MyBatis与SpringMVC相结合实现文件上传、下载功能

环境：maven+SpringMVC + Spring + MyBatis + MySql

本文主要说明如何使用input上传文件到服务器指定目录，或保存到数据库中；如何从数据库下载文件，和显示图像文件并实现缩放。

将文件存储在数据库中，一般是存文件的byte数组，对应的数据库数据类型为blob。

首先要创建数据库，此处使用MySql数据库。

注意：文中给出的代码多为节选重要片段，并不齐全。

1. 前期准备

使用maven创建一个springMVC+spring+mybatis+mysql的项目。

关于如何整合Spring+mybatis+mysql，请见MyBatis简介与配置MyBatis+Spring+MySql：

MyBatis学习 之 一、MyBatis简介与配置MyBaits+Spring+MySql

关于SpringMVC环境的搭建请见：使用Eclipse构建Maven的SpringMVC项目：

使用Eclipse构建Maven的SpringMVC项目

在前台html中，form的enctype为multipart/form-data。注意input、select的name要和StudentForm中成员一一对应。

上传的url为addAction.do，此action方法的参数中使用StudentForm来映射提交的数据。此时就可以获取到提交的文件的数据。然后我们就对文件进行操作。

创建PHOTO_TBL表：PHOTO_DATA字段用于存放文件，类型为MyBatis的longblob；然后写Mapper的Java接口PhotoMapper：包括增删改查；mapper的xml文件：对应JAVA接口的sql语句。

并且需要Spring配置文件添加一个bean的声明。

下面给出html、action、StudentForm的代码片段；创建PHOTO_TBL表的sql、PhotoMapper.java接口代码、PhotoMapper.xml文件代码。

1.1 html的form表单写法

1.<form action="<c:url value='addAction.do' />" method="post" enctype="multipart/form-data">
2. <table>
3. <tr>
4. <td width="100" align="right">照片：</td>
5. <td><input type="file" name="studentPhoto"/></td>
6. </tr>
7. </table>
8. <input type="submit">
9.</form> 

1.2 action方法

1./**
2. * 新增 - 提交
3. */
4.@RequestMapping(value = "addAction.do")
5.public String add_action(ModelMap model, StudentForm form) {
6.
7.} 

1.3 StudentForm类

1.package liming.student.manager.web.model;
2.
3.import org.springframework.web.multipart.MultipartFile;
4.
5.public class StudentForm extends GeneralForm {
6.
7. private String studentName;
8. private int studentSex;
9. private String studentBirthday;
10. private MultipartFile studentPhoto;
11.
12.} 

1.4 创建PHOTO_TBL

1.CREATE TABLE PHOTO_TBL
2.(
3. PHOTO_ID VARCHAR(100) PRIMARY KEY,
4. PHOTO_DATA LONGBLOB,
5. FILE_NAME VARCHAR(10)
6.); 

1.5 PhotoMapper接口

1.@Repository
2.@Transactional
3.public interface PhotoMapper {
4.
5. public void createPhoto(PhotoEntity entity);
6.
7. public int deletePhotoByPhotoId(String photoId);
8.
9. public int updatePhotoDate(@Param("photoId") String photoId, @Param("photoDate") byte[] photoDate);
10.
11. public PhotoEntity getPhotoEntityByPhotoId(String photoId);
12.
13.} 

1.6 PhotoMapper.xml文件

包括增、删、改、查。其中新增中的photoId使用的是mysql自定义函数自动生成主键。在操作blob时需要制定typeHandler为"org.apache.ibatis.type.BlobTypeHandler。insert、update时参数后面需要指定，resultMap中需要指定。

1.<?xml version="1.0" encoding="UTF-8" ?>
2.<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
3.<mapper namespace="liming.student.manager.data.PhotoMapper">
4. <resultMap type="liming.student.manager.data.model.PhotoEntity" id="photoMapper_resultMap_photoEntity">
5. <id property="photoId" column="PHOTO_ID" javaType="String" jdbcType="VARCHAR" />
6. <result property="photoData" column="PHOTO_DATA" javaType="byte[]" jdbcType="BLOB" typeHandler="org.apache.ibatis.type.BlobTypeHandler" />
7. <result property="fileName" column="FILE_NAME" javaType="String" jdbcType="VARCHAR" />
8. </resultMap>
9.
10. <insert id="createPhoto" parameterType="liming.student.manager.data.model.PhotoEntity">
11. <selectKey keyProperty="photoId" resultType="String" order="BEFORE">
12. select nextval('photo')
13. </selectKey>
14. INSERT INTO PHOTO_TBL(PHOTO_ID,
15. PHOTO_DATA,
16. FILE_NAME)
17. VALUES(#{photoId, jdbcType=VARCHAR},
18. #{photoData, javaType=byte[], jdbcType=BLOB, typeHandler=org.apache.ibatis.type.BlobTypeHandler},
19. #{fileName, jdbcType=VARCHAR})
20. </insert>
21.
22. <delete id="deletePhotoByPhotoId">
23. DELETE FROM PHOTO_TBL
24. WHERE PHOTO_ID = #{photoId, jdbcType=VARCHAR}
25. </delete>
26.
27. <update id="updatephotoData" >
28. UPDATE PHOTO_TBL
29. SET PHOTO_DATA = #{photoData, javaType=byte[], jdbcType=BLOB, typeHandler=org.apache.ibatis.type.BlobTypeHandler},
30. FILE_NAME = #{fileName, jdbcType=VARCHAR}
31. WHERE PHOTO_ID = #{photoId, jdbcType=VARCHAR}
32. </update>
33.
34. <select id="getPhotoEntityByPhotoId" resultMap="photoMapper_resultMap_photoEntity">
35. SELECT PHOTO_ID,
36. PHOTO_DATA,
37. FILE_NAME
38. FROM PHOTO_TBL
39. WHERE PHOTO_ID = #{photoId, jdbcType=VARCHAR}
40. </select>
41.</mapper> 

1.7 spring配置文件

需要Spring配置文件添加一个org.springframework.web.multipart.commons.CommonsMultipartResolver的bean的声明。

1.<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
2. <property name="maxUploadSize" value="1073741824" />
3.</bean> 

2. 将文件到服务器上

1.private static final String uploadFilePath = "d:\\temp_upload_file\\";
2.
3./**
4. * 新增 - 提交 – 只保存文件到服务器上
5. */
6.@RequestMapping(value = "addAction.do")
7.public String add_action(ModelMap model, StudentForm form) {
8.try {
9. MultipartFile uploadFile = form.getStudentPhoto();
10. String filename = uploadFile.getOriginalFilename();
11. InputStream is = uploadFile.getInputStream();
12. // 如果服务器已经存在和上传文件同名的文件，则输出提示信息
13. File tempFile = new File(uploadFilePath + filename);
14. if (tempFile.exists()) {
15. boolean delResult = tempFile.delete();
16. System.out.println("删除已存在的文件：" + delResult);
17. }
18. // 开始保存文件到服务器
19. if (!filename.equals("")) {
20. FileOutputStream fos = new FileOutputStream(uploadFilePath + filename);
21. byte[] buffer = new byte[8192]; // 每次读8K字节
22. int count = 0;
23. // 开始读取上传文件的字节，并将其输出到服务端的上传文件输出流中
24. while ((count = is.read(buffer)) > 0) {
25. fos.write(buffer, 0, count); // 向服务端文件写入字节流
26. }
27. fos.close(); // 关闭FileOutputStream对象
28. is.close(); // InputStream对象
29. }
30. } catch (FileNotFoundException e) {
31. e.printStackTrace();
32. } catch (IOException e) {
33. e.printStackTrace();
34. }
35.} 

3. 将文件上传到数据库中

1./**
2. * 新增 - 提交 – 保存文件到数据库
3. */
4.@RequestMapping(value = "addAction.do")
5.public String add_action(ModelMap model, StudentForm form) {
6. InputStream is = form.getStudentPhoto().getInputStream();
7. byte[] studentPhotoData = new byte[(int) form.getStudentPhoto().getSize()];
8. is.read(studentPhotoData);
9. String fileName = form.getStudentPhoto().getOriginalFilename();
10. PhotoEntity photoEntity = new PhotoEntity();
11. photoEntity.setPhotoData(studentPhotoData);
12. photoEntity.setFileName(fileName);
13. this.photoMapper.createPhoto(photoEntity);
14.} 

4.下载文件

下载文件需要将byte数组还原成文件。

首先使用mybatis将数据库中的byte数组查出来，指定文件名(包括格式)。然后使用OutputStream将文件输入

1.@RequestMapping(value = "downPhotoById")
2.public void downPhotoByStudentId(String id, final HttpServletResponse response){
3. PhotoEntity entity = this.photoMapper.getPhotoEntityByPhotoId(id);
4. byte[] data = entity.getPhotoData();
5. String fileName = entity.getFileName()== null ? "照片.png" : entity.getFileName();
6. fileName = URLEncoder.encode(fileName, "UTF-8");
7. response.reset();
8. response.setHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\"");
9. response.addHeader("Content-Length", "" + data.length);
10. response.setContentType("application/octet-stream;charset=UTF-8");
11. OutputStream outputStream = new BufferedOutputStream(response.getOutputStream());
12. outputStream.write(data);
13. outputStream.flush();
14. outputStream.close();
15.} 

<a href="<%=request.getContextPath() %>/downPhotoById.do?id=8000001">下载照片</a> 

5. 显示byte图片文件

1.@RequestMapping(value = "getPhotoById")
2.public void getPhotoById (String id, final HttpServletResponse response){
3. PhotoEntity entity = this.photoMapper.getPhotoEntityByPhotoId(id);
4. byte[] data = entity.getPhotoData();
5. response.setContentType("image/jpeg");
6. response.setCharacterEncoding("UTF-8");
7. OutputStream outputSream = response.getOutputStream();
8. InputStream in = new ByteArrayInputStream(data);
9. int len = 0;
10. byte[] buf = new byte[1024];
11. while ((len = in.read(buf, 0, 1024)) != -1) {
12. outputSream.write(buf, 0, len);
13. }
14. outputSream.close();
15.} 

<img src="<%=request.getContextPath() %>/getPhotoById.do?id=8000001"/> 

6. 按长宽等比例缩放图片

1.@RequestMapping(value = "getPhotoId")
2.public void getPhotoById (String id, int width, int height, final HttpServletResponse response){
3. PhotoEntity entity = this.photoMapper.getPhotoEntityByPhotoId(id);
4. byte[] data = entity.getPhotoData();
5. if (width != 0 && height != 0) {
6. data = scaleImage(data, width, height);
7. }
8. response.setContentType("image/jpeg");
9. response.setCharacterEncoding("UTF-8");
10. OutputStream outputSream = response.getOutputStream();
11. InputStream in = new ByteArrayInputStream(data);
12. int len = 0;
13. byte[] buf = new byte[1024];
14. while ((len = in.read(buf, 0, 1024)) != -1) {
15. outputSream.write(buf, 0, len);
16. }
17. outputSream.close();
18.}
19.
20.public static byte[] scaleImage(byte[] data, int width, int height) throws IOException {
21. BufferedImage buffered_oldImage = ImageIO.read(new ByteArrayInputStream(data));
22. int imageOldWidth = buffered_oldImage.getWidth();
23. int imageOldHeight = buffered_oldImage.getHeight();
24. double scale_x = (double) width / imageOldWidth;
25. double scale_y = (double) height / imageOldHeight;
26. double scale_xy = Math.min(scale_x, scale_y);
27. int imageNewWidth = (int) (imageOldWidth * scale_xy);
28. int imageNewHeight = (int) (imageOldHeight * scale_xy);
29. BufferedImage buffered_newImage = new BufferedImage(imageNewWidth, imageNewHeight, BufferedImage.TYPE_INT_RGB);
30. buffered_newImage.getGraphics().drawImage(buffered_oldImage.getScaledInstance(imageNewWidth, imageNewHeight, BufferedImage.SCALE_SMOOTH), 0, 0, null);
31. buffered_newImage.getGraphics().dispose();
32. ByteArrayOutputStream outPutStream = new ByteArrayOutputStream();
33. ImageIO.write(buffered_newImage, "jpeg", outPutStream);
34. return outPutStream.toByteArray();
35.} 

<img src="<%=request.getContextPath() %>/getPhotoById.do?id=8000001&width=300&height=300"/> 

以上所述是小编给大家介绍的MyBatis与SpringMVC相结合实现文件上传、下载功能，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对我们网站的支持！