[英]C3P0 one server multiple databases
Good morning, 早上好,
As the title says I want to create a solution to use connection pools to connect to different databases on the same Mysql server. 如标题所示,我想创建一个解决方案以使用连接池连接到同一Mysql服务器上的不同数据库。 I have followed the steps indicated in the following post: 我已按照以下帖子中指示的步骤进行操作:
https://stackoverflow.com/questions/26785842/multiple-data-sources-for-c3p0 https://stackoverflow.com/questions/26785842/multiple-data-sources-for-c3p0
My solution is this: 我的解决方案是这样的:
public class DatabaseUtility
{
public static ComboPooledDataSource getDataSource(String db, String user, String pass) throws PropertyVetoException
{
ComboPooledDataSource cpds = new ComboPooledDataSource();
cpds.setJdbcUrl("jdbc:mysql://X.X.X.X:3306/"+db);
cpds.setUser(user);
cpds.setPassword(pass);
// Optional Settings
cpds.setInitialPoolSize(5);
cpds.setMinPoolSize(5);
cpds.setAcquireIncrement(5);
cpds.setMaxPoolSize(20);
cpds.setMaxStatements(100);
return cpds;
}
public static void main(String[] args) throws SQLException
{
Connection connection = null;
PreparedStatement pstmt = null;
ResultSet resultSet = null;
try
{
//QUERY to DATABASE 1
ComboPooledDataSource dataSource = DatabaseUtility.getDataSource("bd1", "user1", "pass1");
connection = dataSource.getConnection();
pstmt = connection.prepareStatement("SELECT * FROM municipio");
System.out.println("The Connection Object is of Class: " + connection.getClass());
resultSet = pstmt.executeQuery();
while (resultSet.next())
{
System.out.println(resultSet.getString(1) + "," + resultSet.getString(2) + "," + resultSet.getString(3));
}
//QUERY to DATABASE 2
dataSource = DatabaseUtility.getDataSource("bd2", "user2", "pass2");
connection = dataSource.getConnection();
pstmt = connection.prepareStatement("SELECT * FROM alojamiento");
System.out.println("The Connection Object is of Class: " + connection.getClass());
resultSet = pstmt.executeQuery();
while (resultSet.next())
{
System.out.println(resultSet.getString(1) + "," + resultSet.getString(2) + "," + resultSet.getString(3));
}
}
catch (Exception e)
{
connection.rollback();
e.printStackTrace();
}
}
}
Every time I connect to a database, I call the constructor with the specific connection string. 每次我连接到数据库时,我都会使用特定的连接字符串来调用构造函数。
However, I have doubts if this is an efficient solution, or I am doing something wrong ... 但是,我怀疑这是否是有效的解决方案,或者我做错了什么...
PS I'm using a project without Spring. PS我正在使用没有Spring的项目。
I would appreciate your advice, Thanks in advance, 非常感谢您的建议,在此先感谢,
Greetings. 问候。
No, this is definitely not an efficient solution. 不,这绝对不是有效的解决方案。 You are creating a new whole pool of Connections each time you want to grab a Connection. 每次要获取连接时,都将创建一个新的整个连接池。 Try something like this. 尝试这样的事情。
private static ComboPooledDataSource createDataSource(String db, String user, String pass) {
ComboPooledDataSource cpds = new ComboPooledDataSource();
cpds.setJdbcUrl("jdbc:mysql://X.X.X.X:3306/"+db);
cpds.setUser(user);
cpds.setPassword(pass);
// Optional Settings
cpds.setInitialPoolSize(5);
cpds.setMinPoolSize(5);
cpds.setAcquireIncrement(5);
cpds.setMaxPoolSize(20);
cpds.setMaxStatements(100);
return cpds;
}
private static final class DbUserPassword {
final String db;
final String user;
final String password;
DbUserPassword( String db, String user, String password ) {
this.db = db;
this.user = user;
this.password = password;
}
@Override
public boolean equals( Object o ) {
if ( o instanceof DbUserPassword ) {
DbUserPassword that = (DbUserPassword) o;
return ( this.db.equals( that.db ) && this.user.equals( that.user ) && this.password.equals( that.password ) );
}
else {
return false;
}
}
@Override
public int hashCode() {
return db.hashCode() ^ user.hashCode() ^ password.hashCode();
}
}
// MT: protected by class' lock
private static HashMap<DbUserPassword,ComboPooledDataSource> poolMap = new HashMap<>();
public static synchronized ComboPooledDataSource getDataSource(String db, String user, String pass) {
DbUserPassword dbup = new DbUserPassword( db, user, pass );
ComboPooledDataSource out = poolMap.get(dbup);
if ( out == null ) {
out = createDataSource( db, user, pass );
poolMap.put( dbup, out );
}
return out;
}
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