Map 篇

Map 集合工具类

import java.util.HashMap;import java.util.Iterator;import java.util.Map;import java.util.Map.Entry;/** * Map Utils */public class MapUtils {    /** default separator between key and value **/    public static final String DEFAULT_KEY_AND_VALUE_SEPARATOR      = ":";    /** default separator between key-value pairs **/    public static final String DEFAULT_KEY_AND_VALUE_PAIR_SEPARATOR = ",";    private MapUtils() {        throw new AssertionError();    }    /**     * is null or its size is 0     *      * <pre>     * isEmpty(null)   =   true;     * isEmpty({})     =   true;     * isEmpty({1, 2})    =   false;     * </pre>     *      * @param sourceMap     * @return if map is null or its size is 0, return true, else return false.     */    public static <K, V> boolean isEmpty(Map<K, V> sourceMap) {        return (sourceMap == null || sourceMap.size() == 0);    }    /**     * add key-value pair to map, and key need not null or empty     *      * @param map     * @param key     * @param value     * @return <ul>     *         <li>if map is null, return false</li>     *         <li>if key is null or empty, return false</li>     *         <li>return {@link Map#put(Object, Object)}</li>     *         </ul>     */    public static boolean putMapNotEmptyKey(Map<String, String> map, String key, String value) {        if (map == null || StringUtils.isEmpty(key)) {            return false;        }        map.put(key, value);        return true;    }    /**     * add key-value pair to map, both key and value need not null or empty     *      * @param map     * @param key     * @param value     * @return <ul>     *         <li>if map is null, return false</li>     *         <li>if key is null or empty, return false</li>     *         <li>if value is null or empty, return false</li>     *         <li>return {@link Map#put(Object, Object)}</li>     *         </ul>     */    public static boolean putMapNotEmptyKeyAndValue(Map<String, String> map, String key, String value) {        if (map == null || StringUtils.isEmpty(key) || StringUtils.isEmpty(value)) {            return false;        }        map.put(key, value);        return true;    }    /**     * add key-value pair to map, key need not null or empty     *      * @param map     * @param key     * @param value     * @param defaultValue     * @return <ul>     *         <li>if map is null, return false</li>     *         <li>if key is null or empty, return false</li>     *         <li>if value is null or empty, put defaultValue, return true</li>     *         <li>if value is neither null nor empty，put value, return true</li>     *         </ul>     */    public static boolean putMapNotEmptyKeyAndValue(Map<String, String> map, String key, String value,            String defaultValue) {        if (map == null || StringUtils.isEmpty(key)) {            return false;        }        map.put(key, StringUtils.isEmpty(value) ? defaultValue : value);        return true;    }    /**     * add key-value pair to map, key need not null     *      * @param map     * @param key     * @param value     * @return <ul>     *         <li>if map is null, return false</li>     *         <li>if key is null, return false</li>     *         <li>return {@link Map#put(Object, Object)}</li>     *         </ul>     */    public static <K, V> boolean putMapNotNullKey(Map<K, V> map, K key, V value) {        if (map == null || key == null) {            return false;        }        map.put(key, value);        return true;    }    /**     * add key-value pair to map, both key and value need not null     *      * @param map     * @param key     * @param value     * @return <ul>     *         <li>if map is null, return false</li>     *         <li>if key is null, return false</li>     *         <li>if value is null, return false</li>     *         <li>return {@link Map#put(Object, Object)}</li>     *         </ul>     */    public static <K, V> boolean putMapNotNullKeyAndValue(Map<K, V> map, K key, V value) {        if (map == null || key == null || value == null) {            return false;        }        map.put(key, value);        return true;    }    /**     * get key by value, match the first entry front to back     * <ul>     * <strong>Attentions:</strong>     * <li>for HashMap, the order of entry not same to put order, so you may need to use TreeMap</li>     * </ul>     *      * @param <V>     * @param map     * @param value     * @return <ul>     *         <li>if map is null, return null</li>     *         <li>if value exist, return key</li>     *         <li>return null</li>     *         </ul>     */    public static <K, V> K getKeyByValue(Map<K, V> map, V value) {        if (isEmpty(map)) {            return null;        }        for (Entry<K, V> entry : map.entrySet()) {            if (ObjectUtils.isEquals(entry.getValue(), value)) {                return entry.getKey();            }        }        return null;    }    /**     * parse key-value pairs to map, ignore empty key     *      * <pre>     * parseKeyAndValueToMap("","","",true)=null     * parseKeyAndValueToMap(null,"","",true)=null     * parseKeyAndValueToMap("a:b,:","","",true)={(a,b)}     * parseKeyAndValueToMap("a:b,:d","","",true)={(a,b)}     * parseKeyAndValueToMap("a:b,c:d","","",true)={(a,b),(c,d)}     * parseKeyAndValueToMap("a=b, c = d","=",",",true)={(a,b),(c,d)}     * parseKeyAndValueToMap("a=b, c = d","=",",",false)={(a, b),( c , d)}     * parseKeyAndValueToMap("a=b, c=d","=", ",", false)={(a,b),( c,d)}     * parseKeyAndValueToMap("a=b; c=d","=", ";", false)={(a,b),( c,d)}     * parseKeyAndValueToMap("a=b, c=d", ",", ";", false)={(a=b, c=d)}     * </pre>     *      * @param source key-value pairs     * @param keyAndValueSeparator separator between key and value     * @param keyAndValuePairSeparator separator between key-value pairs     * @param ignoreSpace whether ignore space at the begging or end of key and value     * @return     */    public static Map<String, String> parseKeyAndValueToMap(String source, String keyAndValueSeparator,            String keyAndValuePairSeparator, boolean ignoreSpace) {        if (StringUtils.isEmpty(source)) {            return null;        }        if (StringUtils.isEmpty(keyAndValueSeparator)) {            keyAndValueSeparator = DEFAULT_KEY_AND_VALUE_SEPARATOR;        }        if (StringUtils.isEmpty(keyAndValuePairSeparator)) {            keyAndValuePairSeparator = DEFAULT_KEY_AND_VALUE_PAIR_SEPARATOR;        }        Map<String, String> keyAndValueMap = new HashMap<String, String>();        String[] keyAndValueArray = source.split(keyAndValuePairSeparator);        if (keyAndValueArray == null) {            return null;        }        int seperator;        for (String valueEntity : keyAndValueArray) {            if (!StringUtils.isEmpty(valueEntity)) {                seperator = valueEntity.indexOf(keyAndValueSeparator);                if (seperator != -1) {                    if (ignoreSpace) {                        MapUtils.putMapNotEmptyKey(keyAndValueMap, valueEntity.substring(0, seperator).trim(),                                valueEntity.substring(seperator + 1).trim());                    } else {                        MapUtils.putMapNotEmptyKey(keyAndValueMap, valueEntity.substring(0, seperator),                                valueEntity.substring(seperator + 1));                    }                }            }        }        return keyAndValueMap;    }    /**     * parse key-value pairs to map, ignore empty key     *      * @param source key-value pairs     * @param ignoreSpace whether ignore space at the begging or end of key and value     * @return     * @see {@link MapUtils#parseKeyAndValueToMap(String, String, String, boolean)}, keyAndValueSeparator is     *      {@link #DEFAULT_KEY_AND_VALUE_SEPARATOR}, keyAndValuePairSeparator is     *      {@link #DEFAULT_KEY_AND_VALUE_PAIR_SEPARATOR}     */    public static Map<String, String> parseKeyAndValueToMap(String source, boolean ignoreSpace) {        return parseKeyAndValueToMap(source, DEFAULT_KEY_AND_VALUE_SEPARATOR, DEFAULT_KEY_AND_VALUE_PAIR_SEPARATOR,                ignoreSpace);    }    /**     * parse key-value pairs to map, ignore empty key, ignore space at the begging or end of key and value     *      * @param source key-value pairs     * @return     * @see {@link MapUtils#parseKeyAndValueToMap(String, String, String, boolean)}, keyAndValueSeparator is     *      {@link #DEFAULT_KEY_AND_VALUE_SEPARATOR}, keyAndValuePairSeparator is     *      {@link #DEFAULT_KEY_AND_VALUE_PAIR_SEPARATOR}, ignoreSpace is true     */    public static Map<String, String> parseKeyAndValueToMap(String source) {        return parseKeyAndValueToMap(source, DEFAULT_KEY_AND_VALUE_SEPARATOR, DEFAULT_KEY_AND_VALUE_PAIR_SEPARATOR,                true);    }    /**     * join map     *      * @param map     * @return     */    public static String toJson(Map<String, String> map) {        if (map == null || map.size() == 0) {            return null;        }        StringBuilder paras = new StringBuilder();        paras.append("{");        Iterator<Map.Entry<String, String>> ite = map.entrySet().iterator();        while (ite.hasNext()) {            Map.Entry<String, String> entry = (Map.Entry<String, String>)ite.next();            paras.append("\"").append(entry.getKey()).append("\":\"").append(entry.getValue()).append("\"");            if (ite.hasNext()) {                paras.append(",");            }        }        paras.append("}");        return paras.toString();    }}