java运用反射拼接sql语句

public Boolean Regist(Student student) throws IllegalAccessException, SQLException {
        Integer flag=-1;
        StringBuffer stringBuffer=new StringBuffer("insert into tb_student (");
        Class clazz=student.getClass();
        Field[] declaredFields = clazz.getDeclaredFields();
        for (Field field : declaredFields) {
            field.setAccessible(true); //运行修改私有类字段值
            String key = field.getName();//获取字段名
            Object value=field.get(student);//获取字段值
            if (value!=null){
                stringBuffer.append(Stringutil.toSqlString(key) +",");
            }//根据条件拼接sql
        }
        stringBuffer=stringBuffer.deleteCharAt(stringBuffer.length()-1);
        stringBuffer.append(") values(");
        for (Field declaredField : declaredFields) {
            declaredField.setAccessible(true);
            Object value=declaredField.get(student);
            if (value!=null){
                stringBuffer.append("'"+value+"',");
            }
        }
        stringBuffer=stringBuffer.deleteCharAt(stringBuffer.length()-1);
        stringBuffer.append(");");
        System.out.println(stringBuffer);

        Connection connection= DButil.getConnection();
        PreparedStatement preparedStatement = connection.prepareStatement(stringBuffer.toString());
        flag=preparedStatement.executeUpdate();
        if (flag==-1){
            return false;
        }
         return true;
    }

stringUtil类：用来修改字符串格式以便映射数据库 

public class Stringutil {
    public static String toSqlString(String str){
        str= str.replaceAll("([A-Z])","_$1").toLowerCase();
        return str;
    }
}