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
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
|
/*
* Copyright 2000-2014 Vaadin Ltd.
*
* Licensed 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
*
* http://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.
*/
package com.vaadin.data.util.sqlcontainer.connection;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.HashSet;
import java.util.Set;
/**
* Simple implementation of the JDBCConnectionPool interface. Handles loading
* the JDBC driver, setting up the connections and ensuring they are still
* usable upon release.
*/
@SuppressWarnings("serial")
public class SimpleJDBCConnectionPool implements JDBCConnectionPool {
private int initialConnections = 5;
private int maxConnections = 20;
private String driverName;
private String connectionUri;
private String userName;
private String password;
private transient Set<Connection> availableConnections;
private transient Set<Connection> reservedConnections;
private boolean initialized;
public SimpleJDBCConnectionPool(String driverName, String connectionUri,
String userName, String password) throws SQLException {
if (driverName == null) {
throw new IllegalArgumentException(
"JDBC driver class name must be given.");
}
if (connectionUri == null) {
throw new IllegalArgumentException(
"Database connection URI must be given.");
}
if (userName == null) {
throw new IllegalArgumentException(
"Database username must be given.");
}
if (password == null) {
throw new IllegalArgumentException(
"Database password must be given.");
}
this.driverName = driverName;
this.connectionUri = connectionUri;
this.userName = userName;
this.password = password;
/* Initialize JDBC driver */
try {
Class.forName(driverName).newInstance();
} catch (Exception ex) {
throw new RuntimeException("Specified JDBC Driver: " + driverName
+ " - initialization failed.", ex);
}
}
public SimpleJDBCConnectionPool(String driverName, String connectionUri,
String userName, String password, int initialConnections,
int maxConnections) throws SQLException {
this(driverName, connectionUri, userName, password);
this.initialConnections = initialConnections;
this.maxConnections = maxConnections;
}
private void initializeConnections() throws SQLException {
availableConnections = new HashSet<Connection>(initialConnections);
reservedConnections = new HashSet<Connection>(initialConnections);
for (int i = 0; i < initialConnections; i++) {
availableConnections.add(createConnection());
}
initialized = true;
}
@Override
public synchronized Connection reserveConnection() throws SQLException {
if (!initialized) {
initializeConnections();
}
if (availableConnections.isEmpty()) {
if (reservedConnections.size() < maxConnections) {
availableConnections.add(createConnection());
} else {
throw new SQLException("Connection limit has been reached.");
}
}
Connection c = availableConnections.iterator().next();
availableConnections.remove(c);
reservedConnections.add(c);
return c;
}
@Override
public synchronized void releaseConnection(Connection conn) {
if (conn == null || !initialized) {
return;
}
/* Try to roll back if necessary */
try {
if (!conn.getAutoCommit()) {
conn.rollback();
}
} catch (SQLException e) {
/* Roll back failed, close and discard connection */
try {
conn.close();
} catch (SQLException e1) {
/* Nothing needs to be done */
}
reservedConnections.remove(conn);
return;
}
reservedConnections.remove(conn);
availableConnections.add(conn);
}
private Connection createConnection() throws SQLException {
Connection c = DriverManager.getConnection(connectionUri, userName,
password);
c.setAutoCommit(false);
if (driverName.toLowerCase().contains("mysql")) {
try {
Statement s = c.createStatement();
s.execute("SET SESSION sql_mode = 'ANSI'");
s.close();
} catch (Exception e) {
// Failed to set ansi mode; continue
}
}
return c;
}
@Override
public void destroy() {
for (Connection c : availableConnections) {
try {
c.close();
} catch (SQLException e) {
// No need to do anything
}
}
for (Connection c : reservedConnections) {
try {
c.close();
} catch (SQLException e) {
// No need to do anything
}
}
}
private void writeObject(java.io.ObjectOutputStream out) throws IOException {
initialized = false;
out.defaultWriteObject();
}
}
|
