数据库几个中间件的关系及大致原理

mysql架构示意图：

最原始的JDBC实现（mysql-connctor-java）： 加载JDBC驱动程序 → 建立数据库连接Connection → 创建执行SQL的语句Statement(preparedStatement) → 处理执行结果ResultSet → 释放资源

 

DataSource->Connection->Statement

 

DataSource的核心方法:

public interface DataSource extends CommonDataSource,Wrapper {

　　Connection getConnection() throws SQLException;

　　Connection getConnection(String username, String password)
　　throws SQLException;
}

Connection核心api：

public interface Connection extends Wrapper, AutoCloseable {

　　Statement createStatement() throws SQLException;

　　PreparedStatement prepareStatement(String sql) throws SQLException;

　　CallableStatement prepareCall(String sql) throws SQLException;

　　void setAutoCommit(boolean autoCommit) throws SQLException;

　　boolean getAutoCommit() throws SQLException;

　　void commit() throws SQLException;

　　void rollback() throws SQLException;

　　void close() throws SQLException;

　　boolean isClosed() throws SQLException;
}

Statement核心API定义，执行静态的sql：

public interface Statement extends Wrapper, AutoCloseable {

　　ResultSet executeQuery(String sql) throws SQLException;

　　int executeUpdate(String sql) throws SQLException;

　　void close() throws SQLException;

　　boolean execute(String sql, String columnNames[]) throws SQLException;

　　boolean isClosed() throws SQLException;

　　public boolean isCloseOnCompletion() throws SQLException;

}

ibatis的核心应该是重写statement

sharding-jdbc核心应该也是对statement

druid核心应该是Connection

各个中间件通过Statement的execute向下递归调用