me.icymint.libra.jdbc.query.multi.QueryTokens Maven / Gradle / Ivy

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package me.icymint.libra.jdbc.query.multi;

import java.sql.Connection;

import me.icymint.libra.jdbc.JdbcAccessException;
import me.icymint.libra.jdbc.query.SqlQuery;

/**
 * 一组相关JDBC执行序列。其用于定义一组有序的JDBC查询序列。规定了初始参数和最后返回参数的形式。
 * 
 * @author Daniel Yu
 * @since 2013-3-14
 * 
 * @param 
 *            最后返回结果。
 * @param 
 *            查询初始参数。
 */
public class QueryTokens implements SqlQuery {

	private static class Q {
		private Object p = null;

		private Q(Object p) {
			this.p = p;
		}

		@SuppressWarnings("unchecked")
		private  P getResult() {
			return (P) p;
		}

		@SuppressWarnings("unchecked")
		private  Q query(Connection conn, QueryToken token)
				throws JdbcAccessException {
			this.p = token.query().query(conn, token.sql(),
					token.p() == null ? (P) this.getResult() : token.p());
			return this;
		}
	}

	private QueryToken x;
	private QueryToken[] ys;
	private QueryToken z;

	public QueryTokens(QueryToken x, QueryToken[] ys,
			QueryToken z) {
		this.x = x;
		this.ys = ys;
		this.z = z;
	}

	@Override
	public T query(Connection conn, String sql, P p) throws JdbcAccessException {
		Q q = new Q(p).query(conn, z);
		for (QueryToken y : ys) {
			q = q.query(conn, y);
		}
		q = q.query(conn, x);
		return q.getResult();
	}
}