Spring执行顺序与ApplicationContext

一、spring容器初始化bean对象的顺序是listener-->filter-->servlet，其中

stattic>构造方法 > @Autowired > @PostConstruct。

故在static方法里面调用某个Bean，不可以用Autowired ，可以让通过ApplicationContext获取Bean。

二、如果在servlet初始化之前使用注解获取bean，是获取不到的，因为还没有注入进去。这时候我们可以通过以下几种方法来获取ApplicationContext

1、方法一：

package com.demo.util;import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;/*** 获得整个工程的上下文环境**/
public final class SpringContextUtil {/*** 上下文*/private static ApplicationContext ctu;/*** 私有构造函数*/private SpringContextUtil() {super();}public static void setApplicationContext(ApplicationContext applicationContext){ctu = applicationContext;}/*** 获得上下文** @return ApplicationContext*/public static ApplicationContext getApplicationContext() {return ctu;}}

public classUser{private static Userservice userService;private static RoleService roleService;static{userService= (Userservice ) SpringContextUtil.getApplicationContext().getBean("userService");roleService= (RoleService ) SpringContextUtil.getApplicationContext().getBean("roleService");}public staic void addUser(User user,Role role)userService.insert(user);}
}

@Override方法也会在@ Autowired之前执行，这样使用到的@Autowired加载的bean会为null，故也需要像上面那样，如：

public class ExecuteAddJob implements org.quartz.Job{private static JobService jobService;private static JobSchedule jobSchedule;static{jobService = (JobService) SpringContextUtil.getApplicationContext().getBean("jobService");jobSchedule = (JobSchedule) SpringContextUtil.getApplicationContext().getBean("jobSchedule");}@Overridepublic void execute(JobExecutionContext context)throws JobExecutionException {//获取未执行过的jobList jobList = jobService.getUnExecutedJobs();if (CollectionUtils.isNotEmpty(jobList)) {for (Job job : jobList) {try {jobSchedule.addJob(job);//添加到schedule后，状态更新为已执行job.setState(JobStatus.EXECUTE.getStatus());jobService.updateJob(job);} catch (SchedulerException e) {e.printStackTrace();}}}}}

启动类：

package com.demo;import com.demo.util.SpringContextUtil;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ApplicationContext;@SpringBootApplication
public class SecurityApplication {public static void main(String args[]){ApplicationContext applicationContext = SpringApplication.run(SecurityApplication.class, args);//实例化上下文对象SpringContextUtil.setApplicationContext(applicationContext);}
}

如果是在filter过滤器中获取spring的bean：

Bean都是被Spring容器管理的，使用的时候，直接通过注解@Autowired，注入即可

在Filter中，不能使用@Autowired注解注入，通过注解获取到的为null
Filter并没有被Spring容器管理，它是运行在Tomcat上的，是由Servlet来管理的

ServletContext sc = req.getSession().getServletContext();XmlWebApplicationContext cxt = (XmlWebApplicationContext) WebApplicationContextUtils.findWebApplicationContext(sc);redisClient = (RedisClient) cxt.getBean("redisClient");

2、方法二：

package com.demo.factory;import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;@Component
public class ApplicationContextRegister implements ApplicationContextAware {private static Logger logger = LoggerFactory.getLogger(ApplicationContextRegister.class);private static ApplicationContext APPLICATION_CONTEXT;/*** 设置spring上下文* @param applicationContext spring上下文* @throws BeansException* */@Overridepublic void setApplicationContext(ApplicationContext applicationContext) throws BeansException {logger.debug("ApplicationContext registed-->{}", applicationContext);DefaultBeanFactory.setSpringApplicationContext(applicationContext);APPLICATION_CONTEXT = applicationContext;}/*** 获取容器* @return*/public static ApplicationContext getApplicationContext() {return APPLICATION_CONTEXT;}/*** 获取容器对象* @param type* @param * @return*/public static  T getBean(Class type) {return APPLICATION_CONTEXT.getBean(type);}
}

package com.demo.factory;import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;public class DefaultBeanFactory {private static ApplicationContext context = null;private static DefaultBeanFactory instance = null;private static Object lock = new Object();private DefaultBeanFactory(String filepath){try {context = new ClassPathXmlApplicationContext(filepath);} catch (Exception e) {}}@SuppressWarnings("static-access")private DefaultBeanFactory(ApplicationContext context){try {this.context = context;} catch (Exception e) {}}public static void setSpringApplicationContext(ApplicationContext context){synchronized (lock) {instance = new DefaultBeanFactory(context);}}public static DefaultBeanFactory getInstance() {if(instance == null || context == null){throw new RuntimeException("Spring context is null!");}return instance;}public static DefaultBeanFactory getInstance(String filepath) {synchronized (lock) {instance = new DefaultBeanFactory(filepath);}return instance;}public Object getBean(String name) {return context.getBean(name);}
}

bean获取类：

package com.demo.factory;import com.demo.service.UserService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;public class ServiceFactory {private static Logger logger = LoggerFactory.getLogger(ServiceFactory.class);private static ServiceFactory instance = new ServiceFactory();private final String USER_SERVICE_BEAN="userService";public ServiceFactory() {// TODO Auto-generated constructor stub}public static ServiceFactory getInstance() {if (instance == null) {instance = new ServiceFactory();}return instance;}public UserService createUserService() {try {return (UserService) DefaultBeanFactory.getInstance().getBean(USER_SERVICE_BEAN);} catch (Exception e) {throw new RuntimeException("创建 USER_SERVICE BEAN 异常", e);}}}

启动类不需要做修改：

@SpringBootApplication
@MapperScan("com.demo.dao")
public class JobStart {public static void main(String[] args) {SpringApplication.run(JobStart.class, args);}
}

应用：

package com.demo.job;
import com.demo.dao.UserDao;
import com.demo.dto.User;
import com.demo.factory.ServiceFactory;
import com.demo.service.UserService;
import org.quartz.Job;
import org.quartz.JobExecutionContext;
import org.quartz.JobExecutionException;
import org.springframework.beans.factory.annotation.Autowired;import java.text.SimpleDateFormat;
import java.util.Date;public class MyDbJob implements Job{private static UserService userService;static {userService = ServiceFactory.getInstance().createUserService();}@Overridepublic void execute(JobExecutionContext arg0) throws JobExecutionException {System.out.print("执行db");User user = new User();user.setName("名称");user.setAge(18);userService.insert(user);}}

3、方法三：

以上方法在BasicHttpAuthenticationFilter中获取不到bean，

以下方法测试可用：

ServletContext servletContext = request.getServletContext();ApplicationContext context = WebApplicationContextUtils.getWebApplicationContext(servletContext);redisClient = (RedisClient) context.getBean("redisClient");

应用：

package com.shiro.jwt.handler;import com.shiro.jwt.dto.CommonConstant;
import com.shiro.jwt.dto.JwtToken;
import com.shiro.jwt.util.RedisClient;
import org.apache.shiro.authc.AuthenticationException;
import org.apache.shiro.util.AntPathMatcher;
import org.apache.shiro.web.filter.authc.BasicHttpAuthenticationFilter;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.http.HttpStatus;
import org.springframework.util.ObjectUtils;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.context.support.WebApplicationContextUtils;import javax.servlet.ServletContext;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;public class JwtFilter extends BasicHttpAuthenticationFilter {private static RedisClient redisClient;private AntPathMatcher antPathMatcher =new AntPathMatcher();/* static {//获取不到bean，报错spring context is nullredisClient = ServiceFactory.getInstance().createRedisClient();}*//*** 执行登录认证(判断请求头是否带上token)* @param request* @param response* @param mappedValue* @return*/@Overrideprotected boolean isAccessAllowed(ServletRequest request, ServletResponse response, Object mappedValue) {System.out.println("JwtFilter-->>>isAccessAllowed-Method:init()");//如果请求头不存在token,则可能是执行登陆操作或是游客状态访问,直接返回trueif (isLoginAttempt(request, response)) {return true;}//如果存在,则进入executeLogin方法执行登入,检查token 是否正确try {executeLogin(request, response);return true;} catch (Exception e) {throw new AuthenticationException("Token失效请重新登录");}}/*** 判断用户是否是登入,检测headers里是否包含token字段*/@Overrideprotected boolean isLoginAttempt(ServletRequest request, ServletResponse response) {ServletContext servletContext = request.getServletContext();ApplicationContext context = WebApplicationContextUtils.getWebApplicationContext(servletContext);redisClient = (RedisClient) context.getBean("redisClient");System.out.println("JwtFilter-->>>isLoginAttempt-Method:init()");HttpServletRequest req = (HttpServletRequest) request;if(antPathMatcher.match("/login",req.getRequestURI())){return true;}String token = req.getHeader(CommonConstant.ACCESS_TOKEN);if (token == null) {return false;}Object o = redisClient.get(CommonConstant.PREFIX_USER_TOKEN,token);if(ObjectUtils.isEmpty(o)){return false;}System.out.println("JwtFilter-->>>isLoginAttempt-Method:返回true");return true;}/*** 重写AuthenticatingFilter的executeLogin方法丶执行登陆操作*/@Overrideprotected boolean executeLogin(ServletRequest request, ServletResponse response) throws Exception {System.out.println("JwtFilter-->>>executeLogin-Method:init()");HttpServletRequest httpServletRequest = (HttpServletRequest) request;String token = httpServletRequest.getHeader(CommonConstant.ACCESS_TOKEN);//Access-TokenJwtToken jwtToken = new JwtToken(token);// 提交给realm进行登入,如果错误他会抛出异常并被捕获, 反之则代表登入成功,返回truegetSubject(request, response).login(jwtToken);return true;}/*** 对跨域提供支持*/@Overrideprotected boolean preHandle(ServletRequest request, ServletResponse response) throws Exception {System.out.println("JwtFilter-->>>preHandle-Method:init()");HttpServletRequest httpServletRequest = (HttpServletRequest) request;HttpServletResponse httpServletResponse = (HttpServletResponse) response;httpServletResponse.setHeader("Access-control-Allow-Origin", httpServletRequest.getHeader("Origin"));httpServletResponse.setHeader("Access-Control-Allow-Methods", "GET,POST,OPTIONS,PUT,DELETE");httpServletResponse.setHeader("Access-Control-Allow-Headers", httpServletRequest.getHeader("Access-Control-Request-Headers"));// 跨域时会首先发送一个option请求，这里我们给option请求直接返回正常状态if (httpServletRequest.getMethod().equals(RequestMethod.OPTIONS.name())) {httpServletResponse.setStatus(HttpStatus.OK.value());return false;}return super.preHandle(request, response);}
}

4、方法四：

BeanFactory factory = WebApplicationContextUtils.getRequiredWebApplicationContext(request.getServletContext());myService= (LogModuleService) factory.getBean("myService");

如：

package com.demo.service.impl;
import com.demo.service.LogModuleService;
import org.springframework.stereotype.Service;@Service("logModuleService")
public class LogModuleServiceImpl implements LogModuleService {@Overridepublic void insertLogModuleRecord(String moduleCode) {System.out.println("访问模块"+moduleCode);}
}

拦截器获取这个Bean：

package com.demo.interceptor;
import com.demo.service.LogModuleService;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.web.context.support.WebApplicationContextUtils;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;@Component
public class LogModuleInterceptor implements HandlerInterceptor{private LogModuleService logModuleService;@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {......String moduleCode = null;BeanFactory factory = WebApplicationContextUtils.getRequiredWebApplicationContext(request.getServletContext());logModuleService = (LogModuleService) factory.getBean("logModuleService");logModuleService.insertLogModuleRecord(moduleCode);}return true;}
}

本文来自互联网用户投稿，文章观点仅代表作者本人，不代表本站立场，不承担相关法律责任。如若转载，请注明出处。 如若内容造成侵权/违法违规/事实不符，请点击【内容举报】进行投诉反馈！