java - 在jsp页面中调用java函数

Question

我有一个名为 FaceDetection.java 的 java 文件，它有一个名为 FaceDetectionMain 的函数，并且带有两个参数。java 文件没有任何主函数。现在我在 jsp 页面中调用这个 java 类文件函数，如下所示:

FaceDetection.FaceDetectionMain(imagepath,imagename);

但是我遇到了如下异常:

Apr 21, 2014 10:44:23 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [jsp] in context with path [/SharedCrpto1] threw exception [Unable to compile class for JSP: 

An error occurred at line: 90 in the jsp file: /uploadwebcamimage.jsp
FaceDetection cannot be resolved
87:          fos.write(imageData);
88:          String imagepath=filesstore+"\\"+imagename+".png";
89:          
90:          Boolean flag=FaceDetection.FaceDetectionMain(imagepath,imagename);
91:         %>
92:     </body>
93: </html>


Stacktrace:] with root cause
org.apache.jasper.JasperException: Unable to compile class for JSP: 

An error occurred at line: 90 in the jsp file: /uploadwebcamimage.jsp
FaceDetection cannot be resolved
87:          fos.write(imageData);
88:          String imagepath=filesstore+"\\"+imagename+".png";
89:          
90:          Boolean flag=FaceDetection.FaceDetectionMain(imagepath,imagename);
91:         %>
92:     </body>
93: </html>

请帮我删除此异常。异常的完整 stackTrace 是:

at org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:97)
at org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:330)
at org.apache.jasper.compiler.JDTCompiler.generateClass(JDTCompiler.java:457)
at org.apache.jasper.compiler.Compiler.compile(Compiler.java:374)
at org.apache.jasper.compiler.Compiler.compile(Compiler.java:352)
at org.apache.jasper.compiler.Compiler.compile(Compiler.java:339)
at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:594)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:344)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:462)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:563)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:399)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:317)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:204)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:182)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:311)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:722)

Answer 1

使用默认包不是一种好的做法，并且经常会导致像您遇到的问题(您无法导入默认包，因此无需尝试页面导入指令)尝试将您的类放入一个包并导入它，你应该发现它可以正常工作。