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MultipartResolver实现文件上传功能

作者：紫_色　　发布时间：2021-06-19 22:38:15　

标签：MultipartResolver,文件上传

springMVC默认的解析器里面是没有加入对文件上传的解析的,，使用springmvc对文件上传的解析器来处理文件上传的时需要用springmvc提供的MultipartResolver的申明，又因为CommonsMultipartResolver实现了MultipartResolver接口，所以我们可以在springmvc配置文件中这样配置：

<bean id="multipartResolver"
class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<property name="defaultEncoding" value="utf-8" />
<property name="maxUploadSize" value="10485760000" />
<property name="maxInMemorySize" value="40960" />
</bean>

首先引入文件上传所需要的包,commons-logging-*.jar commons-io-*.jar commons-fileupload-*.jar

新建一个JSP页面.

<％@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"％>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>文件上传</title>
</head>
<body>
<％--<form action="user/fileUpload" method="post" enctype="multipart/form-data">--％>
<form action="user/fileUpload" method="post" enctype="multipart/form-data">
<input type="file" name="fileUpload" />
<input type="submit" value="上传" />
</form>
</body>
</html>

springmvc上传文件的形式有很多,这里我介绍两种.

第一种,看Controller

package gd.hz.springmvc.controller;

import java.io.File;
import java.io.IOException;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.multipart.commons.CommonsMultipartFile;
import org.springframework.web.servlet.ModelAndView;

@Controller("userController")
@RequestMapping("user")
public class UserController {

// 处理文件上传一
@RequestMapping(value = "fileUpload", method = RequestMethod.POST)
public ModelAndView fileUpload(
@RequestParam("fileUpload") CommonsMultipartFile file) {
// 获取文件类型
System.out.println(file.getContentType());
// 获取文件大小
System.out.println(file.getSize());
// 获取文件名称
System.out.println(file.getOriginalFilename());

// 判断文件是否存在
if (!file.isEmpty()) {
String path = "D:/" + file.getOriginalFilename();
File localFile = new File(path);
try {
file.transferTo(localFile);
} catch (IllegalStateException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
return new ModelAndView("dataSuccess");
}
}

类CommonsMultipartFile为我们提供了许多对文件处理的方法.例如文件大小,上传文件名称,文件类型,具体用法可以查看spring的文档.transferTo就是将文件输出到指定地方.

文件上传的第二种方法,这种方法比较常用:

package gd.hz.springmvc.controller;

import java.io.File;
import java.io.IOException;
import java.util.Iterator;

import javax.servlet.http.HttpServletRequest;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.multipart.MultipartHttpServletRequest;
import org.springframework.web.multipart.commons.CommonsMultipartResolver;

@Controller("userController")
@RequestMapping("user")
public class UserController {

// 处理文件上传二
@RequestMapping(value = "fileUpload2", method = RequestMethod.POST)
public String fileUpload2(HttpServletRequest request)
throws IllegalStateException, IOException {
// 设置上下方文
CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver(
request.getSession().getServletContext());

// 检查form是否有enctype="multipart/form-data"
if (multipartResolver.isMultipart(request)) {
MultipartHttpServletRequest multiRequest = (MultipartHttpServletRequest) request;

Iterator<String> iter = multiRequest.getFileNames();
while (iter.hasNext()) {

// 由CommonsMultipartFile继承而来,拥有上面的方法.
MultipartFile file = multiRequest.getFile(iter.next());
if (file != null) {
String fileName = "demoUpload" + file.getOriginalFilename();
String path = "D:/" + fileName;

File localFile = new File(path);
file.transferTo(localFile);
}

}
}
return "dataSuccess";
}
}

MultipartHttpServletRequest提供了更加灵活的方法,可以获取多个文件和文件名,可以遍历获得每个文件.

来源：http://mylfd.iteye.com/blog/1893648

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MultipartResolver实现文件上传功能

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