基于ssm的文件上傳到服務器，存入數據庫

1.在maven中導入依賴

    <dependency>
      <groupId>commons-fileupload</groupId>
      <artifactId>commons-fileupload</artifactId>
      <version>${commons-fileupload.version}</version>
    </dependency>
    <dependency>
      <groupId>commons-io</groupId>
      <artifactId>commons-io</artifactId>
      <version>${commons-io.version}</version>
    </dependency>

2.在spring-mvc配置文件中添加

    <!-- 定義文件解釋器 -->
    <bean name="multipartResolver"
          class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <!--設置文件大小：單位字節-->
        <property name="maxInMemorySize" value="1024" />
        <property name="defaultEncoding" value="UTF-8" />
        <property name="maxUploadSize" value="5000000"/>
    </bean>

3.定義上傳文件工具類

package com.nz.homework.utils;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.springframework.util.FileCopyUtils;
import org.springframework.web.multipart.MultipartFile;
import java.io.*;
import java.util.UUID;
public class UploadUtils {
    public String upload(String path,MultipartFile multipartFile){
        //返回文件的類型,在此處中并沒有用到，只是列出getContentType是返回文件的類型
        String type = multipartFile.getContentType();
        //拿到文件的原始名稱，即例如a.jpg
        String originalFilename = multipartFile.getOriginalFilename();
        //判斷是否為空
        if (originalFilename==null){
            return null;
        }
        //因為上傳文件只有一個upload目錄，所有的文件都會放在這個文件下，會堆積大量的文件，所以把文件進行分開在upload不同的目錄中，利用hash算法就行計算分配目錄。例如upload/4/5;或者upload/5/5;這種
        //拿到文件原名稱的hashcode
        int hashCode = originalFilename.hashCode();
        //拿到upload下第一個目錄的名稱upload/n
        int dir1 = hashCode & 0xf;
        //拿到upload下的n目錄下的目錄名稱upload/n/n
        int dir2 = (hashCode & 0xf0) >> 4;
        //拼接路徑，path是傳過來的文件保存路徑，即upload的真實路徑,
        String dir = path + File.separator+dir1 + File.separator + dir2;
        把路徑丟到File文件中
        File file = new File(dir);
        //如果d:\1\2這個文件夾不存在，才創建
        if (!file.exists()){
            file.mkdirs();
        }
        //生成新的UUID.randomUUID().toString()：為了防止文件名重復
        String newFileName = UUID.randomUUID().toString().replace("-","")+"."+originalFilename.substring(originalFilename.lastIndexOf(".")+1);
        InputStream is = null;
        OutputStream os = null;
        try {
            is = multipartFile.getInputStream();
            os = new FileOutputStream(dir+File.separator+newFileName);
            //對文件進行復制
            FileCopyUtils.copy(is,os);
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            if (is!=null){
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (os!=null){
                try {
                    os.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        //返回文件的路徑，以便保存到數據庫中
        return dir1+File.separator+dir2+File.separator+newFileName;
    }
}

4.在service的實現類中實現

@Service("/bookService")
public class BookServiceImpl implements BookService {
    private static final String UPLOAD_DIR= "D:\\code\\week15\\practice\\src\\main\\webapp\\upload";
    //不建議用new UploadUtils，因為要低耦合，建議把UploadUtils類的upload方法換成靜態的方法
    private UploadUtils uploadUtils = new UploadUtils();
    @Resource
    BookMapper bookMapper;
        @Override
    public int insertBook(MultipartFile multipartFile, Book book) {
        String newPath = uploadUtils.upload(UPLOAD_DIR, multipartFile);
        //設置存到數據庫的img路徑
        book.setImg(newPath);
        return bookMapper.addBook(book);
    }
}

5.controller層代碼

    @RequestMapping("/addBook")
    //Result為工具類，參考上一篇的分頁中有完整的Result代碼
    public Result addBook(MultipartFile multipartFile, Book book){
        try {
            if (multipartFile.isEmpty()){
                return Result.error();
            }
            int rows = bookService.insertBook(multipartFile,book);
            return Result.success(rows);
        } catch (Exception e) {
            log.error(e.getMessage());
        }
        return Result.error();
    }

6.entity層代碼

@Data
public class Book {
    /**
    * 圖書ID
    */
    private Integer bid;
    /**
    * 圖書名稱
    */
    private String name;
    /**
    * 作者
    */
    private String author;
    private Double price;
    private Date crtTime;
    private String Img;
}

配置tomcat虛擬路徑

1.第一步

2.第二步，點擊External Souce

3.第三步，選擇要上傳的位置，web下的upload，點擊upload，然后重啟tomcat即可

前端中的form表單結合FormData

<!DOCTYPE html>
<html lang="en" xmlns:border="http://www.w3.org/1999/xhtml">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="js/jquery.js"></script>
    <script>
        $(function () {
            $("#upload").click(function () {
            //$('#uploadForm')[0]為選擇器，不規定為id選擇器，前提是該選擇器能獲取file文件，然后放入到formData中
                var formData = new FormData($('#uploadForm')[0]);
                console.log(formData.get("file"))
                if (formData ==={} || formData===""){
                    alert("請選擇文件")
                }
                formData.append("multipartFile",formData.get("file"));
                //調用formData的append方法，將book屬性都添加進去，img填空白即可。
                formData.append("name","龍哥傳");
                formData.append("author","龍哥");
                formData.append("price","10.33");
                formData.append("img","");
                $.ajax({
                    type: 'post',
                    url: "http://localhost:8080/practice/book/addBook",
                    data: formData,
                    cache: false,
                    processData: false,
                    contentType: false,
                    success:(function (results) {
                    if (results.data!==0 || results.status === 200){
                        alert("成功")
                    }
                    }),
                    error:(function () {
                    alert("上傳失敗");
                }),
            });
         });
     });
    </script>
</head>
<body>
<form id="uploadForm" enctype="multipart/form-data">
    文件:<input id="file" type="file" name="file"/>
</form>
<button id="upload">上傳文件</button>
</body>
</html>