适配器模式将某个类的接口转换成客户端期望的另一个接口表示,目的是消除由于接口不匹配所造成的类的兼容性问题
上篇文章我讲完了5种创建型模式,这章开始,我将讲下7种结构型模式:适配器模式、装饰模式、代理模式、外观模式、桥接模式、组合模式、享元模式。其中对象的适配器模式是各种模式的起源,我们看下面的图:
public class Source {
public void sourceMethod() {
System.out.println("this is Source Method!");
}
}
public interface Target {
/* 与原类中的方法相同 */
public void sourceMethod();
/* 新类的方法 */
public void targetMethod();
}
public class Adapter extends Source implements Target {
@Override
public void targetMethod() {
System.out.println("this is the Target Method!");
}
}
测试类:这样Target接口的实现类就具有了Source类的功能。
public class Test {
public static void main(String[] args) {
Target target = new Adapter();
target.sourceMethod(); /* this is Source Method! */
target.targetMethod(); /* this is the Target Method! */
}
}
只需要修改上述的Adapter类
public class Wrapper implements Target {
private Source source;
public Wrapper(Source source){
super();
this.source = source;
}
@Override
public void targetMethod() {
System.out.println("this is the Target Method!");
}
@Override
public void sourceMethod() {
source.sourceMethod();
}
}
测试类:输出和类的适配器模式是一样的,但是适配的方法不同
public class AdapterTest {
public static void main(String[] args) {
Source source = new Source();
Target target = new Wrapper(source);
target.sourceMethod(); /* this is Source Method! */
target.targetMethod(); /* this is the Target Method! */
}
}
总体来说就是,原类设计成接口,用抽象了类去实现接口,业务操作类去继承抽象类并实现具体业务即可。
在实现业务逻辑的时候很方便
public interface Source {
public void sourceMethod_1() {
System.out.println("this is Source Method_1!");
}
public void sourceMethod_2() {
System.out.println("this is Source Method_2!");
}
}
public abstract class WrapperInte implements Source{
public void sourceMethod_1(){}
public void sourceMethod_2(){}
}
public class SourceSup_1 extends WrapperInte {
public void sourceMethod_1(){
System.out.println("the source interface's first SourceSup_1!");
}
}
public class SourceSup_2 extends WrapperInte {
public void sourceMethod_2(){
System.out.println("the source interface's second SourceSup_2!");
}
}
测试类:
public class Test {
public static void main(String[] args) {
Source source1 = new SourceSup_1();
Source source2 = new SourceSup_2();
/* the source interface's first SourceSup_1! */
source1.sourceMethod_1();
/* this is Source Method! */
source1.sourceMethod_2();
source2.sourceMethod_1();
source2.sourceMethod_2();
}
}