第8章 数据库连接池

*数据库连接池的基本思想：为数据库建立一个缓冲池，预先在缓冲池中放入一定数量的连接，当需要建立数据库连接时，只需要从缓冲池中取出一个，使用完毕后再放回

*数据库连接池负责分配、管理和释放数据库连接，它语序应用程序重复使用一个现有的数据库连接，而不是重新建立一个。

1.C3P0数据库连接池

*导入jar包

*进入c3p0doc文档，查询配置方法

 *在src下创建c3p0-config.xml

<c3p0-config>
    <named-config name="helloC3P0">
        
        <property name="driverClass">com.mysql.cj.jdbc.Driverproperty>
        <property name="jdbcUrl">jdbc:mysql://localhost:3306/test?serverTimezone=UTC&useSSL=falseproperty>
        <property name="user">rootproperty>
        <property name="password">123456property>
        
        <property name="acquireIncrement">5property>
        <property name="initialPoolSize">10property>
        <property name="minPoolSize">10property>
        <property name="maxPoolSize">100property>
        <property name="maxStatements">50property>
        <property name="maxStatementsPerConnection">5property>
 
    named-config>
c3p0-config>

*使用c3p0数据库连接池获取连接

    public void testGetConnection2() throws SQLException {
        ComboPooledDataSource cpds = new ComboPooledDataSource("helloC3P0");
        Connection conn = cpds.getConnection();
        System.out.println(conn);
    }

2.DBCP数据库连接池

*导入jar包

*在src下创建dbcp.properties配置文件

driverClassNmae=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://@localhost:3306/test?serverTimezone=UTC&useSSL=false
username=root
password=168465

 *使用DBCP数据库连接池获取连接

public void testGetConnection2() throws Exception {
        Properties pros=new Properties();
        InputStream is = ClassLoader.getSystemClassLoader().getResourceAsStream("dbcp.properties");
        pros.load(is);
        DataSource source = BasicDataSourceFactory.createDataSource(pros);
        Connection conn = source.getConnection();
        System.out.println(conn);
    }

3.Druid数据库连接池

*导入jar包

*在src下创建druid.properties配置文件

username=root
password=321684635
url=jdbc:mysql://localhost:3306/test?serverTimezone=UTC&useSSL=false&allowPublicKeyRetrieval=true&rewriteBatchedStatements=true
driverClassName=com.mysql.cj.jdbc.Driver

 *使用Druid数据库连接池获取连接

 public void getConnection() throws Exception {
        Properties pros = new Properties();
        InputStream is = ClassLoader.getSystemClassLoader().getResourceAsStream("druid.properties");
        pros.load(is);
        DataSource source = DruidDataSourceFactory.createDataSource(pros);
        Connection conn = source.getConnection();
        System.out.println(conn);
    }

*使用Druid的JDBCUtiles

    private static DataSource source;
    static {
        try {
            Properties pros=new Properties();
            InputStream is = ClassLoader.getSystemClassLoader().getResourceAsStream("druid.properties");
            pros.load(is);
            source= DruidDataSourceFactory.createDataSource(pros);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public static Connection getConnection() throws SQLException {
        return source.getConnection();
    }