Question

Hello Java和JSP大师请帮我理清一下。我一直试图解决这个问题2个星期，但完全失败了，它真的给我很多压力。我创建了三个jsp文件和一个java bean，但是收到了一条错误消息。这些是bin和类路径根。

CLASSPATH： C：\ Program Files \ Apache Software Foundation \ Tomcat 7.0 \ lib \ jsp-api.jar;
路径： C：\ glassfish3 \ jdk \ bin;

首先让我提供jsp文件，然后提供我一直在研究的java bean文件。我对jsp很新。

<HTML>
<BODY>
<FORM METHOD = POST ACTION = "SaveName.jsp">
What's your name ? <INPUT TYPE = TEXT NAME = username SIZE = 20 > <BR>
What's your e-mail?<INPUT TYPE = TEXT NAME = email SIZE = 20 > <BR>
What's your age ?  <INPUT TYPE = TEXT NAME = age SIZE = 4 >
<P> <INPUT TYPE = SUBMIT >
</FORM>
</BODY>
</HTML>

form.jsp

<jsp : useBean id = "user" class="user.UserData" scope="session"/>
<jsp : setProperty name = "user" property = "*"/>
<HTML>
<BODY>
<A HREF="NextPage.jsp">Continue</A>
</BODY>
</HTML>

SaveName.jsp

<jsp : useBean id = "user" class = "user.UserData" scope = "session"/>
<HTML>
<BODY>
You entered<BR>
Name: <%= user.getUsername()%> <BR />
Email: <%= user.getEmail()%> <BR />
Age: <%= user.getAge()%> <BR />
</BODY>
</HTML>

NextPage.jsp上

我已将以上三个文件保存在以下根路径中： C：\ Program Files \ Apache Software Foundation \ Tomcat 7.0 \ webapps \ jsp pages

package user;
public class UserData 
{

String username;
String email;
int age;

public void setUsername ( String value)

{
username=value;

}

public void setEmail ( String value)

{
email=value;

}

public void setAge ( int value)
{
age=value;

}

public String getUsername() 
{
return username;
}

public String getEmail()
{
return email;
}

public int getAge()
{
return age;
}

}

UserData.java编译成UserData.class

我已经在上面的根文件夹中保存了上面的java bean（.java和.class文件），虽然我刚刚创建了classes文件夹，因为它不存在。 C：\ Program Files \ Apache Software Foundation \ Tomcat 7.0 \ webapps \ ROOT \ WEB-INF \ classes \ user

以下是错误代码。

HTTP Status 500 - Unable to compile class for JSP:
type Exception report

message Unable to compile class for JSP:

description The server encountered an internal error that prevented it from fulfilling this request.

exception

org.apache.jasper.JasperException: Unable to compile class for JSP: 

An error occurred at line: 5 in the jsp file: /NextPage.jsp
user cannot be resolved
2: <HTML>
3: <BODY>
4: You entered<BR>
5: Name: <%= user.getUsername()%> <BR />
6: Email: <%= user.getEmail()%> <BR />
7: Age: <%= user.getAge()%> <BR />
8: </BODY>


An error occurred at line: 6 in the jsp file: /NextPage.jsp
user cannot be resolved
3: <BODY>
4: You entered<BR>
5: Name: <%= user.getUsername()%> <BR />
6: Email: <%= user.getEmail()%> <BR />
7: Age: <%= user.getAge()%> <BR />
8: </BODY>
9: </HTML>

An error occurred at line: 7 in the jsp file: /NextPage.jsp
user cannot be resolved
4: You entered<BR>
5: Name: <%= user.getUsername()%> <BR />
6: Email: <%= user.getEmail()%> <BR />
7: Age: <%= user.getAge()%> <BR />
8: </BODY>
9: </HTML>


 Stacktrace:
org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:103)
org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:366)
org.apache.jasper.compiler.JDTCompiler.generateClass(JDTCompiler.java:468)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:378)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:353)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:340)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:646)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:357)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)

note The full stack trace of the root cause is available in the Apache Tomcat/7.0.47 logs.
Apache Tomcat/7.0.47

Answer 1

你宣布：

<jsp : useBean id = "user" class="user.UserData" scope="session"/>

这意味着在HttpSession中有一个名为“user”的属性。

您编码：

<%= user.getUsername()%>

这意味着必须有名为'user'的JSP VARIABLE。所以你错了。

正确的方式：

${user.username}

HTTP状态500 - 无法为JSP编译类：

1 个答案: