桥接模式（Bridge）

分离接口与实现，以实现替换实现时不必修改客户端。

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Abstraction（BusinessObject）

定义类的接口；

RefinedAbstraction（CustomerBusinessObject）

扩展接口；

Implementor(DataObject)

定义实现类的接口，这个接口可以不和Abstraction接口吻合，实际上会完全不同。实现类的接口提供基础的操作，而Abstraction定义基于基础操作的高层操作。

ConcreteImplementor(CustomersDataObject)

实现Implementor接口和定义它自己具体实现。

代码：

//Abstraction

public abstract class BusinessObject{

//Fields

private DataObject dataObject;

protected String group;

public BusinessObject(String group){

this.group=group;

}

public DataObject getDataObject(){

return dataObject;

}

public void setDataObject(DataObject value){

dataObject=value;

}

public void Next(){

dataObject.NextRecord();

}

public void Prior(){

dataObject.PriorRecord();

}

public void New(String name){

dataObject.NewRecord(name);

}

public void Delete(String name){

dataObject.DeleteRecord(name);

}

public void Show(){

dataObject.ShowRecord();

}

public void ShowAll(){

System.out.println(“Customer Group:”+group);

dataObject.ShowAllRecords();

}

}

//RefinedAbstraction

public class CustomerBusinessObject extends BusinessObject{

public CustomerBusinessObject(String group){

super(group);

}

public void ShowAll(){

System.out.println(“--------------------”);

super.ShowAll();

System.out.println(“--------------------“);

}
}

//Implementor

public interface DataObject{

public void NextRecord();

public void PriorRecord();

public void NewRecord(String name);

public void DeleteRecord(String name);

public void ShowRecord();

public void ShowAllRecords();

}

//ConcreteImplementor

package org.colimas.doxygen.qtools;

import java.util.*;

public class CustomersDataObject implements DataObject {

private ArrayList customers=new ArrayList();

private int current = 0;

public CustomersDataObject() {

// Loaded from a database

customers.add( "Jim Jones" );

customers.add( "Samual Jackson" );

customers.add( "Allen Good" );

customers.add( "Ann Stills" );

customers.add( "Lisa Giolani" );

}

public void NextRecord() {

if( current <= customers.size()-1)

current++;

}

public void PriorRecord() {

if( current > 0 )

current--;

}

public void NewRecord(String name) {

customers.add( name );

}

public void DeleteRecord(String name) {

customers.remove( name );

}

public void ShowRecord() {

System.out.println(customers.get(current).toString());

}

public void ShowAllRecords() {

for (int i=0;i<customers.size();i++)

System.out.println(customers.get(i).toString());

}

}

//Client

public class BusinessApp {

public static void main(String[] args) {

BusinessObject customers =

new CustomerBusinessObject("Chicago");

//Set ConcreteImplementor

customers.setDataObject(new CustomersDataObject());

//Exercise the bridge

customers.Show();

customers.Next();

customers.Show();

customers.Next();

customers.Show();

customers.New( "Henry Velasquez" );

customers.ShowAll();

}

}

Output

Jim Jones
Samual Jackson
Allen Good

------------------------
Customer Group: <city><place><code><span style="FONT-SIZE: 10pt; COLOR: white"><font size="1">Chicago</font></span></code></place></city>
Jim Jones
Samual Jackson
Allen Good
Ann Stills
Lisa Giolani
Henry Velasquez
------------------------