数据库：mysql + mybatis

文件：本项目保存的是excel文件，其他文件应该也是适用的

最近由于项目原因，需将文件保存到数据库中，最先开始设计新增一个类型为blob的字段，结果保存没有问题，但下载的时候如果该excel文件里包含特殊公式，或者版本不兼容时，会丢失样式和内容，最终解决方式：将bolb类型改为mediumtext(或则text)，text最大支持64kb的文件，mediumtext最大支持16M的文件，可视情况进行设置

例如：alter table ab_report_history add column fileContent mediumtext COMMENT '文件内容';

重点：保存时将文件转换为String后，base64编码，下载时将内容取出来，base64解码

示例：

java代码：

保存时：

AbReportHistory record = new AbReportHistory();

record.setFileContent(FileUtil.encodeBase64File(myfile)); //注意此方法

下载时：

new BASE64Decoder().decodeBuffer(编码后的string); //通过此方法解码

java字段类型：

private String fileContent;

mybatis

--------------------------------以上是将文件保存到数据库的关键内容--------------------------------------------------------

以下提供相关工具类：

package *.*.*.*;

import java.io.BufferedInputStream;

import java.io.BufferedOutputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.IOException;

import java.nio.ByteBuffer;

import java.nio.channels.FileChannel;

import javax.servlet.ServletOutputStream;

import javax.servlet.http.HttpServletResponse;

import org.springframework.web.multipart.MultipartFile;

import sun.misc.BASE64Decoder;

import sun.misc.BASE64Encoder;

/**

* 文件操作工具类

* @author sunddylee

* @date 2016年12月20日

*

*/

public class FileUtil {

/**

* NIO way

* 读取excel文件

* @param filePath

* @param fileName

* @throws Exception

*/

public static byte[] readExcelFiletoByteArray(String filePath) throws Exception {

File f = new File(filePath);

if (!f.exists()) {

throw new FileNotFoundException(filePath);

}

FileChannel channel = null;

FileInputStream fs = null;

try {

fs = new FileInputStream(f);

channel = fs.getChannel();

ByteBuffer byteBuffer = ByteBuffer.allocate((int) channel.size());

while ((channel.read(byteBuffer)) > 0) {

// do nothing

// System.out.println("reading");

}

return byteBuffer.array();

} catch (IOException e) {

e.printStackTrace();

throw e;

} finally {

try {

channel.close();

} catch (IOException e) {

e.printStackTrace();

}

try {

fs.close();

} catch (IOException e) {

e.printStackTrace();

}

}

}

/**

* 下载excel文件

* @param response

* @param filePath

* @param fileName：带有后缀名的文件名 例如 a.xls

* @throws Exception

*/

public static void downloadExcelFile(HttpServletResponse response, String filePath, String fileName) throws Exception {

BufferedInputStream bis = null;

BufferedOutputStream bos = null;

try {

// 设置response参数，可以打开下载页面

response.reset();

response.setContentType("application/vnd.ms-excel;charset=utf-8");

response.setHeader("Content-Disposition", "attachment;filename="

+ new String((fileName).getBytes(), "iso-8859-1"));

ServletOutputStream out = response.getOutputStream();

bis = new BufferedInputStream(new FileInputStream(filePath));

bos = new BufferedOutputStream(out);

byte[] buff = new byte[2048];

int bytesRead;

// Simple read/write loop.

while (-1 != (bytesRead = bis.read(buff, 0, buff.length))) {

bos.write(buff, 0, bytesRead);

}

} catch (IOException e) {

throw e;

} finally {

if (bis != null)

bis.close();

if (bos != null)

bos.close();

}

}

public static void downloadExcelFile(HttpServletResponse response, String fileName, byte[] fileContent) throws Exception {

BufferedOutputStream bos = null;

try {

// 设置response参数，可以打开下载页面

response.reset();

response.setContentType("application/vnd.ms-excel;charset=utf-8");

response.setHeader("Content-Disposition", "attachment;filename="

+ new String((fileName).getBytes(), "iso-8859-1"));

ServletOutputStream out = response.getOutputStream();

bos = new BufferedOutputStream(out);

if(null != fileContent){

bos.write(fileContent);

}

} catch (IOException e) {

throw e;

} finally {

if (bos != null)

bos.close();

}

}

/**

* 将文件转成base64 字符串

* @param path文件路径

* @return *

* @throws Exception

*/

public static String encodeBase64File(String path) throws Exception {

File file = new File(path);

FileInputStream inputFile = new FileInputStream(file);

byte[] buffer = new byte[(int) file.length()];

inputFile.read(buffer);

inputFile.close();

return new BASE64Encoder().encode(buffer);

}

public static String encodeBase64File(MultipartFile file) throws Exception {

return new BASE64Encoder().encode(file.getBytes());

}

public static byte[] decoderBase64File(String base64Code) throws Exception {

return new BASE64Decoder().decodeBuffer(base64Code);

}

/**

* 将base64字符解码保存文件

* @param base64Code

* @param targetPath

* @throws Exception

*/

public static void decoderBase64File(String base64Code, String targetPath)

throws Exception {

byte[] buffer = new BASE64Decoder().decodeBuffer(base64Code);

FileOutputStream out = new FileOutputStream(targetPath);

out.write(buffer);

out.close();

}

/**

* 将base64字符保存文本文件

* @param base64Code

* @param targetPath

* @throws Exception

*/

public static void toFile(String base64Code, String targetPath)

throws Exception {

byte[] buffer = base64Code.getBytes();

FileOutputStream out = new FileOutputStream(targetPath);

out.write(buffer);

out.close();

}

public static void main(String[] args) {

try {

String base64Code = encodeBase64File("E:\\test\\test1.xls");

System.out.println(base64Code);

decoderBase64File(base64Code, "E:\\test\\test.xls");

// toFile(base64Code, "D:\\three.txt");

} catch (Exception e) {

e.printStackTrace();

}

}

}