找不到JSF属性

Question

我在一个非常简单的JSF页面上遇到了一些麻烦，我正在尝试在这里找到的其他解决方案，但是它们都不起作用。 您能帮我发现一下，为什么我不能使这个简单的JSF示例工作吗？

这是pom.xml

<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/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.mkyong.core</groupId>
    <artifactId>primefaces</artifactId>
    <packaging>war</packaging>
    <version>1.0-SNAPSHOT</version>
    <name>primefaces Maven Webapp</name>
    <url>http://maven.apache.org</url>

    <repositories>
        <repository>
            <id>prime-repo</id>
            <name>PrimeFaces Maven Repository</name>
            <url>http://repository.primefaces.org</url>
            <layout>default</layout>
        </repository>
    </repositories>

    <dependencies>

        <!-- PrimeFaces -->
        <dependency>
            <groupId>org.primefaces</groupId>
            <artifactId>primefaces</artifactId>
            <version>4.0</version>
        </dependency>

        <!-- JSF 2 -->
        <dependency>
            <groupId>com.sun.faces</groupId>
            <artifactId>jsf-api</artifactId>
            <version>2.2.4</version>
        </dependency>

        <dependency>
            <groupId>com.sun.faces</groupId>
            <artifactId>jsf-impl</artifactId>
            <version>2.2.4</version>
        </dependency>

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

        <!--Servlet api already provided by tomcat-->
        <!--<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>

        <!-- Tomcat 6 need this -->
        <dependency>
            <groupId>com.sun.el</groupId>
            <artifactId>el-ri</artifactId>
            <version>1.0</version>
        </dependency>


    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>2.3.2</version>
                <configuration>
                    <source>1.6</source>
                    <target>1.6</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

这是web.xml

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
    http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
         id="WebApp_ID" version="3.0">

    <!-- Change to "Production" when you are ready to deploy -->
    <context-param>
        <param-name>javax.faces.PROJECT_STAGE</param-name>
        <param-value>Development</param-value>
    </context-param>

    <!-- Welcome page -->
    <welcome-file-list>
        <welcome-file>faces/index.xhtml</welcome-file>
    </welcome-file-list>

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

    <!-- Map these files with JSF -->
    <servlet-mapping>
        <servlet-name>Faces Servlet</servlet-name>
        <url-pattern>/faces/*</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>Faces Servlet</servlet-name>
        <url-pattern>*.jsf</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>Faces Servlet</servlet-name>
        <url-pattern>*.faces</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>Faces Servlet</servlet-name>
        <url-pattern>*.xhtml</url-pattern>
    </servlet-mapping>

</web-app>

这是faces-config.xml

 <?xml version='1.0' encoding='UTF-8'?>
<faces-config version="2.2"
              xmlns="http://xmlns.jcp.org/xml/ns/javaee"
              xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
              xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-facesconfig_2_2.xsd">
</faces-config>

这是视图页面index.xhtml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
        "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:h="http://xmlns.jcp.org/jsf/html"
      xmlns:f="http://xmlns.jcp.org/jsf/core"
      xmlns:ui="http://xmlns.jcp.org/jsf/facelets"
      xmlns:p="http://primefaces.org/ui">
<h:head>
</h:head>
<h:body>
    <h:form>
        Enter your name
        <h:inputText value="#{helloBean.input}" />
        <h:commandButton value="submit" action="#{helloBean.submit}" />
    </h:form>
    <h:outputText value="#{helloBean.output}" />


</h:body>
</html>

这是后台bean EditorBean

package com.mykong.editor;

import javax.faces.bean.ManagedBean;
import javax.faces.bean.RequestScoped;

@ManagedBean
@RequestScoped
public class HelloBean {

    private String input;
    private String output;

    public void submit() {
        output = String.format("Hello %s!", input);
    }

    public String getInput() {
        return input;
    }

    public String getOutput() {
        return output;
    }

    public void setInput(String input) {
        this.input = input;
    }

}

编译正确，我使用命令mvn tomcat:run部署，但是当我在字段上键入内容并单击Submit按钮时，我看到的是一个例外：

javax.el.PropertyNotFoundException: /index.xhtml @15,51 value="#{helloBean.input}": Target Unreachable, identifier 'helloBean' resolved to null
    at com.sun.faces.facelets.el.TagValueExpression.getType(TagValueExpression.java:100)
    at com.sun.faces.renderkit.html_basic.HtmlBasicInputRenderer.getConvertedValue(HtmlBasicInputRenderer.java:95)
    at javax.faces.component.UIInput.getConvertedValue(UIInput.java:1046)
    at javax.faces.component.UIInput.validate(UIInput.java:976)
    at javax.faces.component.UIInput.executeValidate(UIInput.java:1249)
    at javax.faces.component.UIInput.processValidators(UIInput.java:712)
    at javax.faces.component.UIForm.processValidators(UIForm.java:253)
    at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1258)
    at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1258)
    at javax.faces.component.UIViewRoot.processValidators(UIViewRoot.java:1195)
    at com.sun.faces.lifecycle.ProcessValidationsPhase.execute(ProcessValidationsPhase.java:76)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:198)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:646)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    at java.lang.Thread.run(Thread.java:724)
Caused by: javax.el.PropertyNotFoundException: Target Unreachable, identifier 'helloBean' resolved to null
    at com.sun.el.parser.AstValue.getTarget(AstValue.java:131)
    at com.sun.el.parser.AstValue.getType(AstValue.java:76)
    at com.sun.el.ValueExpressionImpl.getType(ValueExpressionImpl.java:195)
    at com.sun.faces.facelets.el.TagValueExpression.getType(TagValueExpression.java:98)
    ... 25 more

Answer 1

在pom.xml -您正在使用JSF 2.2。 您的.xhtml文件使用http://java.sun.com/...命名空间。 问题在于JSF 2.2引入了以http://xmlns.jcp.org/...开头的新名称空间。

╔════════════════════════════════════════╦═════════════════════════════════════════╗
║             Old namespace              ║            JSF 2.2 namespace            ║
╠════════════════════════════════════════╬═════════════════════════════════════════╣
║ http://java.sun.com/jsf/core           ║ http://xmlns.jcp.org/jsf/core           ║
║ http://java.sun.com/jsf/html           ║ http://xmlns.jcp.org/jsf/html           ║
║ http://java.sun.com/jsf/facelets       ║ http://xmlns.jcp.org/jsf/facelets       ║
║ http://java.sun.com/jsf/composite      ║ http://xmlns.jcp.org/jsf/composite      ║
║ http://java.sun.com/jsp/jstl/core      ║ http://xmlns.jcp.org/jsp/jstl/core      ║
║ http://java.sun.com/jsp/jstl/functions ║ http://xmlns.jcp.org/jsp/jstl/functions ║
╚════════════════════════════════════════╩═════════════════════════════════════════╝

编辑：

另外， faces-config.xml应该适用于2.2：

<?xml version='1.0' encoding='UTF-8'?>
<faces-config version="2.2"
    xmlns="http://xmlns.jcp.org/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-facesconfig_2_2.xsd">

</faces-config>

更新：

在GlassFish 4.0上测试过的代码可以正常工作，EL2.2和Tomcat 6必须存在问题，有关详细信息，请参见此处 。

Answer 2

我目前正在将EL 2.2与Tomcat 6服务器一起使用。 我需要的是：

<dependency>
    <groupId>javax.el</groupId>
    <artifactId>el-api</artifactId>
    <version>2.2</version>
</dependency>

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

您的pom文件中没有第一个。 Appart从那里开始，您包含了el-ri ，这可能会在您的el库之间造成冲突，如@rdcrng所示。

同样，您的Web应用程序已针对Servlet 3.0配置。 这就是您在web.xml文件version="3.0" 。 Tomcat是Servlet 2.5容器，与之不兼容 。

UPDATE

这就是我在Tomcat 6（Primefaces，Mojarra和EL 2.2）中用于测试目的的项目的Maven配置：

<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.mycompany</groupId>
    <artifactId>basic-jsf</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>war</packaging>

    <name>basic-jsf</name>
    <url>http://maven.apache.org</url>

    <repositories>
        <repository>
            <id>prime-repo</id>
            <name>PrimeFaces Maven Repository</name>
            <url>http://repository.primefaces.org</url>
            <layout>default</layout>
        </repository>
    </repositories>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.1</version>
                <configuration>
                    <source>1.6</source>
                    <target>1.6</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

    <dependencies>
        <dependency>
            <groupId>org.primefaces</groupId>
            <artifactId>primefaces</artifactId>
            <version>3.5</version>
        </dependency>
        <dependency>
            <groupId>com.sun.faces</groupId>
            <artifactId>jsf-api</artifactId>
            <version>2.1.25</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>com.sun.faces</groupId>
            <artifactId>jsf-impl</artifactId>
            <version>2.1.25</version>
            <scope>compile</scope>
        </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.el</groupId>
            <artifactId>el-api</artifactId>
            <version>2.2</version>
        </dependency>

        <dependency>
            <groupId>org.glassfish.web</groupId>
            <artifactId>el-impl</artifactId>
            <version>2.2</version>
        </dependency>
    </dependencies>
</project>

我的web.xml文件也很简单：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    id="WebApp_ID" version="2.5">
    <display-name>jsf2testproject</display-name>

    <welcome-file-list>
        <welcome-file>index.xhtml</welcome-file>
    </welcome-file-list>
    <context-param>
        <param-name>com.sun.faces.expressionFactory</param-name>
        <param-value>com.sun.el.ExpressionFactoryImpl</param-value>
    </context-param>

    <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>*.xhtml</url-pattern>
    </servlet-mapping>

    <context-param>
        <param-name>javax.faces.PROJECT_STAGE</param-name>
        <param-value>Development</param-value>
    </context-param>
</web-app>