How to implement file upload - JavaWeb

Go directly to the code (  development,  framework): ideaSpringBoot

The first is Controllerto write:

package com.xxx.Controller;

import com.xxx.Tools.ImgTool;
import com.xxx.bean.Msg;
import org.apache.tomcat.util.http.fileupload.FileUploadBase;
import org.apache.tomcat.util.http.fileupload.FileUploadBase.*;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

@RestController
@RequestMapping(value = "/img")
public class ImgUploadController {

    @PostMapping(value = "/upload")
    public Msg uploadImg(@RequestParam(value = "img") MultipartFile img, HttpServletRequest request) throws IOException, FileSizeLimitExceededException {
        if (img == null){
            return Msg.fail().add("describe", "参数不能为空");
        } else {
            try {
                Map<String , Object> map = new HashMap<>();
                map = ImgTool.upload(img, request);
                if (map.get("resultStr").equals("300")){
                    return Msg.fail().add("describe", "文件格式不支持");
                } else {
                    return Msg.success().add("imgurl", map.get("resultStr"));
                }
            } catch (Exception e){
                return Msg.fail().add("describe", e);
            }
        }
    }
}

upload()The class where the function is located, contains some other toolmethods:

package com.xxx.Tools;

import com.xxx.bean.Picture;
import org.springframework.web.multipart.MultipartFile;
import javax.servlet.http.HttpServletRequest;
import java.io.File;
import java.io.IOException;
import java.util.Calendar;
import java.util.HashMap;
import java.util.Map;
import java.util.UUID;

public class ImgTool {

    /**
     * Upload an image and return the image path
     */
    public static Map<String, Object> upload(MultipartFile file, HttpServletRequest request) throws IOException {
        Map<String, Object> map = new HashMap<>();

        // Filter legal file types 
        String fileName = file.getOriginalFilename();
        String suffix = fileName.substring(fileName.lastIndexOf(".") + 1);
        String allowSuffixs = "gif,jpg,jpeg,bmp,png,ico" ;
         if (allowSuffixs.indexOf(suffix) == -1 ){
             // 300 means the file format does not support 
            map.put("resultStr", "300" );
            System.out.println( "The file format is not supported" );
             return map;
        }

        // Get the real path 
        String localPath = request.getServletContext().getRealPath("/" );

        // Create a new directory 
        String uri = File.separator + getNowDateStr(File.separator);
        File dir = new File(localPath + "/static/ProjectImgs/" + uri);
        if (!dir.exists()){
            dir.mkdirs();
        }

        // Create a new file 
        String newFileName = getUniqueFileName();
        File f = new File(dir.getPath() + File.separator + newFileName + "." + suffix);

        // Copy the data in the input stream to a new file 
        org.apache.commons.io.FileUtils.copyInputStreamToFile(file.getInputStream(), f);

        // Create a picture object 
        Picture pic = new Picture();
        pic.setLocalPath(f.getAbsolutePath());
        pic.setName(f.getName());
        // Replace \\ in the path with /, in line with the browser's grading rules 
        pic.setUrl(localPath.replace("\\", "/" )
                 + "static/ProjectImgs"
                + uri.replace("\\", "/") + "/" + newFileName + "." + suffix);

        // Insert into database
         // ... 

        map.put( "resultStr" , pic.getUrl());

        return map;
    }

    /**
     * Get the current date string
     * @param separator
     * @return
     */
    public static String getNowDateStr(String separator){
        Calendar now = Calendar.getInstance();
         int year = now.get(Calendar.YEAR);
         // remember to add one to month (because it counts from 0 by default) 
        int month = now.get(Calendar.MONTH)+1 ;
         int day = now.get(Calendar.DATE);

        return year + separator + month + separator + day;
    }

    // Generate a unique file name 
    public  static String getUniqueFileName(){
        String str = UUID.randomUUID().toString();
        return str.replace("-", "");
    }
}

Picturekind:

package com.xxx.bean;

import java.util.Date;

public class Picture {

    private String localPath;
    private String name;
    private String url;
    private Date addTime;

    public Picture() {
    }

    public Picture(String localPath, String name, String url, Date addTime) {
        this.localPath = localPath;
        this.name = name;
        this.url = url;
        this.addTime = addTime;
    }

    public String getLocalPath() {
        return localPath;
    }

    public void setLocalPath(String localPath) {
        this.localPath = localPath;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public Date getAddTime() {
        return addTime;
    }

    public void setAddTime(Date addTime) {
        this.addTime = addTime;
    }
}

In normal Webdevelopment, the above general writing method can be adapted to your own project needs with a little modification. For example , you need to set various restrictions on uploading files in the SSMframework ;dispatchServlet.xml

You SpringBootcan .ymlconfigure the file path in the file and the Applicationfile size property in the class where the project starts.

The following is SpringBootthe reference writing method of the configuration file size, which is written in the class ShouguoApplication, that is, the entry program segment:

package com.xxx;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.MultipartConfigFactory;
import org.springframework.context.annotation.Bean;
import javax.servlet.MultipartConfigElement;

@SpringBootApplication
public  class ShouguoApplication {

    public static void main(String[] args) {
        SpringApplication.run(ShouguoApplication.class, args);
    }

    /**
     * File upload configuration
     */
    @Bean
    public MultipartConfigElement multipartConfigElement(){
        MultipartConfigFactory factory = new MultipartConfigFactory();
         // maxSize 
        factory.setMaxFileSize("10240KB" );
         // Set the total upload data size 
        factory.setMaxRequestSize("102400KB" );
         return factory.createMultipartConfig();
    }
}