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  • Myeclipse中JDBC连接池的配置【转】

    软件版本myeclispe8.0,自带tomcat6.0.13。

    jdbc:mysql-connector-java-5.1.13-bin.jar


    第一步:建立工程。

    在Myeclipse中file->new->web project。

    因为在测试数据源(jsp)时用到了标签库,所以可以在这里选上jsdl支持,当然也可以在工程建好后右键工程文件夹->myeclipse->add JSTL

    Libraries…实现同样的功能。


    第二步:导入jdbc的jar包。

    要直接将mysql-connector-java-3.1.7-bin.jar复制到“工程文件夹/WebRoot/WEB-INF/lib”文件夹下。这时,myeclipse会自动生成一个

    Referenced Libraries,不用管。


    第三步:建立context.xml文件。

    在“工程文件夹/WebRoot/META-INF”下,新建context.xml文件。文件内容如下:

    <?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=""
    driverClassName="com.mysql.jdbc.Driver"
    url="jdbc:mysql://localhost:3306/javatest?autoReconnect=true" />
    </Context>

    解释:
    name="jdbc/mysql"   //连接名,jndi中使用。具在JSP中用<sql:query var="rs" dataSource="jdbc/mysql">调用,servlet用 DataSource ds

    = (DataSource)ctx.lookup("java:comp/env/jdbc/mysql");调用。这里是tomcat的格式,不同的服务器可能有所不同。

    auth="Container"    
    type="javax.sql.DataSource"   
    maxActive="100"
    maxIdle="30"
    maxWait="10000"
    username="root"    //mysql的用户名
    password=""        //mysql的用户密码,我这里是空 
    driverClassName="com.mysql.jdbc.Driver"   //驱动类名,一般确定
    url="jdbc:mysql://localhost:3306/javatest?autoReconnect=true" //javatest是mysql中要使用的数据库名

    第四步:修改web.xml文件。

    在web.xml文件中添加以下内容:                  //重要一定添加进去

    <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>

    这部分内容一般是确定的。

    OK,现在可以测试数据源是否好了。下面是JSP测试文件:

    <%@ page language="java" import="java.util.*" pageEncoding="ISO-8859-1"%>
    <%@ taglib uri="http://java.sun.com/jsp/jstl/sql" prefix="sql" %>
    <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
    <%
    String path = request.getContextPath();
    String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
    %>
    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
    <html>
    <head>
        <base href="<%=basePath%>">
        
        <title>My JSP 'MyJsp.jsp' starting page</title>
        
        <meta http-equiv="pragma" content="no-cache">
        <meta http-equiv="cache-control" content="no-cache">
        <meta http-equiv="expires" content="0">    
        <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
        <meta http-equiv="description" content="This is my page">
        <!--
        <link rel="stylesheet" type="text/css" href="styles.css">
        -->
    <sql:query var="rs" dataSource="jdbc/mysql">
    select id, username, password from user
    </sql:query>
    </head>
    
    <body>
       <h2>Results</h2>
    
    <c:forEach var="row" items="${rs.rows}">
        Foo ${row.username}<br/>
        Bar ${row.password}<br/>
    </c:forEach> <br>
    </body>
    </html>

    当然,如果你用servlet测试数据源也是可以的,下面是一个servlet测试例子:

    package fx;
    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 DsTest extends HttpServlet
    {
        /**
         * Constructor of the object.
         */
        public DsTest()
        {
            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 user");
               rs.next();
               out.print(rs.getString(2));
            } 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
        }
    }

    我的mysql数据库名为javatest,表名为user,有三列"id","username","password"。servlet运行结果将打印出user表中的第一个用户名。

    注意:如果你新建servlet,myeclipse会自动帮你在web.xml中生成相应的mapping,而这部分内容可能“插”进

    <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>

    中,造成错误。注意自己手动调整。      //要看一下,因为我的好像没有这段代码

    别外,注意myeclipse中的servlet映射为“服务器ip:端口/工程文件名/servlet/servlet名”。

    还有就是最好使用外部自己配置的Tomcat,并将mysql-connector-java-5.1.13-bin.jar包放到Tomcat的lib目录下。

    最好不要用MyEclipse自带的Tomcat,因为我的MyEclipse提示org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot load JDBC driver class 'com.mysql.jdbc.Driver'

    即Tomcat出现异常,找不到jdbc驱动包

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  • 原文地址:https://www.cnblogs.com/wxy325/p/3008864.html
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