文章目录
路还在继续,梦还在期许
1、页面表单
1.1、单文件上传
<form method="post" th:action="@{/upload}" enctype="multipart/form-data">
<input type="file" name="file"><br>
<input type="submit" value="提交">
</form>
1.2、多文件上传
<form method="post" th:action="@{/upload}" enctype="multipart/form-data">
<input type="file" name="file" multiple><br>
<input type="submit" value="提交">
</form>
2、文件上传实现
MultipartFile:自动封装上传来的文件
@RequestPart:获取表单内的文件项
2.1、代码
//自动封装上传过来的文件
@PostMapping("/upload")
public String upload(@RequestParam("email") String email,
@RequestParam("username") String username,
@RequestPart("headerImg") MultipartFile headerImg,
@RequestPart("photos") MultipartFile[] photos) throws IOException {
// 获取上传的信息
log.info("上传的信息:email={},username={},headerImg={},photos={}",
email,username,headerImg.getSize(),photos.length);
// 判断上传文件非空
if(!headerImg.isEmpty()){
// 获取上传文件名字
String originalFilename = headerImg.getOriginalFilename();
// 保存到服务器指定地址
headerImg.transferTo(new File("H:\\cache\\"+originalFilename));
}
// 判断多上传文件不为空
if(photos.length > 0){
// 遍历数组中对象
for (MultipartFile photo : photos) {
// 方式同上
if(!photo.isEmpty()){
String originalFilename = photo.getOriginalFilename();
photo.transferTo(new File("H:\\cache\\"+originalFilename));
}
}
}
// 上传成功,跳转到主页面
return "main";
}
2.2、配置
配置类位置:org.springframework.boot.autoconfigure.web.servlet.MultipartProperties
前缀:spring.servlet.multipart
spring:
servlet:
multipart:
maxFileSize: 10MB # 单个文件大小
maxRequestSize: 100MB # 整体上传文件大小
3、自动配置原理
3.1、MultipartAutoConfiguration类
自动配置类位置:org.springframework.boot.autoconfigure.web.servlet.MultipartAutoConfiguration
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass({
Servlet.class, StandardServletMultipartResolver.class, MultipartConfigElement.class })
@ConditionalOnProperty(prefix = "spring.servlet.multipart", name = "enabled", matchIfMissing = true)
@ConditionalOnWebApplication(type = Type.SERVLET)
@EnableConfigurationProperties(MultipartProperties.class)
public class MultipartAutoConfiguration {
private final MultipartProperties multipartProperties;
public MultipartAutoConfiguration(MultipartProperties multipartProperties) {
this.multipartProperties = multipartProperties;
}
// 文件上传配置信息
@Bean
@ConditionalOnMissingBean({
MultipartConfigElement.class, CommonsMultipartResolver.class })
public MultipartConfigElement multipartConfigElement() {
return this.multipartProperties.createMultipartConfig();
}
// 文件上传解析器
@Bean(name = DispatcherServlet.MULTIPART_RESOLVER_BEAN_NAME)
@ConditionalOnMissingBean(MultipartResolver.class)
public StandardServletMultipartResolver multipartResolver() {
StandardServletMultipartResolver multipartResolver = new StandardServletMultipartResolver();
multipartResolver.setResolveLazily(this.multipartProperties.isResolveLazily());
return multipartResolver;
}
}
3.2、原理步骤
1、请求进来使用文件上传解析器判断(isMultipart),是上传请求类型就包装(resolveMultipart,返回MultipartHttpServletRequest)文件上传请求。
2、参数解析器来解析请求中的文件内容封装成MultipartFile。
3、将request中文件信息封装为一个Map;MultiValueMap<String, MultipartFile> ,使用 FileCopyUtils 实现文件流的拷贝
@PostMapping("/upload")
public String upload(@RequestParam("email") String email,
@RequestParam("username") String username,
@RequestPart("headerImg") MultipartFile headerImg,
@RequestPart("photos") MultipartFile[] photos)