Java拦截器Interceptor和过滤器Filte的执行顺序和区别

目录

• 1、实现原理不同
• 2、使用范围不同
• 3、触发时机不同
• 4、拦截的请求范围不同
• 5、注入Bean情况不同
• 6、控制执行顺序不同

public interface FilterChain {
    void doFilter(ServletRequest var1, ServletResponse var2) throws IOException, ServletException;
}

public final class ApplicationFilterChain implements FilterChain {
    @Override
    public void doFilter(ServletRequest request, ServletResponse response) {
            ...//省略
            internalDoFilter(request,response);
    }
 
    private void internalDoFilter(ServletRequest request, ServletResponse response){
    if (pos < n) {
            //获取第pos个filter    
            ApplicationFilterConfig filterConfig = filters[pos++];        
            Filter filter = filterConfig.getFilter();
            ...
            filter.doFilter(request, response, this);
        }
    }
 
}

  @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
 
        filterChain.doFilter(servletRequest, servletResponse);
    }

@Controller
@RequestMapping()
public class Test {
 
    @RequestMapping("/test1")
    @ResponseBody
    public String test1(String a) {
        System.out.println("我是controller");
        return null;
    }
}

@Component
public class TestServiceImpl implements TestService {
 
    @Override
    public void a() {
        System.out.println("我是方法A");
    }
}

@Autowired
    private TestService testService;
 
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
 
        System.out.println("Filter 处理中");
        testService.a();
        filterChain.doFilter(servletRequest, servletResponse);
    }
Filter 处理中
我是方法A
Interceptor 前置
我是controller
Interceptor 处理中
Interceptor 后置

@Configuration
public class MyMvcConfig implements WebMvcConfigurer {
 
    @Bean
    public MyInterceptor getMyInterceptor(){
        System.out.println("注入了MyInterceptor");
        return new MyInterceptor();
    }
 
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
 
        registry.addInterceptor(getMyInterceptor()).addPathPatterns("/**");
    }
}

@Order(Ordered.HIGHEST_PRECEDENCE)
@Component
public class MyFilter2 implements Filter {

 @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new MyInterceptor2()).addPathPatterns("/**").order(2);
        registry.addInterceptor(new MyInterceptor1()).addPathPatterns("/**").order(1);
        registry.addInterceptor(new MyInterceptor()).addPathPatterns("/**").order(3);
    }

protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {
 
        try {
         ...........
            try {
 
                // 获取可以执行当前Handler的适配器
                HandlerAdapter ha = getHandlerAdapter(mappedHandler.getHandler());
 
                // Process last-modified header, if supported by the handler.
                String method = request.getMethod();
                boolean isGet = "GET".equals(method);
                if (isGet || "HEAD".equals(method)) {
                    long lastModified = ha.getLastModified(request, mappedHandler.getHandler());
                    if (logger.isDebugEnabled()) {
                        logger.debug("Last-Modified value for [" + getRequestUri(request) + "] is: " + lastModified);
                    }
                    if (new ServletWebRequest(request, response).checkNotModified(lastModified) && isGet) {
                        return;
                    }
                }
                // 注意： 执行Interceptor中PreHandle()方法
                if (!mappedHandler.applyPreHandle(processedRequest, response)) {
                    return;
                }
 
                // 注意：执行Handle【包括我们的业务逻辑，当抛出异常时会被Try、catch到】
                mv = ha.handle(processedRequest, response, mappedHandler.getHandler());
 
                if (asyncManager.isConcurrentHandlingStarted()) {
                    return;
                }
                applyDefaultViewName(processedRequest, mv);
 
                // 注意：执行Interceptor中PostHandle 方法【抛出异常时无法执行】
                mappedHandler.applyPostHandle(processedRequest, response, mv);
            }
        }
        ...........
    }

boolean applyPreHandle(HttpServletRequest request, HttpServletResponse response) throws Exception {
        HandlerInterceptor[] interceptors = this.getInterceptors();
        if(!ObjectUtils.isEmpty(interceptors)) {
            for(int i = 0; i < interceptors.length; this.interceptorIndex = i++) {
                HandlerInterceptor interceptor = interceptors[i];
                if(!interceptor.preHandle(request, response, this.handler)) {
                    this.triggerAfterCompletion(request, response, (Exception)null);
                    return false;
                }
            }
        }
 
        return true;
    }
void applyPostHandle(HttpServletRequest request, HttpServletResponse response, @Nullable ModelAndView mv) throws Exception {
        HandlerInterceptor[] interceptors = this.getInterceptors();
        if(!ObjectUtils.isEmpty(interceptors)) {
            for(int i = interceptors.length - 1; i >= 0; --i) {
                HandlerInterceptor interceptor = interceptors[i];
                interceptor.postHandle(request, response, this.handler, mv);
            }
        }
    }