servlet JDBC mysql数据库连接池

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具体操作过程：

1、配置全局数据库连接池

在<tomcat安装目录>\conf\server.xml文件中找到<GlobalNamingResources>标签，添加下列配置：

<Resource name="jdbc/webdb"   auth="Container"              type="javax.sql.DataSource"              driverClassName="com.mysql.jdbc.Driver"              url="jdbc:mysql://localhost:3306/webdb?characterEncoding=UTF-8"              username="root"    password="root"    maxActive="200"    maxIdle="50"    maxWait="3000" />

2、下载JDBC驱动的jar包，放在tomcat的lib目录下
3、在创建的webdemo工程中web.xml文件中增加下列配置：

<resource-ref> <res-ref-name>jdbc/webdb</res-ref-name> <res-type>javax.sql.DataSource</res-type> <res-auth>Container</res-auth> <res-sharing-scope>Shareable</res-sharing-scope> </resource-ref>

4、在webdemo工程的META-INF目录下增加一个context.xml文件，内容如下：

<?xml version="1.0" encoding="UTF-8"?><Context>  <Listener className="org.apache.catalina.startup.TldConfig"/>  <Listener className="org.apache.catalina.startup.TldConfig"/>  <Listener className="org.apache.catalina.startup.TldConfig"/>  <Listener className="org.apache.catalina.startup.TldConfig"/>  <Resource   auth="Container"    description="webdb"    name="jdbc/webdb"    password="root"    username="root"    type="javax.sql.DataSource"    driverClassName="com.mysql.jdbc.Driver"    url="jdbc:mysql://localhost:3306/webdb?characterEncoding=UTF-8" /></Context>

5、访问数据库事例java文件

package chapter4;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;public class Helloworld extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html; charset=UTF-8");PrintWriter out = response.getWriter();try{javax.naming.Context ctx = new javax.naming.InitialContext();javax.sql.DataSource ds = (javax.sql.DataSource)ctx.lookup("java:/comp/env/jdbc/webdb");Connection conn = ds.getConnection();PreparedStatement pst = conn.prepareStatement("SELECT * FROM t_dictionary");ResultSet rs = pst.executeQuery();StringBuilder table = new StringBuilder();table.append("<table border='1'>");table.append("<tr><td>eg-name</td><td>ch-name</td></tr>");while(rs.next()){table.append("<tr><td>"+rs.getString("english")+"</td><td>");table.append(rs.getString("chinese")+"</td></tr>");}table.append("</table>");out.println(table.toString());pst.close();}catch(Exception e){out.println(e.getMessage());}}}

差不多servlet访问mysql数据库能测试成功。

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