ch07.htm

corba比较入门级的介绍详细间接了corba访问发布各种细节。

<TT>32: // Destructor.</TT>
<TT>33: AccountImpl::~AccountImpl() {</TT>
<TT>34: </TT>
<TT>35:     free(myAccountNumber);</TT>
<TT>36:     free(myCreationDate);</TT>
<TT>37: }</TT>
<TT>38: </TT>
<TT>39: char* AccountImpl::accountNumber() {</TT>
<TT>40: </TT>
<TT>41:     return CORBA::strdup(myAccountNumber);</TT>
<TT>42: }</TT>
<TT>43: </TT>
<TT>44: char* AccountImpl::creationDate() {</TT>
<TT>45: </TT>
<TT>46:     return CORBA::strdup(myCreationDate);</TT>
<TT>47: }</TT>
<TT>48: </TT>
<TT>49: CORBA::Float AccountImpl::balance() {</TT>
<TT>50: </TT>
<TT>51:     return myBalance;</TT>
<TT>52: }</TT>
<TT>53: </TT>
<TT>54: CustomerList* AccountImpl::getCustomers() {</TT>
<TT>55: </TT>
<TT>56:     return &amp;myOwners;</TT>
<TT>57: }</TT>
<TT>58: </TT>
<B><TT>59:</TT></B><TT> CORBA::Float AccountImpl::withdraw(CORBA::Float amount) <B>throw</B></TT>
<B><TT>60:</TT></B><TT>         <B>(InvalidAmountException, InsufficientFundsException)</B> {</TT>
<B><TT>61:</TT></B><TT> </TT>
<B><TT>62:</TT></B><TT>     <B>// Disallow the withdrawal of negative amounts and throw an</B></TT>
<B><TT>63:</TT></B><TT>     <B>// exception if this is attempted.</B></TT>
<B><TT>64:</TT></B><TT>     <B>if (amount &lt; 0.0) {</B></TT>
<B><TT>65:</TT></B><TT>         <B>cout &lt;&lt; &quot;AccountImpl: Attempted to withdraw invalid &quot;</B></TT>
<B><TT>66:</TT></B><TT>                 <B>&lt;&lt; &quot;amount.&quot; &lt;&lt; endl;</B></TT>
<B><TT>67:</TT></B><TT>         <B>throw InvalidAmountException();</B></TT>
<B><TT>68:</TT></B><TT>     <B>}</B></TT>
<B><TT>69:</TT></B><TT> </TT>
<B><TT>70:</TT></B><TT>     <B>// Disallow withdrawal of an amount greater than the current</B></TT>
<B><TT>71:</TT></B><TT>     <B>// balance and throw an exception if this is attempted.</B></TT>
<B><TT>72:</TT></B><TT>     <B>if (amount &gt; myBalance) {</B></TT>
<B><TT>73:</TT></B><TT>         <B>cout &lt;&lt; &quot;AccountImpl: Insufficient funds to withdraw &quot;</B></TT>
<B><TT>74:</TT></B><TT>                 <B>&lt;&lt; &quot;specified amount.&quot; &lt;&lt; endl;</B></TT>
<B><TT>75:</TT></B><TT>         <B>throw InsufficientFundsException();</B></TT>
<B><TT>76:</TT></B><TT>     <B>}</B></TT>
<TT>77: </TT>
<TT>78:     myBalance -= amount;</TT>
<TT>79: </TT>
<TT>80:     return myBalance;</TT>
<TT>81: }</TT>
<TT>82: </TT>
<B><TT>83:</TT></B><TT> CORBA::Float AccountImpl::deposit(CORBA::Float amount) <B>throw</B></TT>
<B><TT>84:</TT></B><TT>         <B>(InvalidAmountException) </B>{</TT>
<TT>85: </TT>
<B><TT>86:</TT></B><TT>     <B>// Disallow the deposit of negative amounts and throw an</B></TT>
<B><TT>87:</TT></B><TT>     <B>// exception if this is attempted.</B></TT>
<B><TT>88:</TT></B><TT>     <B>if (amount &lt; 0.0) {</B></TT>
<B><TT>89:</TT></B><TT>         <B>cout &lt;&lt; &quot;AccountImpl: Attempted to deposit invalid amount.&quot;</B></TT>
<B><TT>90:</TT></B><TT>                 <B>&lt;&lt; endl;</B></TT>
<B><TT>91:</TT></B><TT>         <B>throw InvalidAmountException();</B></TT>
<B><TT>92:</TT></B><TT>     <B>}</B></TT>
<TT>93: </TT>
<TT>94:     myBalance += amount;</TT>
<TT>95: </TT>
<TT>96:     return myBalance;
97: }</TT> </FONT></PRE>
<P>The modified <TT>withdraw()</TT> method in <TT>AccountImpl</TT> first checks the
amount that the client wishes to withdraw. If the amount is negative, it is rejected
by the <TT>withdraw()</TT> method, and an <TT>InvalidAmountException</TT> is thrown.
If the amount is non-negative, the <TT>Account</TT> balance is checked to see whether
sufficient funds are available to withdraw the requested amount. (Recall that overdraft
protection is not a current feature of the system.) If there are insufficient funds
to cover the withdrawal, <TT>withdraw()</TT> throws an <TT>InsufficientFundsException</TT>.</P>
<P>The <TT>deposit()</TT> method of <TT>AccountImpl</TT> works similarly; an <TT>InvalidAmountException</TT>
is thrown if the caller attempts to deposit a negative amount into an <TT>Account</TT>
(which would really be a withdrawal). Any amount can be deposited into an <TT>Account</TT>,
so there is no need for <TT>deposit()</TT> to ever throw an <TT>InsufficientFundsException</TT>.
<H3><A NAME="Heading12"></A><FONT COLOR="#000077">CheckingAccountImpl</FONT></H3>
<P>Listings 7.18 and 7.19 contain further changes required to add exception capability
to the <TT>Bank</TT> application.
<H4><FONT COLOR="#000077">Listing 7.18. Modified CheckingAccountImpl.h.</FONT></H4>
<PRE><FONT COLOR="#0066FF"><TT> 1: // CheckingAccountImpl.h</TT>
<TT> 2: </TT>
<TT> 3: #ifndef CheckingAccountImpl_h</TT>
<TT> 4: #define CheckingAccountImpl_h</TT>
<TT> 5: </TT>
<TT> 6: #include &quot;../CheckingAccount_s.h&quot;</TT>
<TT> 7: #include &quot;AccountImpl.h&quot;</TT>
<TT> 8: </TT>
<TT> 9: class CheckingAccountImpl : public _sk_CheckingAccount {</TT>
<TT>10: </TT>
<TT>11: public:</TT>
<TT>12: </TT>
<TT>13:     // Constructor.</TT>
<TT>14:     //</TT>
<TT>15:     // accountNumber - Account number.</TT>
<TT>16:     // creationDate - Account creation date.</TT>
<TT>17:     // initialBalance - Initial Account balance.</TT>
<TT>18:     // customer - Initial Account owner.</TT>
<TT>19:     CheckingAccountImpl(const char* accountNumber, const char*</TT>
<TT>20:             creationDate, CORBA::Float initialBalance, Customer_ptr</TT>
<TT>21:             customer);</TT>
<TT>22: </TT>
<TT>23:     // Destructor.</TT>
<TT>24:     ~CheckingAccountImpl();</TT>
<TT>25: </TT>
<TT>26:     // These methods are described in Account.idl.</TT>
<TT>27:     virtual char* accountNumber();</TT>
<TT>28:     virtual char* creationDate();</TT>
<TT>29:     virtual CORBA::Float balance();</TT>
<TT>30:     virtual CustomerList* getCustomers();</TT>
<B><TT>31:</TT></B><TT>     virtual CORBA::Float withdraw(CORBA::Float amount) <B>throw</B></TT>
<B><TT>32:</TT></B><TT>             <B>(InvalidAmountException, InsufficientFundsException);</B></TT>
<B><TT>33:</TT></B><TT>     virtual CORBA::Float deposit(CORBA::Float amount) <B>throw</B></TT>
<B><TT>34:</TT></B><TT>             <B>(InvalidAmountException);</B></TT>
<TT>35: </TT>
<TT>36: private:</TT>
<TT>37: </TT>
<TT>38:     // Default constructor.</TT>
<TT>39:     CheckingAccountImpl();</TT>
<TT>40: </TT>
<TT>41:     // My associated AccountImpl object.</TT>
<TT>42:     AccountImpl myAccount;</TT>
<TT>43: };</TT>
<TT>44: 
45: #endif</TT></FONT></PRE>
<H4><FONT COLOR="#000077">Listing 7.19. Modified CheckingAccountImpl.cpp.</FONT></H4>
<PRE><FONT COLOR="#0066FF"><TT> 1: // CheckingAccountImpl.cpp</TT>
<TT> 2: </TT>
<TT> 3: #include &quot;CheckingAccountImpl.h&quot;</TT>
<TT> 4: </TT>
<TT> 5: // Constructor.</TT>
<TT> 6: //</TT>
<TT> 7: // accountNumber - Account number.</TT>
<TT> 8: // creationDate - Account creation date.</TT>
<TT> 9: // initialBalance - Initial Account balance.</TT>
<TT>10: // customer - Initial Account owner.</TT>
<TT>11: CheckingAccountImpl::CheckingAccountImpl(const char* accountNumber,</TT>
<TT>12:         const char* creationDate, CORBA::Float initialBalance,</TT>
<TT>13:         Customer_ptr customer) : myAccount(accountNumber,</TT>
<TT>14:         creationDate, initialBalance, customer) {</TT>
<TT>15: </TT>
<TT>16: }</TT>
<TT>17: </TT>
<TT>18: // Default constructor.</TT>
<TT>19: CheckingAccountImpl::CheckingAccountImpl() : myAccount(NULL, NULL,</TT>
<TT>20:         0.0, Customer::_nil()) {</TT>
<TT>21: </TT>
<TT>22: }</TT>
<TT>23: </TT>
<TT>24: // Destructor.</TT>
<TT>25: CheckingAccountImpl::~CheckingAccountImpl() {</TT>
<TT>26: </TT>
<TT>27: }</TT>
<TT>28: </TT>
<TT>29: char* CheckingAccountImpl::accountNumber() {</TT>
<TT>30: </TT>
<TT>31:     return myAccount.accountNumber();</TT>
<TT>32: }</TT>
<TT>33: </TT>
<TT>34: char* CheckingAccountImpl::creationDate() {</TT>
<TT>35: </TT>
<TT>36:     return myAccount.creationDate();</TT>
<TT>37: }</TT>
<TT>38: </TT>
<TT>39: CORBA::Float CheckingAccountImpl::balance() {</TT>
<TT>40: </TT>
<TT>41:     return myAccount.balance();</TT>
<TT>42: }</TT>
<TT>43: </TT>
<TT>44: CustomerList* CheckingAccountImpl::getCustomers() {</TT>
<TT>45: </TT>
<TT>46:     return myAccount.getCustomers();</TT>
<TT>47: }</TT>
<TT>48: </TT>
<TT>49: CORBA::Float CheckingAccountImpl::withdraw(CORBA::Float amount)</TT>
<B><TT>50:</TT></B><TT>         <B>throw (InvalidAmountException, InsufficientFundsException)</B></TT>
<TT>51:         {</TT>
<TT>52: </TT>
<TT>53:     return myAccount.withdraw(amount);</TT>
<TT>54: }</TT>
<TT>55: </TT>
<TT>56: CORBA::Float CheckingAccountImpl::deposit(CORBA::Float amount)</TT>
<B><TT>57:</TT></B><TT>         <B>throw (InvalidAmountException)</B> {</TT>
<TT>58: </TT>
<TT>59:     return myAccount.deposit(amount);
60: }</TT> </FONT></PRE>
<P>Again, the <TT>withdraw()</TT> and <TT>deposit()</TT> methods can throw the <TT>InvalidAmountException</TT>
or <TT>InsufficientFundsException</TT>, or the <TT>InvalidAmountException</TT>, respectively.
Note, however, that none of these exceptions are explicitly thrown within the methods
themselves. Recall that the <TT>withdraw()</TT> and <TT>deposit()</TT> operations
on the <TT>myAccount</TT> member (which is an <TT>AccountImpl</TT> object) can throw
these exceptions. Because these exceptions are not caught by the methods in <TT>CheckingAccountImpl</TT>,
the exceptions are simply passed back to the caller of the <TT>CheckingAccountImpl</TT>
method.
<H3><A NAME="Heading13"></A><FONT COLOR="#000077">SavingsAccountImpl</FONT></H3>
<P>The changes for <TT>SavingsAccountImpl</TT>, as shown in Listings 7.20 and 7.21,
closely resemble the changes made in <TT>CheckingAccountImpl</TT>.
<H4><FONT COLOR="#000077">Listing 7.20. Modified SavingsAccountImpl.h.</FONT></H4>
<PRE><FONT COLOR="#0066FF"><TT> 1: // SavingsAccountImpl.h</TT>
<TT> 2: </TT>
<TT> 3: #ifndef SavingsAccountImpl_h</TT>
<TT> 4: #define SavingsAccountImpl_h</TT>
<TT> 5: </TT>
<TT> 6: #include &quot;../SavingsAccount_s.h&quot;</TT>
<TT> 7: #include &quot;AccountImpl.h&quot;</TT>
<TT> 8: </TT>
<TT> 9: class SavingsAccountImpl : public AccountImpl {</TT>
<TT>10: </TT>
<TT>11: public:</TT>
<TT>12: </TT>
<TT>13:     // Constructor.</TT>
<TT>14:     //</TT>
<TT>15:     // accountNumber - Account number.</TT>
<TT>16:     // creationDate - Account creation date.</TT>
<TT>17:     // initialBalance - Initial Account balance.</TT>
<TT>18:     // customer - Initial Account owner.</TT>
<TT>19:     // interestRate - Initial Account interest rate.</TT>
<TT>20:     SavingsAccountImpl(const char* accountNumber, const char*</TT>
<TT>21:             creationDate, CORBA::Float initialBalance, Customer_ptr</TT>
<TT>22:             customer, CORBA::Float interestRate);</TT>
<TT>23: </TT>
<TT>24:     // Destructor.</TT>
<TT>25:     ~SavingsAccountImpl();</TT>
<TT>26: </TT>
<TT>27:     // These methods are described in Account.idl.</TT>
<TT>28:     virtual char* accountNumber();</TT>
<TT>29:     virtual char* creationDate();</TT>
<TT>30:     virtual CORBA::Float balance();</TT>
<TT>31:     virtual CustomerList* getCustomers();</TT>
<B><TT>32:</TT></B><TT>     virtual CORBA::Float withdraw(CORBA::Float amount) <B>throw</B></TT>
<B><TT>33:</TT></B><TT>             <B>(InvalidAmountException, InsufficientFundsException);</B></TT>
<B><TT>34:</TT></B><TT>     virtual CORBA::Float deposit(CORBA::Float amount) <B>throw</B></TT>
<B><TT>35:</TT></B><TT>             <B>(InvalidAmountException);</B></TT>
<TT>36: </TT>
<TT>37:     // These methods are described in SavingsAccount.idl.</TT>
<TT>38:        virtual CORBA::Float interestRate();</TT>
<B><TT>39:</TT></B><TT>     virtual CORBA::Float setInterestRate(CORBA::Float rate) <B>throw</B></TT>
<B><TT>40:</TT></B><TT>             <B>(InvalidAmountException);</B></TT>
<TT>41: </TT>
<TT>42: private:</TT>
<TT>43: </TT>
<TT>44:     // Default constructor.</TT>
<TT>45:     SavingsAccountImpl();</TT>
<TT>46: </TT>
<TT>47:     // This Account's interest rate.</TT>
<TT>48:     CORBA::Float myInterestRate;</TT>
<TT>49: </TT>
<TT>50:     // My associated AccountImpl object.</TT>
<TT>51:     AccountImpl myAccount;</TT>
<TT>52: };</TT>
<TT>53: 
54: #endif</TT></FONT></PRE>
<H4><FONT COLOR="#000077">Listing 7.21. Modified SavingsAccountImpl.cpp.</FONT></H4>
<PRE><FONT COLOR="#0066FF"><TT> 1: // SavingsAccountImpl.cpp</TT>
<TT> 2: </TT>
<TT> 3: #include &quot;SavingsAccountImpl.h&quot;</TT>
<TT> 4: </TT>
<TT> 5: // Constructor.</TT>
<TT> 6: //</TT>
<TT> 7: // accountNumber - Account number.</TT>
<TT> 8: // creationDate - Account creation date.</TT>
<TT> 9: // initialBalance - Initial Account balance.</TT>
<TT>10: // customer - Initial Account owner.</TT>
<TT>11: // interestRate - Initial Account interest rate.</TT>
<TT>12: SavingsAccountImpl::SavingsAccountImpl(const char* accountNumber,</TT>
<TT>13:         const char* creationDate, CORBA::Float initialBalance,</TT>
<TT>14:         Customer_ptr customer, CORBA::Float interestRate) :</TT>
<TT>15:         myAccount(accountNumber, creationDate, initialBalance,</TT>
<TT>16:         customer), myInterestRate(interestRate) {</TT>
<TT>17: </TT>
<TT>18: }</TT>
<TT>19: </TT>
<TT>20: // Default constructor.</TT>
<TT>21: SavingsAccountImpl::SavingsAccountImpl() : myAccount(NULL, NULL,</TT>
<TT>22:         0.0, Customer::_nil()), myInterestRate(0.0) {</TT>
<TT>23: </TT>
<TT>24: }</TT>
<TT>25: </TT>
<TT>26: // Destructor.</TT>
<TT>27: SavingsAccountImpl::~SavingsAccountImpl() {</TT>
<TT>28: </TT>
<TT>29: }</TT>
<TT>30: </TT>
<TT>31: char* SavingsAccountImpl::accountNumber() {</TT>
<TT>32: </TT>
<TT>33:     return myAccount.accountNumber();</TT>
<TT>34: }</TT>
<TT>35: </TT>
<TT>36: char* SavingsAccountImpl::creationDate() {</TT>
<TT>37: </TT>
<TT>38:     return myAccount.creationDate();</TT>