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我不明白的目的DatabaseAccess class。我很好奇,对象名称“conDA”如何包含数据库连接,即使不使用我创建的getConnection()方法也不使用。示例“con2 = new Connection2(conDA);”那“conDA”对象名称是如何被理解为数据库的连接? 这里是代码:Java,将数据库连接传递到不同的类。
import java.sql.*;
public class Connection1
{
static Connection connection;
static ConnectionDA conDA;
static Connection2 con2;
public static void main(String args[]) throws ClassNotFoundException, SQLException
{
conDA = new ConnectionDA(getConnection());
System.out.println("Con1 Connected!!");
con2 = new Connection2(conDA);
}
public static Connection getConnection() throws ClassNotFoundException, SQLException
{
Class.forName("com.ibm.db2.jcc.DB2Driver");
connection = DriverManager.getConnection("jdbc:db2://localhost:50000/Sample", "ZeroCool","siliconvalley");
return connection;
}
}
二等
import java.sql.*;
public class Connection2
{
ConnectionDA conDA;
Connection3 con3;
public Connection2(ConnectionDA conDA) throws ClassNotFoundException
{
this.conDA = new ConnectionDA(conDA.getConnection());
this.conDA = conDA;
System.out.println("Con2 Connected!!");
con3 = new Connection3(conDA);
}
}
三等奖
import java.sql.*;
public class Connection3
{
ConnectionDA conDA;
public Connection3(ConnectionDA conDA) throws ClassNotFoundException
{
this.conDA = new ConnectionDA(conDA.getConnection());
this.conDA = conDA;
System.out.println("Con3 Connected!!");
}
}
数据库访问类
import java.sql.*;
public class ConnectionDA
{
Connection connection;
public ConnectionDA(Connection connection) throws ClassNotFoundException
{
this.connection = connection;
System.out.println("ConDA Established!!!");
}
public Connection getConnection()
{
return connection;
}
}
所以,我只需要调用ConnectionDA建立到其他类的连接?如果是这种情况,每次初始化conDA对象名称时,getConnection()方法的用法是什么? – ZeroCool 2015-03-02 14:35:13
你有方法getConection()获取连接,在你需要它的情况下出于某种原因。 – 2015-03-02 14:37:39