Spring Boot入门——文件上传与下载

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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;@Controllerpublic 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@Configurationpublic 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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