下面来看一个MySQL数据库的实现：
/**
*MySQL备份恢复实现
* @author 杨尚川
*/
@Service("MYSQL")
public class MySQLBackupService extends AbstractBackupService{
/**
* MySQL备份数据库实现
* @return
*/
@Override
public boolean backup() {
try {
String path=getBackupFilePath()+DateTypeConverter.toFileName(new Date())+".bak";
String command=PropertyHolder.getProperty("db.backup.command");
command=command.replace("${db.username}"， username);
command=command.replace("${db.password}"， password);
command=command.replace("${module.short.name}"， PropertyHolder.getProperty("module.short.name"));
Runtime runtime = Runtime.getRuntime();
Process child = runtime.exec(command);
InputStream in = child.getInputStream();
try(OutputStreamWriter writer = new OutputStreamWriter(new FileOutputStream(path)， "utf8");BufferedReader reader = new BufferedReader(new InputStreamReader(in， "utf8"))){
String line=reader.readLine();
while (line != null) {
writer.write(line+" ");
line=reader.readLine();
}
writer.flush();
}
LOG.debug("备份到："+path);
return true;
} catch (Exception e) {
LOG.error("备份出错"，e);
}
return false;
}
/**
* MySQL恢复数据库实现
* @param date
* @return
*/
@Override
public boolean restore(String date) {
try {
String path=getBackupFilePath()+date+".bak";
String command=PropertyHolder.getProperty("db.restore.command");
command=command.replace("${db.username}"， username);
command=command.replace("${db.password}"， password);
command=command.replace("${module.short.name}"， PropertyHolder.getProperty("module.short.name"));
Runtime runtime = Runtime.getRuntime();
Process child = runtime.exec(command);
try(OutputStreamWriter writer = new OutputStreamWriter(child.getOutputStream()， "utf8");BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(path)， "utf8"))){
String line=reader.readLine();
while (line != null) {
writer.write(line+" ");
line=reader.readLine();
}
writer.flush();
}
LOG.debug("从 "+path+" 恢复");
return true;
} catch (Exception e) {
LOG.error("恢复出错"，e);
}
return false;
}
}
　　这里的关键有两点，一是从配置文件db.properties或db.local.properties中获取指定的命令进行备份和恢复操作，二是为实现类指定注解@Service("MYSQL")，这里服务名称必须和配置文件db.properties或db.local.properties中jpa.database的值一致，jpa.database的值指定了当前使用哪一种数据库，如下所示：
#mysql
db.driver=com.mysql.jdbc.Driver
db.url=jdbc:mysql://localhost:3306/${module.short.name}?useUnicode=true&characterEncoding=UTF-8&createDatabaseIfNotExist=true&autoReconnect=true
db.username=ENC(i/TOu44AD6Zmz0fJwC32jQ==)
db.password=ENC(i/TOu44AD6Zmz0fJwC32jQ==)
jpa.database=MYSQL
db.backup.command=mysqldump  -u${db.username} -p${db.password} ${module.short.name}
db.restore.command=mysql -u${db.username} -p${db.password} ${module.short.name}