Spring实现文件上传功能

时间：2021-05-20

本篇文章，我们要来做一个Spring的文件上传功能：

1. 创建一个Maven的web工程，然后配置pom.xml文件，增加依赖：

<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> <version>1.0.2.RELEASE</version></dependency>

2.在webapp目录下的index.jsp文件中输入一个表单：

<html><body><form method="POST" enctype="multipart/form-data" action="/upload"> File to upload: <input type="file" name="file"><br /> Name: <input type="text" name="name"><br /> <br /> <input type="submit" value="Upload"> Press here to upload the file!</form></body></html>

这个表单就是我们模拟的上传页面。

3. 编写处理这个表单的Controller：

import java.io.BufferedOutputStream;import java.io.File;import java.io.FileOutputStream; 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.bind.annotation.ResponseBody;import org.springframework.web.multipart.MultipartFile; @Controllerpublic class FileUploadController { @RequestMapping(value="/upload", method=RequestMethod.GET) public @ResponseBody String provideUploadInfo() { return "You can upload a file by posting to this same URL."; } @RequestMapping(value="/upload", method=RequestMethod.POST) public @ResponseBody String handleFileUpload(@RequestParam("name") String name, @RequestParam("file") MultipartFile file){ if (!file.isEmpty()) { try { byte[] bytes = file.getBytes(); BufferedOutputStream stream = new BufferedOutputStream(new FileOutputStream(new File(name + "-uploaded"))); stream.write(bytes); stream.close(); return "You successfully uploaded " + name + " into " + name + "-uploaded !"; } catch (Exception e) { return "You failed to upload " + name + " => " + e.getMessage(); } } else { return "You failed to upload " + name + " because the file was empty."; } } }

4. 然后我们对上传的文件做一些限制，同时编写main方法来启动这个web ：

import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.EnableAutoConfiguration;import org.springframework.boot.context.embedded.MultiPartConfigFactory;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.Configuration; import javax.servlet.MultipartConfigElement; @Configuration@ComponentScan@EnableAutoConfigurationpublic class Application { @Bean public MultipartConfigElement multipartConfigElement() { MultiPartConfigFactory factory = new MultiPartConfigFactory(); factory.setMaxFileSize("128KB"); factory.setMaxRequestSize("128KB"); return factory.createMultipartConfig(); } public static void main(String[] args) { SpringApplication.run(Application.class, args); }}

5. 然后访问http://localhost:8080/upload就可以看到页面了。

上面的例子是实现的是单个文件上传的功能，假定我们现在要实现文件批量上传的功能的话，我们只需要简单的修改一下上面的代码就行，考虑到篇幅的问题，下面只是贴出和上面不同的代码，没有贴出的说明和上面一样。：

1.　　新增batchUpload.jsp文件

<html><body><form method="POST" enctype="multipart/form-data" action="/batch/upload"> File to upload: <input type="file" name="file"><br /> File to upload: <input type="file" name="file"><br /> <input type="submit" value="Upload"> Press here to upload the file!</form></body></html>

2. 新增BatchFileUploadController.java文件：

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.ResponseBody;import org.springframework.web.multipart.MultipartFile;import org.springframework.web.multipart.MultipartHttpServletRequest; import javax.servlet.http.HttpServletRequest;import java.io.BufferedOutputStream;import java.io.File;import java.io.FileOutputStream;import java.util.List; /** * Created by wenchao.ren on 2014/4/26. */ @Controllerpublic class BatchFileUploadController { @RequestMapping(value="/batch/upload", method= RequestMethod.POST) public @ResponseBody String handleFileUpload(HttpServletRequest request){ List<MultipartFile> files = ((MultipartHttpServletRequest)request).getFiles("file"); for (int i =0; i< files.size(); ++i) { MultipartFile file = files.get(i); String name = file.getName(); if (!file.isEmpty()) { try { byte[] bytes = file.getBytes(); BufferedOutputStream stream = new BufferedOutputStream(new FileOutputStream(new File(name + i))); stream.write(bytes); stream.close(); } catch (Exception e) { return "You failed to upload " + name + " => " + e.getMessage(); } } else { return "You failed to upload " + name + " because the file was empty."; } } return "upload successful"; }}

这样一个简单的批量上传文件的功能就ok了，是不是很简单啊。

注意：上面的代码只是为了演示而已，所以编码风格上采取了随性的方式，不建议大家模仿。

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。

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