任意对象转化为JSON

import java.beans.IntrospectionException;
    import java.beans.Introspector;
    import java.beans.PropertyDescriptor;
    import java.math.BigDecimal;
    import java.math.BigInteger;
    import java.util.List;
    import java.util.Map;
    import java.util.Set;
    /**
     * 序列化对象为JSON格式 遵循JSON组织公布标准
     * 
     * @date 2008/05/07
     * @version 1.0.0
     */
    public class Json {
        /** Commons Logging instance. */
        private static org.apache.commons.logging.Log log = org.apache.commons.logging.LogFactory.getLog(Json.class);
        /**
         * @param obj 任意对象
         * @return String
         */
        public static String object2json(Object obj) {
            StringBuilder json = new StringBuilder();
            if (obj == null) {
                json.append("\"\"");
            } else if (obj instanceof String || obj instanceof Integer || obj instanceof Float || obj instanceof Boolean
                    || obj instanceof Short || obj instanceof Double || obj instanceof Long || obj instanceof BigDecimal
                    || obj instanceof BigInteger || obj instanceof Byte) {
                json.append("\"").append(string2json(obj.toString())).append("\"");
            } else if (obj instanceof Object[]) {
                json.append(array2json((Object[]) obj));
            } else if (obj instanceof List) {
                json.append(list2json((List<?>) obj));
            } else if (obj instanceof Map) {
                json.append(map2json((Map<?, ?>) obj));
            } else if (obj instanceof Set) {
                json.append(set2json((Set<?>) obj));
            } else {
                json.append(bean2json(obj));
            }
            return json.toString();
        }
        /**
         * @param bean bean对象
         * @return String
         */
        public static String bean2json(Object bean) {
            StringBuilder json = new StringBuilder();
            json.append("{");
            PropertyDescriptor[] props = null;
            try {
                props = Introspector.getBeanInfo(bean.getClass(), Object.class).getPropertyDescriptors();
            } catch (IntrospectionException e) {
            }
            if (props != null) {
                for (int i = 0; i < props.length; i++) {
                    try {
                        String name = object2json(props[i].getName());
                        String value = object2json(props[i].getReadMethod().invoke(bean));
                        json.append(name);
                        json.append(":");
                        json.append(value);
                        json.append(",");
                    } catch (Exception e) {
                    }
                }
                json.setCharAt(json.length() - 1, '}');
            } else {
                json.append("}");
            }
            return json.toString();
        }
        /**
         * @param list list对象
         * @return String
         */
        public static String list2json(List<?> list) {
            StringBuilder json = new StringBuilder();
            json.append("[");
            if (list != null && list.size() > 0) {
                for (Object obj : list) {
                    json.append(object2json(obj));
                    json.append(",");
                }
                json.setCharAt(json.length() - 1, ']');
            } else {
                json.append("]");
            }
            return json.toString();
        }
        /**
         * @param array 对象数组
         * @return String
         */
        public static String array2json(Object[] array) {
            StringBuilder json = new StringBuilder();
            json.append("[");
            if (array != null && array.length > 0) {
                for (Object obj : array) {
                    json.append(object2json(obj));
                    json.append(",");
                }
                json.setCharAt(json.length() - 1, ']');
            } else {
                json.append("]");
            }
            return json.toString();
        }
        /**
         * @param map map对象
         * @return String
         */
        public static String map2json(Map<?, ?> map) {
            StringBuilder json = new StringBuilder();
            json.append("{");
            if (map != null && map.size() > 0) {
                for (Object key : map.keySet()) {
                    json.append(object2json(key));
                    json.append(":");
                    json.append(object2json(map.get(key)));
                    json.append(",");
                }
                json.setCharAt(json.length() - 1, '}');
            } else {
                json.append("}");
            }
            return json.toString();
        }
        /**
         * @param set 集合对象
         * @return String
         */
        public static String set2json(Set<?> set) {
            StringBuilder json = new StringBuilder();
            json.append("[");
            if (set != null && set.size() > 0) {
                for (Object obj : set) {
                    json.append(object2json(obj));
                    json.append(",");
                }
                json.setCharAt(json.length() - 1, ']');
            } else {
                json.append("]");
            }
            return json.toString();
        }
        /**
         * @param s 参数
         * @return String
         */
        public static String string2json(String s) {
            if (s == null)
                return "";
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < s.length(); i++) {
                char ch = s.charAt(i);
                switch (ch) {
                case '"':
                    sb.append("\\\"");
                    break;
                case '\\':
                    sb.append("\\\\");
                    break;
                case '\b':
                    sb.append("\\b");
                    break;
                case '\f':
                    sb.append("\\f");
                    break;
                case '\n':
                    sb.append("\\n");
                    break;
                case '\r':
                    sb.append("\\r");
                    break;
                case '\t':
                    sb.append("\\t");
                    break;
                case '/':
                    sb.append("\\/");
                    break;
                default:
                    if (ch >= '\u0000' && ch <= '\u001F') {
                        String ss = Integer.toHexString(ch);
                        sb.append("\\u");
                        for (int k = 0; k < 4 - ss.length(); k++) {
                            sb.append('0');
                        }
                        sb.append(ss.toUpperCase());
                    } else {
                        sb.append(ch);
                    }
                }
            }
            return sb.toString();
        }
    }