Implement file upload in SpringBoot

1. To create a SpringBoot project, you need to import the dependencies of spring-boot-starter-web

         <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

2. Write the core configuration application.properties of the file

server.port=2100
#文件的保存地址
file-save-path=D:/a/f/picture/

#是否开启文件上传支持，默认为true。
spring.servlet.multipart.enabled=true 
#文件写入磁盘的阈值，默认为0。
spring.servlet.multipart.file-size-threshold=0
#上传文件的临时保存位置。
spring.servlet.multipart.location=D:/1javaweb/b
#上传的单个文件的最大大小，默认为1MB。
spring.servlet.multipart.max-file-size=30MB
#多文件上传时文件的总大小，默认为10MB。
spring.servlet.multipart.max-request-size=10MB
#文件是否延迟解析，默认为false。
spring.servlet.multipart.resolve-lazily=false

3. Write the control layer

import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;
import javax.servlet.http.HttpServletRequest;
import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.UUID;


@RestController
public class FileUploadController {
    @Value("${file-save-path}")
    private String fileSavePath;

    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd/");

    @RequestMapping("/upload")
    public String upload(MultipartFile uploadFile, HttpServletRequest req) {
        String filePath = "";
        String format = sdf.format(new Date());
        File folder = new File(fileSavePath + format);
        if (!folder.isDirectory()) {
            folder.mkdirs();
            String oldName = uploadFile.getOriginalFilename();
            String newName = UUID.randomUUID().toString() +
                    oldName.substring(oldName.lastIndexOf("."), oldName.length());
            try {
                uploadFile.transferTo(new File(folder, newName));
                filePath = req.getScheme() + "://" + req.getServerName() + ":" +
                        req.getServerPort() + "/uploadFile/" + format + newName;
            } catch (IOException e) {
                return "上传失败! ";
            }
        }
        String oldName = uploadFile.getOriginalFilename();
        String newName = UUID.randomUUID().toString().replace("-","") +
                oldName.substring(oldName.lastIndexOf("."), oldName.length());
        try {
            uploadFile.transferTo(new File(folder, newName));
            filePath = req.getScheme() + "://" + req.getServerName() + ":" +
                    req.getServerPort() + "/uploadFile/" + format + newName;
        } catch (IOException e) {
            return "上传失败! ";
        }
        return filePath;
    }
}

4. Create a static directory under resources, and then create an update.html page

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title></head>
<body>
    <!--enctype 属性规定在发送到服务器之前应该如何对表单数据进行编码。-->
<form action="/upload" method="post" enctype="multipart/form-data">
    <input type="file" name="uploadFile" value="请选择文件" required>
    <input type="submit" value="上传">
</form>
</body>
</html>

5. If you want to query the file or picture just uploaded in the cache, you need to add the following configuration class

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class WebConfig implements WebMvcConfigurer {

    @Value("${file-save-path}")
    private String fileSavePath;
    
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/uploadFile/**")
                .addResourceLocations("file:"+fileSavePath);
    }
}

6. If you want any ip to be accessible, you need to add the following configuration class

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.CorsRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class CarsConfig implements WebMvcConfigurer {
    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/**")//所有的都配置跨域
                .allowedOrigins("*")//所有的请求可以访问跨域的资源
                 .allowedHeaders("*")//所有的请求头都可以访问
        .allowedMethods("GET","POST","PUT","DELETE","HEAD","OPTION")//什么类型的请求都可以访问后端资源
         .maxAge(3600)//服务端存储相关信息的时间      秒
        ;
    }
}

7. Start our SpringBoot project and visit this address

http://localhost:2100/update.html

If we configure the WebConfig configuration class just now, we can directly access the uploaded address in the browser, and we can see the picture we just uploaded

If cross-domain access is configured, it can be accessed through our ip, and can also be accessed on other computers

Query the ip of the local computer:

1. Shortcut key: win+r, enter cmd in the pop-up window and click OK

2. Input
ipconfig
Find the ip of your computer in the current LAN

Implement file upload in SpringBoot

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