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情況：maven+SpringMVC + Spring + MyBatis + MySql
本文重要解釋若何應用input上傳文件到辦事器指定目次，或保留到數據庫中；若何從數據庫下載文件，和顯示圖象文件並完成縮放。
將文件存儲在數據庫中，普通是存文件的byte數組，對應的數據庫數據類型為blob。
起首要創立數據庫，此處應用MySql數據庫。
留意：文中給出的代碼多為節選主要片斷，其實不齊備。
1. 後期預備
應用maven創立一個springMVC+spring+mybatis+mysql的項目。
關於若何整合Spring+mybatis+mysql，請見MyBatis簡介與設置裝備擺設MyBatis+Spring+MySql：
MyBatis進修 之 1、MyBatis簡介與設置裝備擺設MyBaits+Spring+MySql
關於SpringMVC情況的搭建請見：應用Eclipse構建Maven的SpringMVC項目：
應用Eclipse構建Maven的SpringMVC項目
在前台html中，form的enctype為multipart/form-data。留意input、select的name要和StudentForm中成員逐個對應。
上傳的url為addAction.do，此action辦法的參數中應用StudentForm來映照提交的數據。此時便可以獲得到提交的文件的數據。然後我們就對文件停止操作。
創立PHOTO_TBL表：PHOTO_DATA字段用於寄存文件，類型為MyBatis的longblob；然後寫Mapper的Java接口PhotoMapper：包含增刪改查；mapper的xml文件：對應JAVA接口的sql語句。
而且須要Spring設置裝備擺設文件添加一個bean的聲明。
上面給出html、action、StudentForm的代碼片斷；創立PHOTO_TBL表的sql、PhotoMapper.java接口代碼、PhotoMapper.xml文件代碼。
1.1 html的form表單寫法
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辦法
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類
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 創立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
包含增、刪、改、查。個中新增中的photoId應用的是mysql自界說函數主動生成主鍵。在操作blob時須要制訂typeHandler為"org.apache.ibatis.type.BlobTypeHandler。insert、update時參數前面須要指定，resultMap中須要指定。
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設置裝備擺設文件
須要Spring設置裝備擺設文件添加一個org.springframework.web.multipart.commons.CommonsMultipartResolver的bean的聲明。
1.<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"> 2. <property name="maxUploadSize" value="1073741824" /> 3.</bean>
2. 將文件到辦事器上
1.private static final String uploadFilePath = "d:\\temp_upload_file\\";
2.
3./**
4. * 新增 - 提交 – 只保留文件到辦事器上
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. // 假如辦事器曾經存在和上傳文件同名的文件，則輸入提醒信息
13. File tempFile = new File(uploadFilePath + filename);
14. if (tempFile.exists()) {
15. boolean delResult = tempFile.delete();
16. System.out.println("刪除已存在的文件：" + delResult);
17. }
18. // 開端保留文件到辦事器
19. if (!filename.equals("")) {
20. FileOutputStream fos = new FileOutputStream(uploadFilePath + filename);
21. byte[] buffer = new byte[8192]; // 每次讀8K字節
22. int count = 0;
23. // 開端讀取上傳文件的字節，並將其輸入到辦事真個上傳文件輸入流中
24. while ((count = is.read(buffer)) > 0) {
25. fos.write(buffer, 0, count); // 向辦事端文件寫入字撙節
26. }
27. fos.close(); // 封閉FileOutputStream對象
28. is.close(); // InputStream對象
29. }
30. } catch (FileNotFoundException e) {
31. e.printStackTrace();
32. } catch (IOException e) {
33. e.printStackTrace();
34. }
35.}
3. 將文件上傳到數據庫中
1./**
2. * 新增 - 提交 – 保留文件到數據庫
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.下載文件
下載文件須要將byte數組復原成文件。
起首應用mybatis將數據庫中的byte數組查出來，指定文件名(包含格局)。然後應用OutputStream將文件輸出
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">下載照片</a>
5. 顯示byte圖片文件
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. 按長寬等比例縮放圖片
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"/>
以上所述是小編給年夜家引見的MyBatis與SpringMVC相聯合完成文件上傳、下載功效，願望對年夜家有所贊助，假如年夜家有任何疑問請給我留言，小編會實時答復年夜家的。在此也異常感激年夜家對網站的支撐！
