Struts2整合Spring，Action配置报错，请问什么情况？

Question

项目使用了SSH，用注解的方式装备bean，如果只在Dao，service层注解。没有问题可以正常启动tomcat，bean也装配成功，可以正常访问。如果action也加了注解就会启动失败，并且报错

启动tomcat时的异常：

[ERROR] 2016-02-25 17:21:24,427 [ pool-2-thread-1:1123 ] method:initWebApplicationContextContext initialization failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'policeLoginAction' defined in file [E:Workspaceseclispe.metadata.pluginsorg.eclipse.wst.server.coretmp0wtpwebappszyhCity160129WEB-INFclassescomsafeactionpolicePoliceLoginAction.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.safe.action.police.PoliceLoginAction]: Constructor threw exception; nested exception is java.lang.NullPointerException
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1076)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1021)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:504)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:304)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:300)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:195)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:700)
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:760)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:482)
	at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:403)
	at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:306)
	at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:106)
	at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4765)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5260)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1525)
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1515)
	at java.util.concurrent.FutureTask.run(FutureTask.java:262)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
	at java.lang.Thread.run(Thread.java:745)
Caused by: org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.safe.action.police.PoliceLoginAction]: Constructor threw exception; nested exception is java.lang.NullPointerException
	at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:164)
	at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:89)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1069)
	... 22 more
Caused by: java.lang.NullPointerException
	at org.apache.struts2.ServletActionContext.getRequest(ServletActionContext.java:112)
	at com.safe.action.BaseAction.<init>(BaseAction.java:23)
	at com.safe.action.police.PoliceLoginAction.<init>(PoliceLoginAction.java:15)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
	at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:148)
	... 24 more

action：

package com.safe.action.police;

import java.text.SimpleDateFormat;
import java.util.Date;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;

import com.safe.action.BaseAction;
import com.safe.model.Police;
import com.safe.service.PoliceService;
import com.safe.util.ConstantUtil;

@Controller
public class PoliceLoginAction extends BaseAction {
	private static final long serialVersionUID = 1L;
	@Autowired
	private PoliceService policeService;

	private String policeNo;
	private String pwd;// 叫做授权码 只有在开发测试时使用 2016年1月20日15:34:02
	private String token;

	public String getPoliceNo() {
		return policeNo;
	}

	public void setPoliceNo(String policeNo) {
		this.policeNo = policeNo;
	}

	public String getPwd() {
		return pwd;
	}

	public void setPwd(String pwd) {
		this.pwd = pwd;
	}

	public String getToken() {
		return token;
	}

	public void setToken(String token) {
		this.token = token;
	}

	@Override
	public String execute() throws Exception {
		String returnStr = SUCCESS;
		System.out.println(
				new SimpleDateFormat("yyyy-MM-dd HH
              

Answer 1

找到一个解决办法给ACTION加注解@Lazy(true)，但是感觉这个不是最好的办法。

Answer 2

想不到还有人在使用struts。。。。。

Answer 3

新的疑问：spring容器applicationContext默认创建Bean是单例作用域。Struts2的action是多例的，如果给action加上注解被Spring管理。会不会在作用域上又冲突？

Answer 4

第二种办法IOC注入： BaseAction实现接口ServletRequestAware 并实现方法setServletRequest。可以注入HttpRequest实例，通过request.getSession()获得HttpSession

Answer 5

异常原因分析：因为action加了注解，而容器使用的是ApplicationContext（默认启动容器立即加载Bean）。在action中使用了父类BaseAction的属性session，所以启动Spring容器时就会调用session的初始化方法ServletActionContext.getRequest()

.getSession();此时，没有用户访问，也就没有请求，所以request为空，调用.getSession()方法时报空指针。

Answer 6

自己顶 

Answer 7

可以说的详细点吗？

Answer 8

回复
实现“org.apache.struts2.interceptor.SessionAware“即可

Answer 9

回复
谢谢，还有一个问题：spring配置action时该使用单例还是其他的作用域？

Answer 10

回复
这个拿到的是map不是HttpSession @Override public void setSession(Map<String, Object> session) { this.session=session; }

Answer 11

回复
没毛病啊，不就是存值取值嘛，这里面的值和httpsession的值是对应的。@controller注解原先是给springmvc使用的，默认是单例，但是struts2用的时候不要单例，每次请求新建

Answer 12

要获取session不应该使用这种方式，在省城bean的时候这个方法返回的还是空指针，要获取session应该是实现相应的接口，完成依赖注入

Answer 13

真的吗？谢谢。

Answer 14

最优的解决方案就是不用struts2了，改用springmvc，我保证，你用了之后就会再也不想用回来struts2的