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上传文件是互联网中常常应用的场景之一#xff0c;最典型的情况就是上传头像等#xff0c;今天就带着带着大家做一个 Spring
Boot 上传文件的小案例。
1、pom依赖
?xml version1.0 encodingUTF-8?
project xml…SpringBoot文件上传
上传文件是互联网中常常应用的场景之一最典型的情况就是上传头像等今天就带着带着大家做一个 Spring
Boot 上传文件的小案例。
1、pom依赖
?xml version1.0 encodingUTF-8?
project xmlnshttp://maven.apache.org/POM/4.0.0 xmlns:xsihttp://www.w3.org/2001/XMLSchema-instancexsi:schemaLocationhttp://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsdmodelVersion4.0.0/modelVersionparentgroupIdorg.springframework.boot/groupIdartifactIdspring-boot-starter-parent/artifactIdversion2.1.0.RELEASE/version/parentgroupIdcom.example/groupIdartifactIdspring-boot-file-upload/artifactIdversion0.0.1-SNAPSHOT/versionnamespring-boot-file-upload/namedescriptionspring-boot-file-upload/descriptionpropertiesjava.version1.8/java.version/propertiesdependenciesdependencygroupIdorg.springframework.boot/groupIdartifactIdspring-boot-starter-web/artifactId/dependencydependencygroupIdorg.springframework.boot/groupIdartifactIdspring-boot-starter-thymeleaf/artifactId/dependencydependencygroupIdorg.springframework.boot/groupIdartifactIdspring-boot-devtools/artifactIdoptionaltrue/optional/dependency/dependenciesbuildpluginsplugingroupIdorg.springframework.boot/groupIdartifactIdspring-boot-maven-plugin/artifactId/plugin/plugins/build/project引入了spring-boot-starter-thymeleaf做页面模板引擎写一些简单的上传示例。
2、启动类设置
package com.example;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;SpringBootApplication
public class Application {public static void main(String[] args) {SpringApplication.run(Application.class, args);}
}3、配置文件
#http://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#common-application-properties
#search multipart
spring.servlet.multipart.max-file-size10MB
spring.servlet.multipart.max-request-size10MB4、编写前端页面
上传页面upload.html
!DOCTYPE html
html
bodyh1Spring Boot file upload example/h1form methodPOST action/upload enctypemultipart/form-datainput typefile namefile/br/br/input typesubmit valueSubmit/
/form/body
/html非常简单的一个 Post 请求一个选择框选择文件一个提交按钮效果如下。 上传结果展示页面uploadStatus.html
!DOCTYPE html
html langen xmlns:thhttp://www.thymeleaf.org
bodyh1Spring Boot - Upload Status/h1div th:if${message}h2 th:text${message}/
/div/body
/html效果图如下 5、编写上传控制类
访问 localhost 自动跳转到上传页面
package com.example.controller;import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.servlet.mvc.support.RedirectAttributes;import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;Controller
public class UploadController {// 上传的文件的保存路径private static String UPLOADED_FOLDER D:\\content\\【完】SpringBoot\\【完】007-SpringBoot文件上传\\;GetMapping(/)public String index() {return upload;}PostMapping(/upload)public String singleFileUpload(RequestParam(file) MultipartFile file,RedirectAttributes redirectAttributes) {if (file.isEmpty()) {redirectAttributes.addFlashAttribute(message, Please select a file to upload);return redirect:uploadStatus;}try {// 获取文件并设置保存路径byte[] bytes file.getBytes();Path dir Paths.get(UPLOADED_FOLDER);Path path Paths.get(UPLOADED_FOLDER file.getOriginalFilename());// 不存在的话则创建if (!Files.exists(dir)) {Files.createDirectories(dir);}Files.write(path, bytes);// 该方法可以直接上传到目标文件// file.transferTo(target);redirectAttributes.addFlashAttribute(message,You successfully uploaded file.getOriginalFilename() );} catch (IOException e) {redirectAttributes.addFlashAttribute(message, Server throw IOException);e.printStackTrace();}return redirect:/uploadStatus;}GetMapping(/uploadStatus)public String uploadStatus() {return uploadStatus;}}上面代码的意思就是通过MultipartFile读取文件信息如果文件为空跳转到结果页并给出提示如果不为空
读取文件流并写入到指定目录最后将结果展示到页面。
MultipartFile是Spring上传文件的封装类包含了文件的二进制流和文件属性等信息在配置文件中也可对相
关属性进行配置基本的配置信息如下 spring.http.multipart.enabledtrue #默认支持文件上传. spring.http.multipart.file-size-threshold0 #支持文件写入磁盘. spring.http.multipart.location # 上传文件的临时目录 spring.http.multipart.max-file-size1Mb # 最大支持文件大小 spring.http.multipart.max-request-size10Mb # 最大支持请求大小
最常用的是最后两个配置内容限制文件上传大小上传时超过大小会抛出异常。
更多配置信息参考这里
https://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#common-application-properties
6、异常处理
package com.example.controller;import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.multipart.MultipartException;
import org.springframework.web.servlet.mvc.support.RedirectAttributes;/*** 全局异常处理*/
ControllerAdvice
public class GlobalExceptionHandler {//https://jira.spring.io/browse/SPR-14651//4.3.5 supports RedirectAttributes redirectAttributesExceptionHandler(MultipartException.class)public String handleError1(MultipartException e, RedirectAttributes redirectAttributes) {redirectAttributes.addFlashAttribute(message, e.getCause().getMessage());return redirect:/uploadStatus;}
}设置一个ControllerAdvice用来监控Multipart上传的文件大小是否受限当出现此异常时在前端页面给出提
示。利用ControllerAdvice可以做很多东西比如全局的统一异常处理等。
这样一个使用 Spring Boot 上传文件的简单 Demo 就完成了。
