Error configuring application listener of class

SEVERE: Error configuring application listener of class com.bonc.hq.listener.ServletUploadListener

java.lang.InstantiationException: com.bonc.hq.listener.ServletUploadListener

at java.lang.Class.newInstance0(Class.java:359)

at java.lang.Class.newInstance(Class.java:327)

at org.apache.catalina.core.DefaultInstanceManager.newInstance(DefaultInstanceManager.java:140)

at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4888)

at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5467)

at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)

at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)

at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)

at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)

at java.util.concurrent.FutureTask.run(FutureTask.java:166)

at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)

at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)

at java.lang.Thread.run(Thread.java:722)

今天寫上傳文件的servlet，使用了progresslistener，寫完重啓tomcat 報上面的錯誤，查了很久才查出緣由：

我寫的listener中只有一個帶參數的構造函數，沒寫默認的構造函數，tomcat容器實例化這個listener的時候就報錯了

加一個默認構造函數就ok了