public class Query<T> {

    private DBUtil db = DBUtil.getInstance();

    private List<T> list = null;

    private int totleCount = -1;

    private Class<T> entityClass;

    private String sql = null;

    @SuppressWarnings("unchecked")
    public Query(String sql) {

        this.entityClass = (Class<T>) ((ParameterizedType) getClass()
                .getGenericSuperclass()).getActualTypeArguments()[0];
        this.sql = sql;
        this.list = excute(sql);
    }
    

        public int getCount() {

        return totleCount;
    }

    public List<T> getGridData(int start, int size) {

        if (start + size > totleCount) {
            size = totleCount - start;
        }
        return list.subList(start, start + size);

    }

    public List<T> getQueryData() {

        return list;
    }

    public List<T> excute(String sql) {

        ArrayList<T> list = null;
        Statement stm = db.getStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,
                ResultSet.CONCUR_READ_ONLY);
        ResultSet rst = null;
        try {
            rst = stm.executeQuery(sql);
            rst.last();
            totleCount = rst.getRow();
            rst.beforeFirst();
            list = new ArrayList<T>(totleCount);
            while (rst.next()) {
                ResultSetMetaData metaData = rst.getMetaData();
                T t = entityClass.newInstance();
                for (int j = 1; j <= metaData.getColumnCount(); j++) {
                    String name = metaData.getColumnName(j);
                    try {
                        Field field = entityClass.getDeclaredField(name
                                .substring(0, 1).toLowerCase()
                                + name.substring(1));
                        Method method = entityClass.getMethod("set"
                                + name.substring(0, 1).toUpperCase()
                                + name.substring(1), field.getType());
                        String type = field.toGenericString();
                        if (type.contains("java.lang.String")) {
                            method.invoke(t, rst.getString(name));
                        } else if (type.contains("java.lang.Integer")) {
                            method.invoke(t, rst.getInt(name));
                        } else if (type.contains("java.lang.Double")) {
                            method.invoke(t, rst.getDouble(name));
                        } else if (type.contains("java.sql.Date")) {
                            method.invoke(t, rst.getDate(name));

                        } else if (type.contains("java.sql.Timestamp")) {
                            method.invoke(t, rst.getTimestamp(name));
                        }
                    } catch (NoSuchFieldException e) {
                        /*
                         * System.out.println("找不到字段" + name.substring(0,
                         * 1).toLowerCase() + name.substring(1) + "，将忽略处理。");
                         */
                    }

                }
                list.add(t);
            }

        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally {
            db.freeResource(stm, rst);
        }
        return list;
    }

    }