MyBatis核心对象之StatementHandler

StatementHandler ResultHandler ParameterHandler Executor

org.apache.ibatis.executor.statement.StatementHandler

org.apache.ibatis.session.ResultHandler

org.apache.ibatis.executor.parameter.ParameterHandler

org.apache.ibatis.executor.Executor

public interface StatementHandler {

	//获取语句

    Statement prepare(Connection connection, Integer transactionTimeout)

        throws SQLException;

	//设置参数

    void parameterize(Statement statement)

        throws SQLException;

	//操作

    void batch(Statement statement)

        throws SQLException;

	//操作

    int update(Statement statement)

        throws SQLException;

	//操作

    <E> List<E> query(Statement statement, ResultHandler resultHandler)

        throws SQLException;

	//操作

    <E> Cursor<E> queryCursor(Statement statement)

        throws SQLException;

	//获取BoundSql

    BoundSql getBoundSql();

	//获取参数处理器

    ParameterHandler getParameterHandler();

}

public class RoutingStatementHandler implements StatementHandler {

    private final StatementHandler delegate;

    //核心，根据ms的语句类型来创建相应的StatementHandler

    public RoutingStatementHandler(Executor executor, MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) {

        switch (ms.getStatementType()) {

            case STATEMENT:

                delegate = new SimpleStatementHandler(executor, ms, parameter, rowBounds, resultHandler, boundSql);

                break;

            case PREPARED:

                delegate = new PreparedStatementHandler(executor, ms, parameter, rowBounds, resultHandler, boundSql);

                break;

            case CALLABLE:

                delegate = new CallableStatementHandler(executor, ms, parameter, rowBounds, resultHandler, boundSql);

                break;

            default:

                throw new ExecutorException("Unknown statement type: " + ms.getStatementType());

        }

    }

    @Override

    public Statement prepare(Connection connection, Integer transactionTimeout) throws SQLException {

        return delegate.prepare(connection, transactionTimeout);

    }

    @Override

    public void parameterize(Statement statement) throws SQLException {

        delegate.parameterize(statement);

    }

    @Override

    public void batch(Statement statement) throws SQLException {

        delegate.batch(statement);

    }

    @Override

    public int update(Statement statement) throws SQLException {

        return delegate.update(statement);

    }

    @Override

    public <E> List<E> query(Statement statement, ResultHandler resultHandler) throws SQLException {

        return delegate.query(statement, resultHandler);

    }

    @Override

    public <E> Cursor<E> queryCursor(Statement statement) throws SQLException {

        return delegate.queryCursor(statement);

    }

    @Override

    public BoundSql getBoundSql() {

        return delegate.getBoundSql();

    }

    @Override

    public ParameterHandler getParameterHandler() {

        return delegate.getParameterHandler();

    }

}

@startuml

interface StatementHandler

class RoutingStatementHandler

StatementHandler <|.. RoutingStatementHandler

abstract class BaseStatementHandler

class PreparedStatementHandler

class CallableStatementHandler

class SimpleStatementHandler

StatementHandler <|.. BaseStatementHandler

BaseStatementHandler <|-- PreparedStatementHandler

BaseStatementHandler <|-- CallableStatementHandler

BaseStatementHandler <|-- SimpleStatementHandler

@enduml