mysql架構示意圖：
最原始的JDBC實現（mysql-connctor-java）： 加載JDBC驅動程序 → 建立數據庫連接Connection → 創建執行SQL的語句Statement(preparedStatement) → 處理執行結果ResultSet → 釋放資源
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定義，執行靜態的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的核心應該是重寫statement
sharding-jdbc核心應該也是對statement
druid核心應該是Connection
各個中間件通過Statement的execute向下遞歸調用