myBatis + SpringMVC上傳,、下載文件

IT技術(shù)武館 2015-10-12

展開全文

環(huán)境：maven+SpringMVC + Spring + MyBatis + MySql

本文主要說明如何使用input上傳文件到服務器指定目錄，或保存到數(shù)據(jù)庫中,；如何從數(shù)據(jù)庫下載文件,，和顯示圖像文件并實現(xiàn)縮放。

將文件存儲在數(shù)據(jù)庫中,，一般是存文件的byte數(shù)組,，對應的數(shù)據(jù)庫數(shù)據(jù)類型為blob。

首先要創(chuàng)建數(shù)據(jù)庫,，此處使用MySql數(shù)據(jù)庫,。

注意：文中給出的代碼多為節(jié)選重要片段，并不齊全,。

1. 前期準備

使用maven創(chuàng)建一個springMVC+spring+mybatis+mysql的項目,。

關(guān)于如何整合Spring+mybatis+mysql,，請見MyBatis簡介與配置MyBatis+Spring+MySql：

MyBatis學習之一、MyBatis簡介與配置MyBaits+Spring+MySql

關(guān)于SpringMVC環(huán)境的搭建請見：使用Eclipse構(gòu)建Maven的SpringMVC項目：

使用Eclipse構(gòu)建Maven的SpringMVC項目

在前臺html中,，form的enctype為multipart/form-data,。注意input、select的name要和StudentForm中成員一一對應,。

上傳的url為addAction.do,，此action方法的參數(shù)中使用StudentForm來映射提交的數(shù)據(jù)。此時就可以獲取到提交的文件的數(shù)據(jù),。然后我們就對文件進行操作,。

創(chuàng)建PHOTO_TBL表：PHOTO_DATA字段用于存放文件，類型為MyBatis的longblob,；然后寫Mapper的Java接口PhotoMapper：包括增刪改查,；mapper的xml文件：對應JAVA接口的sql語句。

并且需要Spring配置文件添加一個bean的聲明,。

下面給出html,、action、StudentForm的代碼片段,；創(chuàng)建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

<form action="<c:url value='addAction.do' />" method="post" enctype="multipart/form-data">
<table>
<tr>
<td width="100" align="right">照片：</td>
<td><input type="file" name="studentPhoto"/></td>
</tr>
</table>
<input type="submit">
</form>

1.2 action方法

/**
* 新增 - 提交
*/
@RequestMapping(value = "addAction.do")
public String add_action(ModelMap model, StudentForm form) {
}

1.3 StudentForm類

package liming.student.manager.web.model;
import org.springframework.web.multipart.MultipartFile;
public class StudentForm extends GeneralForm {
private String studentName;
private int studentSex;
private String studentBirthday;
private MultipartFile studentPhoto;
}

1.4 創(chuàng)建PHOTO_TBL

CREATE TABLE PHOTO_TBL
(
PHOTO_ID VARCHAR(100) PRIMARY KEY,
PHOTO_DATA LONGBLOB,
FILE_NAME VARCHAR(10)
);

1.5 PhotoMapper接口

@Repository
@Transactional
public interface PhotoMapper {
public void createPhoto(PhotoEntity entity);
public int deletePhotoByPhotoId(String photoId);
public int updatePhotoDate(@Param("photoId") String photoId, @Param("photoDate") byte[] photoDate);
public PhotoEntity getPhotoEntityByPhotoId(String photoId);
}

1.6 PhotoMapper.xml文件

包括增、刪,、改,、查。其中新增中的photoId使用的是mysql自定義函數(shù)自動生成主鍵,。在操作blob時需要制定typeHandler為"org.apache.ibatis.type.BlobTypeHandler,。insert、update時參數(shù)后面需要指定,，resultMap中需要指定,。

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-////DTD Mapper 3.0//EN" "http:///dtd/mybatis-3-mapper.dtd">
<mapper namespace="liming.student.manager.data.PhotoMapper">
<resultMap type="liming.student.manager.data.model.PhotoEntity" id="photoMapper_resultMap_photoEntity">
<id property="photoId" column="PHOTO_ID" javaType="String" jdbcType="VARCHAR" />
<result property="photoData" column="PHOTO_DATA" javaType="byte[]" jdbcType="BLOB" typeHandler="org.apache.ibatis.type.BlobTypeHandler" />
<result property="fileName" column="FILE_NAME" javaType="String" jdbcType="VARCHAR" />
</resultMap>
<insert id="createPhoto" parameterType="liming.student.manager.data.model.PhotoEntity">
<selectKey keyProperty="photoId" resultType="String" order="BEFORE">
select nextval('photo')
</selectKey>
INSERT INTO PHOTO_TBL(PHOTO_ID,
PHOTO_DATA,
FILE_NAME)
VALUES(#{photoId, jdbcType=VARCHAR},
#{photoData, javaType=byte[], jdbcType=BLOB, typeHandler=org.apache.ibatis.type.BlobTypeHandler},
#{fileName, jdbcType=VARCHAR})
</insert>
<delete id="deletePhotoByPhotoId">
DELETE FROM PHOTO_TBL
WHERE PHOTO_ID = #{photoId, jdbcType=VARCHAR}
</delete>
<update id="updatephotoData" >
UPDATE PHOTO_TBL
SET PHOTO_DATA = #{photoData, javaType=byte[], jdbcType=BLOB, typeHandler=org.apache.ibatis.type.BlobTypeHandler},
FILE_NAME = #{fileName, jdbcType=VARCHAR}
WHERE PHOTO_ID = #{photoId, jdbcType=VARCHAR}
</update>
<select id="getPhotoEntityByPhotoId" resultMap="photoMapper_resultMap_photoEntity">
SELECT PHOTO_ID,
PHOTO_DATA,
FILE_NAME
FROM PHOTO_TBL
WHERE PHOTO_ID = #{photoId, jdbcType=VARCHAR}
</select>
</mapper>

1.7 spring配置文件

需要Spring配置文件添加一個org.springframework.web.multipart.commons.CommonsMultipartResolver的bean的聲明。

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

2. 將文件到服務器上

private static final String uploadFilePath = "d:\\temp_upload_file\\";
/**
* 新增 - 提交 – 只保存文件到服務器上
*/
@RequestMapping(value = "addAction.do")
public String add_action(ModelMap model, StudentForm form) {
try {
MultipartFile uploadFile = form.getStudentPhoto();
String filename = uploadFile.getOriginalFilename();
InputStream is = uploadFile.getInputStream();
// 如果服務器已經(jīng)存在和上傳文件同名的文件,，則輸出提示信息
File tempFile = new File(uploadFilePath + filename);
if (tempFile.exists()) {
boolean delResult = tempFile.delete();
System.out.println("刪除已存在的文件：" + delResult);
}
// 開始保存文件到服務器
if (!filename.equals("")) {
FileOutputStream fos = new FileOutputStream(uploadFilePath + filename);
byte[] buffer = new byte[8192]; // 每次讀8K字節(jié)
int count = 0;
// 開始讀取上傳文件的字節(jié),，并將其輸出到服務端的上傳文件輸出流中
while ((count = is.read(buffer)) > 0) {
fos.write(buffer, 0, count); // 向服務端文件寫入字節(jié)流
}
fos.close(); // 關(guān)閉FileOutputStream對象
is.close(); // InputStream對象
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}

3. 將文件上傳到數(shù)據(jù)庫中

/**
* 新增 - 提交 – 保存文件到數(shù)據(jù)庫
*/
@RequestMapping(value = "addAction.do")
public String add_action(ModelMap model, StudentForm form) {
InputStream is = form.getStudentPhoto().getInputStream();
byte[] studentPhotoData = new byte[(int) form.getStudentPhoto().getSize()];
is.read(studentPhotoData);
String fileName = form.getStudentPhoto().getOriginalFilename();
PhotoEntity photoEntity = new PhotoEntity();
photoEntity.setPhotoData(studentPhotoData);
photoEntity.setFileName(fileName);
this.photoMapper.createPhoto(photoEntity);
}

4.下載文件

下載文件需要將byte數(shù)組還原成文件。

首先使用mybatis將數(shù)據(jù)庫中的byte數(shù)組查出來,，指定文件名(包括格式),。然后使用OutputStream將文件輸入

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

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

5. 顯示byte圖片文件

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

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

6. 按長寬等比例縮放圖片

@RequestMapping(value = "getPhotoId")
public void getPhotoById (String id, int width, int height, final HttpServletResponse response){
PhotoEntity entity = this.photoMapper.getPhotoEntityByPhotoId(id);
byte[] data = entity.getPhotoData();
if (width != 0 && height != 0) {
data = scaleImage(data, width, height);
}
response.setContentType("image/jpeg");
response.setCharacterEncoding("UTF-8");
OutputStream outputSream = response.getOutputStream();
InputStream in = new ByteArrayInputStream(data);
int len = 0;
byte[] buf = new byte[1024];
while ((len = in.read(buf, 0, 1024)) != -1) {
outputSream.write(buf, 0, len);
}
outputSream.close();
}
public static byte[] scaleImage(byte[] data, int width, int height) throws IOException {
BufferedImage buffered_oldImage = ImageIO.read(new ByteArrayInputStream(data));
int imageOldWidth = buffered_oldImage.getWidth();
int imageOldHeight = buffered_oldImage.getHeight();
double scale_x = (double) width / imageOldWidth;
double scale_y = (double) height / imageOldHeight;
double scale_xy = Math.min(scale_x, scale_y);
int imageNewWidth = (int) (imageOldWidth * scale_xy);
int imageNewHeight = (int) (imageOldHeight * scale_xy);
BufferedImage buffered_newImage = new BufferedImage(imageNewWidth, imageNewHeight, BufferedImage.TYPE_INT_RGB);
buffered_newImage.getGraphics().drawImage(buffered_oldImage.getScaledInstance(imageNewWidth, imageNewHeight, BufferedImage.SCALE_SMOOTH), 0, 0, null);
buffered_newImage.getGraphics().dispose();
ByteArrayOutputStream outPutStream = new ByteArrayOutputStream();
ImageIO.write(buffered_newImage, "jpeg", outPutStream);
return outPutStream.toByteArray();
}