spring mvc利用MultipartResolver解析Multipart/form-data进行文件上传

2022-04-30 13:20:31

之前的表单数据都是文本数据，现记录：利用MultipartResolver进行文件上传。

①首先，需引入commons-fileUpload和commons-io jar包，pom.xml文件的坐标：

spring
mvc利用MultipartResolver解析Multipart/form-data进行文件上传

<properties>
      <spring.version>3.2.1.RELEASE</spring.version>
  </properties>
  <dependencies>
          <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-webmvc</artifactId>
                <version>${spring.version}</version>
            </dependency>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-web</artifactId>
                <version>${spring.version}</version>
            </dependency>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-context</artifactId>
                <version>${spring.version}</version>
            </dependency>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-core</artifactId>
                <version>${spring.version}</version>
            </dependency>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-beans</artifactId>
                <version>${spring.version}</version>
            </dependency>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-aop</artifactId>
                <version>${spring.version}</version>
            </dependency>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-tx</artifactId>
                <version>${spring.version}</version>
            </dependency>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-jdbc</artifactId>
                <version>${spring.version}</version>
            </dependency>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-test</artifactId>
                <version>${spring.version}</version>
            </dependency>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-context-support</artifactId>
                <version>${spring.version}</version>
            </dependency>

          <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.16</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.8.2</version>
        </dependency>
        <dependency>
                <groupId>org.apache.velocity</groupId>
                <artifactId>velocity</artifactId>
                <version>1.7</version>
            </dependency>
            <dependency>
                <groupId>org.apache.velocity</groupId>
                <artifactId>velocity-tools</artifactId>
                <version>2.0</version>
                <exclusions>
                    <exclusion>
                        <groupId>org.apache.struts</groupId>
                        <artifactId>struts-core</artifactId>
                    </exclusion>
                    <exclusion>
                        <groupId>org.apache.struts</groupId>
                        <artifactId>struts-taglib</artifactId>
                    </exclusion>
                    <exclusion>
                        <groupId>org.apache.struts</groupId>
                        <artifactId>struts-tiles</artifactId>
                    </exclusion>
                    <exclusion>
                        <groupId>sslext</groupId>
                        <artifactId>sslext</artifactId>
                    </exclusion>
                </exclusions>
            </dependency>

            <dependency>
                <groupId>servletapi</groupId>
                <artifactId>servlet-api</artifactId>
                <version>2.4</version>
                <optional>true</optional>
            </dependency>
            <dependency>
                <groupId>javax.servlet</groupId>
                <artifactId>jstl</artifactId>
                <version>1.2</version>
            </dependency>
            <dependency>
                <groupId>jspapi</groupId>
                <artifactId>jsp-api</artifactId>
                <version>2.0</version>
                <optional>true</optional>
            </dependency>

            
            <dependency>
                <groupId>org.hibernate</groupId>
                <artifactId>hibernate-validator</artifactId>
                <version>4.2.0.Final</version>
                
            </dependency>
            <dependency>
                <groupId>commons-fileupload</groupId>
                <artifactId>commons-fileupload</artifactId>
                <version>1.3.1</version>
            </dependency>
            <dependency>
                <groupId>commons-io</groupId>
                <artifactId>commons-io</artifactId>
                <version>2.2</version>
            </dependency>
  </dependencies>

View Code

② 修改表单页面：

<form method="post" enctype="multipart/form-data">
    <div>
        <label for="userName">userName:</label>
        <input name="userName" value="$!user.userName">
        <span>$!br.getFieldError("userName").getDefaultMessage()</span>
    </div>

    <div>
        <label for="email">Email:</label>
        <input name="email" value="$!user.email">
    </div>

    <div>
        <label for="age">age:</label>
        <input name="age" value="$!user.age">
    </div>

    <div>
        <label for="image">image:</label>
        <input type="file" name="image">
    </div>
    <button type="submit">Submit</button>
</form>

View Code

③ 处理multipart 表单的方法：

    //处理表单输入
    @RequestMapping(method=RequestMethod.POST)
    //@Valid是对user参数的验证
    public String addForm(@Valid User user,BindingResult br,@RequestParam(value="image",required=false)MultipartFile image,Model model){
        if(br.hasErrors()){
            model.addAttribute("br",br);
            return "/user/edit";
        }
        LOG.info("Image:"+image.getName()+"  Image Size:"+image.getSize());
//        saveImage();
        userService.saveUser(user);
        return "redirect:/home/"+user.getUserName();
    }

注意到输入参数增加了@RequestParam(value="image",required=false)MultipartFile image，这是将上传的图片文件赋给MultipartFile。但DispatcherServlet并不知道如何处理multipart的表单数据，需要一个multipart解析器将post请求的数据抽取处理，然后再将数据通过DispatcherServlet传递给Controller。

③ spring提供了一个Multipart解析器，需要在spring上下文中注册：

<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <property name="maxUploadSize" value="100000"></property>
    </bean>

这个bean的id是有讲究的，当DispatcherServlet查找multipart解析器时，会查找id为multipartResolver的Bean。若定义的bean id 不是multipartResolver，DispatcherServlet会对它进行忽略。

可以画成下图进行理解：

spring mvc利用MultipartResolver解析Multipart/form-data进行文件上传,布布扣,bubuko.com

spring mvc利用MultipartResolver解析Multipart/form-data进行文件上传

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