SpringMVC实现文件上传下载的全过程

前言

文件的上传和下载都是基于io复制,只不过

文件上传是浏览器向服务器发送报文

文件下载是服务器向浏览器发送报文

提示：以下是本篇文章正文内容，下面案例可供参考

一、通用配置

pom.xml

    <dependencies>
        <!-- springmvc -->
        <dependency>
            <groupid>org.springframework</groupid>
            <artifactid>spring-webmvc</artifactid>
            <version>5.3.13</version>
        </dependency>

        <!-- 日志 -->
        <dependency>
            <groupid>ch.qos.logback</groupid>
            <artifactid>logback-classic</artifactid>
            <version>1.2.3</version>
        </dependency>

        <!-- servletapi -->
        <dependency>
            <groupid>javax.servlet</groupid>
            <artifactid>javax.servlet-api</artifactid>
            <version>4.0.1</version>
            <scope>provided</scope>
        </dependency>

        <!-- spring5和thymeleaf整合包 -->
        <dependency>
            <groupid>org.thymeleaf</groupid>
            <artifactid>thymeleaf-spring5</artifactid>
            <version>3.0.12.release</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/commons-fileupload/commons-fileupload -->
        <dependency>
            <groupid>commons-fileupload</groupid>
            <artifactid>commons-fileupload</artifactid>
            <version>1.3.1</version>
        </dependency>
<!--        springmvc end-->

        <!--    导入spring坐标-->
        <dependency>
            <groupid>org.springframework</groupid>
            <artifactid>spring-context</artifactid>
            <version>5.3.11</version>
        </dependency>
<!--        导入测试坐标-->
        <dependency>
            <groupid>junit</groupid>
            <artifactid>junit</artifactid>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
        <!--    测试坐标-->
<!--        导入集成测试坐标-->
        <dependency>
            <groupid>org.springframework</groupid>
            <artifactid>spring-test</artifactid>
            <version>5.3.13</version>
        </dependency>
        <!--        集成测试坐标end-->
        <!--        导入mysql坐标-->
        <dependency>
            <groupid>mysql</groupid>
            <artifactid>mysql-connector-java</artifactid>
            <version>8.0.24</version>
        </dependency>
        <!--        mysql坐标end-->
        <!--        导入druid连接池-->
        <dependency>
            <groupid>com.alibaba</groupid>
            <artifactid>druid</artifactid>
            <version>1.2.8</version>
        </dependency>
        <!--        导入druid连接池end-->
        <!--        导入spring上下文-->
        <dependency>
            <groupid>org.springframework</groupid>
            <artifactid>spring-context</artifactid>
            <version>5.3.11</version>
        </dependency>
        <!--        导入spring上下文end-->
<!--        导入spring web开发api start-->
        <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>javax.servlet.jsp-api</artifactid>
            <version>2.3.3</version>
        </dependency>
        <!--        导入spring web开发end-->
<!--        导入jackson的依赖-->
        <dependency>
            <groupid>com.fasterxml.jackson.core</groupid>
            <artifactid>jackson-databind</artifactid>
            <version>2.12.1</version>
        </dependency>
        <!--上传功能的关键jar -->
        <!-- https://mvnrepository.com/artifact/commons-fileupload/commons-fileupload -->
        <dependency>
            <groupid>commons-fileupload</groupid>
            <artifactid>commons-fileupload</artifactid>
            <version>1.3.1</version>
        </dependency>
    </dependencies>

上传功能的关键jar

web.xml

<?xml version="1.0" encoding="utf-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/xmlschema-instance"
         xsi:schemalocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">
    <!--配置springmvc的编码过滤器-->
    <!--    springmvc中处理编码的过滤器一定要配置到其他过滤器之前，否则无效-->
    <!-- 字符集过滤器 -->
    <filter>
        <description>字符集过滤器</description>
        <filter-name>characterencodingfilter</filter-name>
        <filter-class>org.springframework.web.filter.characterencodingfilter</filter-class>
        <init-param>
            <description>字符集编码</description>
            <param-name>encoding</param-name>
            <param-value>utf-8</param-value>
        </init-param>
        <init-param>
            <param-name>forceencoding</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>

    <!-- 字符集拦截 -->
    <filter-mapping>
        <filter-name>characterencodingfilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>


    <filter>
        <filter-name>hiddenhttpmethodfilter</filter-name>
        <filter-class>org.springframework.web.filter.hiddenhttpmethodfilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>hiddenhttpmethodfilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    <!--    注册前端控制器dispatcherservlet-->
    <servlet>
        <servlet-name>dispatcherservlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.dispatcherservlet</servlet-class>
        <init-param>
            <param-name>contextconfiglocation</param-name>
            <param-value>classpath:springmvc.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>dispatcherservlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

springmvc.xml

<?xml version="1.0" encoding="utf-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/xmlschema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemalocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <!--    扫描组件-->
    <context:component-scan base-package="com.vector"/>

    <!-- 配置thymeleaf视图解析器 -->
    <bean id="viewresolver" class="org.thymeleaf.spring5.view.thymeleafviewresolver">
        <property name="order" value="1"/>
        <property name="characterencoding" value="utf-8"/>
        <property name="templateengine">

            <bean class="org.thymeleaf.spring5.springtemplateengine">
                <property name="templateresolver">
                    <bean class="org.thymeleaf.spring5.templateresolver.springresourcetemplateresolver">

                        <!-- 视图前缀 -->
                        <property name="prefix" value="/web-inf/templates/"/>

                        <!-- 视图后缀 -->
                        <property name="suffix" value=".html"/>
                        <property name="templatemode" value="html5"/>
                        <property name="characterencoding" value="utf-8" />
                    </bean>
                </property>
            </bean>
        </property>
    </bean>

    <!-- 处理响应中文内容乱码 -->
    <bean class="org.springframework.http.converter.stringhttpmessageconverter">
        <property name="defaultcharset" value="utf-8" />
        <property name="supportedmediatypes">
            <list>
                <value>text/html</value>
                <value>application/json</value>
            </list>
        </property>
    </bean>

    <mvc:view-controller path="/" view-name="index"/>
    <mvc:view-controller path="/file" view-name="file"/>
    <mvc:default-servlet-handler/>
    <mvc:annotation-driven/>

    <!--必须通过文件解析器的解析才能将文件转换为multipartfile对象-->
    <bean id="multipartresolver" class="org.springframework.web.multipart.commons.commonsmultipartresolver"></bean>
</beans>

实现页面跳转,vue文件解析,上传内容解析的关键

file.html内容demo

<body>
<a th:href="@{/testdown}" rel="external nofollow" >下载1.jpg</a>
<form th:action="@{/testup}" method="post" enctype="multipart/form-data">
    头像: <input type="file" name="photo"><br>
    <input type="submit" value="上传">
</form>
</body>

二、实现文件下载,上传功能

package com.vector.controller;

import org.springframework.beans.factory.annotation.value;
import org.springframework.http.httpheaders;
import org.springframework.http.httpstatus;
import org.springframework.http.responseentity;
import org.springframework.stereotype.controller;
import org.springframework.util.multivaluemap;
import org.springframework.web.bind.annotation.requestmapping;
import org.springframework.web.multipart.multipartfile;

import javax.annotation.resource;
import javax.servlet.servletcontext;
import javax.servlet.http.httpsession;
import java.io.file;
import java.io.fileinputstream;
import java.io.ioexception;
import java.io.inputstream;
import java.util.uuid;

@controller
public class fileupanddowncontroller {

    @requestmapping("/testdown")
    public responseentity<byte[]> testresponseentity(httpsession session) throws ioexception {
        //获取servletcontext对象
        servletcontext servletcontext = session.getservletcontext();
        //获取服务器中文件的真实路径
        string realpath = servletcontext.getrealpath("/static/img/1.jpg");
        //创建输入流
        inputstream is = new fileinputstream(realpath);
        //创建字节数组
        byte[] bytes = new byte[is.available()];
        //将流读到字节数组中
        is.read(bytes);
        //创建httpheaders对象设置响应头信息
        multivaluemap<string, string> headers = new httpheaders();
        //设置要下载方式以及下载文件的名字
        //content-disposition 固定回复内容格式  attachment以附件形式下载  filename=1.jpg文件名
        //可以将filename拼接为动态命名
        headers.add("content-disposition", "attachment;filename=1.jpg");
        //设置响应状态码
        httpstatus statuscode = httpstatus.ok;
        //创建responseentity对象
        responseentity<byte[]> responseentity = new responseentity<>(bytes, headers, statuscode);
        //关闭输入流
        is.close();
        return responseentity;
    }
    @requestmapping("/testup")
    public string testup(@value("multipartresolver") multipartfile photo,httpsession session) throws ioexception {
        //获取上传的文件的文件名
        string filename = photo.getoriginalfilename();
        //处理文件重名问题
        //重名问题是java.io中写入同一文件默认覆盖原文件内容导致图片被覆盖.
        //获取文件名后缀
        string suffixname = filename.substring(filename.lastindexof("."));
        //将uuid作为文件名  uuid是32位随机数,几乎不可能会重复
        filename = uuid.randomuuid().tostring() + suffixname;
        //获取服务器中photo目录的路径
        servletcontext servletcontext = session.getservletcontext();
        string photopath = servletcontext.getrealpath("photo");
        file file = new file(photopath);
        //判断服务器是否存在该路径
        if(!file.exists()){
            file.mkdir();
        }
        string finalpath = photopath + file.separator + filename;
        //实现上传功能
        photo.transferto(new file(finalpath));
        return "success";
    }
}

下载功能测试

上传功能测试

 

总结

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