restful api上传文件（基础）-springboot

基于restful api格式的文件上传（只是上传到本地）：

package com.nxz.controller;import com.nxz.entity.FileInfo;import org.springframework.web.bind.annotation.PostMapping;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;import org.springframework.web.multipart.MultipartFile;import java.io.File;import java.io.IOException;import java.util.Date;@RestController@RequestMapping("/file")public class FileController {@PostMappingpublic FileInfo update(MultipartFile file) throws IOException {System.out.println(file.getName());System.out.println(file.getOriginalFilename());System.out.println(file.getSize());String holder = "G:\\0001-myproject\\mysecurity\\mysecurity-demo\\src\\main\\java\\com\\nxz\\controller";File localFile = new File(holder, new Date().getTime() + ".txt");file.transferTo(localFile);retu new FileInfo(localFile.getAbsolutePath());}}

 

测试用例：

//伪造的mvc环境@Autowiredprivate WebApplicationContext webApplicationContext;private MockMvc mockMvc;@Beforepublic void before() {mockMvc = MockMvcBuilders.webAppContextSetup(webApplicationContext).build();}@Testpublic void whenUploadSuccess() throws Exception {String file = mockMvc.perform(MockMvcRequestBuilders.fileUpload("/file").file(new MockMultipartFile("file", "test.txt", "multipart/form-data", "hello".getBytes("UTF-8")))).andExpect(MockMvcResultMatchers.status().isOk()).andRetu().getResponse().getContentAsString();System.out.println(file);}

测试用例执行完之后输出文件绝对路径：

{"path":"G:\\mysecurity\\mysecurity-demo\\src\\main\\java\\com\\nxz\\controller\\1556463660034.txt"}

 

 

下载：

 @GetMapping("/{id}")public void downLoad(@PathVariable String id, HttpServletRequest request, HttpServletResponse response) throws IOException {String holder = "G:\\0001-myproject\\mysecurity\\mysecurity-demo\\src\\main\\java\\com\\nxz\\controller";try (InputStream inputStream = new FileInputStream(new File(holder, id + ".txt"));OutputStream outputStream = response.getOutputStream();) {response.setContentType("application/x-download");response.addHeader("Content-Disposition", "attachment;filename=test.txt");//重新定义下载后名称//将文件输入流复制到输出刘超过年 commons-io依赖IOUtils.copy(inputStream, outputStream);outputStream.flush();}}

访问：http://localhost:8080/user/1

 

 

springboot中上传文件：

java中和文件上传的类又两个：CommonsMultipartResolver，另一个就是StandardServletMultipartResolver，其中commonsMultipartResolver需要commons-fileupload支持，二StandardServletMultipartReslover是servlet3.0默认支持的，tomcat7以上版本就开始支持servlet7.0，springboot22.0之后支持的tomcat版本在7之后，因此是支持StandardServletMultipartReslover的

首先 springboot只要配置好pom（有spring-boot-starter-web依赖），就能自动支持文件上传（包括单文件和多文件），那么springboot中文件上传是怎样起作用的

1、pom依赖，下边这些依赖中，和配置文件上传有关的就是spring-boot-autoconfig依赖

<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency>---->>><dependency>  <groupId>org.springframework.boot</groupId>  <artifactId>spring-boot-starter</artifactId>  <version>2.1.3.RELEASE</version>  <scope>compile</scope></dependency>---->>>><dependency>  <groupId>org.springframework.boot</groupId>  <artifactId>spring-boot-autoconfigure</artifactId>  <version>2.1.3.RELEASE</version>  <scope>compile</scope></dependency>

 

2、那么看下spring-boot-autoconfig jar包中的spring.factories文件中的内容，这个文件中全都是和springboot自动配置相关的类的全文件名，其中和文件上传有关的是

org.springframework.boot.autoconfigure.web.servlet.MultipartAutoConfiguration,\

3、进入这个类中（具体个各种autoconfiguration自动加载类是什么时候加载的，需要看springboot的启动来注解和启动类）

@Configuration@ConditionalOnClass({ Servlet.class, StandardServletMultipartResolver.class,MultipartConfigElement.class }) //这个注解表示存在servlet、StandardServletMultipartResolver、multipartConfigElement文件时才加载该类@ConditionalOnProperty(prefix = "spring.servlet.multipart", name = "enabled", matchIfMissing = true)//配置文件的前缀@ConditionalOnWebApplication(type = Type.SERVLET)//servlet@EnableConfigurationProperties(MultipartProperties.class)//配置文件类 public class MultipartAutoConfiguration { private final MultipartProperties multipartProperties; public MultipartAutoConfiguration(MultipartProperties multipartProperties) { this.multipartProperties = multipartProperties; } @Bean @ConditionalOnMissingBean({ MultipartConfigElement.class, CommonsMultipartResolver.class })//当没有commonsMultipartResolver文件时，初始化该bean public MultipartConfigElement multipartConfigElement() { retu this.multipartProperties.createMultipartConfig(); } @Bean(name = DispatcherServlet.MULTIPART_RESOLVER_BEAN_NAME) @ConditionalOnMissingBean(MultipartResolver.class) public StandardServletMultipartResolver multipartResolver() { StandardServletMultipartResolver multipartResolver = new StandardServletMultipartResolver();//springboot默认的文件上传的类 multipartResolver.setResolveLazily(this.multipartProperties.isResolveLazily()); retu multipartResolver; } }