直接上代码 ( idea 开发，SpringBoot 框架 )：

首先是Controller的写法：

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
     
       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()函数所在的类，包含一些其他的tool方法 ：

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 {    /**     * 上传图片，并返回图片路径     */    public static Map
     
       upload(MultipartFile file, HttpServletRequest request) throws IOException {        Map
      
        map = new HashMap<>();        //过滤合法的文件类型        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代表文件格式不支持            map.put("resultStr", "300");            System.out.println("文件格式不支持");            return map;        }        //获取真实路径        String localPath = request.getServletContext().getRealPath("/");        //创建新目录        String uri = File.separator + getNowDateStr(File.separator);        File dir = new File(localPath + "/static/ProjectImgs/" + uri);        if (!dir.exists()){            dir.mkdirs();        }        //创建新文件        String newFileName = getUniqueFileName();        File f = new File(dir.getPath() + File.separator + newFileName + "." + suffix);        //将输入流中的数据复制到新文件        org.apache.commons.io.FileUtils.copyInputStreamToFile(file.getInputStream(), f);        //创建picture对象        Picture pic = new Picture();        pic.setLocalPath(f.getAbsolutePath());        pic.setName(f.getName());        //将路径中的\\替换成/，符合浏览器的分级规则        pic.setUrl(localPath.replace("\\", "/")                + "static/ProjectImgs"                + uri.replace("\\", "/") + "/" + newFileName + "." + suffix);        //插入到数据库        //...        map.put("resultStr", pic.getUrl());        return map;    }    /**     * 获取当前日期字符串     * @param separator     * @return     */    public static String getNowDateStr(String separator){        Calendar now = Calendar.getInstance();        int year = now.get(Calendar.YEAR);        //month 记得加一（因为默认从0开始计数）        int month = now.get(Calendar.MONTH)+1;        int day = now.get(Calendar.DATE);        return year + separator + month + separator + day;    }    //生成唯一的文件名    public static String getUniqueFileName(){        String str = UUID.randomUUID().toString();        return str.replace("-", "");    }}
      
     

Picture类：

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;    }}

在通常的Web开发中，上面的通用写法只要稍加改动边可以适应自己的项目需求，比如在SSM框架中需要在dispatchServlet.xml中设置上传文件的各种限制；

在SpringBoot中可以在.yml文件中配置文件路径，在项目起始的Application类中配置文件大小属性。

下面是SpringBoot中配置文件大小的参考写法，写在类ShouguoApplication，即入口程序段中：

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;@SpringBootApplicationpublic class ShouguoApplication {    public static void main(String[] args) {        SpringApplication.run(ShouguoApplication.class, args);    }    /**     * 文件上传配置     */    @Bean    public MultipartConfigElement multipartConfigElement(){        MultipartConfigFactory factory = new MultipartConfigFactory();        //maxSize        factory.setMaxFileSize("10240KB");        //设置总上传数据总大小        factory.setMaxRequestSize("102400KB");        return factory.createMultipartConfig();    }}