使用Apache Commons FileUpload组件上传文件

梦里梦外; 2021-12-05 15:11 304阅读 0赞

**引入依赖：**

<dependency>
                <groupId>commons-fileupload</groupId>
                <artifactId>commons-fileupload</artifactId>
                <version>1.3.1</version>
            </dependency>
            <dependency>
                <groupId>commons-io</groupId>
                <artifactId>commons-io</artifactId>
                <version>2.4</version>
            </dependency>

使用Apache Commons FileUpload组件上传文件时

List<FileItem> items = upload.parseRequest(request);

items 大小总是为0，在Spring Boot中有默认的文件上传组件，在使用ServletFileUpload时需要关闭Spring Boot的默认配置

在SpringBoot 2.x中使用Apache Commons FileUpload组件上传时，需要关闭SpringBoot默认上传组件2.x配置如代码块所示。1.x的配置为：spring.http.multipart.enabled=false

#禁用MultipartResolver提供的默认值
    spring:
      servlet:
        multipart:
          enabled: false

**页面Demo：**

表单上传注意事项：form表单的内容格式要定义成multipart/form-data格式，post请求

<!DOCTYPE html>
    <html xmlns:th="http://www.thymeleaf.org">
    <head>
        <meta  charset="UTF-8">
        <title>文件上传</title>
    </head>
    <body>
    <form action="fileUpload" method="post" enctype="multipart/form-data">
        <div align="center">
            <fieldset style="width:80%">
                <legend>上传文件</legend><br/>
                <div align="left">上传文件1</div>
                <div align="left">
                    <input type="file" name="file1"/>
                </div>
                <div align="left">上传文件2</div>
                <div align="left">
                    <input type="file" name="file2"/>
                </div>
                <div>
                    <div align='left'>上传文件描述1</div>
                    <div align='left'><input type="text" name="description1"/></div>
                </div>
                <div>
                    <div align='left'>上传文件描述2</div>
                    <div align='left'><input type="text" name="description2"/></div>
                </div>
                <div>
                    <div align='left'>
                        <input type='submit' value="上传文件"/>
                    </div>
                </div>
            </fieldset>
        </div>
    </form>
    </div>
    </body>
    </html>

**后台代码工具类：**

import org.apache.commons.fileupload.FileItem;
    import org.apache.commons.fileupload.disk.DiskFileItemFactory;
    import org.apache.commons.fileupload.servlet.ServletFileUpload;
    import org.springframework.stereotype.Controller;
    import org.springframework.util.ResourceUtils;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    import org.springframework.web.bind.annotation.ResponseBody;
    
    import javax.servlet.http.HttpServletRequest;
    import java.io.*;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;
    import java.util.Set;
    
    @Controller
    public class FileUpload {
    
        @RequestMapping(value = "/fileUpload", method = RequestMethod.POST)
        @ResponseBody
        public void fileUpload(HttpServletRequest request) throws Exception {
            boolean upload = uploadFileUtil(request);
            System.out.println("上传结果" + upload);
        }
    
         //在开发测试模式时，得到的地址为：{项目跟目录}/target/classes/excelupload/
        //在打包成jar正式发布时，得到的地址为：{发布jar包目录}/excelupload
        public static boolean uploadFileUtil(HttpServletRequest request) throws Exception {
            //获取跟目录
            File path = new File(ResourceUtils.getURL("classpath:").getPath());
            if (!path.exists()) {
                path = new File("");
            }
            //如果上传目录为根目录下面的excelupload，则可以如下获取
            File upload = new File(path.getAbsolutePath(), "excelupload/");
            if (!upload.exists()) {
                upload.mkdirs();
            }
            System.out.println("upload url:" + upload.getAbsolutePath());
            //拿到请求上传的文件
            Map<String, Object> map = uploadFile(request);
            Set<Map.Entry<String, Object>> entries = map.entrySet();
            for (Map.Entry<String, Object> mapEntry : entries) {
                Object value = mapEntry.getValue();
                if (value instanceof FileItem) {
                    FileItem fileItem = (FileItem) value;
                    if(fileItem.getSize()>0) {
                        String key = mapEntry.getKey();
                        String[] split = key.split("\\:");
                        fileItem.write(new File(upload.toString()+"/" + split[1]));
                    }
                } else {
                    System.out.println("该处为上传文件描述内容:" + mapEntry.getKey()+"值为："+mapEntry.getValue());
                }
            }
            return true;
        }
    
        public static Map<String, Object> uploadFile(HttpServletRequest request) {
            Map<String, Object> parameters = new HashMap<String, Object>();
            //1、使用apache commons-fileupload组件文件上传
            // 默认最多允许存储1024个字节
            DiskFileItemFactory factory = new DiskFileItemFactory();
            //超过10M以上的文件 通过临时文件夹来上传 10*1024
            factory.setSizeThreshold(DiskFileItemFactory.DEFAULT_SIZE_THRESHOLD);
            //判断表单属性enctype，值为“multipart/form-data”
            if (ServletFileUpload.isMultipartContent(request)) {
                //创建一个FileItem工厂 通过DiskFileItemFactory对象创建文件上传核心组件
                ServletFileUpload upload = new ServletFileUpload(factory);
                upload.setSizeMax(1024 * 1024 * 20);
                upload.setHeaderEncoding("UTF-8");
                try {
                    //通过文件上传核心组件解析request请求，获取到所有的FileItem对象
                    List<FileItem> items = upload.parseRequest(request);
                    //遍历表单的所有表单项（FileItem） 并对其进行相关操作
                    for (FileItem item : items) {
                        //判断这个表单项如果是一个普通的表单项
                        if (item.isFormField()) {
                            String fieldName = item.getFieldName();
                            String value = new String(item.getString("UTF-8"));
                            parameters.put(fieldName, value);
                        } else {//如果不是表单的普通文本域，就是文件上传域，取输入流
                            //文件上传域，取输入流,如果是文件流的话，设置key为，form表单+文件名":"分割
                            parameters.put(item.getFieldName() + ":" + item.getName(), item);
                        }
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
            return parameters;
        }
    }

**Ajax请求上传文件：**

页面

<!DOCTYPE html>
    <html>
    <head>
        <meta charset="UTF-8">
        <title>文件上传</title>
        <script type="text/javascript" src="jquery/jquery-1.11.1-min.js"></script>
       
        <script type="text/javascript">
           $(function () {
               $("#uploadBtn").click(function () {
                   var formData = new FormData();
                   //注意：这里不能获取文件的路径，路径是一个字符串，这里应该是一个“文件上传控件的DOM对象”。
                   formData.append("FileUpload", $("#FileUpload")[0].files[0]);
                   //发送ajax post请求，向服务器传一个excel文件
                   $.ajax({
                       type: "post",
                       url: "ajaxFileUpload",
                       data: formData,
                       beforeSend: function () {
                           return true;
                       },
                       contentType: false, //不设置请求头的内容类型，默认的请求头类型是：application/x-www-form-urlencoded，这里不采用它，用：formData ，对应的是：enctype=multipart/form-data
                       processData: false, //禁止jquery对formData进行格式化预处理
                       success: function (json) {
                           alert(json)
                           if (json.result) {
                               alert("上传成功")
                           } else {
                               alert("上传失败");
                           }
                       }
                   });
               });
           });
        </script>
    </head>
    <body>
    <div align="left">上传文件Ajax</div>
    <div align="left">
        <input type="file" name="file1" id="FileUpload"/>
    </div>
    <button type="button" id="uploadBtn">Ajax上传</button>
    </div>
    </body>
    </html>

后端代码：

@RequestMapping(value = "/ajaxFileUpload", method = RequestMethod.POST)
        @ResponseBody
        public Map<String,Object> ajaxFileUpload(HttpServletRequest request) throws Exception {
            Map<String,Object> map =new HashMap<>();
            boolean upload = uploadFileUtil(request);
            System.out.println("Ajax上传结果" + upload);
            if (upload) {
                map.put("result", upload);
            } else {
                map.put("result", upload);
            }
            return map;
        }

参考：[Spring MVC使用commons fileupload实现文件上传功能][Spring MVC_commons fileupload]

[Spring MVC_commons fileupload]: https://www.cnblogs.com/-crazysnail/p/3923135.html