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HF S&J 389 Question

 
Peter Du
Greenhorn
Posts: 14
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I have tried the example in p389 with Tomcat 5.0.18. Here are some problem I encountered and some questions.

First when tested according to the instructions at p88-p390, the container can not find the class, see details error message at "Error 1:"

Then I compare it with the the jsp2 example in tomcat, I found in the tomcat example, even if the method return type is int, but in the TLD they use java.lang.String not int in <function-signature>, after change int to java.lang.String in the taglib of P389 example, I tested again and i got the same error.

After that I try to add a wiered java.lang.Void in <function-signature>, the container can not find the method. see details message at "Error 3"

Finally I change the method in DiceRoller to "public static int rollDice(String name) {...}" ,change the <function-signature> in TLD to "<function-signature>java.lang.String rollDice(java.lang.String)</function-signature>", and change "${mine:rollIt()}" to "${mine:rollIt("2")}" in the JSP, then everything works fine.

My question is the above means that we can not call a method with no arguments with EL?

Thanks in advance.


The following is the errors i got for each case:

Error 1: when use original "<function-signature>int rollDice()</function-signature>"
in TLD file, we got following exception:

org.apache.jasper.JasperException: The class specified in the method signature in TLD for the function mine:rollIt cannot be found.
org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:94)
org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:404)
org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:219)
org.apache.jasper.compiler.Validator$1MapperELVisitor.visit(Validator.java:1405)
org.apache.jasper.compiler.ELNode$Function.accept(ELNode.java:163)
org.apache.jasper.compiler.ELNode$Nodes.visit(ELNode.java:234)
org.apache.jasper.compiler.ELNode$Visitor.visit(ELNode.java:275)
org.apache.jasper.compiler.ELNode$Root.accept(ELNode.java:94)
org.apache.jasper.compiler.ELNode$Nodes.visit(ELNode.java:234)
org.apache.jasper.compiler.Validator$ValidateVisitor.getFunctionMapper(Validator.java:1420)
org.apache.jasper.compiler.Validator$ValidateVisitor.visit(Validator.java:637)
org.apache.jasper.compiler.Node$ELExpression.accept(Node.java:913)
org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2180)
org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2230)
org.apache.jasper.compiler.Node$Visitor.visit(Node.java:2236)
org.apache.jasper.compiler.Node$Root.accept(Node.java:485)
org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2180)
org.apache.jasper.compiler.Validator.validate(Validator.java:1515)
org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:247)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:456)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:439)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:552)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:291)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:301)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:248)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)



Error 2: when change "<function-signature>int rollDice()</function-signature>" to
"<function-signature>java.lang.String rollDice()</function-signature>"
in TLD file, we got following exception:

org.apache.jasper.JasperException: The class specified in the method signature in TLD for the function mine:rollIt cannot be found.
org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:94)
org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:404)
org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:219)
org.apache.jasper.compiler.Validator$1MapperELVisitor.visit(Validator.java:1405)
org.apache.jasper.compiler.ELNode$Function.accept(ELNode.java:163)
org.apache.jasper.compiler.ELNode$Nodes.visit(ELNode.java:234)
org.apache.jasper.compiler.ELNode$Visitor.visit(ELNode.java:275)
org.apache.jasper.compiler.ELNode$Root.accept(ELNode.java:94)
org.apache.jasper.compiler.ELNode$Nodes.visit(ELNode.java:234)
org.apache.jasper.compiler.Validator$ValidateVisitor.getFunctionMapper(Validator.java:1420)
org.apache.jasper.compiler.Validator$ValidateVisitor.visit(Validator.java:637)
org.apache.jasper.compiler.Node$ELExpression.accept(Node.java:913)
org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2180)
org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2230)
org.apache.jasper.compiler.Node$Visitor.visit(Node.java:2236)
org.apache.jasper.compiler.Node$Root.accept(Node.java:485)
org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2180)
org.apache.jasper.compiler.Validator.validate(Validator.java:1515)
org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:247)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:456)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:439)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:552)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:291)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:301)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:248)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)

Error 3: when change "<function-signature>int rollDice()</function-signature>" to
"<function-signature>java.lang.String rollDice(java.lang.Void)</function-signature>"
in TLD file, we got following exception:

org.apache.jasper.JasperException: Method "rollDice" for function "rollIt" not found in class "foo.DiceRoller"
org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:94)
org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:404)
org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:219)
org.apache.jasper.compiler.Validator$1MapperELVisitor.visit(Validator.java:1410)
org.apache.jasper.compiler.ELNode$Function.accept(ELNode.java:163)
org.apache.jasper.compiler.ELNode$Nodes.visit(ELNode.java:234)
org.apache.jasper.compiler.ELNode$Visitor.visit(ELNode.java:275)
org.apache.jasper.compiler.ELNode$Root.accept(ELNode.java:94)
org.apache.jasper.compiler.ELNode$Nodes.visit(ELNode.java:234)
org.apache.jasper.compiler.Validator$ValidateVisitor.getFunctionMapper(Validator.java:1420)
org.apache.jasper.compiler.Validator$ValidateVisitor.visit(Validator.java:637)
org.apache.jasper.compiler.Node$ELExpression.accept(Node.java:913)
org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2180)
org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2230)
org.apache.jasper.compiler.Node$Visitor.visit(Node.java:2236)
org.apache.jasper.compiler.Node$Root.accept(Node.java:485)
org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2180)
org.apache.jasper.compiler.Validator.validate(Validator.java:1515)
org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:247)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:456)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:439)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:552)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:291)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:301)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:248)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)


Peter Du
SCJP 1.4
Nov 26, 2004
 
Peter Du
Greenhorn
Posts: 14
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Sorry, I test the example with Tomcat 5.0.28 and find HF p389 example works fine. So It's a bug of Tomcat 5.0.18 and not the EL functions.

Peter Du
Nov. 26, 2004
 
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