Spring 文件上传功能

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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;@Controller
public 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
@EnableAutoConfiguration
public 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.
*/@Controller
public 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";
}
}