DbQueryUtils.java revision ab2a24c126f35ae4aefb469f91094e5972abd8f0 
1/*
2 * Copyright (C) 2011 The Android Open Source Project
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 */
16package com.android.providers.contacts.util;
17
18import android.content.ContentValues;
19import android.database.DatabaseUtils;
20import android.text.TextUtils;
21
22import java.util.HashMap;
23import java.util.Set;
24
25/**
26 * Static methods for helping us build database query selection strings.
27 */
28public class DbQueryUtils {
29    // Static class with helper methods, so private constructor.
30    private DbQueryUtils() {
31    }
32
33    /** Returns a WHERE clause asserting equality of a field to a value. */
34    public static String getEqualityClause(String field, String value) {
35        return getClauseWithOperator(field, "=", value);
36    }
37
38    /** Returns a WHERE clause asserting equality of a field to a value. */
39    public static String getEqualityClause(String field, long value) {
40        return getClauseWithOperator(field, "=", value);
41    }
42
43    /** Returns a WHERE clause asserting in-equality of a field to a value. */
44    public static String getInequalityClause(String field, long value) {
45        return getClauseWithOperator(field, "!=", value);
46    }
47
48    private static String getClauseWithOperator(String field, String operator, String value) {
49        StringBuilder clause = new StringBuilder();
50        clause.append("(");
51        clause.append(field);
52        clause.append(" ").append(operator).append(" ");
53        DatabaseUtils.appendEscapedSQLString(clause, value);
54        clause.append(")");
55        return clause.toString();
56    }
57
58    private static String getClauseWithOperator(String field, String operator, long value) {
59        StringBuilder clause = new StringBuilder();
60        clause.append("(");
61        clause.append(field);
62        clause.append(" ").append(operator).append(" ");
63        clause.append(value);
64        clause.append(")");
65        return clause.toString();
66    }
67
68    /** Concatenates any number of clauses using "AND". */
69    public static String concatenateClauses(String... clauses) {
70        StringBuilder builder = new StringBuilder();
71        for (String clause : clauses) {
72            if (!TextUtils.isEmpty(clause)) {
73                if (builder.length() > 0) {
74                    builder.append(" AND ");
75                }
76                builder.append("(");
77                builder.append(clause);
78                builder.append(")");
79            }
80        }
81        return builder.toString();
82    }
83
84    /**
85     * Checks if the given ContentValues contains values within the projection
86     * map.
87     *
88     * @throws IllegalArgumentException if any value in values is not found in
89     * the projection map.
90     */
91    public static void checkForSupportedColumns(HashMap<String, String> projectionMap,
92            ContentValues values) {
93        checkForSupportedColumns(projectionMap.keySet(), values, "Is invalid.");
94    }
95
96    /**
97     * @see #checkForSupportedColumns(HashMap, ContentValues)
98     */
99    public static void checkForSupportedColumns(Set<String> allowedColumns, ContentValues values,
100            String msgSuffix) {
101        for (String requestedColumn : values.keySet()) {
102            if (!allowedColumns.contains(requestedColumn)) {
103                throw new IllegalArgumentException("Column '" + requestedColumn + "'. " +
104                        msgSuffix);
105            }
106        }
107    }
108
109    /**
110     * Escape values to be used in LIKE sqlite clause.
111     *
112     * The LIKE clause has two special characters: '%' and '_'.  If either of these
113     * characters need to be matched literally, then they must be escaped like so:
114     *
115     * WHERE value LIKE 'android\_%' ESCAPE '\'
116     *
117     * The ESCAPE clause is required and no default exists as the escape character in this context.
118     * Since the escape character needs to be defined as part of the sql string, it must be
119     * provided to this method so the escape characters match.
120     *
121     * @param sb The StringBuilder to append the escaped value to.
122     * @param value The value to be escaped.
123     * @param escapeChar The escape character to be defined in the sql ESCAPE clause.
124     */
125    public static void escapeLikeValue(StringBuilder sb, String value, char escapeChar) {
126        for (int i = 0; i < value.length(); i++) {
127            char ch = value.charAt(i);
128            if (ch == '%' || ch == '_') {
129                sb.append(escapeChar);
130            }
131            sb.append(ch);
132        }
133    }
134
135}
136