过滤器与拦截器(二)---简单实现

springboot下的Filter过滤器；Spring的GenericFilterBean过滤器；springmvc的HandlerInterceptorAdapter拦截器；

Filter

Filter要使请求继续被处理，就一定要显示调用filterChain.doFilter()

自定义Filter，@WebFilter形式
@WebFilter形式控制不了多个过滤器之间的执行顺序,默认是按照class名字首字母的ASCII的字母排序.
并且需要在启动类上加上@ServletComponentScan扫描过滤器


package com.fchan.espractice.filter;

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;

@WebFilter(filterName = "tokenFilter", urlPatterns = "/testMybatisTrsanctional/*")
public class TokenFilter implements Filter, ApplicationContextAware {

private ApplicationContext applicationContext;
    @Autowired
    private ObjectMapper objectMapper;

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest)servletRequest;
        String token = request.getHeader("token");
        if(!StringUtils.isEmpty(token)){
            filterChain.doFilter(servletRequest, servletResponse);
        }
    
        HttpServletResponse response = (HttpServletResponse) servletResponse;
        response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
        response.setContentType(MediaType.APPLICATION_JSON_UTF8_VALUE);
        Map<String,Object> map = new HashMap<>();
        map.put("name","李四");
        ServletOutputStream outputStream = response.getOutputStream();
        outputStream.write(objectMapper.writeValueAsBytes(map));
        outputStream.close();
    
    }
    
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }
}

启动类加上扫描注解

package com.fchan.espractice;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;
import org.springframework.context.annotation.Bean;
import org.springframework.transaction.PlatformTransactionManager;

@SpringBootApplication
@MapperScan("com.fchan.espractice.dao")
//ServletComponentScan扫描自定义Filter，可以指定包路径
@ServletComponentScan
public class EsPracticeApplication {

    @Bean
    public Object testBean(PlatformTransactionManager platformTransactionManager){
        System.out.println(">>>>>>>>>>" + platformTransactionManager.getClass().getName());
        return new Object();
    }
    
    public static void main(String[] args) {
        SpringApplication.run(EsPracticeApplication.class, args);
    }

}

过滤器方式2，自定义执行顺序
自定义的2个过滤器

package com.fchan.espractice.filter;

import lombok.extern.slf4j.Slf4j;

import javax.servlet.*;
import java.io.IOException;


@Slf4j
public class TestFilter implements Filter {


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

package com.fchan.espractice.filter;

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.util.StringUtils;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;


public class TokenFilter implements Filter, ApplicationContextAware {

    private ApplicationContext applicationContext;
    @Autowired
    private ObjectMapper objectMapper;
    
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest)servletRequest;
        String token = request.getHeader("token");
        if(!StringUtils.isEmpty(token)){
            filterChain.doFilter(servletRequest, servletResponse);
        }
    
        HttpServletResponse response = (HttpServletResponse) servletResponse;
        response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
        response.setContentType(MediaType.APPLICATION_JSON_UTF8_VALUE);
        Map<String,Object> map = new HashMap<>();
        map.put("name","李四");
        ServletOutputStream outputStream = response.getOutputStream();
        outputStream.write(objectMapper.writeValueAsBytes(map));
        outputStream.close();
    
    }
    
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }
}

配置2个过滤器

多个过滤器之间order数值小的执行顺序优先

package com.fchan.espractice.filter.config;

import com.fchan.espractice.filter.TestFilter;
import com.fchan.espractice.filter.TokenFilter;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class MyFilterConfig {

    @Bean
    public TestFilter testFilter(){
        return new TestFilter();
    }


    @Bean
    public TokenFilter tokenFilter(){
        return new TokenFilter();
    }


    @Bean
    public FilterRegistrationBean<TestFilter> TestFilterFilterRegistrationBean(@Autowired TestFilter testFilter){
        FilterRegistrationBean<TestFilter> filterRegistrationBean = new FilterRegistrationBean<>();
        filterRegistrationBean.setFilter(testFilter);
        filterRegistrationBean.addUrlPatterns("/*");
        //order数值小的顺序优先
        filterRegistrationBean.setOrder(2);
        return filterRegistrationBean;
    }


    @Bean
    public FilterRegistrationBean<TokenFilter> TokenFilterFilterRegistrationBean(@Autowired TokenFilter tokenFilter){
        FilterRegistrationBean<TokenFilter> filterRegistrationBean = new FilterRegistrationBean<>();
        filterRegistrationBean.setFilter(tokenFilter);
        filterRegistrationBean.addUrlPatterns("/*");
        filterRegistrationBean.setOrder(3);
        return filterRegistrationBean;
    }
}

Spring的GenericFilterBean过滤器
org.springframework.web.filter.GenericFilterBean是spring对Servelet的Filter的实现，我们继承GenericFilterBean后可以将Servelet的Filter纳入spring的容器中作为bean;

@Order(-999)数值越小执行优先级越高

自定义的过滤器

package com.fchan.espractice.filter;

import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.annotation.Order;
import org.springframework.http.MediaType;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;
import org.springframework.web.filter.GenericFilterBean;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

@Component
@Order(-999)
public class MySpringFilter extends GenericFilterBean {

    @Autowired
    private ObjectMapper objectMapper;


    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest)servletRequest;
        String token = request.getHeader("token");
        if(!StringUtils.isEmpty(token)){
            filterChain.doFilter(servletRequest, servletResponse);
        }
    
        HttpServletResponse response = (HttpServletResponse) servletResponse;
        response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
        response.setContentType(MediaType.APPLICATION_JSON_UTF8_VALUE);
        Map<String,Object> map = new HashMap<>();
        map.put("name","李四");
        ServletOutputStream outputStream = response.getOutputStream();
        outputStream.write(objectMapper.writeValueAsBytes(map));
        outputStream.close();
    }
}

Springmvc的HandlerInterceptorAdapter拦截器
在HandlerInterceptorAdapter中主要提供了以下的方法：

preHandle：在方法被调用前执行。在该方法中可以做类似校验的功能。如果返回true，则继续调用下一个拦截器。如果返回false，则中断执行，也就是说我们想调用的方法不会被执行，但是你可以修改response为你想要的响应。
postHandle：在方法执行后调用。
afterCompletion：在整个请求处理完毕后进行回调，也就是说视图渲染完毕或者调用方已经拿到响应。
自定义拦截器

package com.fchan.espractice.intercept;

import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.MediaType;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.HashMap;
import java.util.Map;

@Component
public class GlobalIntercept extends HandlerInterceptorAdapter {

    @Autowired
    private ObjectMapper objectMapper;


    public GlobalIntercept() {
        super();
    }
    
    /**
     * false拦截
     * true放行
     * @param request
     * @param response
     * @param handler
     * @return
     * @throws Exception
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        String token = request.getHeader("token");
        if(!StringUtils.isEmpty(token)){
            return true;
        }
    
        response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
        response.setContentType(MediaType.APPLICATION_JSON_UTF8_VALUE);
        Map<String,Object> map = new HashMap();
        map.put("name","张三");
        ServletOutputStream outputStream = response.getOutputStream();
        outputStream.write(objectMapper.writeValueAsBytes(map));
        outputStream.close();


        return false;
    }

}

配置拦截器,及顺序说明
多个拦截器的话按照
registry.addInterceptor
的添加顺序来执行

package com.fchan.espractice.intercept.config;

import com.fchan.espractice.intercept.GlobalIntercept;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class InterceptConfig implements WebMvcConfigurer, ApplicationContextAware {

    private ApplicationContext applicationContext;


    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(applicationContext.getBean(GlobalIntercept.class));
    }
    
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }
}