用Java实现数据库应用系统

　　我们在做信息系统的时候，都要访问数据库，我最近接手一个项目，项目组决定使用Java编写，我负责数据层的设计和编码，为了提高代码的重用性和提高项目的开发效率。我们开发了一个通用的数据库连接和完成基本操作的类库，个人认为这个类在做MIS系统时还是有一定的价值，所以总结出来，介绍给大家。
　　连接工厂，实现了DataSource接口

package skydev.modules.data;
import java.sql.*;
import javax.sql.DataSource;
import java.io.PrintWriter;
public class ConnectionFactory implements DataSource {
private String userName;
private String passWord;
private String driverName;
private String url;
private java.sql.Connection connection;

/**
* 根据设置的连接参数创建一个新的连接实例
* @return
*/
private Connection getNewConnection() {
try {
this.connection.close(); //试图关闭连接
}
finally {
this.connection = null; //释放连接
try {
Class.forName(this.driverName); //加载驱动程序
//DriverManager.registerDriver(driver);
try {
this.connection = DriverManager.getConnection(this.url, this.userName,
this.password);
}
catch (SQLException e) {
throw e;
}
}
finally {
return this.connection; //返回新建立的连接
}
}
}

public String getUserName() {
return userName;
}

public void setUserName(String userName) {
this.userName = userName;
}

public String getPassword() {
return password;
}

public void setPassword(String password) {
this.password = password;
}

public String getDriverName() {
return driverName;
}

public void setDriverName(String driverName) {
this.driverName = driverName;
}

public String getUrl() {
return url;
}

public void setUrl(String url) {
this.url = url;
}

public java.sql.Connection getConnection() {
if (connection != null) {
try {
if (connection.isClosed()) {
connection = null;
getNewConnection();
}
}
catch (SQLException ex) {
}
}
if (connection == null) { //没有设置连接则创建一个连接
getNewConnection();
}
return connection;
}

public Connection getConnection(String userName, String password) throws
SQLException {
this.setUserName(userName);
this.setPassword(password);
return getConnection();
}

public PrintWriter getLogWriter() {
return null;
}

public void setLogWriter(PrintWriter printWriter) {
}

public void setLoginTimeout(int int0) {
}

public int getLoginTimeout() {