web.xml中"web-app_2_5.xsd"引起的EL表达式无效异常
web.xml中"web-app_2_5.xsd"引起的EL表达式无效异常
org.apache.jasper.JasperException: Unable to convert string "${tasks}" to class "java.util.Collection" for attribute "items": Property Editor not registered with the PropertyEditorManager
这种异常，试着调了不少时间，tasks是从后台传过来的list集，在前台jsp页面不能使用${tasks},弄的我莫名其妙怎么会出现这样的问题，其实从后台取值并传值到前台来根本就没有错，而前台JSP页面EL表达式无效，解析不到EL表达式，引起的原因是web.xml中：
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
注意里面的web-app_2_5.xsd，就是这个引起的，在web-app_2_4.xsd中就不会出现这种问题(这个版本的isELIgnored默认设置为false)。
在不改变web.xml2.5版本的情况下解决办法是：在jsp页面头加:<%@page isELIgnored="false"%> 问题得以解决。
org.apache.jasper.JasperException: Unable to convert string "${tasks}" to class "java.util.Collection" for attribute "items": Property Editor not registered with the PropertyEditorManager
这种异常，试着调了不少时间，tasks是从后台传过来的list集，在前台jsp页面不能使用${tasks},弄的我莫名其妙怎么会出现这样的问题，其实从后台取值并传值到前台来根本就没有错，而前台JSP页面EL表达式无效，解析不到EL表达式，引起的原因是web.xml中：
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
注意里面的web-app_2_5.xsd，就是这个引起的，在web-app_2_4.xsd中就不会出现这种问题(这个版本的isELIgnored默认设置为false)。
在不改变web.xml2.5版本的情况下解决办法是：在jsp页面头加:<%@page isELIgnored="false"%> 问题得以解决。
自定义标签
index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="gbk"%>
< %@page import="com.cn.tag.Person"%>
<%@ taglib uri="/mytag" prefix="hello" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>My JSP 'index.jsp' starting page</title>
</head>
<%
List<Person> persons = new ArrayList<Person>();
Person p1 = new Person("caodaoxi",25," [email protected]");
Person p2 = new Person("caodaoxi",25," [email protected]");
Person p3 = new Person("caodaoxi",25," [email protected]");
Person p4 = new Person("caodaoxi",25," [email protected]");
Person p5 = new Person("caodaoxi",25," [email protected]");
persons.add(p1);
persons.add(p2);
persons.add(p3);
persons.add(p4);
persons.add(p5);
%>
<hello:tb ps="<%=persons%>"/>
</body>
</html>
< %@page import="com.cn.tag.Person"%>
<%@ taglib uri="/mytag" prefix="hello" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>My JSP 'index.jsp' starting page</title>
</head>
<%
List<Person> persons = new ArrayList<Person>();
Person p1 = new Person("caodaoxi",25," [email protected]");
Person p2 = new Person("caodaoxi",25," [email protected]");
Person p3 = new Person("caodaoxi",25," [email protected]");
Person p4 = new Person("caodaoxi",25," [email protected]");
Person p5 = new Person("caodaoxi",25," [email protected]");
persons.add(p1);
persons.add(p2);
persons.add(p3);
persons.add(p4);
persons.add(p5);
%>
<hello:tb ps="<%=persons%>"/>
</body>
</html>
hello.tld
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.2//EN"
" http://java.sun.com/dtd/web-jsptaglibrary_1_2.dtd">
<taglib>
<tlib-version>1.0</tlib-version>
<jsp-version>1.2</jsp-version>
<short-name>hello</short-name>
<tag>
<name>hello</name>
<tag-class>com.cn.tag.Hello</tag-class>
<body-content>empty</body-content>
<attribute>
<name>color</name>
<required>true</required>
</attribute>
<attribute>
<name>backgroundImage</name>
<required>false</required>
</attribute>
</tag>
<tag>
<name>tb</name>
<tag-class>com.cn.tag.TagDemo1</tag-class>
<body-content>empty</body-content>
<attribute>
<name>ps</name>
<required>false</required>
<rtexprvalue>true</rtexprvalue>
<type>java.util.List</type>
</attribute>
</tag>
</taglib>
<!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.2//EN"
" http://java.sun.com/dtd/web-jsptaglibrary_1_2.dtd">
<taglib>
<tlib-version>1.0</tlib-version>
<jsp-version>1.2</jsp-version>
<short-name>hello</short-name>
<tag>
<name>hello</name>
<tag-class>com.cn.tag.Hello</tag-class>
<body-content>empty</body-content>
<attribute>
<name>color</name>
<required>true</required>
</attribute>
<attribute>
<name>backgroundImage</name>
<required>false</required>
</attribute>
</tag>
<tag>
<name>tb</name>
<tag-class>com.cn.tag.TagDemo1</tag-class>
<body-content>empty</body-content>
<attribute>
<name>ps</name>
<required>false</required>
<rtexprvalue>true</rtexprvalue>
<type>java.util.List</type>
</attribute>
</tag>
</taglib>
TagDemo1.java
package com.cn.tag;
import java.io.IOException;
import java.util.List;
import java.util.List;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.TagSupport;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.TagSupport;
/*
*项目名称：tag
*类名： TagDemo1.java
*作者： 曹道喜
*创建日期： Oct 17, 2011 11:52:56 AM
*类说明：
*/
public class TagDemo1 extends TagSupport {
private List<Person> ps = null;
public List<Person> getPs() {
return ps;
}
public void setPs(List<Person> ps) {
this.ps = ps;
}
@Override
public int doStartTag() throws JspException {
// TODO Auto-generated method stub
JspWriter out = pageContext.getOut();
StringBuffer buffer = new StringBuffer();
System.out.print("-------------");
try {
buffer.append("<table>" +
"<tr>" +
"<th>姓名</th>" +
"<th>年龄</th>" +
"<th>邮箱</th>" +
"</tr>"
);
System.out.print(buffer.toString());
if(ps!=null&&ps.size()!=0){
for(Person person:ps){
buffer.append("<tr>" +
"<td>"+person.getName()+"</td>" +
"<td>"+person.getAge()+"</td>" +
"<td>"+person.getEmail()+"</td>" +
"</tr>"
);
}
}else{
buffer.append("<td>没有想要的数据</td>");
}
buffer.append("</table>");
out.write(buffer.toString());
out.flush();
out.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return TagSupport.SKIP_BODY;
}
@Override
public int doEndTag() throws JspException {
// TODO Auto-generated method stub
return super.doEndTag();
}
@Override
public int doAfterBody() throws JspException {
// TODO Auto-generated method stub
return super.doAfterBody();
}
*项目名称：tag
*类名： TagDemo1.java
*作者： 曹道喜
*创建日期： Oct 17, 2011 11:52:56 AM
*类说明：
*/
public class TagDemo1 extends TagSupport {
private List<Person> ps = null;
public List<Person> getPs() {
return ps;
}
public void setPs(List<Person> ps) {
this.ps = ps;
}
@Override
public int doStartTag() throws JspException {
// TODO Auto-generated method stub
JspWriter out = pageContext.getOut();
StringBuffer buffer = new StringBuffer();
System.out.print("-------------");
try {
buffer.append("<table>" +
"<tr>" +
"<th>姓名</th>" +
"<th>年龄</th>" +
"<th>邮箱</th>" +
"</tr>"
);
System.out.print(buffer.toString());
if(ps!=null&&ps.size()!=0){
for(Person person:ps){
buffer.append("<tr>" +
"<td>"+person.getName()+"</td>" +
"<td>"+person.getAge()+"</td>" +
"<td>"+person.getEmail()+"</td>" +
"</tr>"
);
}
}else{
buffer.append("<td>没有想要的数据</td>");
}
buffer.append("</table>");
out.write(buffer.toString());
out.flush();
out.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return TagSupport.SKIP_BODY;
}
@Override
public int doEndTag() throws JspException {
// TODO Auto-generated method stub
return super.doEndTag();
}
@Override
public int doAfterBody() throws JspException {
// TODO Auto-generated method stub
return super.doAfterBody();
}
}