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