【SpringMVC---文件上传与下载】

2021-08-09 01:42:52

SpringMVC文件上传

一、步骤

1、导包

<dependencies>
        <dependency>
            <groupId>commons-fileupload</groupId>
            <artifactId>commons-fileupload</artifactId>
            <version>1.4</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.1</version>
        </dependency>
    </dependencies>

2、添加Spring配置

<?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
        https://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">

    <!--自动扫描包， 让指定包下的注解生效，由IOC容器统一管理-->
    <context:component-scan base-package="com.darkerg.controller"/>
    <!--让Spring MVC不处理静态资源 .css .js .html .mp3 .mp4-->
    <mvc:default-servlet-handler />
    <!--解决json 乱码配置-->
    <mvc:annotation-driven>
        <mvc:message-converters register-defaults="true">
            <bean class="org.springframework.http.converter.StringHttpMessageConverter">
                <constructor-arg value="UTF-8"/>
            </bean>
            <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
                <property name="objectMapper">
                    <bean class="org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean">
                        <property name="failOnEmptyBeans" value="false"/>
                    </bean>
                </property>
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>

    <!--支持mvc注解驱动
        在spring中一般采用@RequestMapping注解完成映射关系， 要想使@RequestMapping注解生效，必须向上下文注册DefaultAnnotationHandlerMapping
        和一个AnnotationMethodHandlerAdapter实例，这两个实例分别在类级别和方法级别处理， 而annotation-driven配置帮助我们自动完成上述两个实例的注入-->
    <mvc:annotation-driven />

        <!--处理器解析器-->
        <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="InternalResourceViewResolver">
            <!--前缀-->
            <property name="prefix" value="/WEB-INF/jsp/"/>
            <!--后缀-->
            <property name="suffix" value=".jsp"/>
        </bean>
    


    <!--文件上传的配置-->
    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <!--请求的编码格式，必须和jsp的pageEncoding属性一致，以便正确的读取表单的内容，默认为ISO-8859-1 -->
        <property name="defaultEncoding" value="utf-8"/>
        <!--上传文件大小上限，单位为字节(10485760=10M)-->
        <property name="maxUploadSize" value="104865760"/>
        <property name="maxInMemorySize" value="40960"/>
    </bean>

</beans>

3、web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="https://jakarta.ee/xml/ns/jakartaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee https://jakarta.ee/xml/ns/jakartaee/web-app_5_0.xsd"
         version="5.0">
    <!--配置DispatcherServlet： 这个是SpringMVC的核心，请求分发器，前端控制器-->
    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <!--DispatcherServlet要绑定spring的配置文件-->
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:springmvc-servlet.xml</param-value>
        </init-param>
        <!--启动级别 1-->
        <load-on-startup>1</load-on-startup>
    </servlet>
    <!--/: 只匹配所有的请求，不会去匹配jsp页面-->
    <!--/*: 配所有的请求，包括jsp页面-->
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

    <filter>
        <filter-name>encoding</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>encoding</filter-name>
        <url-pattern>/</url-pattern>
    </filter-mapping>

</web-app>

4、前端jsp代码

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
  <title>$Title$</title>
</head>
<body>

<form action="${pageContext.request.contextPath}/upload" enctype="multipart/form-data" method="post">
  <input type="file" name="file"/>
  <input type="submit" value="upload">
</form>

</body>
</html>

二、方式一

package com.darkerg.controller;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.commons.CommonsMultipartFile;

import javax.servlet.http.HttpServletRequest;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;

@RestController
public class FileController {

    //@RequestParam("file") 将name = file控件得到的文件封装成CommonsMultipartFile对象
    //批量上传CommonsMultipartFile则为数组即可
    @RequestMapping("/upload")
    public String fileUpload(@RequestParam("file")CommonsMultipartFile file, HttpServletRequest request) throws IOException {

        //获取文件名：file.getOriginalFilename();
        String uploadFileName = file.getOriginalFilename();

        //如果文件名为空，直接回到首页
        if ("".equals(uploadFileName)){
            return "redirect:/index.jsp";
        }

        System.out.println("上传文件名："+uploadFileName);

        //上传路径保存设置
        String path = request.getServletContext().getRealPath("/upload");
        //如果路径不存在，创建一个
        File realPath = new File(path);
        if (!realPath.exists()){
            realPath.mkdir();
        }
        System.out.println("上传文件保存地址："+realPath);

        InputStream is = file.getInputStream();//文件输入流
        FileOutputStream os = new FileOutputStream(new File(realPath, uploadFileName));//文件输出流

        //读取写出
        int len = 0;
        byte[] buffer = new byte[1024];
        while ((len=is.read(buffer))!=-1){
            os.write(buffer,0,len);
            os.flush();
        }
        os.close();
        is.close();
        return "redirect:/index.jsp";
    }

}

效果：

三、方式二

/*
        采用file.Transto来保存上传的文件
     */
    @RequestMapping("upload2")
    public String fileUpload2(@RequestParam("file") CommonsMultipartFile file,HttpServletRequest request) throws IOException {

        //上传路径保存设置
        String path = request.getServletContext().getRealPath("/upload");
        //如果路径不存在，创建一个
        File realPath = new File(path);
        if (!realPath.exists()){
            realPath.mkdir();
        }
        System.out.println("上传文件保存地址："+realPath);

        //通过CommonsMultipartFile的方法直接写文件（注意这个时候)
        file.transferTo(new File(realPath + "/" + file.getOriginalFilename()));

        return "redirect:/index.jsp";
    }

修改一下前端的请求

四、文件下载

1、文件下载步骤：

设置response响应头
读取文件 -- InputStream
写出文件 -- OutputStream
执行操作
关闭流（先开后关)

2、代码实现

@RequestMapping("/download")
    public String downloads(HttpServletResponse response,HttpServletRequest request) throws Exception{
        //要下载图片的地址
        String path = request.getServletContext().getRealPath("/upload");
        String fileName = "1.jpg";

        //1.设置response响应头
        response.reset();//设置页面不缓存，清空buffer
        response.setCharacterEncoding("UTF-8");//字符编码
        response.setContentType("multipart/form-data");//二进制传输数据

        //设置响应头
        response.setHeader("Content-Disposition",
                "attachment;fileName="+ URLEncoder.encode(fileName,"UTF-8"));

        File file = new File(path, fileName);

        //2、读取文件------输入流
        FileInputStream input = new FileInputStream(file);

        //3.写出文件----输出流
        OutputStream out = response.getOutputStream();

        byte[] buff = new byte[1024];
        int index = 0;

        //4。执行  写出操作
        while ((index=input.read(buff))!=-1){
            out.write(buff,0,index);
            out.flush();
        }
        out.close();
        input.close();
        return null;
    }

3、图片的保存位置

项目发布后的upload文件夹下

【SpringMVC---文件上传与下载】

码农公寓

SpringMVC文件上传

一、步骤

1、导包

2、添加Spring配置

3、web.xml

4、前端jsp代码

二、方式一

三、方式二

四、文件下载

1、文件下载步骤：

2、代码实现

3、图片的保存位置

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