124.【SpringBoot 源码刨析C】（四）

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<div th:replace="~{}"></div>

1.Filter: 是Servlet定义的原生组件。好处:脱离Spring也能够使用
2.Interceptor: 是Spring定义的接口。可以使用Spring的自动装配功能

package com.jsxs.servlet;
import lombok.extern.slf4j.Slf4j;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;
/**
 * @Author Jsxs
 * @Date 2023/7/8 17:58
 * @PackageName:com.jsxs.servlet
 * @ClassName: MyFilter
 * @Description: TODO   配置过滤器
 * @Version 1.0
 */
@Slf4j
//@WebFilter(urlPatterns = {"/css/*","/imag/*"})   //设置拦截我们CSS和imag的所有文件
public class MyFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
       log.info("MyFilter初始化完成.....");
    }
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        log.info("MyFilter工作中.....");
        chain.doFilter(request,response);
    }
    @Override
    public void destroy() {
        log.info("MyFilter初始化销毁.....");
    }
}

package com.jsxs.config;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class LoginHandlerInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
//        登入成功之后存在登入后的session
        if (request.getSession().getAttribute("LoginUser")!=null){
            return true;
        }else {
            request.setAttribute("msg","没有权限请先进行登入");
            request.getRequestDispatcher("/index.html").forward(request,response);
            return false;
        }
    }
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);
    }
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        HandlerInterceptor.super.afterCompletion(request, response, handler, ex);
    }
}

/**
 * 1、编写一个拦截器实现HandlerInterceptor接口
 * 2、拦截器注册到容器中（实现WebMvcConfigurer的addInterceptors）
 * 3、指定拦截规则【如果是拦截所有，静态资源也会被拦截】
 */
@Configuration
public class AdminWebConfig implements WebMvcConfigurer {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new LoginInterceptor())
                .addPathPatterns("/**")  //所有请求都被拦截包括静态资源
                .excludePathPatterns("/","/login","/css/**","/fonts/**","/images/**","/js/**"); //放行的请求
    }
}

1. 需要指定 enctype
2. 单个文件上传 什么也不加
3. 多个文件上传 需要加上: multiple 属性
<form method="post" action="/upload" enctype="multipart/form-data">
 单文件   <input type="file" name="file"><br>
多文件    <input type="file" name="file" multiple><br>
    <input type="submit" value="提交">
</form>

1.一定要加上参数注解 @RequestPart
    /**
     * MultipartFile 自动封装上传过来的文件,以后文件上传用这个类型和注解
     * @param email
     * @param username
     * @param headerImg
     * @param photos
     * @return
     */
    @PostMapping("/upload")
    public String upload(@RequestParam("email") String email,
                         @RequestParam("username") String username,
                         @RequestPart("headerImg") MultipartFile headerImg,
                         @RequestPart("photos") MultipartFile[] photos) throws IOException {
        log.info("上传的信息：email={}，username={}，headerImg={}，photos={}",
                email,username,headerImg.getSize(),photos.length);
        if(!headerImg.isEmpty()){
            //保存到文件服务器，OSS服务器
            String originalFilename = headerImg.getOriginalFilename();  //获取上传的文件名
            headerImg.transferTo(new File("H:\\cache\\"+originalFilename)); //这个方法直接传输了,内部封装了InputStrean和OutStream流(需要指定路径+文件名即可)
        }
        if(photos.length > 0){
            for (MultipartFile photo : photos) {
                if(!photo.isEmpty()){
                    String originalFilename = photo.getOriginalFilename();
                    photo.transferTo(new File("H:\\cache\\"+originalFilename)); //遍历传输各个文件
                }
            }
        }
        return "main";
    }

MultipartAutoConfiguration 类
MultipartProperties 类

在自定义的4xx页面或者5xx页面的某个提示标签中可以这么写
th:text="${status}"  ->在配置的错误页面中会获得返回的状态码
th:text="${message}"  ->在配置的错误页面中会获得返回的信息