Erlang入门：gen_server实例操作与练习2

标签：erlang   入门教程   实例   gen_server   

-module(bank_server3).
-behaviour(gen_server).

-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]).
-export([create_account/2]).

-define(I(F), io:format(F++"~n", [])).
-define(I(F, A), io:format(F++"~n", A)).

% --------------------------------------------------------------------
% API
% --------------------------------------------------------------------

%%'银行开户，并存入初始金额
-spec create_account(Name, Money) -> any() when
      Name :: atom(),
      Money :: integer().

create_account(Name, Money)->
    %% gen_server:start(Mod, Args, Options)
    {ok, Pid} = gen_server:start(?MODULE, [Money], []),
    %% 假设年费为10
    Pid ! {yearly, 60},
    erlang:register(Name, Pid).

% --------------------------------------------------------------------
% Callback
% --------------------------------------------------------------------

init([Money]) ->
    {ok, Money}.

handle_call(check, _From, Money) ->
    {reply, Money, Money};

handle_call(Request, _From, State) ->
    ?I("handle_call: ~p", [Request]),
    Reply = ok,
    {reply, Reply, State}.

handle_cast(Msg, State) ->
    ?I("handle_cast: ~p", [Msg]),
    {noreply, State}.

%%'存钱
handle_info({deposit, AddMoney}, Money) ->
    NewMoney = Money + AddMoney,
    ?I("deposit money: ~w -> ~w", [Money, NewMoney]),
    {noreply, NewMoney};
%%.

%%'取钱(可透支)
handle_info({cash1, SubMoney}, Money) ->
    NewMoney = Money - SubMoney,
    ?I("deposit money: ~w -> ~w", [Money, NewMoney]),
    {noreply, NewMoney};
%%.

%%'取钱(不可透支)
handle_info({cash2, SubMoney}, Money) ->
    NewMoney = Money - SubMoney,
    case NewMoney > 0 of
        true ->
            %% 支取成功
            ?I("deposit money: ~w -> ~w", [Money, NewMoney]),
            {noreply, NewMoney};
        false ->
            %% 支取失败 提示余额不足
            ?I("Insufficient balance, current money is ~w", [Money]),
            {noreply, Money}
    end;
%%.

%%'扣年费（这里假设10秒为一年）
handle_info({yearly, Payment}, Money) ->
    Year = case get(year) of
        undefined -> 
            put(year, 0),
            0;
        Y -> 
            YY = Y + 1,
            put(year, YY),
            YY
    end,
    erlang:send_after(60 * 1000, self(), {yearly, Payment}),
    Reply = if 
        Money =< 0 ->
            %% 没有钱可以扣
            Money;
        Year =:= 0 ->
            %% 还不到一年，不用扣
            Money;
        true ->
            NewMoney = Money - Payment,
            case NewMoney > 0 of
                true ->
                    %% 扣费成功
                    ?I("Yearly Payment: ~w -> ~w", [Money, NewMoney]),
                    NewMoney;
                false ->
                    %% 余额不足以扣年费，则扣到0为止
                    ?I("Yearly Payment: ~w -> ~w", [Money, 0]),
                    0
            end
    end,
    {noreply, Reply};
%%.

%%'查询
handle_info(check, Money) ->
    ?I("Current money is: ~w", [Money]),
    {noreply, Money};

handle_info({From, check}, Money) ->
    %% ?I("Send result to: ~w", [From]),
    From ! {self(), Money},
    {noreply, Money};
%%.

handle_info(stop1, Money) ->
    ?I("Receive STOP1"),
    Reason = "Force STOP",
    {stop, Reason, Money};

handle_info(stop2, Money) ->
    ?I("Receive STOP2"),
    Reason = normal,
    {stop, Reason, Money};

handle_info(Info, State) ->
    ?I("handle_info: ~p", [Info]),
    {noreply, State}.

terminate(Reason, _State) ->
    ?I("terminate: ~p", [Reason]),
    ok.

code_change(_OldVsn, State, _Extra) ->
    {ok, State}.

Erlang入门：gen_server实例操作与练习2

标签：erlang   入门教程   实例   gen_server   

原文地址：http://blog.csdn.net/zhongruixian/article/details/42737031