【SpringMVC】007-SpringMVC文件上传

落日映苍穹つ 2023-10-05 08:06 28阅读 0赞

# 一、文件上传原理 #

## 1、文件上传的必要前提 ##

①form表单的enctype取值必须是：multipart/form-data；

默认值为application/x-www-form-urlencoded，enctype是表单请求正文的类型

②method属性的取值必须是Post；

③提供一个文件选择域<input type="file"/>

## 2、原理分析 ##

默认application/x-www-form-urlencoded上传的数据全部是键值对的形式，使用multipart/form-data会将表单分开为几个部分；

# 二、传统方式的文件上传 #

## HelloController类： ##

package com.zibo.controller;
    
    import org.apache.commons.fileupload.FileItem;
    import org.apache.commons.fileupload.disk.DiskFileItemFactory;
    import org.apache.commons.fileupload.servlet.ServletFileUpload;
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    
    import javax.servlet.http.HttpServletRequest;
    import java.io.File;
    import java.util.List;
    
    //控制器
    @Controller
    public class HelloController {
        //设置路径为"/hello"
        @RequestMapping(value = "/hello")
        public String sayHello(HttpServletRequest request) throws Exception {
            //使用fileupload组件来完成文件上传
            //指定文件上传的位置
            String path = request.getSession().getServletContext().getRealPath("/uploads");
            //判断该路径是否存在，若不存在创建该路径
            File file = new File(path);
            System.out.println(path);
            if(!file.exists()){
                boolean mkdirs = file.mkdirs();
                if (mkdirs){
                    //解析request对象，获取文件
                    DiskFileItemFactory factory = new DiskFileItemFactory();
                    ServletFileUpload upload = new ServletFileUpload(factory);
                    //解析request
                    List<FileItem> items = upload.parseRequest(request);
                    //遍历
                    for (FileItem item : items) {
                        //判断当前item对象是否是一个上传文件项
                        if(!item.isFormField()){
                            //是上传文件项
                            //获取到上传文件的名称
                            String itemName = item.getName();
                            //完成文件上传
                            item.write(new File(path,itemName));
                            //删除临时文件
                            item.delete();
                        }
                    }
                }
            }
            //控制台打印"Hello Spring MVC!"
            System.out.println("Hello Spring MVC!");
            return "success";
        }
    }

## index.jsp页面： ##

<%--
      Created by IntelliJ IDEA.
      User: ZiBo
      Date: 2020/8/9
      Time: 14:52
      To change this template use File | Settings | File Templates.
    --%>
    <%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
    <html>
    <head>
        <title>Title</title>
    </head>
    <body>
        <h3>入门程序！</h3>
        <h3>文件上传！</h3>
        <form action="hello" method="post" enctype="multipart/form-data">
            选择文件：<input type="file" name="upload"/><br/>
            提交表单：<input type="submit" value="提交表单"/><br/>
        </form>
    </body>
    </html>

## pom.xml： ##

<?xml version="1.0" encoding="UTF-8"?>
    
    <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
      <modelVersion>4.0.0</modelVersion>
    
      <groupId>org.example</groupId>
      <artifactId>SpringMVC01</artifactId>
      <version>1.0-SNAPSHOT</version>
      <packaging>war</packaging>
    
      <name>SpringMVC01 Maven Webapp</name>
      
      <url>http://www.example.com</url>
    
      <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <spring.version>5.2.8.RELEASE</spring.version>
      </properties>
    
      <dependencies>
        <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-context</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-webmvc</artifactId>
          <version>${spring.version}</version>
        </dependency>
        <dependency>
          <groupId>javax.servlet</groupId>
          <artifactId>javax.servlet-api</artifactId>
          <version>4.0.1</version>
          <scope>provided</scope>
        </dependency>
        <dependency>
          <groupId>javax.servlet.jsp</groupId>
          <artifactId>jsp-api</artifactId>
          <version>2.2</version>
          <scope>provided</scope>
        </dependency>
        
        <dependency>
          <groupId>com.fasterxml.jackson.core</groupId>
          <artifactId>jackson-databind</artifactId>
          <version>2.11.2</version>
        </dependency>
        
        <dependency>
          <groupId>com.fasterxml.jackson.core</groupId>
          <artifactId>jackson-core</artifactId>
          <version>2.11.2</version>
        </dependency>
        
        <dependency>
          <groupId>com.fasterxml.jackson.core</groupId>
          <artifactId>jackson-annotations</artifactId>
          <version>2.11.2</version>
        </dependency>
        
        <dependency>
          <groupId>commons-fileupload</groupId>
          <artifactId>commons-fileupload</artifactId>
          <version>1.4</version>
        </dependency>
        
        <dependency>
          <groupId>commons-io</groupId>
          <artifactId>commons-io</artifactId>
          <version>2.7</version>
        </dependency>
      </dependencies>
    
      <build>
        <finalName>SpringMVC01</finalName>
        <pluginManagement>
          <plugins>
            <plugin>
              <artifactId>maven-clean-plugin</artifactId>
              <version>3.1.0</version>
            </plugin>
            
            <plugin>
              <artifactId>maven-resources-plugin</artifactId>
              <version>3.0.2</version>
            </plugin>
            <plugin>
              <artifactId>maven-compiler-plugin</artifactId>
              <version>3.8.0</version>
            </plugin>
            <plugin>
              <artifactId>maven-surefire-plugin</artifactId>
              <version>2.22.1</version>
            </plugin>
            <plugin>
              <artifactId>maven-war-plugin</artifactId>
              <version>3.2.2</version>
            </plugin>
            <plugin>
              <artifactId>maven-install-plugin</artifactId>
              <version>2.5.2</version>
            </plugin>
            <plugin>
              <artifactId>maven-deploy-plugin</artifactId>
              <version>2.8.2</version>
            </plugin>
          </plugins>
        </pluginManagement>
      </build>
    </project>

## 运行结果（成功上传）： ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz_size_16_color_FFFFFF_t_70][]

# 三、SpringMVC框架文件上传原理分析 #

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz_size_16_color_FFFFFF_t_70 1][]

### 备注： ###

**文件解析器代码如下：**

<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
            <property name="maxUploadSize" value="10495760"/>
        </bean>

# 四、SpringMVC方式的文件上传 #

## HelloController类： ##

package com.zibo.controller;
    
    import org.apache.commons.fileupload.FileItem;
    import org.apache.commons.fileupload.disk.DiskFileItemFactory;
    import org.apache.commons.fileupload.servlet.ServletFileUpload;
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.multipart.MultipartFile;
    
    import javax.servlet.http.HttpServletRequest;
    import java.io.File;
    import java.util.List;
    
    //控制器
    @Controller
    public class HelloController {
        //设置路径为"/hello"
        @RequestMapping(value = "/hello")
        public String sayHello(HttpServletRequest request, MultipartFile upload) throws Exception {
            //使用fileupload组件来完成文件上传
            //指定文件上传的位置
            String path = request.getSession().getServletContext().getRealPath("/uploads");
            //判断该路径是否存在，若不存在创建该路径
            File file = new File(path);
            System.out.println(path);
            if(!file.exists()){
                boolean mkdirs = file.mkdirs();
                if (mkdirs){
                    //获取到上传文件的名称
                    String filename = upload.getOriginalFilename();
                    //完成文件上传
                    assert filename != null;
                    upload.transferTo(new File(path,filename));
                }
            }
            //控制台打印"Hello Spring MVC!"
            System.out.println("Hello Spring MVC!");
            return "success";
        }
    }

## spring-mvc.xml： ##

<?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
           xmlns:mvc="http://www.springframework.org/schema/mvc"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xmlns:context="http://www.springframework.org/schema/context"
           xsi:schemaLocation="
            http://www.springframework.org/schema/beans
            http://www.springframework.org/schema/beans/spring-beans.xsd
            http://www.springframework.org/schema/mvc
            http://www.springframework.org/schema/mvc/spring-mvc.xsd
            http://www.springframework.org/schema/context
            http://www.springframework.org/schema/context/spring-context.xsd">
        
        <context:component-scan base-package="com.zibo.controller"/>
        
        
        <bean id="internalResourceViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
            <property name="prefix" value="/WEB-INF/pages/"/>
            <property name="suffix" value=".jsp"/>
        </bean>
        
        <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
            <property name="maxUploadSize" value="10495760"/>
        </bean>
        
        <mvc:resources mapping="/js/**" location="/js/"/>
        
        <mvc:annotation-driven/>
    </beans>

## 运行结果（上传成功）： ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz_size_16_color_FFFFFF_t_70 2][]

# 五、跨服务器文件上传（略） #

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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20200811122008955.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz_size_16_color_FFFFFF_t_70 2]: https://img-blog.csdnimg.cn/20200811123549940.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI5Njg5MzQz,size_16,color_FFFFFF,t_70