3. SpringMVC文件上传和下载
3.1 上传
在controller中有两种方式
新建一个module，一套流程整体下来。测试能运行即可
−−>导入jar包💻
<!--文件上传--> <dependency> <groupId>commons-fileupload</groupId> <artifactId>commons-fileupload</artifactId> <version>1.3.3</version> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>4.0.1</version> </dependency>
−−>index.jsp💻
<%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>文件上传和下载</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>
−−>applicationContext.xml中配置bean💻
<!--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"/> <property name="maxInMemorySize" value="40960"/> </bean>
−−>FileController💻
package com.hxl.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.*; @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 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"; } /* * 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"); 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"; } }
−−>测试：💻
3.2 下载
1、设置 response 响应头
2、读取文件 – InputStream
3、写出文件 – OutputStream
4、执行操作
5、关闭流 （先开后关）
−−>index.jsp💻
<a href="${pageContext.request.contextPath}/download">点击下载</a>
−−>增加一个upload文件💻
并且把要下载的图片弄进去
−−>controller💻
@RequestMapping(value="/download") public String downloads(HttpServletResponse response , HttpServletRequest request) throws Exception{ //要下载的图片地址 String path = request.getServletContext().getRealPath("/upload"); //String fileName = "你想要下载的文件,要加上后缀"; 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 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 "ok"; }
−−>测试：💻
文末小惊喜
