测试的tomcat为apache-tomcat-6.0.18 ，数据库为mysql和oracle。
配置步骤如下：
1、把数据库的JDBC驱动放入D:\apache-tomcat-6.0.18\lib目录下
2、在D:\apache-tomcat-6.0.18\conf\web.xml文件中，将下面代码加入到web.xml中：
<
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
>
<
resource
-
ref
>
<
description
>
DB Connection
description
>
<
res
-
ref
-
name
>
jdbc
/
oracle
res
-
ref
-
name
>
<
res
-
type
>
javax.sql.DataSource
res
-
type
>
<
res
-
auth
>
Container
res
-
auth
>
resource
-
ref
>
3、在D:\apache-tomcat-6.0.18\conf\server.xml文件中,在Host节点下添加Context子节点，配置如下
<
Context path
=
"
/ljqtest
"
docBase
=
"
ljqtest
"
debug
=
"
5
"
reloadable
=
"
true
"
crossContext
=
"
true
"
>
<
Resource name
=
"
jdbc/mysql
"
type
=
"
javax.sql.DataSource
"
username
=
"
root
"
password
=
"
mysql
"
driverClassName
=
"
org.gjt.mm.mysql.Driver
"
url
=
"
jdbc:mysql://localhost:3306/shop
"
maxIdle
=
"
2
"
maxWait
=
"
50
"
maxActive
=
"
4
"
>
<
parameter
>
<
name
>
removeAbandoned
name
>
<
value
>
true
value
>
parameter
>
Resource
>
<
Resource name
=
"
jdbc/oracle
"
type
=
"
javax.sql.DataSource
"
username
=
"
test
"
password
=
"
test
"
driverClassName
=
"
oracle.jdbc.driver.OracleDriver
"
url
=
"
jdbc:oracle:thin:@localhost:1521:ORCL
"
maxIdle
=
"
2
"
maxWait
=
"
50
"
maxActive
=
"
4
"
>
<
parameter
>
<
name
>
removeAbandoned
name
>
<
value
>
true
value
>
parameter
>
Resource
>
Context
>
Host
>
或者
<
Context path
=
"
/uimcardprj
"
docBase
=
"
uimcardprj
"
debug
=
"
5
"
reloadable
=
"
true
"
crossContext
=
"
true
"
>
<
Resource name
=
"
jdbc/ycxkDB
"
type
=
"
javax.sql.DataSource
"
username
=
"
ycxk
"
password
=
"
xmzh
"
driverClassName
=
"
oracle.jdbc.driver.OracleDriver
"
url
=
"
jdbc:oracle:thin:@(DESCRIPTION =(ADDRESS = (PROTOCOL = TCP)(HOST = 134.128.48.250)(PORT = 1521))(CONNECT_DATA =(SERVER = DEDICATED)(SERVICE_NAME = orcl)))
"
maxIdle
=
"
2
"
maxWait
=
"
50
"
maxActive
=
"
4
"
>
Resource
>
Context
>
Host
>
注意：path为D:\apache-tomcat-6.0.18\webapps目录下的工程名称
4、把web工程项目部署在D:\apache-tomcat-6.0.18\webapps目录下
4、把web工程项目部署在D:\apache-tomcat-6.0.18\webapps目录下
MysqlConn类：获取Mysql数据源
package
com.ljq.test;
import
java.sql.Connection;
import
java.sql.SQLException;
import
javax.naming.Context;
import
javax.naming.InitialContext;
import
javax.sql.DataSource;
public
final
class
MysqlConn {
//
懒汉式单例(使用时才new)
private
static
MysqlConn instance
=
null
;
MysqlConn() {
}
//
延迟初始化(用到的时候才加载)(推荐)
//
public static synchronized JdbcConn
//
getInstance(){}->这样不好，因为每调用一次就同步，效率非常低
public
static
MysqlConn getInstance() {
if
(instance
==
null
) {
synchronized
(MysqlConn.
class
) {
//
可能会产生并发的问题，我们对他进行同步
if
(instance
==
null
) {
instance
=
new
MysqlConn();
}
}
}
return
instance;
}
private
DataSource getDataSource() {
DataSource ds
=
null
;
try
{
Context ctx
=
new
InitialContext();
ds
=
(DataSource) ctx.lookup(
"
java:comp/env/jdbc/mysql
"
);
}
catch
(Exception e) {
System.out.println(
"
数据源获取失败
"
);
e.printStackTrace();
}
return
ds;
}
public
Connection getConn() {
Connection conn
=
null
;
try
{
conn
=
getDataSource().getConnection();
}
catch
(SQLException e) {
System.out.println(
"
数据库连接失败
"
);
e.printStackTrace();
}
return
conn;
}
}
OraclelConn类：获取Oracle数据源
package
com.ljq.test;
import
java.sql.Connection;
import
java.sql.SQLException;
import
javax.naming.Context;
import
javax.naming.InitialContext;
import
javax.sql.DataSource;
public
final
class
OracleConn {
//
懒汉式单例(使用时才new)
private
static
OracleConn instance
=
null
;
OracleConn() {
}
//
延迟初始化(用到的时候才加载)(推荐)
//
public static synchronized JdbcConn
//
getInstance(){}->这样不好，因为每调用一次就同步，效率非常低
public
static
OracleConn getInstance() {
if
(instance
==
null
) {
synchronized
(OracleConn.
class
) {
//
可能会产生并发的问题，我们对他进行同步
if
(instance
==
null
) {
instance
=
new
OracleConn();
}
}
}
return
instance;
}
private
DataSource getDataSource() {
DataSource ds
=
null
;
try
{
Context ctx
=
new
InitialContext();
ds
=
(DataSource) ctx.lookup(
"
java:comp/env/jdbc/mysql
"
);
}
catch
(Exception e) {
System.out.println(
"
数据源获取失败
"
);
e.printStackTrace();
}
return
ds;
}
public
Connection getConn() {
Connection conn
=
null
;
try
{
conn
=
getDataSource().getConnection();
}
catch
(SQLException e) {
System.out.println(
"
数据库连接失败
"
);
e.printStackTrace();
}
return
conn;
}
}
页面index.jsp:打印数据库连接对象
<
body
>
mysql连接对象为：
<%
Connection conn
=
MysqlConn.getInstance().getConn();
%><%=
conn
%><%
conn.close();
%><
br
/>
oracle连接对象为：
<%
Connection conn2
=
MysqlConn.getInstance().getConn();
%><%=
conn2
%><%
conn2.close();
%><
br
/>
body
>
5、启动tomcat，在浏览器中输入： http://localhost:8083/ljqtest/，输出如下：