帮偶看看这个计数器的Bean，^_^

oath911 2005-06-22 12:25:36

j.jsp文件
<%@page contentType="text/html;charset=gb2312"%>

<html>
<body>
<jsp.useBean id="a" sacope="session" class="pp.addone"/>
<jsp.useBean id="b" sacope="page" class="pp.display"/>
已经有
<jsp:getProperty id="b" property="counter" />
人访问！
</body>
</html>

addone.java文件
package pp;
import java.io.*;
import java.lang.*;

public class addone
{
private String s1 = new String();

public addone()
{
try
{
BufferedReader buff = new BufferedReader(new FileReader("c.txt"));
String s = buff.readLine();
int i = Integer.parseInt(s);
i++;
buff.close();
s=Integer.toString(i);
PrintWriter pw = new PrintWriter(new BufferedWriter(new FileWriter("c.txt")));
pw.println(s);
pw.close();
}catch(IOException e){}
}
}

display.java文件
package pp;
import java.io.*;
import java.lang.*;

public class display
{
String counter = null;
public String getCounter()
{

try
{
BufferedReader buff = new BufferedReader(new FileReader("c.txt"));
counter = buff.readLine();

}catch(IOException e){}

return counter;
}
}
下面是测试的结果：class文件放的地方应该是对的在myapp\WEB-INF\classes\pp下面

exception

org.apache.jasper.JasperException: /jishuq.jsp(10,0) GetProperty: Mandatory attribute name missing
org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:39)
org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:409)
org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:200)
org.apache.jasper.compiler.JspUtil.checkAttributes(JspUtil.java:283)
org.apache.jasper.compiler.Validator$ValidateVisitor.visit(Validator.java:459)
org.apache.jasper.compiler.Node$GetProperty.accept(Node.java:1062)
org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2163)
org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2213)
org.apache.jasper.compiler.Node$Visitor.visit(Node.java:2219)
org.apache.jasper.compiler.Node$Root.accept(Node.java:456)
org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2163)
org.apache.jasper.compiler.Validator.validate(Validator.java:1475)
org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:214)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:470)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:451)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:439)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:511)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:295)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

...全文

156 15 打赏收藏转发到动态举报

写回复

用AI写文章

15 条回复

切换为时间正序

请发表友善的回复…

发表回复

oath911 2005-06-22

打赏
举报

dddddddddddddddddddddddddddddddddddddddddddddddddd

oath911 2005-06-22

打赏
举报

thx!!!!!!!!!!!!!!!!
多谢各位！！！！！！！！！！！！！！

hongke1490 2005-06-22

打赏
举报

你的jsp文件应该这么写：
<%@page contentType="text/html;charset=gb2312"%>
<html>
<body>
<jsp:useBean id="a" scope="page" class="pp.addone"/>
<jsp:useBean id="b" scope="page" class="pp.display"/>
已经有
<jsp:getProperty name="b" property="counter" />
人访问！
</body>
</html>
不会有错的，我已经试过了

hongke1490 2005-06-22

打赏
举报

不能用jsp.useBean
必须用jsp:useBean

cxmty 2005-06-22

打赏
举报

up
我也出现这个问题哦
怎么办？

oath911 2005-06-22

打赏
举报

已经加了还是这样报错，说没有实体；

hongke1490 2005-06-22

打赏
举报

c.txt应该放在tomcat的bin文件加中

oath911 2005-06-22

打赏
举报

exception

org.apache.jasper.JasperException: Attempted a bean operation on a null object.
org.apache.jasper.runtime.JspRuntimeLibrary.handleGetProperty(JspRuntimeLibrary.java:601)
org.apache.jsp.jishuq_jsp._jspService(jishuq_jsp.java:50)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

上面几位，我已经改成name = b 了，但是还是有错，是不是要改tomcat的xml文件？？

hongke1490 2005-06-22

打赏
举报

j.jsp
<%@page contentType="text/html;charset=gb2312"%>
<html>
<body>
<jsp:useBean id="a" scope="page" class="pp.addone"/>
<jsp:useBean id="b" scope="page" class="pp.display"/>
已经有
<jsp:getProperty name="b" property="counter" />
人访问！
</body>
</html>

notruiyi 2005-06-22

打赏
举报

b这个BEAN的SCOPE改成APPLICATION

daixin163 2005-06-22

打赏
举报

Jimmy_0220 2005-06-22

打赏
举报

是因为<jsp:getProperty id="b" property="counter" />代码有错，counter这个属性在另一个类里，
我看不懂 <jsp.useBean id="a" sacope="session" class="pp.addone"/>
<jsp.useBean id="b" sacope="page" class="pp.display"/>
和<jsp:getProperty id="b" property="counter" />是什么意思？

andy_zhang_ping 2005-06-22