SpringMVC-文件上传和下载

文件上传和下载

1、添加框架支持，配置web.xml文件

<?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">

    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>

        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:applicationContext.xml</param-value>
        </init-param>

        <load-on-startup>1</load-on-startup>
    </servlet>

    <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>

2、配置applicationContext.xml文件

<?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">

    <mvc:default-servlet-handler/>
    <context:component-scan base-package="com.kuang.controller"/>
    <!--配置注解驱动（含乱码处理）-->
    <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>

    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <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属性一直，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"/>
        <property name="maxInMemorySize" value="40960"/>
    </bean>

</beans>

3、创建Controller类实现上传

1. 方法一

   @RestController
   public class FileController {
   
       @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
           OutputStream 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";
       }
   
   }
   

2. 方法二：

   @RestController
   public class FileController {
       @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();
           }
   
           // 上传文件地址
           System.out.println("上传文件保存地址：" + realPath);
   
           // 通过CommonsMultipatrFile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";
       }
   
   }
   

4、配置Controller类实现下载

@RestController
public class FileController {
     @RequestMapping(value = "/download")
    public String downloads(HttpServletResponse response,HttpServletRequest request) throws IOException{

        System.out.println("进入方法");
        // 要下载的图片地址
        String path = request.getServletContext().getRealPath(("/upload"));
        String fileName = "xq.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"); // 二进制传出数据
        // 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
        InputStream 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;
    }

}