C3p0数据库连接池的创建方法

方法一：

package C3P0;
import java.sql.Connection;
import java.sql.SQLException;
import java.beans.PropertyVetoException;
import com.mchange.v2.c3p0.ComboPooledDataSource;
public class DBPool{
   private static DBPool dbPool;
   private ComboPooledDataSource dataSource;

   static {
           dbPool = new DBPool();
   }

   public DBPool(){
           try {
                 dataSource = new ComboPooledDataSource();
                 dataSource.setUser( "id" );
                 dataSource.setPassword( "pw" );
                 dataSource.setJdbcUrl("jdbc:mysql: //127.0.0.1:3306/test?
autoReconnect= true &useUnicode= true &characterEncoding=GB2312");
                 dataSource.setDriverClass( "com.mysql.jdbc.Driver" );
                 dataSource.setInitialPoolSize( 2 );
                 dataSource.setMinPoolSize( 1 );
                 dataSource.setMaxPoolSize( 10 );
                 dataSource.setMaxStatements( 50 );
                 dataSource.setMaxIdleTime( 60 );
           } catch (PropertyVetoException e) {
               throw new RuntimeException(e);
           }
   }

   public final static DBPool getInstance(){
           return dbPool;
   }

   public final Connection getConnection(){
           try {
               return dataSource.getConnection();
           }   catch (SQLException e)   {
               throw new RuntimeException( "无法从数据源获取连接" ,e);
           }
   }

   public static void main(String[] args) throws SQLException {
        Connection con = null ;
        try {
        con = DBPool.getInstance().getConnection();
        } catch (Exception e){
        } finally {
        if (con != null )
        con.close();
        }
        }

}

方法二：

c3p0方法：
  配置文件：c3p0-config.xml
  "1.0" encoding= "UTF-8" ?>

"userApp" >
"driverClass" >com.mysql.jdbc.Driver
"jdbcUrl" >jdbc:mysql: //localhost:3306/test
"user" >root
"password" > 123456
"acquireIncrement" > 5
"initialPoolSize" > 10
"minPoolSize" > 10
"maxPoolSize" > 20
"maxStatements" > 0
"maxStatementsPerConnection" > 5

"master-of-the-universe" >
"acquireIncrement" > 1
"initialPoolSize" > 1
"minPoolSize" > 1
"maxPoolSize" > 5
"maxStatementsPerConnection" > 50



连接数据库：
  package cn.langzi.jdbc.c3p0;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import javax.sql.DataSource;
import com.mchange.v2.c3p0.ComboPooledDataSource;
public class DbConnection {
private static DataSource dataSource;
static {
dataSource = new ComboPooledDataSource( "userApp" );
}
public static Connection getConnectioon() throws SQLException{
return dataSource.getConnection();
}
}

方法三：

public final class ConnectionManager {
 private static ConnectionManager instance;

 public ComboPooledDataSource ds;
 private static String c3p0Properties = "c3p0.properties" ;

 private ConnectionManager() throws Exception {
  Properties p = new Properties();
  p.load( this .getClass().getResourceAsStream(c3p0Properties));
  ds = new ComboPooledDataSource();
  ds.setUser(p.getProperty( "user" ));
  ds.setPassword(p.getProperty( "user" ));
  ds.setJdbcUrl(p.getProperty( "user" ));
  ds.setDriverClass(p.getProperty( "user" ));
  ds.setInitialPoolSize(Integer.parseInt(p.getProperty( "initialPoolSize" )));
  ds.setMinPoolSize(Integer.parseInt(p.getProperty( "minPoolSize" )));
  ds.setMaxPoolSize(Integer.parseInt(p.getProperty( "maxPoolSize" )));
  ds.setMaxStatements(Integer.parseInt(p.getProperty( "maxStatements" )));
  ds.setMaxIdleTime(Integer.parseInt(p.getProperty( "maxIdleTime" )));
 }

 public static final ConnectionManager getInstance() {
  if (instance == null ) {
   try {
    instance = new ConnectionManager();
   } catch (Exception e) {
    e.printStackTrace();
   }
  }
  return instance;
 }

 public synchronized final Connection getConnection() {
  try {
   return ds.getConnection();
  } catch (SQLException e) {
   e.printStackTrace();
  }
  return null ;
 }

 protected void finalize() throws Throwable {
  DataSources.destroy(ds); // 关闭datasource
  super .finalize();
 }
}