Erlang入门：gen_server范例操作与练习2

Erlang入门：gen_server实例操作与练习2
Eshell V5.10.4 (abort with ^G)
1> bank_server3:create_account(name1, 1000).
true
2> name1 ! check.
Current money is: 1000
check
3> erlang:send(name1, check).
Current money is: 1000
check
4> erlang:send(name1, abcd).
handle_info: abcd
abcd
Yearly Payment: 940 -> 880
5> gen_server:cast(name1, msg1).
handle_cast: msg1
ok
6> gen_server:cast(name123, msg1).
ok
7> name123 ! check.
** exception error: bad argument
in operator !/2
called as name123 ! check
Yearly Payment: 880 -> 820
8> gen_server:call(name1, msg1).
handle_call: msg1
ok
9> erlang:send(name1, stop1).
Receive STOP1
terminate: "Force STOP"
stop1
10>
=ERROR REPORT==== 15-Jan-2015::09:02:35 ===
** Generic server <0.34.0> terminating
** Last message in was stop1
** When Server state == 820
** Reason for termination ==
** "Force STOP"


Eshell V5.10.4 (abort with ^G)
1> bank_server3:create_account(name2, 1000).
true
2> name2 ! stop2.
Receive STOP2
terminate: normal
stop2

-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}.