Java 如何从jsp页面引用用户函数

我用板条箱包装了一个简单的助手，它根据控制器名称、操作名称和参数列表生成一个超链接

public static String actionLink(String text, String controller, String action, String[] args) {
String result, URI = "";

    URI = controller + "/" + action + "/";
        for (int i = 0; i < args.length; i++) {
        URI = URI + args[i];
    }

    result = "<a href=\"" + URI + "\">" + text + "</a>";

    return result;

}

publicstaticstringactionlink（字符串文本、字符串控制器、字符串操作、字符串[]参数）{
字符串结果，URI=“”；
URI=控制器+“/”+操作+“/”；
对于（int i=0；i

我从jsp页面调用它的函数：

<%@page import="com.ACME.mvc3.helpers.Utils"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ page session="false" %>
<c:forEach items="${model}" var="item">
      <tr>          
        <td height="20"><p><%=Utils.actionLink( ${item.name}, "topic", "", ${item.id} )%></p></td>
      </tr>
</c:forEach>

当显示网页时，会引发异常。我应该修复什么来使用我的助手函数

异常文本：

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

An error occurred at line: 26 in the jsp file: /WEB-INF/views/home.jsp
Syntax error, insert ")" to complete MethodInvocation
23:             <td height="10"><hr width="100%" size="2" /></td>
24:           </tr>
25:           <tr>          
26:             <td height="20"><p><%=${Utils.actionLink(item.name, "topic", "", new String(item.id) )}%></p></td>
27:             <td width = 10%>
28:             </td>
29:           </tr>


An error occurred at line: 26 in the jsp file: /WEB-INF/views/home.jsp
Syntax error, insert ";" to complete Statement
23:             <td height="10"><hr width="100%" size="2" /></td>
24:           </tr>
25:           <tr>          
26:             <td height="20"><p><%=${Utils.actionLink(item.name, "topic", "", new String(item.id) )}%></p></td>
27:             <td width = 10%>
28:             </td>
29:           </tr>


An error occurred at line: 26 in the jsp file: /WEB-INF/views/home.jsp
$ cannot be resolved to a variable
23:             <td height="10"><hr width="100%" size="2" /></td>
24:           </tr>
25:           <tr>          
26:             <td height="20"><p><%=${Utils.actionLink(item.name, "topic", "", new String(item.id) )}%></p></td>
27:             <td width = 10%>
28:             </td>
29:           </tr>


An error occurred at line: 26 in the jsp file: /WEB-INF/views/home.jsp
item.name cannot be resolved to a type
23:             <td height="10"><hr width="100%" size="2" /></td>
24:           </tr>
25:           <tr>          
26:             <td height="20"><p><%=${Utils.actionLink(item.name, "topic", "", new String(item.id) )}%></p></td>
27:             <td width = 10%>
28:             </td>
29:           </tr>


An error occurred at line: 26 in the jsp file: /WEB-INF/views/home.jsp
An anonymous class cannot subclass the final class String
23:             <td height="10"><hr width="100%" size="2" /></td>
24:           </tr>
25:           <tr>          
26:             <td height="20"><p><%=${Utils.actionLink(item.name, "topic", "", new String(item.id) )}%></p></td>
27:             <td width = 10%>
28:             </td>
29:           </tr>


An error occurred at line: 26 in the jsp file: /WEB-INF/views/home.jsp
item.id cannot be resolved to a type
23:             <td height="10"><hr width="100%" size="2" /></td>
24:           </tr>
25:           <tr>          
26:             <td height="20"><p><%=${Utils.actionLink(item.name, "topic", "", new String(item.id) )}%></p></td>
27:             <td width = 10%>
28:             </td>
29:           </tr>


An error occurred at line: 26 in the jsp file: /WEB-INF/views/home.jsp
Syntax error on token ")", { expected
23:             <td height="10"><hr width="100%" size="2" /></td>
24:           </tr>
25:           <tr>          
26:             <td height="20"><p><%=${Utils.actionLink(item.name, "topic", "", new String(item.id) )}%></p></td>
27:             <td width = 10%>
28:             </td>
29:           </tr>


An error occurred at line: 130 in the generated java file
Syntax error, insert "}" to complete Block

An error occurred at line: 130 in the generated java file
Syntax error, insert "while ( Expression ) ;" to complete BlockStatements

org.apache.jasper.jaspereException:无法为JSP编译类：
jsp文件：/WEB-INF/views/home.jsp的第26行出现错误
语法错误，请插入“）”以完成方法调用
23:

27:             
28:             
29:           
jsp文件：/WEB-INF/views/home.jsp的第26行出现错误
语法错误，请插入“；”以完成语句
23:

27:             
28:             
29:           
jsp文件：/WEB-INF/views/home.jsp的第26行出现错误
无法将$解析为变量
23:

27:             
28:             
29:           
jsp文件：/WEB-INF/views/home.jsp的第26行出现错误
无法将item.name解析为类型
23:

27:             
28:             
29:           
jsp文件：/WEB-INF/views/home.jsp的第26行出现错误
匿名类不能对最终的类字符串进行子类化
23:

27:             
28:             
29:           
jsp文件：/WEB-INF/views/home.jsp的第26行出现错误
无法将item.id解析为类型
23:

27:             
28:             
29:           
jsp文件：/WEB-INF/views/home.jsp的第26行出现错误
令牌“）”上的语法错误，{应为
23:

27:             
28:             
29:           
生成的java文件的第130行出现错误
语法错误，插入“}”以完成块
生成的java文件的第130行出现错误
语法错误，请插入“while（Expression）；”以完成BlockStatements

更好的方法是使用JSTL函数

您应该在

WEB-INF/yoursite.tld中定义它：

<function>
    <name>escape</name>
    <function-class>com.foo.util.WebUtils</function-class>
    <function-signature>String escape(java.lang.String)</function-signature>
</function>


逃跑
com.foo.util.WebUtils
字符串转义（java.lang.String）

然后您可以将其用作
${ys:escape（str）}
（导入名称空间后。查找任何.tld文件以查看其其余部分的外观）
我找到了解决问题的方法。JSP以以下方式查看：

<%@page import="com.epam.mvc3.helpers.Utils"%>
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ page session="false" %>
<c:forEach items="${model}" var="item">
   <!-- The following line defines the type of the item variable -->
   <jsp:useBean id="item" type="com.ACME.mvc3.model.Topic"/>
   <tr>
       <!-- The following line doesn't need curly braces -->          
       <td height="20"><p><%=Utils.actionLink(item.getName(), "topic", "details") %></p></td>
   </tr>
</c:forEach>



异常消息/堆栈跟踪将非常有用。您是否尝试添加包：
复制并粘贴异常消息，以便我们也可以看到它。