Spring 文件上传功能

时间：2023-12-19 12:07:56

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";

    }

}

　　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。

参考资料：

1. MultipartResolver也可以实现文件上传功能。参考文章：http://mylfd.iteye.com/blog/1893648

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