Struts2整合Spring，Action配置报错，请问什么情况？?报错

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:\Workspaces\eclispe\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\zyhCity160129\WEB-INF\classes\com\safe\action\police\PoliceLoginAction.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

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🇲🇲ss").format(new Date()) + " login:" + policeNo + "---" + pwd);
		Police police = policeService.login(policeNo, pwd, token);

		if (police == null) {
			message = "登录失败！";
			code = 0;
			returnStr = "fail";
			// return "fail"; 返回json的时候，如果此处return，就不会执行后面的发送json
		} else {
			jsonMap.put("token", police.getToken());
			jsonMap.put("police", police);
			session.setMaxInactiveInterval(ConstantUtil.HTTPSESSION_life);// 设置session闲置间隔（有效期），单位：秒
			// 登陆状态标识符
			session.setAttribute("policeId", police.getId());// 登录警员的Id
			session.setAttribute("loginName", policeNo);// 验证在线状态时使用，如果为null则表示没有登录
			session.setAttribute("identity", "police");// 登陆者身份类别
		}
		returnJson();
		return returnStr;
	}

}

package com.safe.action;

import java.util.HashMap;
import java.util.Map;

import javax.servlet.http.HttpSession;

import org.apache.struts2.ServletActionContext;


import com.opensymphony.xwork2.ActionSupport;
import com.safe.util.ConstantUtil;
import com.safe.util.JsonUtil;

public class BaseAction extends ActionSupport {
	private static final long serialVersionUID = 1L;
	
	protected int code = 1;// 响应登陆状态码，1成功 0失败
	protected String message = ConstantUtil.RETURN_OK;
	
	protected Map<String, Object> jsonMap = new HashMap<String, Object>();	

	protected HttpSession session = ServletActionContext.getRequest()//这一行报空指针
			.getSession();

如果，没有在action加@Controller注解，则没有异常，并且BaseAction中的函数可也以正常调用。