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 { @PostMapping public 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); return new FileInfo(localFile.getAbsolutePath()); } }

 

测试用例：

//伪造的mvc环境
 @Autowired private WebApplicationContext webApplicationContext; private MockMvc mockMvc; @Before public void before() { mockMvc = MockMvcBuilders.webAppContextSetup(webApplicationContext).build(); } @Test public 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()) .andReturn().getResponse().getContentAsString(); System.out.println(file); }

测试用例执行完以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");//从新定义下载后名称 //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，另外一个就是StandardServletMultipartResolver，其中commonsMultipartResolver须要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以后支持的tomcat版本在7以后，所以是支持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做用的

一、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>

 

二、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,\

三、进入这个类中（具体个各类autoconfiguration自动加载类是何时加载的，须要看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() { return 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()); return multipartResolver; } }