Tomcat 7、JSF 2、Spring 3、Java 6
访问 jsf 页面时,UserBean.java 中的 userService.checkUser(getLogin()) 出现 NullPointerException(userService 为 null)。
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app 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"
version="2.5">
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:applicationContext.xml</param-value>
</context-param>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<listener>
<listener-class>org.springframework.web.context.request.RequestContextListener</listener-class>
</listener>
<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>*.jsf</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>Faces Servlet</servlet-name>
<url-pattern>/faces/*</url-pattern>
</servlet-mapping>
</web-app>
faces-config.xml
<faces-config 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-facesconfig_2_0.xsd"
version="2.0">
<application>
<el-resolver>org.springframework.web.jsf.el.SpringBeanFacesELResolver</el-resolver>
<resource-bundle>
<base-name>i18n</base-name>
<var>msg</var>
</resource-bundle>
<locale-config>
<default-locale>en</default-locale>
<supported-locale>ru</supported-locale>
</locale-config>
</application>
</faces-config>
applicationContext.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd">
<!-- Services Beans -->
<bean id="userService" class="service.UserServiceImpl">
<property name="userDao" ref="userDao"/>
</bean>
<!-- DAOs -->
<bean id="userDao" class="dao.UserDaoImpl">
<property name="sessionFactory" ref="sessionFactory"/>
</bean>
<!-- Hibernate session factory -->
<bean id="sessionFactory"
class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
<property name="configLocation">
<value>classpath:/hibernate.cfg.xml</value>
</property>
</bean>
<tx:annotation-driven/>
<bean id="transactionManager"
class="org.springframework.orm.hibernate4.HibernateTransactionManager">
<property name="sessionFactory" ref="sessionFactory"/>
</bean>
</beans>
UsersBean.java
package beans;
import service.UserService;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.ManagedProperty;
import javax.faces.bean.SessionScoped;
import java.io.Serializable;
@ManagedBean(name="usersBean")
@SessionScoped
public class UsersBean implements Serializable{
private String login;
private String password;
@ManagedProperty(name = "userService", value = "#{userService}")
private UserService userService;
...Getters, setters for every field...
public void checkRegistred(){
userService.checkUser(getLogin());
}
}
xhtml 文件
<?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://java.sun.com/jsf/html"
xmlns:ui="http://java.sun.com/jsf/facelets">
<h:head>
<title>Simple JSF Facelets page</title>
</h:head>
<h:body>
<ui:composition template="layout.xhtml">
<ui:define name="content">
<h:link value="First page" outcome="index.xhtml"></h:link>
<br/>
<h:link value="Third page" outcome="third.xhtml"></h:link>
<br/>
Hello #{usersBean.login} with pass #{usersBean.password}
<br/>
You are #{usersBean.checkRegistred()}
</ui:define>
</ui:composition>
</h:body>
</html>
最佳答案
查看 this question及其答案。在您的情况下,当您使用 XML 配置时,为了使用 @autowired 注释,您还需要修改您的 userServide 声明,如下所示:
<bean id="userService" class="service.UserServiceImpl" autowire-candidate="true">
<property name="userDao" ref="userDao"/>
</bean>
将 autowire-candidate
属性设置为 true 后,userService
将可用于 Autowiring 。
更新:
package beans;
import ...
@SessionScoped
public class UsersBean implements Serializable {
private String login;
private String password;
@Autowired
private UserService userService;
...Getters, setters for every field...
public void checkRegistred(){
userService.checkUser(getLogin());
}
}
此外,在您的 XML 中应该可以找到:
<context:component-scan base-package="beans.*" />
<context:annotation-config />
关于java - 将 Spring 服务 bean 注入(inject) JSF ManagedBean 时出现 NullPointerException,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/10417665/