单文件上传
底层是使用 Apache fileupload 组件完成上传，Spring MVC 对这种方式进行了封装。
- pom.xml
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>2.5</version>
</dependency>
<dependency>
<groupId>commons-fileupload</groupId>
<artifactId>commons-fileupload</artifactId>
<version>1.3.3</version>
</dependency>
- html
<html>
<head>
<title>Title</title>
</head>
<body>
<form action="/file/upload" method="post" enctype="multipart/form-data">
<input type="file" name="img"/>
<input type="submit" value="上传"/>
</form>
<img src="${path}">
</body>
</html>
1、input 的 type 设置为 file。
2、form 的 method 设置为 post（get 请求只能将文件名传给服务器）
3、from 的 enctype 设置为 multipart-form-data（如果不设置只能将文件名传给服务器）
- Handler
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.multipart.MultipartFile;
import javax.servlet.http.HttpServletRequest;
import java.io.File;
import java.io.IOException;
@Controller
@RequestMapping("/file")
public class FileHandler {
@PostMapping("/upload")
public String upload(MultipartFile img, HttpServletRequest request){
if(img.getSize()>0){
//获取接收到的文件的保存路径
String path = request.getServletContext().getRealPath("file");
//.getOriginalFilename() 获取上传的文件原名
String name = img.getOriginalFilename();
File file = new File(path,name);
try {
img.transferTo(file);// 将上传文件存到指定目录中
//保存上传之后的文件路径
request.setAttribute("path","/file/"+name);
} catch (IOException e) {
e.printStackTrace();
}
}
return "upload";
}
}
这是比较原生的写法
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 java.io.*;
@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";
}
}
- springmvc.xml
<!-- 配置上传组件 这个bean的id必须为：multipartResover，否则报400-->
<bean id="myMmultipart" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<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>
- web.xml 添加如下配置，否则客户端无法访问静态资源png
<servlet-mapping>
<servlet-name>default</servlet-name>
<url-pattern>*.png</url-pattern>
</servlet-mapping>
多文件上传
pom.xml
<dependency>
<groupId>jstl</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>
<dependency>
<groupId>taglibs</groupId>
<artifactId>standard</artifactId>
<version>1.1.2</version>
</dependency>
JSP
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ page isELIgnored="false" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<form action="/file/uploads" method="post" enctype="multipart/form-data">
file1:<input type="file" name="imgs"/><br/>
file2:<input type="file" name="imgs"/><br/>
file3:<input type="file" name="imgs"><br/>
<input type="submit" value="上传"/>
</form>
<c:forEach items="${files}" var="file" >
<img src="${file}" width="300px">
</c:forEach>
</body>
</html>
Handler
@PostMapping("/uploads")
public String uploads(MultipartFile[] imgs,HttpServletRequest request){
List<String> files = new ArrayList<>();
for (MultipartFile img:imgs){
if(img.getSize()>0){
//获取保存上传文件的file路径
String path = request.getServletContext().getRealPath("file");
//获取上传的文件名
String name = img.getOriginalFilename();
File file = new File(path,name);
try {
img.transferTo(file);
//保存上传之后的文件路径
files.add("/file/"+name);
} catch (IOException e) {
e.printStackTrace();
}
}
}
request.setAttribute("files",files);
return "uploads";
}
下载
- JSP
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<a href="/file/download/1">1.png</a>
<a href="/file/download/2">2.png</a>
<a href="/file/download/3">3.png</a>
</body>
</html>
- Handler
@GetMapping("/download/{name}")
public void download(@PathVariable("name") String name, HttpServletRequest request, HttpServletResponse response){
if(name != null){
name += ".png";
String path = request.getServletContext().getRealPath("file");
File file = new File(path,name);
OutputStream outputStream = null;
if( file.exists() ){
response.setContentType("application/forc-download");
response.setHeader("Content-Disposition","attachment;filename="+name);
try {
outputStream = response.getOutputStream();
outputStream.write(FileUtils.readFileToByteArray(file));
outputStream.flush();
} catch ( IOException e) {
e.printStackTrace();
} finally {
if( outputStream != null ){
try {
outputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
}
