Question

我是jsp的新手。我正在学习useBean方法，并且在

中有一个例子

http://www.studytonight.com/jsp/getproperty-tag.php

向下滚动，你会发现它。

这是我的jsp文件：

<html>
<head>
    <title>Welcome Page</title>
</head>
<jsp:useBean id="person" type="PersonBean" scope="request"/>   <body>
    Hello,  <jsp:getProperty name="person" property="name"/>      </body> </html>

这是我的PersonBean.java文件，编译成类文件并放入 classes文件：

import java.io.Serializable;
public class PersonBean implements Serializable
{
 private String name="Hello World";
    public PersonBean()
   {
    this.name="Hello";
   }
   public void setName(String name)
   {
    this.name = name;
   }
   public String getName()
   {
    return name;
   }
}

我收到错误： jsp文件中的第5行：/hello1.jsp发生错误 PersonBean无法解析为类型

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

An error occurred at line: 5 in the jsp file: /hello1.jsp
PersonBean cannot be resolved to a type
2:     <head>
3:         <title>Welcome Page</title>
4:     </head>
5:     <jsp:useBean id="person" type="PersonBean" scope="request"/>
6:   <body>
7:         Hello,  <jsp:getProperty name="person" property="name"/>   
8:   </body>


An error occurred at line: 5 in the jsp file: /hello1.jsp
PersonBean cannot be resolved to a type
2:     <head>
3:         <title>Welcome Page</title>
4:     </head>
5:     <jsp:useBean id="person" type="PersonBean" scope="request"/>
6:   <body>
7:         Hello,  <jsp:getProperty name="person" property="name"/>   
8:   </body>


An error occurred at line: 7 in the jsp file: /hello1.jsp
PersonBean cannot be resolved to a type
4:     </head>
5:     <jsp:useBean id="person" type="PersonBean" scope="request"/>
6:   <body>
7:         Hello,  <jsp:getProperty name="person" property="name"/>   
8:   </body>
9: </html>


An error occurred at line: 7 in the jsp file: /hello1.jsp
PersonBean cannot be resolved to a type
4:     </head>
5:     <jsp:useBean id="person" type="PersonBean" scope="request"/>
6:   <body>
7:         Hello,  <jsp:getProperty name="person" property="name"/>   
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:490)
  org.apache.jasper.compiler.Compiler.compile(Compiler.java:379)
  org.apache.jasper.compiler.Compiler.compile(Compiler.java:354)
  org.apache.jasper.compiler.Compiler.compile(Compiler.java:341)
  org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:662)
  org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:364)
  org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395)
  org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339)
  javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
  org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

note The full stack trace of the root cause is available in the Apache Tomcat/7.0.70 logs.

Answer 1

jsp：useBean action tag：

<jsp:useBean id= "instanceName" scope= "page | request | session | application"   
    class= "packageName.className" type= "packageName.className"  
    beanName="packageName.className | <%= expression >" >  
 </jsp:useBean>

1.在包中放置PersonBean类，以便能够在其他类中使用它。默认包中的类对于包本身而言是不可见的。

2.将.class文件放在web-inf/classes。

中

3.在PersonBean声明中指定<jsp:useBean/>的完全限定类名。

此外 - JVM查找默认包类的约定是查看＆＃34; current＆＃34;目录。在服务器环境中，您无法控制＆＃34;当前＆＃34;目录，所以你必须使用一个包。

修改您的代码如下：

PersonBean.java

package com.person;

import java.io.Serializable;

    public class PersonBean implements Serializable {

        private String name="Hello World";
        public PersonBean()
       {
        this.name="Hello";
       }
       public void setName(String name)
       {
        this.name = name;
       }
       public String getName()
       {
        return name;
       }
    }

Person.jsp

<html>
<head>
    <title>Welcome Page</title>
</head>
<jsp:useBean id="person" class="com.person.PersonBean" scope="request"/>    
 Hello, <jsp:getProperty name="person" property="name"/>  
</html>

class无法解析为类型（jsp）

1 个答案: