Mybatis源码之Statement处理器RoutingStatementHandler（三）

RoutingStatementHandler类似路由器，在其构造函数中会根据Mapper文件中设置的StatementType来选择使用SimpleStatementHandler、PreparedStatementHandler和CallableStatementHandler，其实现的接口StatementHandler的方法也是由这三个具体实现类来实现。

源码如下：

/**
* @author Clinton Begin
*/
//类似于路由器
public class RoutingStatementHandler implements StatementHandler {

private final StatementHandler delegate;

//选择三种Statement，SimpleStatementHandler、PreparedStatementHandler和CallableStatementHandler
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());
}

}

//选中的Statement的操作
public Statement prepare(Connection connection) throws SQLException {
return delegate.prepare(connection);
}

public void parameterize(Statement statement) throws SQLException {
delegate.parameterize(statement);
}

public void batch(Statement statement) throws SQLException {
delegate.batch(statement);
}

public int update(Statement statement) throws SQLException {
return delegate.update(statement);
}

public <E> List<E> query(Statement statement, ResultHandler resultHandler) throws SQLException {
return delegate.<E>query(statement, resultHandler);
}

public BoundSql getBoundSql() {
return delegate.getBoundSql();
}

public ParameterHandler getParameterHandler() {
return delegate.getParameterHandler();
}
}