| 1 | /* |
| 2 | * Copyright 2006-2007 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.file.mapping; |
| 18 | |
| 19 | import java.beans.PropertyDescriptor; |
| 20 | import java.util.ArrayList; |
| 21 | import java.util.Collections; |
| 22 | import java.util.List; |
| 23 | |
| 24 | import org.springframework.beans.BeanUtils; |
| 25 | import org.springframework.util.ObjectUtils; |
| 26 | import org.springframework.util.StringUtils; |
| 27 | |
| 28 | /** |
| 29 | * Helper class for calculating bean property matches, according to. |
| 30 | * Used by BeanWrapperImpl to suggest alternatives for an invalid property name.<br/> |
| 31 | * |
| 32 | * Copied and slightly modified from Spring core, |
| 33 | * |
| 34 | * @author Alef Arendsen |
| 35 | * @author Arjen Poutsma |
| 36 | * @author Juergen Hoeller |
| 37 | * @author Dave Syer |
| 38 | * |
| 39 | * @since 1.0 |
| 40 | * @see #forProperty(String, Class) |
| 41 | */ |
| 42 | final class PropertyMatches { |
| 43 | |
| 44 | //--------------------------------------------------------------------- |
| 45 | // Static section |
| 46 | //--------------------------------------------------------------------- |
| 47 | |
| 48 | /** Default maximum property distance: 2 */ |
| 49 | public static final int DEFAULT_MAX_DISTANCE = 2; |
| 50 | |
| 51 | |
| 52 | /** |
| 53 | * Create PropertyMatches for the given bean property. |
| 54 | * @param propertyName the name of the property to find possible matches for |
| 55 | * @param beanClass the bean class to search for matches |
| 56 | */ |
| 57 | public static PropertyMatches forProperty(String propertyName, Class beanClass) { |
| 58 | return forProperty(propertyName, beanClass, DEFAULT_MAX_DISTANCE); |
| 59 | } |
| 60 | |
| 61 | /** |
| 62 | * Create PropertyMatches for the given bean property. |
| 63 | * @param propertyName the name of the property to find possible matches for |
| 64 | * @param beanClass the bean class to search for matches |
| 65 | * @param maxDistance the maximum property distance allowed for matches |
| 66 | */ |
| 67 | public static PropertyMatches forProperty(String propertyName, Class beanClass, int maxDistance) { |
| 68 | return new PropertyMatches(propertyName, beanClass, maxDistance); |
| 69 | } |
| 70 | |
| 71 | |
| 72 | //--------------------------------------------------------------------- |
| 73 | // Instance section |
| 74 | //--------------------------------------------------------------------- |
| 75 | |
| 76 | private final String propertyName; |
| 77 | |
| 78 | private String[] possibleMatches; |
| 79 | |
| 80 | |
| 81 | /** |
| 82 | * Create a new PropertyMatches instance for the given property. |
| 83 | */ |
| 84 | private PropertyMatches(String propertyName, Class beanClass, int maxDistance) { |
| 85 | this.propertyName = propertyName; |
| 86 | this.possibleMatches = calculateMatches(BeanUtils.getPropertyDescriptors(beanClass), maxDistance); |
| 87 | } |
| 88 | |
| 89 | |
| 90 | /** |
| 91 | * Return the calculated possible matches. |
| 92 | */ |
| 93 | public String[] getPossibleMatches() { |
| 94 | return possibleMatches; |
| 95 | } |
| 96 | |
| 97 | /** |
| 98 | * Build an error message for the given invalid property name, |
| 99 | * indicating the possible property matches. |
| 100 | */ |
| 101 | public String buildErrorMessage() { |
| 102 | StringBuffer buf = new StringBuffer(); |
| 103 | buf.append("Bean property '"); |
| 104 | buf.append(this.propertyName); |
| 105 | buf.append("' is not writable or has an invalid setter method. "); |
| 106 | |
| 107 | if (ObjectUtils.isEmpty(this.possibleMatches)) { |
| 108 | buf.append("Does the parameter type of the setter match the return type of the getter?"); |
| 109 | } |
| 110 | else { |
| 111 | buf.append("Did you mean "); |
| 112 | for (int i = 0; i < this.possibleMatches.length; i++) { |
| 113 | buf.append('\''); |
| 114 | buf.append(this.possibleMatches[i]); |
| 115 | if (i < this.possibleMatches.length - 2) { |
| 116 | buf.append("', "); |
| 117 | } |
| 118 | else if (i == this.possibleMatches.length - 2){ |
| 119 | buf.append("', or "); |
| 120 | } |
| 121 | } |
| 122 | buf.append("'?"); |
| 123 | } |
| 124 | return buf.toString(); |
| 125 | } |
| 126 | |
| 127 | |
| 128 | /** |
| 129 | * Generate possible property alternatives for the given property and |
| 130 | * class. Internally uses the <code>getStringDistance</code> method, which |
| 131 | * in turn uses the Levenshtein algorithm to determine the distance between |
| 132 | * two Strings. |
| 133 | * @param propertyDescriptors the JavaBeans property descriptors to search |
| 134 | * @param maxDistance the maximum distance to accept |
| 135 | */ |
| 136 | private String[] calculateMatches(PropertyDescriptor[] propertyDescriptors, int maxDistance) { |
| 137 | List candidates = new ArrayList(); |
| 138 | for (int i = 0; i < propertyDescriptors.length; i++) { |
| 139 | if (propertyDescriptors[i].getWriteMethod() != null) { |
| 140 | String possibleAlternative = propertyDescriptors[i].getName(); |
| 141 | if (calculateStringDistance(this.propertyName, possibleAlternative) <= maxDistance) { |
| 142 | candidates.add(possibleAlternative); |
| 143 | } |
| 144 | } |
| 145 | } |
| 146 | Collections.sort(candidates); |
| 147 | return StringUtils.toStringArray(candidates); |
| 148 | } |
| 149 | |
| 150 | /** |
| 151 | * Calculate the distance between the given two Strings |
| 152 | * according to the Levenshtein algorithm. |
| 153 | * @param s1 the first String |
| 154 | * @param s2 the second String |
| 155 | * @return the distance value |
| 156 | */ |
| 157 | private int calculateStringDistance(String s1, String s2) { |
| 158 | if (s1.length() == 0) { |
| 159 | return s2.length(); |
| 160 | } |
| 161 | if (s2.length() == 0) { |
| 162 | return s1.length(); |
| 163 | } |
| 164 | int d[][] = new int[s1.length() + 1][s2.length() + 1]; |
| 165 | |
| 166 | for (int i = 0; i <= s1.length(); i++) { |
| 167 | d[i][0] = i; |
| 168 | } |
| 169 | for (int j = 0; j <= s2.length(); j++) { |
| 170 | d[0][j] = j; |
| 171 | } |
| 172 | |
| 173 | for (int i = 1; i <= s1.length(); i++) { |
| 174 | char s_i = s1.charAt(i - 1); |
| 175 | for (int j = 1; j <= s2.length(); j++) { |
| 176 | int cost; |
| 177 | char t_j = s2.charAt(j - 1); |
| 178 | if (Character.toLowerCase(s_i) == Character.toLowerCase(t_j)) { |
| 179 | cost = 0; |
| 180 | } else { |
| 181 | cost = 1; |
| 182 | } |
| 183 | d[i][j] = Math.min(Math.min(d[i - 1][j] + 1, d[i][j - 1] + 1), |
| 184 | d[i - 1][j - 1] + cost); |
| 185 | } |
| 186 | } |
| 187 | |
| 188 | return d[s1.length()][s2.length()]; |
| 189 | } |
| 190 | |
| 191 | } |