Tomcat6 MySql JDBC数据源配置

Question

我总是使用Spring的依赖注入来获取数据源对象并在我的DAO中使用它们,但现在,我必须编写一个没有它的应用程序.

有了Spring,我可以这样写:

<bean id="dataSource"
    class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="com.mysql.jdbc.Driver" />
    <property name="url" value="jdbc:mysql://127.0.0.1/app?characterEncoding=UTF-8" />
    <property name="username" value="u" />
    <property name="password" value="p" />
</bean>

但是如何在没有Spring或任何东西的情况下在我的DAO中使用数据源？我只使用servlet和JSP.性能是非常重要的因素.

Answer 1

信不信由你,人们在Spring之前编写应用程序,有些人仍然没有使用它:)在你的情况下,你可以使用Tomcat连接池(在文档中有一个完整的MySQL配置示例).让我总结一下:

首先,把你的司机放进去$CATALINA_HOME/lib.

然后,通过向您的Context添加资源声明,在Tomcat中配置JNDI DataSource :

<Context path="/DBTest" docBase="DBTest"
        debug="5" reloadable="true" crossContext="true">

    <!-- maxActive: Maximum number of dB connections in pool. Make sure you
         configure your mysqld max_connections large enough to handle
         all of your db connections. Set to -1 for no limit.
         -->

    <!-- maxIdle: Maximum number of idle dB connections to retain in pool.
         Set to -1 for no limit.  See also the DBCP documentation on this
         and the minEvictableIdleTimeMillis configuration parameter.
         -->

    <!-- maxWait: Maximum time to wait for a dB connection to become available
         in ms, in this example 10 seconds. An Exception is thrown if
         this timeout is exceeded.  Set to -1 to wait indefinitely.
         -->

    <!-- username and password: MySQL dB username and password for dB connections  -->

    <!-- driverClassName: Class name for the old mm.mysql JDBC driver is
         org.gjt.mm.mysql.Driver - we recommend using Connector/J though.
         Class name for the official MySQL Connector/J driver is com.mysql.jdbc.Driver.
         -->

    <!-- url: The JDBC connection url for connecting to your MySQL dB.
         -->

  <Resource name="jdbc/TestDB" auth="Container" type="javax.sql.DataSource"
               maxActive="100" maxIdle="30" maxWait="10000"
               username="javauser" password="javadude" driverClassName="com.mysql.jdbc.Driver"
               url="jdbc:mysql://localhost:3306/javatest"/>

</Context>

在您的web.xml:中声明此资源:

<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
    version="2.4">
  <description>MySQL Test App</description>
  <resource-ref>
      <description>DB Connection</description>
      <res-ref-name>jdbc/TestDB</res-ref-name>
      <res-type>javax.sql.DataSource</res-type>
      <res-auth>Container</res-auth>
  </resource-ref>
</web-app>

并在您的应用程序中使用JNDI查找获取数据源:

Context initCtx = new InitialContext();
Context envCtx = (Context) initCtx.lookup("java:comp/env");
DataSource ds = (DataSource) envCtx.lookup("jdbc/TestDB");

Connection conn = ds.getConnection();
... use this connection to access the database ...
conn.close();

请注意,这lookup通常用a编码ServiceLocator(当你不能有一个DI容器或框架为你注入时).