【SpringMVC】(十)文件上传与下载

文件上传与下载

环境搭建

pom.xml增加

		<!--文件上传-->
        <dependency>
            <groupId>commons-fileupload</groupId>
            <artifactId>commons-fileupload</artifactId>
            <version>1.4</version>
        </dependency>
        <!--高版本的servlet-api-->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.1</version>
            <scope>provided</scope>
        </dependency>

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">

    <!--1. 注册DispatcherServlet-->
    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <!--关联一个springmvc的配置文件：【servlet-name】-servlet.xml -->
        <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>

    <!-- / 和/* 的区别-->
    <!-- / 匹配所有的请求:(不包括.jsp)-->
    <!-- /* 匹配所有的请求：(包括.jsp)-->
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>


    <!--SpringMVC提供的乱码过滤器-->
    <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>

springmvc-servlet.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">

    <!--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.musecho.controller"/>

    <!--视图解析器ViewResolver：解析DispatcherServlet传递来的ModelAndView-->
    <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>


    <!--JSON乱码问题配置-->
    <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>


</beans>

1. 文件上传

若要使用Spring的文件上传功能，需要在上下文中国配置MultipartResolver。

springmvc-servlet.xml添加配置

	<!--文件上传配置-->
    <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="10485760"/>
        <!--上传文件大小的阀值，低于阀值保存在内存，高于阀值生成硬盘上的临时文件-->
        <property name="maxInMemorySize" value="40960"/>
    </bean>

前端表单：为了能上传文件，method方法必须设置为post，并将enctype设置为multipart/form-data，这样才能使文件以二进制数据形式发送给服务器。

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>$Title$</title>
</head>
<body>
<form action="${pageContext.request.contextPath}/upload2" enctype="multipart/form-data" method="post">
    <input type="file" name="file">
    <input type="submit" value="upload">

    
</form>
</body>
</html>

FileController

@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为数组即可
    @RequestMapping("/upload")
    public String fileUpload(@RequestParam("file") CommonsMultipartFile file, HttpServletRequest request) throws IOException {

        //获取文件名，若为空则返回上传页面
        String fileName = file.getOriginalFilename();
        if ("".equals(fileName)) {
            return "redirect:/index.jsp";
        }
        System.out.println("文件名：" + fileName);


        //设置上传文件保存路径
        String filePath = request.getServletContext().getRealPath("/upload");
        //若路径不存在，创建一个
        File realPath = new File(filePath);
        if (!realPath.exists()) {
            realPath.mkdir();
        }
        System.out.println("文件保存路径：" + realPath);


        //读取写出
        InputStream is = file.getInputStream();
        OutputStream os = new FileOutputStream(new File(realPath, fileName));

        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";
    }

    //采用file.transferTo方法保存上传文件
    @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");
        File realPath = new File(path);
        if (!realPath.exists()) {
            realPath.mkdir();
        }
        System.out.println("上传文件地址：" + realPath);


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


        return "redirect:/index.jsp";
    }

    

}

上传成功

2. 文件下载

index.jsp添加

<a href="${pageContext.request.contextPath}/download">点击这里可以下载图片</a>

FileController添加

	@RequestMapping("/download")
    public String downloads(HttpServletResponse response, HttpServletRequest request) throws IOException {
        //要下载的图片地址
        String path = request.getServletContext().getRealPath("/upload");
        String filename="1.png";


        //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-Dispositon", "attachment;fileName=" + URLEncoder.encode(filename, "UTF-8"));

        File file2 = new File(path, filename);
        //2.读取文件--输入流
        InputStream is = new FileInputStream(file2);
        //3.写出文件--输出流
        OutputStream os = response.getOutputStream();

        //4.执行 写出操作
        byte[] bytes = new byte[1024];
        int len = 0;
        while ((len = is.read(bytes)) != -1) {
            os.write(bytes, 0, len);
            os.flush();
        }
        os.close();
        is.close();

        return null;
    }

文件放在这里

posted @ 2021-02-24 16:00 musecho 阅读(84) 评论(0) 收藏举报

刷新页面返回顶部

musecho

【SpringMVC】(十)文件上传与下载

文件上传与下载

环境搭建

1. 文件上传

2. 文件下载

公告