我在一个非常简单的JSF页面上遇到了一些麻烦，我正在尝试我在这里找到的不同解决方案，但它们都不起作用。你能帮助我发现，为什么我不能把这个简单的JSF工作示例？
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>
这是支持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进行部署，但是当我在字段上键入内容并单击提交按钮时，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
答案 0 :(得分：3)
从您的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/...开头的新命名空间。
╔════════════════════════════════════════╦═════════════════════════════════════════╗
║ 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：
faces-config.xml也适用于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>
<强>更新
在GlassFish 4.0上测试代码并且运行正常，EL2.2和Tomcat 6一定存在问题，详见here。
答案 1 :(得分：1)
我目前正在使用带有Tomcat 6服务器的EL 2.2。我需要的只是：
<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>
你的pom文件中没有第一个。从那里开始，包括el-ri，这可能会在您的el库之间造成冲突，如@rdcrng点。
此外，您的Web应用程序已针对 servlet 3.0 进行了配置。这就是您在web.xml文件version="3.0"中所说的内容。 Tomcat是一个servlet 2.5容器，not compatible就是这个。
<强>更新
这是我在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>