| 1 | /* |
| 2 | * Copyright 2006-2008 the original author or authors. |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package org.springframework.batch.item.database.support; |
| 18 | |
| 19 | import javax.sql.DataSource; |
| 20 | |
| 21 | import org.springframework.util.Assert; |
| 22 | import org.springframework.util.StringUtils; |
| 23 | import org.springframework.batch.item.database.JdbcParameterUtils; |
| 24 | import org.springframework.batch.item.database.PagingQueryProvider; |
| 25 | import org.springframework.dao.InvalidDataAccessApiUsageException; |
| 26 | |
| 27 | import java.util.List; |
| 28 | import java.util.ArrayList; |
| 29 | |
| 30 | /** |
| 31 | * Abstract SQL Paging Query Provider to serve as a base class for all provided |
| 32 | * SQL paging query providers. |
| 33 | * |
| 34 | * Any implementation must provide a way to specify the select clause, from |
| 35 | * clause and optionally a where clause. In addition a way to specify a single |
| 36 | * column sort key must also be provided. This sort key will be used to provide |
| 37 | * the paging functionality. It is recommended that there should be an index for |
| 38 | * the sort key to provide better performance. |
| 39 | * |
| 40 | * Provides properties and preparation for the mandatory "selectClause" and |
| 41 | * "fromClause" as well as for the optional "whereClause". Also provides |
| 42 | * property for the mandatory "sortKey". |
| 43 | * |
| 44 | * @author Thomas Risberg |
| 45 | * @author Dave Syer |
| 46 | * @since 2.0 |
| 47 | */ |
| 48 | public abstract class AbstractSqlPagingQueryProvider implements PagingQueryProvider { |
| 49 | |
| 50 | private String selectClause; |
| 51 | |
| 52 | private String fromClause; |
| 53 | |
| 54 | private String whereClause; |
| 55 | |
| 56 | private String sortKey; |
| 57 | |
| 58 | private boolean ascending = true; |
| 59 | |
| 60 | private int parameterCount; |
| 61 | |
| 62 | private boolean usingNamedParameters; |
| 63 | |
| 64 | /** |
| 65 | * @param selectClause SELECT clause part of SQL query string |
| 66 | */ |
| 67 | public void setSelectClause(String selectClause) { |
| 68 | this.selectClause = removeKeyWord("select", selectClause); |
| 69 | } |
| 70 | |
| 71 | /** |
| 72 | * |
| 73 | * @return SQL SELECT clause part of SQL query string |
| 74 | */ |
| 75 | protected String getSelectClause() { |
| 76 | return selectClause; |
| 77 | } |
| 78 | |
| 79 | /** |
| 80 | * @param fromClause FROM clause part of SQL query string |
| 81 | */ |
| 82 | public void setFromClause(String fromClause) { |
| 83 | this.fromClause = removeKeyWord("from", fromClause); |
| 84 | } |
| 85 | |
| 86 | /** |
| 87 | * |
| 88 | * @return SQL FROM clause part of SQL query string |
| 89 | */ |
| 90 | protected String getFromClause() { |
| 91 | return fromClause; |
| 92 | } |
| 93 | |
| 94 | /** |
| 95 | * @param whereClause WHERE clause part of SQL query string |
| 96 | */ |
| 97 | public void setWhereClause(String whereClause) { |
| 98 | if (StringUtils.hasText(whereClause)) { |
| 99 | this.whereClause = removeKeyWord("where", whereClause); |
| 100 | } |
| 101 | else { |
| 102 | this.whereClause = null; |
| 103 | } |
| 104 | } |
| 105 | |
| 106 | /** |
| 107 | * |
| 108 | * @return SQL WHERE clause part of SQL query string |
| 109 | */ |
| 110 | protected String getWhereClause() { |
| 111 | return whereClause; |
| 112 | } |
| 113 | |
| 114 | /** |
| 115 | * @param sortKey key to use to sort and limit page content |
| 116 | */ |
| 117 | public void setSortKey(String sortKey) { |
| 118 | this.sortKey = sortKey; |
| 119 | } |
| 120 | |
| 121 | /** |
| 122 | * Set the flag that signals that the sort key is applied ascending (default |
| 123 | * true). |
| 124 | * |
| 125 | * @param ascending the ascending value to set |
| 126 | */ |
| 127 | public void setAscending(boolean ascending) { |
| 128 | this.ascending = ascending; |
| 129 | } |
| 130 | |
| 131 | /** |
| 132 | * Get the flag that signals that the sort key is applied ascending. |
| 133 | * |
| 134 | * @return the ascending flag |
| 135 | */ |
| 136 | public boolean isAscending() { |
| 137 | return ascending; |
| 138 | } |
| 139 | |
| 140 | /** |
| 141 | * |
| 142 | * @return sortKey key to use to sort and limit page content |
| 143 | */ |
| 144 | public String getSortKey() { |
| 145 | return sortKey; |
| 146 | } |
| 147 | |
| 148 | /** |
| 149 | * |
| 150 | * @return sortKey key to use to sort and limit page content (without alias) |
| 151 | */ |
| 152 | public String getSortKeyWithoutAlias() { |
| 153 | String sortKey = getSortKey(); |
| 154 | int separator = sortKey.indexOf('.'); |
| 155 | if (separator > 0) { |
| 156 | int columnIndex = separator + 1; |
| 157 | if (columnIndex < sortKey.length()) { |
| 158 | sortKey = sortKey.substring(columnIndex); |
| 159 | } |
| 160 | } |
| 161 | return sortKey; |
| 162 | } |
| 163 | |
| 164 | public int getParameterCount() { |
| 165 | return parameterCount; |
| 166 | } |
| 167 | |
| 168 | public boolean isUsingNamedParameters() { |
| 169 | return usingNamedParameters; |
| 170 | } |
| 171 | |
| 172 | /** |
| 173 | * The sort key placeholder will vary depending on whether named parameters |
| 174 | * or traditional placeholders are used in query strings. |
| 175 | * |
| 176 | * @return place holder for sortKey. |
| 177 | */ |
| 178 | protected String getSortKeyPlaceHolder() { |
| 179 | return usingNamedParameters ? ":_sortKey" : "?"; |
| 180 | } |
| 181 | |
| 182 | /** |
| 183 | * Check mandatory properties. |
| 184 | * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet() |
| 185 | */ |
| 186 | public void init(DataSource dataSource) throws Exception { |
| 187 | Assert.notNull(dataSource); |
| 188 | Assert.hasLength(selectClause, "selectClause must be specified"); |
| 189 | Assert.hasLength(fromClause, "fromClause must be specified"); |
| 190 | Assert.hasLength(sortKey, "sortKey must be specified"); |
| 191 | StringBuilder sql = new StringBuilder(); |
| 192 | sql.append("SELECT ").append(selectClause); |
| 193 | sql.append(" FROM ").append(fromClause); |
| 194 | if (whereClause != null) { |
| 195 | sql.append(" WHERE ").append(whereClause); |
| 196 | } |
| 197 | List<String> namedParameters = new ArrayList<String>(); |
| 198 | parameterCount = JdbcParameterUtils.countParameterPlaceholders(sql.toString(), namedParameters); |
| 199 | if (namedParameters.size() > 0) { |
| 200 | if (parameterCount != namedParameters.size()) { |
| 201 | throw new InvalidDataAccessApiUsageException( |
| 202 | "You can't use both named parameters and classic \"?\" placeholders: " + sql); |
| 203 | } |
| 204 | usingNamedParameters = true; |
| 205 | } |
| 206 | } |
| 207 | |
| 208 | /** |
| 209 | * Method generating the query string to be used for retrieving the first |
| 210 | * page. This method must be implemented in sub classes. |
| 211 | * |
| 212 | * @param pageSize number of rows to read per page |
| 213 | * @return query string |
| 214 | */ |
| 215 | public abstract String generateFirstPageQuery(int pageSize); |
| 216 | |
| 217 | /** |
| 218 | * Method generating the query string to be used for retrieving the pages |
| 219 | * following the first page. This method must be implemented in sub classes. |
| 220 | * |
| 221 | * @param pageSize number of rows to read per page |
| 222 | * @return query string |
| 223 | */ |
| 224 | public abstract String generateRemainingPagesQuery(int pageSize); |
| 225 | |
| 226 | /** |
| 227 | * Method generating the query string to be used for jumping to a specific |
| 228 | * item position. This method must be implemented in sub classes. |
| 229 | * |
| 230 | * @param itemIndex the index of the item to jump to |
| 231 | * @param pageSize number of rows to read per page |
| 232 | * @return query string |
| 233 | */ |
| 234 | public abstract String generateJumpToItemQuery(int itemIndex, int pageSize); |
| 235 | |
| 236 | private String removeKeyWord(String keyWord, String clause) { |
| 237 | String temp = clause.trim(); |
| 238 | String keyWordString = keyWord + " "; |
| 239 | if (temp.toLowerCase().startsWith(keyWordString) && temp.length() > keyWordString.length()) { |
| 240 | return temp.substring(keyWordString.length()); |
| 241 | } |
| 242 | else { |
| 243 | return temp; |
| 244 | } |
| 245 | } |
| 246 | |
| 247 | } |