1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
|
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* <p>
* This package contains two DataSources: {@code PerUserPoolDataSource} and
* {@code SharedPoolDataSource} which provide a database connection pool.
* Below are a couple of usage examples. One shows deployment into a JNDI system.
* The other is a simple example initializing the pool using standard Java code.
* </p>
* <h2>JNDI</h2>
* <p>
* Most
* J2EE containers will provide some way of deploying resources into JNDI. The
* method will vary among containers, but once the resource is available via
* JNDI, the application can access the resource in a container independent
* manner. The following example shows deployment into tomcat (catalina).
* </p>
* <p>In server.xml, the following would be added to the <Context> for your
* webapp:
* </p>
* <pre>
* <Resource name="jdbc/bookstore" auth="Container"
* type="org.apache.tomcat.dbcp.dbcp2.datasources.PerUserPoolPoolDataSource"/>
* <ResourceParams name="jdbc/bookstore">
* <parameter>
* <name>factory</name>
* <value>org.apache.tomcat.dbcp.dbcp2.datasources.PerUserPoolDataSourceFactory</value>
* </parameter>
* <parameter>
* <name>dataSourceName</name><value>java:comp/env/jdbc/bookstoreCPDS</value>
* </parameter>
* <parameter>
* <name>defaultMaxTotal</name><value>30</value>
* </parameter>
* </ResourceParams>
* </pre>
* <p>
* In web.xml. Note that elements must be given in the order of the dtd
* described in the servlet specification:
* </p>
* <pre>
* <resource-ref>
* <description>
* Resource reference to a factory for java.sql.Connection
* instances that may be used for talking to a particular
* database that is configured in the server.xml file.
* </description>
* <res-ref-name>
* jdbc/bookstore
* </res-ref-name>
* <res-type>
* org.apache.tomcat.dbcp.dbcp2.datasources.PerUserPoolDataSource
* </res-type>
* <res-auth>
* Container
* </res-auth>
* </resource-ref>
* </pre>
* <p>
* Apache Tomcat deploys all objects configured similarly to above within the
* <strong>java:comp/env</strong> namespace. So the JNDI path given for
* the dataSourceName parameter is valid for a
* {@code ConnectionPoolDataSource} that is deployed as given in the
* <a href="../cpdsadapter/package-summary.html">cpdsadapter example</a>
* </p>
* <p>
* The {@code DataSource} is now available to the application as shown
* below:
* </p>
* <pre>
* Context ctx = new InitialContext();
* DataSource ds = (DataSource)
* ctx.lookup("java:comp/env/jdbc/bookstore");
* Connection con = null;
* try
* {
* con = ds.getConnection();
* ...
* use the connection
* ...
* }
* finally
* {
* if (con != null)
* con.close();
* }
* </pre>
* <p>
* The reference to the {@code DataSource} could be maintained, for
* multiple getConnection() requests. Or the {@code DataSource} can be
* looked up in different parts of the application code.
* {@code PerUserPoolDataSourceFactory} and
* {@code SharedPoolDataSourceFactory} will maintain the state of the pool
* between different lookups. This behavior may be different in other
* implementations.
* </p>
* <h2>Without JNDI</h2>
* <p>
* Connection pooling is useful in applications regardless of whether they run
* in a J2EE environment and a {@code DataSource} can be used within a
* simpler environment. The example below shows SharedPoolDataSource using
* DriverAdapterCPDS as the back end source, though any CPDS is applicable.
* </p>
* <pre>
* public class Pool {
*
* private static DataSource ds;
*
* static {
* DriverAdapterCPDS cpds = new DriverAdapterCPDS();
* cpds.setDriver("org.gjt.mm.mysql.Driver");
* cpds.setUrl("jdbc:mysql://localhost:3306/bookstore");
* cpds.setUser("foo");
* cpds.setPassword(null);
*
* SharedPoolDataSource tds = new SharedPoolDataSource();
* tds.setConnectionPoolDataSource(cpds);
* tds.setMaxTotal(10);
* tds.setMaxWaitMillis(50);
*
* ds = tds;
* }
*
* public static getConnection() {
* return ds.getConnection();
* }
* }
* </pre>
* <p>
* This class can then be used wherever a connection is needed:
* </p>
* <pre>
* Connection con = null;
* try {
* con = Pool.getConnection();
* ...
* use the connection
* ...
* } finally {
* if (con != null) {
* con.close();
* }
* }
* </pre>
*/
package org.apache.tomcat.dbcp.dbcp2.datasources;
|
