SSM框架中 filter中注入service为空的问题解决

最近在做一个自动登录模块的时候遇到一个问题,在过滤器中调用service层方法时,注入的service为NULL,参考网上的几种解决方案web filter 注入service,用了其中的方法后还是无法解决,会报 No bean named 'AutoLoginFilter' is defined

最后参考https://www.cnblogs.com/chenying99/archive/2012/08/19/2646350.html发现问题应该是在Servlet Dispatcher中所初始化的Bean不能被以外的servlet或者filter使用了,参照上面的方法试着改了配置文件,即给DispatcherServlet单独的一个配置文件sprinvmvc-servlet.xml。配置如下

web.xml



	 
	  
	    default.jsp
	  

 
    org.springframework.web.context.ContextLoaderListener
  
  
    contextConfigLocation
    /WEB-INF/applicationContext.xml
  
  
  
        springmvc
        org.springframework.web.servlet.DispatcherServlet
          
        contextConfigLocation  
          
            /WEB-INF/springmvc-servlet.xml  
          
    	  
        1
    
    
        springmvc
        *.do
    
    
    
        CharacterEncodingFilter
        org.springframework.web.filter.CharacterEncodingFilter
        
            encoding
            UTF-8
        
        
            forceEncoding
            true
        
    
    
        CharacterEncodingFilter
        /*
    
  








	
	
		UserLoginFilter
		com.dh.filter.UserLoginFilter
	
	
		UserLoginFilter
		/privilege/*
	
	
	
	

	DelegatingFilterProxy

	org.springframework.web.filter.DelegatingFilterProxy
	
	
		targetBeanName
	
		AutoLoginFilter
	
	
	
	
		targetFilterLifecycle
	
		true
	
	

	
		
		DelegatingFilterProxy
		
		/*
		
	

  
  
  

applicationContext.xml



    
    
    
     
    
    
	
	    
	

	
	
	
	
	
	 
	
	
	
	
	
	  
	  
	
	
	


	
	
		
		
		
		
		
	
	
	
		
		
		
		
	
		
	
	
		
		
			
	
    
    

springmvc-servlet.xml



    
    
     
	
	 
	
	
	
	
	
	  
	  
	
    

 

AutoLoginFilter

package com.dh.filter;

import java.io.IOException;
import java.sql.SQLException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;
import org.springframework.web.context.support.XmlWebApplicationContext;
import org.springframework.web.filter.OncePerRequestFilter;

import com.dh.model.User;
import com.dh.service.UserService;

@WebFilter
public class AutoLoginFilter extends OncePerRequestFilter {

	@Autowired
	private UserService userService;

	@Override
	public void destroy() {
		
	}

	@Override
	protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain chain)
			throws ServletException, IOException {
		// TODO Auto-generated method stub
		//强转成HttpServletRequest
				HttpServletRequest req = (HttpServletRequest) request;

				User user = (User) req.getSession().getAttribute("user");
				
				if(user==null){
					String cookie_username = null;
					String cookie_password = null;
					
					//获取携带用户名和密码cookie
					Cookie[] cookies = req.getCookies();
					
					
					//测试用 查看cookie
					if(cookies!=null) {
					for(Cookie cookie:cookies){
							System.out.println(cookie.getName());
							System.out.println(cookie.getValue());
					}
					}
					
					
					if(cookies!=null){
						
						for(Cookie cookie:cookies){
							//获得想要的cookie
							if("cookie_username".equals(cookie.getName())){
								cookie_username = cookie.getValue();
							}
							if("cookie_password".equals(cookie.getName())){
								cookie_password = cookie.getValue();
							}
						}
						
					}
					
					if(cookie_username!=null&&cookie_password!=null){
						//去数据库校验该用户名和密码是否正确
						System.out.println(cookie_username+"-------"+cookie_password);
						
						user=userService.login(cookie_username, cookie_password);
						
						
						//完成自动登录 
						req.getSession().setAttribute("user", user);
						
					}
				}
				
				
				//放行
				chain.doFilter(req, response);
	}



}

这样配置后问题解决了,可以在filter中注入service了。

主要以后配置的时候要记得在Servlet Dispatcher中所初始化的Bean不能被以外的servlet或者filter使用了。这样就要分开配置,不能都写在一个配置文件里。

另外在servlet中使用Autowired报空指针可采用下面配置

    public void init(ServletConfig config) throws ServletException  
    {  
        SpringBeanAutowiringSupport.processInjectionBasedOnServletContext(this,      config.getServletContext());  
    } 

总结一下就是servlet和filter是不受spring容器管理的,毕竟spring有自己的一套东西。

最后,可以参考这篇文章,了解一下是怎么回事。

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