外观模式（Facade）

为子系统中的一组接口提供一个一致的界面。Facade模式定义了一个高层接口，这个接口使得这一系统更容易使用。

Facade[/b]（MortgageApplication[/b]）
[/b]知道哪些子系统类负责处理请求。将客户的请求代理给适当的子系统对象。Subsystem classes((Bank, Credit, Loan)
[/b]实现子系统的功能。处理有facade对象指派的任务。没有facade的任何相关信息；即没有引用facade。代码
package design.pattern.facade;

/**
* Subsystem ClassA
* @author tyrone
*
*/
public class Bank {
// Methods
/** @modelguid {0204A2F3-F161-4786-B0AE-34388CFBD12B} */
public boolean SufficientSavings( Customer c )
{
System.out.println("Check bank for "+ c.getName() );
return true;
}

}

package design.pattern.facade;

/**
* Subsystem ClassB
* @author tyrone
*
*/
public class Credit {
// Methods
public boolean GoodCredit( int amount, Customer c )
{
System.out.println( "Check credit for "+ c.getName() );
return true;
}

}

package design.pattern.facade;

/**
* Subsystem ClassC
* @author tyrone
*
*/
public class Loan {
// Methods
public boolean GoodLoan( Customer c )
{
System.out.println( "Check loan for "+ c.getName());
return true;
}

}


package design.pattern.facade;
/**
* @author tyrone
*
*/
public class Customer {
private String name;

public Customer(String name){
this.name=name;
}
public void setName(String name){
this.name=name;
}

public String getName(){
return this.name;
}
}

package design.pattern.facade;

/**
* Facade
* @author tyrone
*
*/
public class MortgageApplication {
// Fields
int amount;
private Bank bank = new Bank();
private Loan loan = new Loan();
private Credit credit = new Credit();

// Constructors
public MortgageApplication( int amount )
{
this.amount = amount;
}

// Methods
public boolean IsEligible( Customer c )
{
// Check creditworthyness of applicant
if( !bank.SufficientSavings( c ) )
return false;
if( !loan.GoodLoan( c ) )
return false;
if( !credit.GoodCredit( amount, c ))
return false;

return true;
}
}

package design.pattern.facade;

/**
* <summary>
* Facade Client
* </summary>
* @author tyrone
*/
public class FacadeApp {
/** @modelguid {67B55D21-888A-422E-B88E-1FBC34D3AA5C} */
public static void main(String[] args)
{
// Create Facade
MortgageApplication mortgage =
new MortgageApplication( 125000 );
// Call subsystem through Facade
mortgage.IsEligible(
new Customer( "Gabrielle McKinsey" ) );

}

}

Output

Check bank for Gabrielle McKinsey Check loan for Gabrielle McKinsey Check credit for Gabrielle McKinsey