1 @Test
 2     public void testDBCP() throws Exception{
 3         DataSource dataSource=null;
 4         //1.创建DBCP数据源实例
 5         dataSource=new BasicDataSource();
 6         //2.为数据源实例指定必须的属性
 7         ((BasicDataSource) dataSource).setUsername("root");
 8         ((BasicDataSource) dataSource).setPassword("123456");
 9         ((BasicDataSource) dataSource).setUrl("jdbc:mysql://localhost:3306/atguigu");
10         ((BasicDataSource) dataSource).setDriverClassName("com.mysql.jdbc.Driver");
11         //3.指定数据源一些可选的属性(可以看下载的Jar包中的index.html)API文档 
12         /*
13          * maxIdle，最大空闲数，数据库连接的最大空闲时间。超过空闲时间，数据库连接将被标记为不可用，然后被释放。设为0表示无限制。
14            MaxActive，连接池的最大数据库连接数。设为0表示无限制。
15            maxWait ，最大建立连接等待时间。如果超过此时间将接到异常。设为-1表示无限制
16                                 【温馨提示】：pool2中修改如下：
17                     maxActive  ==>  maxTotal
18                     maxWait ==> maxWaitMillis
19          */
20         //1).指定数据库连接池中初始化连接的个数
21         ((BasicDataSource) dataSource).setInitialSize(10);
22         //2).指定数据库连接池中最大连接的个数:同一时刻可以同时向数据库申请的数据库连接
23         ((BasicDataSource) dataSource).setMaxTotal(5);
24         //3).指定数据库连接池中最小连接的个数:在连接池中保存的最小空闲连接的数量
25         ((BasicDataSource) dataSource).setMinIdle(5);
26         //4).指定数据库连接池分配连接的最长时间，单位为毫秒，超出改时间将抛出异常
27         ((BasicDataSource) dataSource).setMaxWaitMillis(1000*5);
28         //4.从数据源中获取数据库连接
29     
30         Connection connection=dataSource.getConnection();
31         System.out.println(connection.getClass());
32        
33     }

driver=com.mysql.jdbc.Driver
jdbcUrl=jdbc:mysql://localhost:3306/atguigu
user=root
password=123456
initialSize=10
maxTotal=50
minIdle=5
maxWaitMillis=5000

 1 @Test
 2     public void testDBCPWithDataSourceFactory() throws Exception{
 3         Properties properties=new Properties();
 4         InputStream inputStream=JDBCTest.class.getClassLoader()
 5                 .getResourceAsStream("dbcp.properties");
 6         properties.load(inputStream);
 7         DataSource dataSource=
 8                 BasicDataSourceFactory.createDataSource(properties);
 9         System.out.println(dataSource.getConnection());
10         
11         BasicDataSource basicDataSource=
12                 (BasicDataSource) dataSource;
13         System.out.println(basicDataSource.getMaxTotal());
14         
15     }

import com.mchange.v2.c3p0.*;...ComboPooledDataSource cpds = new ComboPooledDataSource();
cpds.setDriverClass( "org.postgresql.Driver" ); //loads the jdbc driver            
cpds.setJdbcUrl( "jdbc:postgresql://localhost/testdb" );
cpds.setUser("dbuser");                                  
cpds.setPassword("dbpassword");

1     @Test
2     public void testC3P0() throws Exception{
3         ComboPooledDataSource cpds = new ComboPooledDataSource();
4         cpds.setDriverClass( "com.mysql.jdbc.Driver" ); //loads the jdbc driver            
5         cpds.setJdbcUrl( "jdbc:mysql://localhost:3306/atguigu" );
6         cpds.setUser("root");                                  
7         cpds.setPassword("123456");
8         System.out.println(cpds.getConnection());
9     }

五月 09, 2016 4:35:56 下午 com.mchange.v2.log.MLog 
信息: MLog clients using java 1.4+ standard logging.
五月 09, 2016 4:35:57 下午 com.mchange.v2.c3p0.C3P0Registry 
信息: Initializing c3p0-0.9.5.2 [built 08-December-2015 22:06:04 -0800; debug? true; trace: 10]
五月 09, 2016 4:35:57 下午 com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource 
信息: Initializing c3p0 pool... com.mchange.v2.c3p0.ComboPooledDataSource [ acquireIncrement -> 3, acquireRetryAttempts -> 30, acquireRetryDelay -> 1000, autoCommitOnClose -> false, automaticTestTable -> null, breakAfterAcquireFailure -> false, checkoutTimeout -> 0, connectionCustomizerClassName -> null, connectionTesterClassName -> com.mchange.v2.c3p0.impl.DefaultConnectionTester, contextClassLoaderSource -> caller, dataSourceName -> 1hge1d39g158wpld8tx485|1588809, debugUnreturnedConnectionStackTraces -> false, description -> null, driverClass -> com.mysql.jdbc.Driver, extensions -> {}, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, forceSynchronousCheckins -> false, forceUseNamedDriverClass -> false, identityToken -> 1hge1d39g158wpld8tx485|1588809, idleConnectionTestPeriod -> 0, initialPoolSize -> 3, jdbcUrl -> jdbc:mysql://localhost:3306/atguigu, maxAdministrativeTaskTime -> 0, maxConnectionAge -> 0, maxIdleTime -> 0, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 15, maxStatements -> 0, maxStatementsPerConnection -> 0, minPoolSize -> 3, numHelperThreads -> 3, preferredTestQuery -> null, privilegeSpawnedThreads -> false, properties -> {user=******, password=******}, propertyCycle -> 0, statementCacheNumDeferredCloseThreads -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 0, userOverrides -> {}, usesTraditionalReflectiveProxies -> false ]
com.mchange.v2.c3p0.impl.NewProxyConnection@6776ad [wrapping: com.mysql.jdbc.JDBC4Connection@108b2d7]

     * 1.创建c3p0-config.xml文件，参考帮助文档中*   Appendix B: Configuation Files, etc.的内容* 2.创建ComboPooledDataSource实例：*   DataSource dataSource = new ComboPooledDataSource("helloc3p0"); *3.从DataSource实例中获取数据库连接

<c3p0-config><named-config name="helloc3p0"> <!-- 指定数据源的基本属性 --><property name="user">root</property><property name="password">123456</property><property name="driverClass">com.mysql.jdbc.Driver</property><property name="jdbcUrl">jdbc:mysql://localhost:3306/atguigu</property><!-- 若数据库中连接数不足时，一次向数据库服务器申请多少个连接    --><property name="acquireIncrement">5</property><!-- 初始化数据库连接时连接的数量 --><property name="initialPoolSize">10</property><!-- 数据库连接池中最小的数据库连接数 --><property name="minPoolSize">5</property><!-- 数据库连接池中最大的数据库连接数 --><property name="maxPoolSize">10</property><!-- 数据库连接池可以维护的Statement的个数 --><property name="maxStatements">10</property> <!-- 每个连接同时可以使用的Statement对象的个数 --><property name="maxStatementsPerConnection">5</property></named-config>
</c3p0-config>

1     @Test
2     public void testC3P0withConfigFile() throws Exception{
3         DataSource dataSource = 
4                 new ComboPooledDataSource("helloc3p0"); 
5         System.out.println(dataSource.getConnection());
6         ComboPooledDataSource comboPooledDataSource=
7                 (ComboPooledDataSource) dataSource;
8         System.out.println(comboPooledDataSource.getMaxStatements());
9     }

1 五月 09, 2016 4:42:15 下午 com.mchange.v2.log.MLog 
2 信息: MLog clients using java 1.4+ standard logging.
3 五月 09, 2016 4:42:15 下午 com.mchange.v2.c3p0.C3P0Registry 
4 信息: Initializing c3p0-0.9.5.2 [built 08-December-2015 22:06:04 -0800; debug? true; trace: 10]
5 五月 09, 2016 4:42:15 下午 com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource 
6 信息: Initializing c3p0 pool... com.mchange.v2.c3p0.ComboPooledDataSource [ acquireIncrement -> 5, acquireRetryAttempts -> 30, acquireRetryDelay -> 1000, autoCommitOnClose -> false, automaticTestTable -> null, breakAfterAcquireFailure -> false, checkoutTimeout -> 0, connectionCustomizerClassName -> null, connectionTesterClassName -> com.mchange.v2.c3p0.impl.DefaultConnectionTester, contextClassLoaderSource -> caller, dataSourceName -> helloc3p0, debugUnreturnedConnectionStackTraces -> false, description -> null, driverClass -> com.mysql.jdbc.Driver, extensions -> {}, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, forceSynchronousCheckins -> false, forceUseNamedDriverClass -> false, identityToken -> 1hge1d39g1594tqaufcxlm|1588809, idleConnectionTestPeriod -> 0, initialPoolSize -> 10, jdbcUrl -> jdbc:mysql://localhost:3306/atguigu, maxAdministrativeTaskTime -> 0, maxConnectionAge -> 0, maxIdleTime -> 0, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 10, maxStatements -> 10, maxStatementsPerConnection -> 5, minPoolSize -> 5, numHelperThreads -> 3, preferredTestQuery -> null, privilegeSpawnedThreads -> false, properties -> {user=******, password=******}, propertyCycle -> 0, statementCacheNumDeferredCloseThreads -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 0, userOverrides -> {}, usesTraditionalReflectiveProxies -> false ]
7 com.mchange.v2.c3p0.impl.NewProxyConnection@1bcffb5 [wrapping: com.mysql.jdbc.JDBC4Connection@c1f859]
8 10

 1     private static DataSource dataSource=null;
 2     //数据库连接池只被初始化一次
 3     static {
 4         dataSource=new ComboPooledDataSource("helloc3p0");
 5     }
 6     // 获取数据库连接
 7     public static Connection getConnection() throws  Exception{
 8         
 9         /*    ClassNotFoundException, SQLException {
10         Properties properties = new Properties();
11         InputStream inputStream = JDBCTest.class.getClassLoader()
12                 .getResourceAsStream("jdbc.properties");
13         properties.load(inputStream);
14         String user = properties.getProperty("user");
15         String password = properties.getProperty("password");
16         String jdbcUrl = properties.getProperty("jdbcUrl");
17         String driverClass = properties.getProperty("driver");
18         Class.forName(driverClass);
19         Connection connection = DriverManager.getConnection(jdbcUrl, user,
20                 password);*/
21         
22         return dataSource.getConnection();
23     }