SpringMVC文件上传和自定义异常处理解析器

淡淡的烟草味﹌ 2022-12-16 14:26 135阅读 0赞

# SpringMVC文件上传和自定义异常处理解析器 #

### SpringMVC文件上传基于commons-fileupload组件，所以我们要到如commons-fileupload相关的包 ###

<dependency>
        <groupId>commons-fileupload</groupId>
        <artifactId>commons-fileupload</artifactId>
        <version>1.4</version>
    </dependency>
    
    <dependency>
        <groupId>commons-io</groupId>
        <artifactId>commons-io</artifactId>
        <version>2.6</version>
    </dependency>

1.  ## 实现简单文件上传 ##
    
    1.  在SpringMVC中配置CommonsMultipartResolver
        
         *      <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
                </bean>
    2.  编写jsp页面
        
         *      <%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
                <html>
                <head>
                    <title>文件上传</title>
                </head>
                <body>
                <form action="${pageContext.request.contextPath}/file/upload" method="post" enctype="multipart/form-data">
                    文件：<input type="file" name="file" /><br />
                    <input type="submit" value="上传" />
                </form>
                </body>
                </html>
    3.  编写Controller代码
        
         *      package com.fxyh.springmvc.web.controller;
                
                import org.springframework.stereotype.Controller;
                import org.springframework.web.bind.annotation.GetMapping;
                import org.springframework.web.bind.annotation.PostMapping;
                import org.springframework.web.bind.annotation.RequestMapping;
                import org.springframework.web.bind.annotation.ResponseBody;
                import org.springframework.web.multipart.MultipartFile;
                
                import javax.servlet.http.HttpServletRequest;
                import javax.servlet.http.HttpSession;
                import java.io.File;
                import java.io.IOException;
                
                @Controller
                @RequestMapping("/file")
                public class FileController {
                          
                
                    @GetMapping("/upload")
                    public String upload() {
                          
                        return "file/upload";
                    }
                
                    @PostMapping("/upload")
                    public Object upload(MultipartFile file, HttpServletRequest request) {
                          
                        HttpSession session = request.getSession();
                        String uploadPath = session.getServletContext().getRealPath("/files");
                        File uploadFile = new File(uploadPath);
                        if (!uploadFile.exists()) {
                          
                            uploadFile.mkdirs();
                        }
                        String filename = file.getOriginalFilename();
                        try {
                          
                            file.transferTo(new File(uploadFile, filename));
                            request.setAttribute("msg", filename + "上传成功");
                        } catch (IOException e) {
                          
                            e.printStackTrace();
                            request.setAttribute("msg", filename + "上传失败");
                
                        }
                        return "file/success";
                    }
                }
    4.  这里就实现了一个简单的单个文件上传，这个文件会上传到webapp目录下的files文件夹中。
2.  ## 问题 ##
    
    1.  ### 文件名为中文时乱码问题 ###
        
        1.  在CommonsMultipartResolver中配置defaultEncoding属性
            
             *      <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
                       <property name="defaultEncoding" value="UTF-8"/>
                    </bean>
        2.  在web.xml中配置过滤器
            
             *      <filter>
                     <filter-name>characterEncodingFilter</filter-name>
                     <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
                     <init-param>
                       <param-name>encoding</param-name>
                       <param-value>UTF-8</param-value>
                     </init-param>
                    </filter>
                    
                    <filter-mapping>
                     <filter-name>characterEncodingFilter</filter-name>
                     <url-pattern>/*</url-pattern>
                    </filter-mapping>
    2.  ### 多文件上传怎么处理 ###
        
         *  在原来单个的基础上改了一些
            
             *      多文件上传
                    <form action="${pageContext.request.contextPath}/file/uploads" method="post" enctype="multipart/form-data">
                      文件1：<input type="file" name="file" /><br />
                      文件2：<input type="file" name="file" /><br />
                      文件3：<input type="file" name="file" /><br />
                      <input type="submit" value="上传" />
                    </form>
             *      @PostMapping("/uploads")
                    public Object uploads(MultipartFile[] file, HttpServletRequest request) {
                                
                      HttpSession session = request.getSession();
                      String uploadPath = session.getServletContext().getRealPath("/files");
                      File uploadFile = new File(uploadPath);
                      if (!uploadFile.exists()) {
                                
                          uploadFile.mkdirs();
                      }
                      StringBuffer sb = new StringBuffer();
                      for (MultipartFile multipartFile : file) {
                                
                          String filename = multipartFile.getOriginalFilename();
                          try {
                                
                              multipartFile.transferTo(new File(uploadFile, filename));
                              sb.append(filename).append("上传成功,");
                          } catch (IOException e) {
                                
                              e.printStackTrace();
                              sb.append(filename).append("上传失败,");
                          }
                      }
                      request.setAttribute("msg", sb.toString());
                      return "file/success";
                    }
         *  多文件上传时在Controller中使用数组进行接收，然后循环这个数组进行上传。
    3.  ### 文件名冲突怎么办 ###
        
         *  文件上传一般会进行重命名，使用UUID进行重命名
    4.  ### 文件大小怎么控制 ###
        
         *      spring.upload.max_size_per_file=2097152
                spring.upload.max_size_total=10485760
                spring.upload.allow_upload_file_type=png,jpg
         *  在springmvc中引入这个properties文件
            
             *      
                    <bean id="placeholderConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
                      <property name="locations">
                          <array>
                              <value>classpath*:upload.properties</value>
                          </array>
                      </property>
                    </bean>
             *  这两种方法都可以使用
         *      @Value("${spring.upload.max_size_per_file}")
                private Long maxUploadPerFile;
                
                @Value("${spring.upload.max_size_total}")
                private Long maxSizeTotal;
                @PostMapping("/uploads")
                public Object uploads(MultipartFile[] file, HttpServletRequest request) {
                          
                  HttpSession session = request.getSession();
                  String uploadPath = session.getServletContext().getRealPath("/files");
                  File uploadFile = new File(uploadPath);
                  if (!uploadFile.exists()) {
                          
                    uploadFile.mkdirs();
                  }
                  StringBuffer sb = new StringBuffer();
                  for (MultipartFile multipartFile : file) {
                          
                    String filename = multipartFile.getOriginalFilename();
                    String extension = FilenameUtils.getExtension(filename);
                    if (allowUploadFileType.indexOf(extension) < 0){
                          
                      throw new CustomException("上传文件的类型不允许，只能上传" + allowUploadFileType + "文件");
                    }
                    long size = multipartFile.getSize();
                    if (size > maxUploadPerFile) {
                          
                      throw new CustomException("文件大小超过了" + maxUploadPerFile / 1024 / 1024 + "MB");
                    }
                    try {
                          
                      multipartFile.transferTo(new File(uploadFile, filename));
                      sb.append(filename).append("上传成功,");
                    } catch (IOException e) {
                          
                      e.printStackTrace();
                      sb.append(filename).append("上传失败,");
                    }
                  }
                  request.setAttribute("msg", sb.toString());
                  return "file/success";
                }
    5.  ### 文件类型怎么过滤 ###
        
         *  例子见文件大小过滤
    6.  ### 上传目录怎么打散 ###
        
         *  例如根据时间来打散，每天的一个目录或者一天一个目录，然后目录里在分小时，时里面再分分钟
3.  ## 自定义异常处理解析器 ##
    
     *  定义异常
        
         *      package com.fxyh.springmvc.common;
                
                public class CustomException extends RuntimeException {
                          
                   private static final long serialVersionUID = 4902874743631868805L;
                
                   private String message;
                
                   public CustomException() {
                          
                   }
                
                   public CustomException(String message) {
                          
                       super(message);
                       this.message = message;
                   }
                }
     *  定义解析器
        
         *      package com.fxyh.springmvc.common;
                
                import org.springframework.web.servlet.HandlerExceptionResolver;
                import org.springframework.web.servlet.ModelAndView;
                
                import javax.servlet.http.HttpServletRequest;
                import javax.servlet.http.HttpServletResponse;
                
                public class CustomHandlerExceptionResolver implements HandlerExceptionResolver {
                          
                
                   @Override
                   public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) {
                          
                       ModelAndView modelAndView = new ModelAndView();
                       if (ex != null) {
                          
                           if (ex instanceof CustomException) {
                          
                               CustomException customException = (CustomException) ex;
                               String message = customException.getMessage();
                               modelAndView.addObject("error", message);
                               modelAndView.setViewName("common/error");
                           }
                       }
                       return modelAndView;
                   }
                
                }
     *  把这个解析器注册成一个组件
        
         *  在类上使用@Component注解，或者把这个配置在xml中
            
             *      <bean id="customHandlerExceptionResolver" class="com.fxyh.springmvc.common.CustomHandlerExceptionResolver"/>