Unsupported major.minor version 49.0

在Eclipse 3.2 + MyEclipse 5.0 中编译的class文件，发布到WebSphere Application Server 6.0中。

报错：

Error 500: java.lang.LinkageError:
LinkageError while defining class: xxxx Could not be defined due to: xxxxxx (Unsupported major.minor version 49.0) This is often caused by having a class defined at multiple locations within the classloader hierarchy. Other potentia causes include compiling against an older or newer version of the class that has an incompatible method signature.

经查，是WebSphere 6.0不支持JDK1.5。

没有办法，修改Eclipse的JDK配置：

在IDE中，打开Windows--->Preferences，选择Java--->Compiler，设置“Compiler compliance setting”为1.4。

系统会弹出一个rebuild的提示信息，单击“Yes”按钮rebuild一下即可。

    
                                                             by  JRQ

                                                       2007/08/08 沪