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/*
 * Copyright (c) 1997, 2018 Oracle and/or its affiliates. All rights reserved.
 * Copyright 2004 The Apache Software Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package javax.servlet.jsp.jstl.sql;

import java.io.Serializable;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import java.util.SortedMap;
import java.util.TreeMap;

/**
 * 

This class creates a cached version of a ResultSet. * It's represented as a Result implementation, capable of * returing an array of Row objects containing a Column * instance for each column in the row. It is not part of the JSTL * API; it serves merely as a back-end to ResultSupport's static methods. * Thus, we scope its access to the package. * * @author Hans Bergsten * @author Justyna Horwat */ class ResultImpl implements Result, Serializable { private List> rowMap; private List rowByIndex; private String[] columnNames; private boolean isLimited; /** * This constructor reads the ResultSet and saves a cached * copy. * It's important to note that this object will be serializable only * if the objects returned by the ResultSet are serializable too. * * @param rs an open ResultSet, positioned before the first * row * @param startRow beginning row to be cached * @param maxRows query maximum rows limit * @exception java.sql.SQLException if a database error occurs */ public ResultImpl(ResultSet rs, int startRow, int maxRows) throws SQLException { rowMap = new ArrayList>(); rowByIndex = new ArrayList(); ResultSetMetaData rsmd = rs.getMetaData(); int noOfColumns = rsmd.getColumnCount(); // Create the column name array columnNames = new String[noOfColumns]; for (int i = 1; i <= noOfColumns; i++) { columnNames[i-1] = rsmd.getColumnName(i); } // Throw away all rows upto startRow for (int i = 0; i < startRow; i++) { rs.next(); } // Process the remaining rows upto maxRows int processedRows = 0; while (rs.next()) { if ((maxRows != -1) && (processedRows == maxRows)) { isLimited = true; break; } Object[] columns = new Object[noOfColumns]; SortedMap columnMap = new TreeMap(String.CASE_INSENSITIVE_ORDER); // JDBC uses 1 as the lowest index! for (int i = 1; i <= noOfColumns; i++) { Object value = rs.getObject(i); if (rs.wasNull()) { value = null; } columns[i-1] = value; columnMap.put(columnNames[i-1], value); } rowMap.add(columnMap); rowByIndex.add(columns); processedRows++; } } /** * Returns an array of SortedMap objects. The SortedMap * object key is the ColumnName and the value is the ColumnValue. * SortedMap was created using the CASE_INSENSITIVE_ORDER * Comparator so the key is the case insensitive representation * of the ColumnName. * * @return an array of Map, or null if there are no rows */ public SortedMap[] getRows() { if (rowMap == null) { return null; } //should just be able to return SortedMap[] object return rowMap.toArray(new SortedMap[0]); } /** * Returns an array of Object[] objects. The first index * designates the Row, the second the Column. The array * stores the value at the specified row and column. * * @return an array of Object[], or null if there are no rows */ public Object[][] getRowsByIndex() { if (rowByIndex == null) { return null; } //should just be able to return Object[][] object return (Object [][])rowByIndex.toArray(new Object[0][0]); } /** * Returns an array of String objects. The array represents * the names of the columns arranged in the same order as in * the getRowsByIndex() method. * * @return an array of String[] */ public String[] getColumnNames() { return columnNames; } /** * Returns the number of rows in the cached ResultSet * * @return the number of cached rows, or -1 if the Result could * not be initialized due to SQLExceptions */ public int getRowCount() { if (rowMap == null) { return -1; } return rowMap.size(); } /** * Returns true if the query was limited by a maximum row setting * * @return true if the query was limited by a MaxRows attribute */ public boolean isLimitedByMaxRows() { return isLimited; } }





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