Tomcat中配置MySQL数据库连接池
Web開發中與數據庫的連接是必不可少的,而數據庫連接池技術很好的優化了動態頁與數據庫的連接,相比單個連接數據庫連接池節省了很大的資源。用一個通俗的比喻:如果一個人洗澡需花一桶水,那一百個人就要花一百桶水,太浪費了.如果都在池子里洗,洗多少個人都不怕了。
1.將MySQL的JDBC驅動復制到Tomcat安裝目錄里的lib文件夾下。驅動可以從MySQL官網上下載,為jar包。
2.將Tomcat的配置文件Context.xml做如下修改:
<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.
???????? The autoReconnect=true argument to the url makes sure that the
???????? mm.mysql JDBC Driver will automatically reconnect if mysqld closed the
???????? connection.? mysqld by default closes idle connections after 8 hours.
???????? -->
? <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?autoReconnect=true"/>
</Context>
注意代碼中紅色部分:DBTest 改為自己的項目路徑;TestDB改為自己的數據源名,但是后面使用時候要與這里的配置保持一致;javauser和 javauser改為自己MySQL的用戶名密碼;url的格式依次為jdbc:mysql://{你的數據庫服務所在的IP,如果為本機就為localhost}:{你的數據庫服務端口號}/{MySQL中要使用的數據庫名稱}?autoReconnect=true ?。
3.修改項目WEB-INF/web.xml 配置文件(若無,請新建),在“</web-app>”之上添加如下代碼:
? <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>
上步中若修改了數據源名此步中紅色部分請保持與上步中的一致。
4.代碼示例:
Context initContext = new InitialContext();
Context envContext? = (Context)initContext.lookup("java:/comp/env");
DataSource ds = (DataSource)envContext.lookup("jdbc/TestDB");
Connection conn = ds.getConnection();
Statement st = null;
ResultSet rs = null;
st = conn.createStatement();
rs = st.executeQuery(yoursql);
注意紅色部分與上兩步中的一致;yoursql處寫你的sql代碼。
通過1-3步就在Tomcat中配置好了MySQL的數據庫連接池。
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