数据库连接池，DBUtil的模板，dbcp，c3p0

数据库连接池，DBUtil的模板，Druid使用(重点)

一、DBUtil模板

public class DBUtilTest {

    public static Connection connection;

    public static final String URL = "jdbc:mysql:///demo";

    public static final String USERNAME = "";

    public static final String PASSWORD = "";

    static {

        try {

            Class.forName("com.mysql.cj.jdbc.Driver");

        } catch (ClassNotFoundException e) {

            e.printStackTrace();

        }

    }

    public static void testQuery() throws SQLException {

        connection = DriverManager.getConnection(URL,USERNAME,PASSWORD);

        String sql = "select * from emp where id = ?";

        QueryRunner runner = new QueryRunner();

        Emp query = runner.query(connection, sql, new BeanHandler<Emp>(Emp.class), 1);

        System.out.println(query);

    }

    public static void testQuery2() throws SQLException {

        connection = DriverManager.getConnection(URL,USERNAME,PASSWORD);

        String sql = "select * from emp";

        QueryRunner runner = new QueryRunner();

        List<Emp> query = runner.query(connection, sql, new BeanListHandler<Emp>(Emp.class));

        query.forEach((x)->{

            System.out.println(x);

        });

    }

    public static void insert() throws SQLException {

        connection = DriverManager.getConnection(URL,USERNAME,PASSWORD);

        String sql = "insert emp values(null,?,?)";

        QueryRunner runner = new QueryRunner();

        runner.update(connection,sql,1,2);

    }

    public static void main(String[] args) throws SQLException {

        testQuery2();

    }

}

二、数据库连接池

数据库连接池是为了减少频繁开关连接的时间，分析应该具备几个属性

1.初始大小

2.每次扩容大小

3.连接池最大个数

4.空闲连接死亡时间

各种数据库连接池

DBCP
C3P0
Druid
hikariCP

2.1.DBCP模板

public static void main(String[] args) throws SQLException {

        // 数据库连接池资源

        BasicDataSource basicDataSource = new BasicDataSource();

        basicDataSource.setDriverClassName("com.mysql.cj.jdbc.Driver");

        basicDataSource.setUrl("jdbc:mysql:///demo");

        basicDataSource.setUsername("");

        basicDataSource.setPassword("");

        Connection connection = null;

        PreparedStatement preparedStatement = null;

        ResultSet rs = null;

        connection = basicDataSource.getConnection();

        String sql = "select * from emp";

        preparedStatement = connection.prepareStatement(sql);

        rs = preparedStatement.executeQuery();

        while (rs.next()){

            System.out.println(rs.getInt(1)+

                    rs.getString(2)+

                    rs.getString(3));

        }

        connection.close();

    }

2.2.C3P0

public static void main(String[] args) throws PropertyVetoException, SQLException {

    ComboPooledDataSource cpds = new ComboPooledDataSource();

    cpds.setDriverClass( "com.mysql.cj.jdbc.Driver" ); //loads the jdbc driver

    cpds.setJdbcUrl( "jdbc:mysql://120.78.206.78:3306/demo" );

    cpds.setUser("root");

    cpds.setPassword("Root123..");

    cpds.setMaxStatements( 180 );

    Connection conn = cpds.getConnection();

    System.out.println(conn);

    conn.close();

}

第二种参照官网，进行xml配置

2.3.druid

druid是性能最好的数据库连接池

dbcp和c3p0区别，c3p0会自动回收不使用的连接

巴特西

数据库连接池，DBUtil的模板，dbcp，c3p0

数据库连接池，DBUtil的模板，Druid使用(重点)

一、DBUtil模板

二、数据库连接池

2.1.DBCP模板

2.2.C3P0

2.3.druid

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