Spring Boot 文件上传与下载

2022-05-18 16:17:59

原文地址: https://www.cnblogs.com/studyDetail/p/7003253.html

1、在pom.xml文件中添加依赖

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

  <modelVersion>4.0.0</modelVersion>

  <groupId>com.wyl</groupId>

  <artifactId>SpringBootFile</artifactId>

  <version>0.0.1-SNAPSHOT</version>

  <packaging>jar</packaging>

  <name>SpringBootFile</name>

  <url>http://maven.apache.org</url>

  <properties>

    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

      <java.version>1.7</java.version>

  </properties>

  <parent>

      <groupId>org.springframework.boot</groupId>

    <artifactId>spring-boot-starter-parent</artifactId>

    <version>1.5.3.RELEASE</version>

  </parent>

  <dependencies>

    <dependency>

      <groupId>junit</groupId>

      <artifactId>junit</artifactId>

      <version>3.8.1</version>

      <scope>test</scope>

    </dependency>

    <dependency>

        <groupId>org.springframework.boot</groupId>

        <artifactId>spring-boot-starter-web</artifactId>

    </dependency>

    <!-- thymeleaf模板插件 -->

    <dependency>

        <groupId>org.springframework.boot</groupId>

        <artifactId>spring-boot-starter-thymeleaf</artifactId>

    </dependency>

    <!-- devtools插件，热部署 -->

    <dependency>

        <groupId>org.springframework.boot</groupId>

        <artifactId>spring-boot-devtools</artifactId>

        <optional>true</optional>

        <scope>true</scope>

    </dependency>

  </dependencies>

</project>

2、application.properties文件中取消模板文件缓存

spring.thymeleaf.cache=false

3、编写模板文件

file.html

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml" xmlns:th="http://www.thymeleaf.org"

      xmlns:sec="http://www.thymeleaf.org/thymeleaf-extras-springsecurity3">

<head>

<meta charset="UTF-8" />

<title>Insert title here</title>

</head>

<body>

    <h1 th:inlines="text">文件上传</h1>

    <form action="fileUpload" method="post" enctype="multipart/form-data">

        <p>选择文件: <input type="file" name="fileName"/></p>

        <p><input type="submit" value="提交"/></p>

    </form>

</body>

</html>

multifile.html
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:th="http://www.thymeleaf.org"  
      xmlns:sec="http://www.thymeleaf.org/thymeleaf-extras-springsecurity3">
<head>
<meta charset="UTF-8" />
<title>Insert title here</title>
</head>
<body>
    <h1 th:inlines="text">文件上传</h1>
    <form action="multifileUpload" method="post" enctype="multipart/form-data" >
        <p>选择文件1: <input type="file" name="fileName"/></p>
        <p>选择文件2: <input type="file" name="fileName"/></p>
        <p>选择文件3: <input type="file" name="fileName"/></p>
        <p><input type="submit" value="提交"/></p>
    </form>
</body>
</html>

4、编写Controller

import org.springframework.stereotype.Controller;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestParam;

import org.springframework.web.bind.annotation.ResponseBody;

import org.springframework.web.multipart.MultipartFile;

@Controller

public class FileUploadController {

    /*

     * 获取file.html页面

     */

    @RequestMapping("file")

    public String file(){

        return "/file";

    }

    /**

     * 实现文件上传

     * */

    @RequestMapping("fileUpload")

    @ResponseBody

    public String fileUpload(@RequestParam("fileName") MultipartFile file){

        if(file.isEmpty()){

            return "false";

        }

        String fileName = file.getOriginalFilename();

        int size = (int) file.getSize();

        System.out.println(fileName + "-->" + size);

        String path = "F:/test" ;

        File dest = new File(path + "/" + fileName);

        if(!dest.getParentFile().exists()){ //判断文件父目录是否存在

            dest.getParentFile().mkdir();

        }

        try {

            file.transferTo(dest); //保存文件

            return "true";

        } catch (IllegalStateException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

            return "false";

        } catch (IOException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

            return "false";

        }

    }

　　/*
     * 获取multifile.html页面
     */
    @RequestMapping("multifile")
    public String multifile(){
        return "/multifile";
    }
    
    /**
     * 实现多文件上传
     * */
    @RequestMapping(value="multifileUpload",method=RequestMethod.POST)

　　/**public @ResponseBody String multifileUpload(@RequestParam("fileName")List<MultipartFile> files) */
    public @ResponseBody String multifileUpload(HttpServletRequest request){
        
        List<MultipartFile> files = ((MultipartHttpServletRequest)request).getFiles("fileName");
        
        if(files.isEmpty()){
            return "false";
        }

        String path = "F:/test" ;
        
        for(MultipartFile file:files){
            String fileName = file.getOriginalFilename();
            int size = (int) file.getSize();
            System.out.println(fileName + "-->" + size);
            
            if(file.isEmpty()){
                return "false";
            }else{        
                File dest = new File(path + "/" + fileName);
                if(!dest.getParentFile().exists()){ //判断文件父目录是否存在
                    dest.getParentFile().mkdir();
                }
                try {
                    file.transferTo(dest);
                }catch (Exception e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                    return "false";
                } 
            }
        }
        return "true";
    }

}

5、测试

6、多文件上传中遇到的问题

org.apache.tomcat.util.http.fileupload.FileUploadBase$FileSizeLimitExceededException: The field fileName exceeds its maximum permitted size of 1048576 bytes.

Spring Boot默认文件上传大小为2M，多文档上传中总是出现文件大小超出限度

解决方法：

a、在application.properties文件中设置文件大小

# Single file max size

multipart.maxFileSize=50Mb

# All files max size

multipart.maxRequestSize=50Mb

　　但是，事实证明此种方法不能够解决以上问题

b、在启动类App.class文件中配置Bean来设置文件大小

import javax.servlet.MultipartConfigElement;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

import org.springframework.boot.web.servlet.MultipartConfigFactory;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

/**

 * Hello world!

 *

 */

@SpringBootApplication

@Configuration

public class App

{

    public static void main( String[] args )

    {

        System.out.println( "Hello World!" );

        SpringApplication.run(App.class, args);

    }

    /**

     * 文件上传配置

     * @return

     */

    @Bean

    public MultipartConfigElement multipartConfigElement() {

        MultipartConfigFactory factory = new MultipartConfigFactory();

        //单个文件最大

        factory.setMaxFileSize("10240KB"); //KB,MB

        /// 设置总上传数据总大小

        factory.setMaxRequestSize("102400KB");

        return factory.createMultipartConfig();

    }

7、文件下载

@RequestMapping("download")

    public String downLoad(HttpServletResponse response){

        String filename="2.jpg";

        String filePath = "F:/test" ;

        File file = new File(filePath + "/" + filename);

        if(file.exists()){ //判断文件父目录是否存在

            response.setContentType("application/force-download");

            response.setHeader("Content-Disposition", "attachment;fileName=" + filename);

            byte[] buffer = new byte[1024];

            FileInputStream fis = null; //文件输入流

            BufferedInputStream bis = null;

            OutputStream os = null; //输出流

            try {

                os = response.getOutputStream();

                fis = new FileInputStream(file);

                bis = new BufferedInputStream(fis);

                int i = bis.read(buffer);

                while(i != -1){

                    os.write(buffer);

                    i = bis.read(buffer);

                }

            } catch (Exception e) {

                // TODO Auto-generated catch block

                e.printStackTrace();

            }

            System.out.println("----------file download" + filename);

            try {

                bis.close();

                fis.close();

            } catch (IOException e) {

                // TODO Auto-generated catch block

                e.printStackTrace();

            }

        }

        return null;

    }

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