EntityWrapper是个很强大的玩意，支持多条件查询

List<Role> roles=service.list(new QueryWrapper<Role>().like("role_code",name));
        wrapper.groupBy(columns)  //对应sql中分组
        wrapper.eq(column, params) //相当于where条件
        wrapper.in(column, value) //sql中in
        wrapper.notIn(column, value) //sql中 not in
        wrapper.orderBy(columns, isAsc) //排序
        wrapper.exists(value) //相对于sql中exists查询
        wrapper.notExists(value) //相当于sql中not exists查询
        wrapper.notBetween(column, val1, val2) //相当于sql中在某个范围内使用的between
        wrapper.ge(column, params) //大于等于
        wrapper.le(column, params) //小于等于
        wrapper.like(column, value) //模糊查询
        wrapper.having(sqlHaving, params) //条件过滤

 关键字查询和分页

@RequestMapping("user-list")
    public String pageListUsers(Model model,
          @RequestParam(value = "pageNo",required = false) Integer pageNo,
          @RequestParam(value = "keySelect",required = false) String keySelect){
        User user=new User();
        if(pageNo == null){
            pageNo = 1;
        }
        IPage<User> page = new Page<>();
        page.setCurrent(pageNo);
        page.setSize(15);
        IPage<User> page1 = null;
        if(keySelect.length()>0){
            page1= service.page(page,
                    new QueryWrapper<User>()
                            .like("user_name",keySelect)
                            .or().like("account",keySelect)
                            .or().like("password",keySelect)
                            .or().like("user_type",keySelect)
                            .or().like("role_id",keySelect)
            );
        }else{
            page1=service.page(page);
        }
        List<Role> roles = serviceRole.list();
        model.addAttribute("page",page1);
        model.addAttribute("roles" ,roles);
        return "user-list";
    }