数据源配置心得体会

其实在tomcat5下配置数据源的帖子网上也有很多，但是基本上一次成功的不多，为什么呢？ 主要可能有以下几个原因：
1。xml文件配置不正确
2。通过图形化界面去配置（事实证明，通过图形化界面去配置数据源常常会引起bug，所以还是推荐用手动去配置）
3。程序迁移时，第三方的jar的位置放置是否正确（大多数情况下，开发人员可能是把一个现成的应用移植到tomcat服务器上来而遇到了种种原因。）
配置基于DBCP的数据源，主要需要配置server.xml，另外，在web.xml里，也要做resource-ref的配置，也可以不配，但是按照规范，推荐配置。

一个已经配置成功的server.xml如下：
<?xml version='1.0' encoding='utf-8'?>
<Server>
<Listener className="org.apache.catalina.mbeans.ServerLifecycleListener"/>
<Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener"/>
<GlobalNamingResources>
<Environment name="simpleValue" type="java.lang.Integer" value="30"/>
<Resource auth="Container" description="User database that can be updated and saved" name="UserDatabase" type="org.apache.catalina.UserDatabase"/>
<ResourceParams name="UserDatabase">
<parameter>
<name>factory</name>
<value>org.apache.catalina.users.MemoryUserDatabaseFactory</value>
</parameter>
<parameter>
<name>pathname</name>
<value>conf/tomcat-users.xml</value>
</parameter>
</ResourceParams>
</GlobalNamingResources>
<Service name="Catalina">
<Connector acceptCount="100" connectionTimeout="20000" disableUploadTimeout="true" port="8081" redirectPort="8443" maxSpareThreads="75" maxThreads="150" minSpareThreads="25">
</Connector>
<Connector port="8009" protocol="AJP/1.3" protocolHandlerClassName="org.apache.jk.server.JkCoyoteHandler" redirectPort="8443">
</Connector>
<Engine defaultHost="localhost" name="Catalina">
<Host appBase="webapps" name="localhost">
<Logger className="org.apache.catalina.logger.FileLogger" prefix="localhost_log." suffix=".txt" timestamp="true"/>
<Context path="/PUB_J2EE" docBase="PUB_J2EE" debug="5" reloadable="true" crossContext="true">
<Logger className="org.apache.catalina.logger.FileLogger" prefix="localhost_PUBJ2EE_log." suffix=".txt" timestamp="true"/>
<Resource name="jdbc/sqldb" auth="Container" type="javax.sql.DataSource"/>
<Resource name="jdbc/file" auth="Container" type="javax.sql.DataSource"/>
<ResourceParams name="jdbc/sqldb">
<parameter>
<name>factory</name>
<value>org.apache.commons.dbcp.BasicDataSourceFactory</value>
</parameter>
<!-- Class name for mm.mysql JDBC driver -->
<parameter>
<name>driverClassName</name>
<value>com.microsoft.jdbc.sqlserver.SQLServerDriver</value>
</parameter>
<!-- 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.-->
<parameter>
<name>url</name>
<value>jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=PUB_J2EE</value>
</parameter>
<!-- MySQL dB username and password for dB connections -->
<parameter>
<name>username</name>
<value>sa</value>
</parameter>
<parameter>
<name>password</name>
<value>sa</value>
</parameter>
<!-- 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 0 for no limit.-->
<parameter>
<name>maxActive</name>
<value>100</value>
</parameter>
<!-- Maximum number of idle dB connections to retain in pool.
Set to 0 for no limit. -->
<parameter>
<name>maxIdle</name>
<value>30</value>
</parameter>
<!-- 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.-->
<parameter>
<name>maxWait</name>
<value>10000</value>
</parameter>
</ResourceParams>
<ResourceParams name="jdbc/file">
<parameter>
<name>factory</name>
<value>org.apache.commons.dbcp.BasicDataSourceFactory</value>
</parameter>
<!-- Class name for mm.mysql JDBC driver -->
<parameter>
<name>driverClassName</name>
<value>com.microsoft.jdbc.sqlserver.SQLServerDriver</value>
</parameter>
<!-- 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.-->
<parameter>
<name>url</name>
<value>jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=FileSource</value>
</parameter>
<!-- MySQL dB username and password for dB connections -->
<parameter>
<name>username</name>
<value>sa</value>
</parameter>
<parameter>
<name>password</name>
<value>sa</value>
</parameter>
<!-- 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 0 for no limit.-->
<parameter>
<name>maxActive</name>
<value>100</value>
</parameter>
<!-- Maximum number of idle dB connections to retain in pool.
Set to 0 for no limit. -->
<parameter>
<name>maxIdle</name>
<value>30</value>
</parameter>
<!-- 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.-->
<parameter>
<name>maxWait</name>
<value>10000</value>
</parameter>
</ResourceParams>
</Context>
</Host>
<Logger className="org.apache.catalina.logger.FileLogger" prefix="catalina_log." suffix=".txt" timestamp="true"/>
<Realm className="org.apache.catalina.realm.UserDatabaseRealm"/>
</Engine>
</Service>
</Server>