SpringMVC文件上传和下载

上传

1. 导入依赖

<!--文件上传-->
<dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.3.3</version>
</dependency>

2. 写一个上传的页面

<form action="" enctype="multipart/form-data" method="post">
    <input type="file" name="file"/>
    <input type="submit">
</form>

3. 配置bean：multipartResolver

<!--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>

4. 写一个Controller

package controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.multipart.commons.CommonsMultipartFile;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.net.URLEncoder;
 
@Controller
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";
	}
}

下载

页面

<a href="/download">点击下载</a>

controller

//下载
	@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 = "1632824890.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";
	}