作為一個習慣使用myeclipse的人來說,即使是數據庫連接池也肯定是用ide配置了.
下面說一下用數據庫連接池的配置.
1 創建工程.不多說了.
2 添加數據庫連接程序驅動包.直接放到lib目錄下即可
3 配置context.xml文件
<?xml version="1.0" encoding="UTF-8"?> <Context debug="5" reloadable="true"> <Resource name="jdbc/mysql" auth="Container" type="javax.sql.DataSource" maxActive="100" maxIdle="30" maxWait="10000" username="root" password="1234" driverClassName="com.mysql.jdbc.Driver" url="jdbc:mysql://localhost:3306/pos?autoReconnect=true" /> </Context>
解釋： name="jdbc/mysql" //連接名，jndi中使用。具在JSP中用<sql:query var="rs" dataSource="jdbc/mysql">調用，servlet用 DataSource ds = (DataSource)ctx.lookup("java:comp/env/jdbc/mysql");調用。這里是tomcat的格式，不同的服務器可能有所不同。 auth="Container" type="javax.sql.DataSource" maxActive="100" maxIdle="30" maxWait="10000" username="root" //mysql的用戶名 password="" //mysql的用戶密碼，我這里是空 driverClassName="com.mysql.jdbc.Driver" //驅動類名，一般確定 url="jdbc:mysql://localhost:3306/javatest?autoReconnect=true" //javatest是mysql中要使用的數據庫名
4 配置web.xml文件
<resource-ref> <description>DB Connection</description> <res-ref-name>jdbc/mysql</res-ref-name> <res-type>javax.sql.DataSource</res-type> <res-auth>Container</res-auth> </resource-ref>
如此就完成了數據庫的連接.我喜歡用servlet,給出一個servlet的測試代碼:
package com.pos.test; import java.io.IOException; import java.io.PrintWriter; import java.sql.Connection; import java.sql.ResultSet; import java.sql.SQLException; import javax.naming.Context; import javax.naming.InitialContext; import javax.naming.NamingException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.sql.DataSource; public class TEST extends HttpServlet { /** * Constructor of the object. */ public TEST() { super(); } /** * Destruction of the servlet. <br> */ public void destroy() { super.destroy(); // Just puts "destroy" string in log // Put your code here } /** * The doGet method of the servlet. <br> * * This method is called when a form has its tag value method equals to get. * * @param request the request send by the client to the server * @param response the response send by the server to the client * @throws ServletException if an error occurred * @throws IOException if an error occurred */ public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request,response); } /** * The doPost method of the servlet. <br> * * This method is called when a form has its tag value method equals to post. * * @param request the request send by the client to the server * @param response the response send by the server to the client * @throws ServletException if an error occurred * @throws IOException if an error occurred */ public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); PrintWriter out = response.getWriter(); out .println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">"); out.println("<HTML>"); out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>"); out.println(" <BODY>"); out.print(" This is "); out.print(this.getClass()); out.println(", using the POST method"); try { Context ctx = new InitialContext(); DataSource ds = (DataSource)ctx.lookup("java:comp/env/jdbc/mysql"); Connection conn = ds.getConnection(); ResultSet rs=conn.createStatement().executeQuery("select * from admininfo"); while(rs.next()){ out.print(rs.getString(1)); } } catch (NamingException e) { e.printStackTrace(out); System.out.println(e.getMessage()); } catch (SQLException e) { e.printStackTrace(out); } out.println("connection pool connected !!haha"); out.println(" </BODY>"); out.println("</HTML>"); out.flush(); out.close(); } /** * Initialization of the servlet. <br> * * @throws ServletException if an error occurs */ public void init() throws ServletException { // Put your code here } }
這里我的數據庫名稱:pos，我查詢了admininfo表中的第二列的數據。
關鍵代碼：
try { Context ctx = new InitialContext(); DataSource ds = (DataSource)ctx.lookup("java:comp/env/jdbc/mysql"); Connection conn = ds.getConnection(); ResultSet rs=conn.createStatement().executeQuery("select * from admininfo"); while(rs.next()){ out.print(rs.getString(1)); } } catch (NamingException e) { e.printStackTrace(out); System.out.println(e.getMessage()); } catch (SQLException e) { e.printStackTrace(out); }
結果集rs，返回之后跟直接jdbc訪問數據庫差別不大了。
ps：其實我到沒有感覺用數據庫連接池有什么方便之處。但是學習的過程中，示例項目用到，就學習了一下。不然這個地方一直卡住。。。唉～還是太弱了。