<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.10.RELEASE</version>
<relativePath/>
</parent>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
</dependencies>
启动类设置
@SpringBootApplication
public class FileUploadWebApplication {
public static void main(String[] args) throws Exception {
SpringApplication.run(FileUploadWebApplication.class, args);
}
//Tomcat large file upload connection reset
@Bean
public TomcatEmbeddedServletContainerFactory tomcatEmbedded() {
TomcatEmbeddedServletContainerFactory tomcat = new TomcatEmbeddedServletContainerFactory();
tomcat.addConnectorCustomizers((TomcatConnectorCustomizer) connector -> {
if ((connector.getProtocolHandler() instanceof AbstractHttp11Protocol<?>)) {
//-1 means unlimited
((AbstractHttp11Protocol<?>) connector.getProtocolHandler()).setMaxSwallowSize(-1);
}
});
return tomcat;
}
}
tomcatEmbedded这段代码是为了解决，上传文件大于10M出现连接重置的问题。此异常内容GlobalException也捕获不到。
详细内容参考：Tomcat large file upload connection reset
前端页面
<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<body>
<h1>Spring Boot file upload example</h1>
<form method="POST" action="/upload" enctype="multipart/form-data">
<input type="file" name="file" /><br/><br/>
<input type="submit" value="Submit" />
</form>
</body>
</html>
上传结果展示页面：
<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<body>
<h1>Spring Boot - Upload Status</h1>
<div th:if="${message}">
<h2 th:text="${message}"/>
</div>
</body>
</html>
上传控制类
@Controller
public class UploadController {
//Save the uploaded file to this folder
private static String UPLOADED_FOLDER = "F://temp//";
@GetMapping("/")
public String index() {
return "upload";
}
@PostMapping("/upload") // //new annotation since 4.3
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 {
// Get the file and save it somewhere
byte[] bytes = file.getBytes();
Path path = Paths.get(UPLOADED_FOLDER + file.getOriginalFilename());
Files.write(path, bytes);
redirectAttributes.addFlashAttribute("message",
"You successfully uploaded '" + file.getOriginalFilename() + "'");
} catch (IOException e) {
e.printStackTrace();
}
return "redirect:/uploadStatus";
}
@GetMapping("/uploadStatus")
public String uploadStatus() {
return "uploadStatus";
}
}
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.enabled=true #默认支持文件上传.
- spring.http.multipart.file-size-threshold=0 #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-size=1Mb # 最大支持文件大小
- spring.http.multipart.max-request-size=10Mb # 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：Common application properties
异常处理
@ControllerAdvice
public class GlobalExceptionHandler {
@ExceptionHandler(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，感兴趣的同学可以下来了解。
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