java - JSP 和 EL 与 JSF 1.x actionListener 冲突

Question

我正在研究一个 JSF 1.x 示例，该示例在 JSP 中存在一些 EL 冲突。actionListener="#{helloBean.addControls} 行正在解决问题。

错误是:

HTTP Status 500 - /JSP/hello.jsp (line: 37, column: 2) A literal value was specified for attribute actionListener that is defined as a deferred method with a return type of void. JSP.2.3.4 does not permit literal values in this case

我的项目描述如下:

包结构:

Maven 依赖项:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.achutha.labs</groupId>
    <artifactId>02JsfExample</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>war</packaging>
    <name>02JsfExample</name>

    <dependencies>

        <dependency>
            <groupId>javax.faces</groupId>
            <artifactId>jsf-api</artifactId>
            <version>1.2_14</version>
        </dependency>
        <dependency>
            <groupId>javax.faces</groupId>
            <artifactId>jsf-impl</artifactId>
            <version>1.2_14</version>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>servlet-api</artifactId>
            <version>2.5</version>
        </dependency>

        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>jsp-api</artifactId>
            <version>2.1</version>
        </dependency>

        <!-- EL -->
        <dependency>
            <groupId>org.glassfish.web</groupId>
            <artifactId>el-impl</artifactId>
            <version>2.2</version>
        </dependency>


    </dependencies>


    <build>
        <finalName>JavaServerFaces</finalName>

        <plugins>

            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>tomcat-maven-plugin</artifactId>
                <configuration>
                    <url>http://localhost:8090/manager/text</url>
                    <server>TomcatServer</server>
                    <path>/balaji</path>
                </configuration>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>2.3.1</version>
                <configuration>
                    <source>1.6</source>
                    <target>1.6</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

面孔配置:

<?xml version="1.0"?>
<!DOCTYPE faces-config PUBLIC
     "-//Sun Microsystems, Inc.//DTD JavaServer Faces Config 1.0//EN"
     "http://java.sun.com/dtd/web-facesconfig_1_0.dtd">

<faces-config>
    <managed-bean>
        <description> The one and only HelloBean.</description>
        <managed-bean-name>helloBean</managed-bean-name>
        <managed-bean-class>com.achutha.bean.HelloBean</managed-bean-class>
        <managed-bean-scope>session</managed-bean-scope>
    </managed-bean>



    <navigation-rule>
        <description>Navigation From the Hello Page.</description>
        <from-view-id>/JSP/hello.jsp</from-view-id>
        <navigation-case>
            <from-outcome>success</from-outcome>
            <to-view-id>/JSP/goodbye.jsp</to-view-id>
        </navigation-case>
    </navigation-rule>

</faces-config>

部署描述符 (web.xml):

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE web-app
    PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
    "http://java.sun.com/dtd/web-app_2_3.dtd">

<web-app>
    <display-name>Hello, World!</display-name>
    <description>Welcome to JavaServer Faces</description>

    <servlet>
        <servlet-name>Faces Servlet</servlet-name>
        <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>Faces Servlet</servlet-name>
        <url-pattern>/faces/*</url-pattern>
    </servlet-mapping>

    <welcome-file-list>
        <welcome-file>/JSP/hello.jsp</welcome-file>
    </welcome-file-list>


</web-app>

hello.jsp

<%@ taglib uri="http://java.sun.com/jsf/core" prefix="f"%>
<%@ taglib uri="http://java.sun.com/jsf/html" prefix="h"%>

<f:view>
    <html>
<head>
<title>JSF In Action - Hello, world!</title>
</head>
<body>
    <h:form id="welcomeForm">
        <h:outputText id="welcomeOutput" value="Welcome to JavaServer Faces !"
            style="font-family: Arial, sans-serif; font-size: 23; color: green;" />

        <p>
            <h:message id="errors" for="helloInput" style="color: red" />
        </p>

        <p>
            <h:outputLabel for="helloInput">
                <h:outputText id="helloInputLabel"
                    value="Enter Number of controls to display: ">

                </h:outputText>

                <h:inputText id="helloInput" value="#{helloBean.numControls}"
                    required="true">
                    <f:validateLongRange minimum="1" maximum="500" />
                </h:inputText>
            </h:outputLabel>
        </p>

        <p>
            <h:panelGrid id="controlPanel" binding="#{helloBean.controlPanel}"
                columns="20" border="1" cellspacing="0" />
        </p>

        <h:commandButton id="redisplayCommand" type="submit" value="Redisplay"
            actionListener="#{helloBean.addControls}" />

        <h:commandButton id="goodbyeCommand" type="submit" value="Goodbye"
            actionListener="#{helloBean.goodbye}" immediate="true"/>

    </h:form>

</body>

    </html>

</f:view>

再见.jsp:

<%@ taglib uri="http://java.sun.com/jsf/html" prefix="h"%>
<%@ taglib uri="http://java.sun.com/jsf/core" prefix="f"%>
<f:view>
    <html>
<head>
<title>Jsf in Action - Hello World!</title>
</head>
<body>
    <h:form id="goodbyeForm">
        <p>
            <h:outputText id="welcomeOutput" value="Good Bye"
                style="font-family: Arial, sans-serif; font-size: 24; font-style: bold; color: green;" />

        </p>
        <p>
            <h:outputText id="helloBeanOutputLabel"
                value="Number of controls displayed: " />
            <h:outputText id="helloBeanOutputLabel"
                value="#{helloBean.numControls}" />
        </p>
    </h:form>

</body>
    </html>
</f:view>

Bean 类:

package com.achutha.bean;

import java.util.List;

import javax.faces.application.Application;
import javax.faces.component.UIComponent;
import javax.faces.component.html.HtmlOutputText;
import javax.faces.component.html.HtmlPanelGrid;
import javax.faces.context.FacesContext;
import javax.faces.event.ActionEvent;

public class HelloBean {

    private int numControls;
    private HtmlPanelGrid controlPanel;

    public int getNumControls() {
        return numControls;
    }

    public void setNumControls(int numControls) {
        this.numControls = numControls;
    }

    public HtmlPanelGrid getControlPanel() {
        return controlPanel;
    }

    public void setControlPanel(HtmlPanelGrid controlPanel) {
        this.controlPanel = controlPanel;
    }

    public void addControls(ActionEvent actionEvent) {
        Application application = FacesContext.getCurrentInstance()
                .getApplication();

        List<UIComponent> children = controlPanel.getChildren();

        children.clear();

        for (int count = 0; count < numControls; count++) {
            HtmlOutputText output = (HtmlOutputText) application
                    .createComponent(HtmlOutputText.COMPONENT_TYPE);
            output.setValue(" " + count + " ");
            output.setStyle("color: blue");
            children.add(output);
        }
    }

    public String goodbye() {
        return "success";
    }

}

干净部署:应用程序在 Tomcat 7 上正常部署。我检查了 &tomcat_home%/webapps 上部署的包结构，一切都按预期处于正确位置。

但是当我在浏览器上运行该应用程序时，出现以下错误:

HTTP Status 500 - /JSP/hello.jsp (line: 37, column: 2) A literal value was specified for attribute actionListener that is defined as a deferred method with a return type of void. JSP.2.3.4 does not permit literal values in this case

type Exception report

message /JSP/hello.jsp (line: 37, column: 2) A literal value was specified for attribute actionListener that is defined as a deferred method with a return type of void. JSP.2.3.4 does not permit literal values in this case

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

exception

org.apache.jasper.JasperException: /JSP/hello.jsp (line: 37, column: 2) A literal value was specified for attribute actionListener that is defined as a deferred method with a return type of void. JSP.2.3.4 does not permit literal values in this case
    org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:42)
    org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:408)
    org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:149)
    org.apache.jasper.compiler.Validator$ValidateVisitor.checkXmlAttributes(Validator.java:1151)
    org.apache.jasper.compiler.Validator$ValidateVisitor.visit(Validator.java:875)
    org.apache.jasper.compiler.Node$CustomTag.accept(Node.java:1539)
    org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2376)
    org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2428)
    org.apache.jasper.compiler.Validator$ValidateVisitor.visit(Validator.java:894)
    org.apache.jasper.compiler.Node$CustomTag.accept(Node.java:1539)
    org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2376)
    org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2428)
    org.apache.jasper.compiler.Validator$ValidateVisitor.visit(Validator.java:894)
    org.apache.jasper.compiler.Node$CustomTag.accept(Node.java:1539)
    org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2376)
    org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2428)
    org.apache.jasper.compiler.Node$Visitor.visit(Node.java:2434)
    org.apache.jasper.compiler.Node$Root.accept(Node.java:475)
    org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2376)
    org.apache.jasper.compiler.Validator.validateExDirectives(Validator.java:1795)
    org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:217)
    org.apache.jasper.compiler.Compiler.compile(Compiler.java:373)
    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)

我没有找到适合此问题的一站式解决方案。actionListener="#{helloBean.addControls} 行中使用的 EL 导致了复杂性的增加。请告诉我解决方案。

Answer 1

在 web.xml 中进行更改

<webapp>

进入

<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">

除了上面的尝试添加

到您的网络应用程序...

像这样

 <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"
      xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
      id="WebApp_ID">