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JavaBean操作Oracle数据库
摘要: JavaBean操作Oracle数据库
本文以一个完整的JavaBean数据库访问程序简要说明jsp操作数据库。
本程序由3个bean组成，其中WebConstants中定义全局变量，ConnectionManager管理数据库连接，MainBean利用WebConstants和ConnectionManager操作数据库。
首先定义全局变量，如下：
package WebRelease;
public interface WebConstants { public static final String driverClass ="driverClass"; const userId is the user id to connect to database public static final String userId ="comm"; const passWd is the user password to connect to database public static final String passWd ="comm123"; const url is the url to connect to database public static final String url="jdbc:oracle:thin:@10.2.0.1:1521:ORCL"; public static final String selectType ="select"; public static final String connection ="connection"; public static final String connError ="conError"; }
接着创建一个数据库连接管理bean，如下：
package WebRelease;
import java.io.*; import java.beans.*; import java.util.*; import java.sql.*; import WebRelease.WebConstants; import oracle.jdbc.driver.*;
public class ConnectionManager implements WebConstants { private boolean debug = true; protected Connection con; protected DebugWriter writer; PropertyChangeSupport pcs; //////////////////////////////////////////////////////////////////////////////// public ConnectionManager() { pcs = new PropertyChangeSupport(this); writer = new DebugWriter(); } //////////////////////////////////////////////////////////////////////////////// public void setDebug(String b) { debug = b.equals("true"); } //////////////////////////////////////////////////////////////////////////////// public void addPropertyChangeListener( PropertyChangeListener l) { pcs.addPropertyChangeListener(l); } //////////////////////////////////////////////////////////////////////////////// public void removePropertyChangeListener(PropertyChangeListener l) { pcs.removePropertyChangeListener(l); } //////////////////////////////////////////////////////////////////////////////// public void login() { try { DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver()); Class.forName("oracle.jdbc.driver.OracleDriver"); } catch(Exception e) { if(debug) { writer.writeDebug("Error setting driver:"+e.getMessage());} } try { con = DriverManager.getConnection(url,userId,passWd); pcs.firePropertyChange(connection,null,con); if(debug) { writer.writeDebug("connection succeded ! URL:"+url+"User:"+userId+ "Pwd:"+passWd); } } catch(Exception e) { pcs.firePropertyChange(connError,null,e); if(debug) { writer.writeDebug("connection failed ! URL:"+url+"User:"+userId+ "Pwd:"+passWd); } } } }
在MainBean中，侦听数据库是否连接，如果连接则对数据库进行操作：
package WebRelease;
import java.io.*; import java.beans.*; import java.util.*; import java.sql.*; import WebRelease.*;
public class MainBean implements PropertyChangeListener ,WebConstants { private boolean debug = true; protected Connection con; protected DebugWriter writer; //////////////////////////////////////////////////////////////////////////////// public MainBean() { writer = new DebugWriter(); } //////////////////////////////////////////////////////////////////////////////// public void propertyChange(PropertyChangeEvent evt) { String prop = evt.getPropertyName(); //see if we got a connection if(prop.equals(connection)) {//ok so update the local connection try { //make sure it really is a connection con = (Connection)evt.getNewValue(); } catch(Exception e) { writer.writeDebug("Error connecting to database"+e.getMessage()); } } } //////////////////////////////////////////////////////////////////////////////// public void setConnectionManager(ConnectionManager cm) { if(cm != null) { // to remove the old listener from cm // to avoid confusion in the mainbean cm.removePropertyChangeListener(this); cm.addPropertyChangeListener(this); if(debug) { writer.writeDebug("MainBean;Set connection manager"+ cm.toString()); } } else { if(debug) { writer.writeDebug("MainBean;Tried to set a null connection manager"); } } } //////////////////////////////////////////////////////////////////////////////// public boolean isConnected() { //see if datatabe is connected return (con != null); } //////////////////////////////////////////////////////////////////////////////// public void processQuery() { try { Statement stmt=con.createStatement(); ResultSet rs=stmt.executeQuery("select * from hello order by id"); writer.writeDebug("select * from hello order by id"); while(rs.next()) { writer.writeDebug("next"); String str=rs.getString("name"); writer.writeDebug(str+" "); } rs.close(); } catch(Exception e) { }
} }
OK，现在我们来测试一下这个程序，创建一个测试页面：
<%@ page contentType="text/html; charset=gb2312" %>
%>
在tomcat中浏览这个页面，我们应该可以看到输出“Mainbean connect sucess!!!”
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