org.apache.commons.dbcp.SQLNestedException: Cannot create JDBC driver of class '' for connect URL 'null'

错误代码:
    org.apache.commons.dbcp.SQLNestedException: Cannot create JDBC driver of class '' for connect URL 'null'.
错误原因:
    由于程序在执行时不能创建连接池.
解决方法
    1.在Tomcat 5.0.30中
            打开tomcat/conf/server.xml,找到<Host>,并在<Host></Host>中写入:
            <Context path="/myapp" reloadable="true" docBase="G:\\JAVAFile\\myapp\\context" >
    <!--Loader className="org.apache.catalina.loader.DevLoader" reloadable="true" debug="1"/-->
    
  <Resource name="jdbc/appfuse" auth="Container"
  type="javax.sql.DataSource"/>
  
  <ResourceParams name="jdbc/appfuse">
  <parameter>
  <name>factory</name>
  <value>org.apache.commons.dbcp.BasicDataSourceFactory</value>
  </parameter>
  <parameter>
  <name>driverClassName</name>
  <value>org.gjt.mm.mysql.Driver</value>
  </parameter>
  <parameter>
  <name>url</name>
  <value>jdbc:mysql://localhost:3306/appfuse</value>
  </parameter>
  <parameter>
  <name>username</name>
  <value>root</value>
  </parameter>
  <parameter>
  <name>password</name>
  <value></value>
  </parameter>
  <parameter>
  <name>maxActive</name>
  <value>20</value>
  </parameter>
  <parameter>
  <name>maxIdle</name>
  <value>10</value>
  </parameter>
  <parameter>
  <name>maxWait</name>
  <value>-1</value>
  </parameter>
  </ResourceParams>
 </Context>

这样就可以了.

2.在Tomcat5.5.9中
    同样在<Host></Host>中写入:
<Context path="/myapp" docBase="G:\\JAVAFile\\myapp\\context"  swallowOutput="true" crossContext="true"                   reloadable="false">
          <Logger className="org.apache.catalina.logger.FileLogger"
                   prefix="myapp." suffix=".log" timestamp="true"/>
          <Resource name="jdbc/appfuse" auth="Container" type="javax.sql.DataSource"
            username="test"
            password="test"
            driverClassName="com.mysql.jdbc.Driver"
            url="jdbc:mysql://localhost:3306/appfuse?autoReconnect=true"
            maxActive="30"
            maxIdle="5"
            maxWait="50"
            minEvictableIdleTimeMillis="4000"
            timeBetweenEvictionRunsMillis="5000"
            />
         </Context>

就能够解决问题了.