我有一个处理程序类，负责创建用户 User user = UserUtil.create(dbs, dba, jo, user); 我使用下面的代码来模拟静态方法，但它总是返回 null .

@PrepareForTest({ UserHandler.class,UserUtil.class,ModelUtil.class,User.class })
    @Test
    public void testCreate() {
        try {
            DBSession dbSession = mock(DBSession.class);
            DBAdmin admin = mock(DBAdmin.class);
            //private static method execution
            PowerMockito.mockStatic(UserUtil.class);
            PowerMockito.doReturn(userList).when(UserUtil.class,"getUserWithEmailid",new DBSession("testOrg"),admin, request.getParamJo(), jsonString);
            PowerMockito.doNothing().when(UserUtil.class,"validateRoleLeval",new DBSession("testOrg"),9990);
            //public static method execution
            PowerMockito.spy(UserUtil.class);
            PowerMockito.doReturn(jsonString).when(UserUtil.class,"create",dbSession,admin, request.getParamJo(), jsonString);
            UserHandler handler = new UserHandler();
            ZResponse response = handler.create(request);

我不知道上面的代码有什么问题。