehavior.insertBefore(CtBehavior.java:777)
at javassist.CtBehavior.insertBefore(CtBehavior.java:734)
at play.classloading.enhancers.LocalvariablesNamesEnhancer.enhanceThisClass(LocalvariablesNamesEnhancer.java:251)
at play.CorePlugin.enhance(CorePlugin.java:306)
... 19 more
Caused by: javassist.bytecode.BadBytecode: renderDelegate ()V in controllers.Application: conflict: *top* and java.lang.Object
at javassist.bytecode.stackmap.MapMaker.make(MapMaker.java:111)
at javassist.bytecode.MethodInfo.rebuildStackMap(MethodInfo.java:456)
at javassist.bytecode.MethodInfo.rebuildStackMapIf6(MethodInfo.java:438)
at javassist.CtBehavior.insertBefore(CtBehavior.java:768)
... 22 more
Caused by: javassist.bytecode.BadBytecode: conflict: *top* and java.lang.Object
at javassist.bytecode.stackmap.TypeData$BasicType.setType(TypeData.java:156)
at javassist.bytecode.stackmap.Tracer.checkParamTypes(Tracer.java:930)
at javassist.bytecode.stackmap.Tracer.doInvokeMethod(Tracer.java:801)
at javassist.bytecode.stackmap.Tracer.doOpcode148_201(Tracer.java:595)
at javassist.bytecode.stackmap.Tracer.doOpcode(Tracer.java:81)
at javassist.bytecode.stackmap.MapMaker.make(MapMaker.java:187)
at javassist.bytecode.stackmap.MapMaker.make(MapMaker.java:199)
at javassist.bytecode.stackmap.MapMaker.make(MapMaker.java:199)
at javassist.bytecode.stackmap.MapMaker.make(MapMaker.java:199)
at javassist.bytecode.stackmap.MapMaker.traceException(MapMaker.java:221)
at javassist.bytecode.stackmap.MapMaker.make(MapMaker.java:182)
at javassist.bytecode.stackmap.MapMaker.make(MapMaker.java:199)
at javassist.bytecode.stackmap.MapMaker.make(MapMaker.java:164)
at javassist.bytecode.stackmap.MapMaker.make(MapMaker.java:108)
... 25 more
这个问题似乎与javassist jar有关。
解决方案-1:
播放问题列表中建议的解决方案是在dependencies.yml.中排除javassist-jar
require:
- play: exclude:
- org.javassist -> javassist *
链接：问题#1434
然而，这并没有解决我的问题
解决方案-2：(更多解决方案(
其中一个论坛提出这个问题与方法的代码长度有关(在我的例子中是renderDelegate()(。我重构了这个方法以减少行数。这解决了我的问题。
检查本地变量是否已初始化。对于对象，即使在语义上没有必要，也必须使用null来初始化它。
java.io.BufferedWriter bw = null;