json解析

public class JsonUtil {

    /**
     * 转换object类型数据到json格式字符串
     * @param obj
     * @return String
     */
    public static String objectToJson(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(stringToJson(obj.toString())).append("\"");
        } else if (obj instanceof Object[]) {
            json.append(arrayToJson((Object[]) obj));
        } else if (obj instanceof List) {
            json.append(listToJson((List<?>) obj));
        } else if (obj instanceof Map) {
            json.append(mapToJson((Map<?, ?>) obj));
        } else if (obj instanceof Set) {
            json.append(setToJson((Set<?>) obj));
        } else {
            json.append(beanToJson(obj));
        }
        return json.toString();
    }

    /**
     * bean到json格式字符串
     * @return String
     */
    public static String beanToJson(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 = objectToJson(props[i].getName());
                    String value = objectToJson(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();
    }

    /**
     * list数据到json格式字符串
     * @param list
     * @return String
     */
    public static String listToJson(List<?> list) {
        StringBuilder json = new StringBuilder();
        json.append("[");
        if (list != null && list.size() > 0) {
            for (Object obj : list) {
                json.append(objectToJson(obj));
                json.append(",");
            }
            json.setCharAt(json.length() - 1, ']');
        } else {
            json.append("]");
        }
        return json.toString();
    }

    /**
     * 数组类型格式数据到json格式字符串
     * @param array
     * @return String
     */
    public static String arrayToJson(Object[] array) {
        StringBuilder json = new StringBuilder();
        json.append("[");
        if (array != null && array.length > 0) {
            for (Object obj : array) {
                json.append(objectToJson(obj));
                json.append(",");
            }
            json.setCharAt(json.length() - 1, ']');
        } else {
            json.append("]");
        }
        return json.toString();
    }

    /**
     * map类型数据到json格式字符串数据
     * @param map
     * @return String
     */
    public static String mapToJson(Map<?, ?> map) {
        StringBuilder json = new StringBuilder();
        json.append("{");
        if (map != null && map.size() > 0) {
            for (Object key : map.keySet()) {
                json.append(objectToJson(key));
                json.append(":");
                json.append(objectToJson(map.get(key)));
                json.append(",");
            }
            json.setCharAt(json.length() - 1, '}');
        } else {
            json.append("}");
        }
        return json.toString();
    }

    /**
     * set类型数据到json格式字符串
     * @param set
     * @return String
     */
    public static String setToJson(Set<?> set) {
        StringBuilder json = new StringBuilder();
        json.append("[");
        if (set != null && set.size() > 0) {
            for (Object obj : set) {
                json.append(objectToJson(obj));
                json.append(",");
            }
            json.setCharAt(json.length() - 1, ']');
        } else {
            json.append("]");
        }
        return json.toString();
    }

    /**
     * 字符串到json格式
     * @param s
     * @return String
     */
    public static String stringToJson(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();
    }
}