读书笔记_java设计模式深入研究 第六章 桥接模式
1，桥接模式：
将抽象部分与实现部分分离，使他们可以独立变化。桥接模式可以实现的是不同方式的组合完成不同的功能，方式和功能完全分离，使得相互不影响。
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2，UML模型：
3，简单代码实例：
/** * * @(#) IPost.java * @Package pattern.chp06.bridge.simple * * Copyright © JING Corporation. All rights reserved. * */package pattern.chp06.bridge.simple;/** * 类描述：邮局接口类 * * @author: Jing * @version $Id: Exp$ * * History: Dec 23, 2014 3:08:36 PM Jing Created. * */public interface IPost { /** * * 方法说明：发送功能 * * Author： Jing Create Date： Dec 23, 2014 3:08:57 PM * * @return void */ public void post();}
/** * * @(#) MarkPost.java * @Package pattern.chp06.bridge.simple * * Copyright © JING Corporation. All rights reserved. * */package pattern.chp06.bridge.simple;/** * 类描述：挂号信 * * @author: Jing * @version $Id: Exp$ * * History: Dec 23, 2014 3:19:32 PM Jing Created. * */public class MarkPost implements IPost{ public void post() { System.out.println("This is MarkPost"); }}
/** * * @(#) SimplePost.java * @Package pattern.chp06.bridge.simple * * Copyright © JING Corporation. All rights reserved. * */package pattern.chp06.bridge.simple;/** * 类描述：平信邮局 * * @author: Jing * @version $Id: Exp$ * * History: Dec 23, 2014 3:18:39 PM Jing Created. * */public class SimplePost implements IPost{ public void post() { System.out.println("This is SimplePost"); }}
/** * * @(#) AbstractThing.java * @Package pattern.chp06.bridge.simple * * Copyright © JING Corporation. All rights reserved. * */package pattern.chp06.bridge.simple;/** * 类描述：抽象事物 * * @author: Jing * @version $Id: Exp$ * * History: Dec 23, 2014 3:20:37 PM Jing Created. * */public abstract class AbstractThing { private IPost post; public AbstractThing(IPost post) { this.post = post; } public void post(){ post.post(); } }
/** * * @(#) Lettle.java * @Package pattern.chp06.bridge.simple * * Copyright © JING Corporation. All rights reserved. * */package pattern.chp06.bridge.simple;/** * 类描述：普通信件 * * @author: Jing * @version $Id: Exp$ * * History: Dec 23, 2014 3:21:36 PM Jing Created. * */public class Letter extends AbstractThing{ public Letter(IPost post) { super(post); } }
/** * * @(#) Parcel.java * @Package pattern.chp06.bridge.simple * * Copyright © JING Corporation. All rights reserved. * */package pattern.chp06.bridge.simple;/** * 类描述：挂号 * * @author: Jing * @version $Id: Exp$ * * History: Dec 23, 2014 3:22:31 PM Jing Created. * */public class Parcel extends AbstractThing { public Parcel(IPost post) { super(post); }}
/** * * @(#) MainTest.java * @Package pattern.chp06.bridge.simple * * Copyright © JING Corporation. All rights reserved. * */package pattern.chp06.bridge.simple;import org.junit.Test;/** * 类描述： * * @author: Jing * @version $Id: Exp$ * * History: Dec 23, 2014 3:23:16 PM Jing Created. * */public class MainTest { @Test public void testMain() throws Exception { IPost post = new SimplePost(); Letter letter = new Letter(post); letter.post(); }}
4，深入理解桥接模式
-1，桥接模式强调 包含 替代 继承
这种方式，但对于功能和事物来说两者分离，不会相互影响。
-2，JDK中桥接模式：Collectios.sort方法，借助Arrays.sort方法实现其自身内部的排序。
5，应用
实现读取本地或者远程URL文件，文件类型是文本或图像文件。
分析：
基本到手后实现的思路会如下所示，在TextRead中判断是本地还是URL方法，在其中调用不同的流读写。
但是，当文件类型增多时，会实现多个子类重写，同时会破坏原有方法，需要改进原有方法。我们可以对功能方法进行复杂的拆分，如下UML
代码如下：
/** * * @(#) Iread.java * @Package pattern.chp06.bridge.read * * Copyright © JING Corporation. All rights reserved. * */package pattern.chp06.bridge.read;/** * 类描述：抽象功能类 * * @author: Jing * @version $Id: Exp$ * * History: Dec 24, 2014 9:41:15 AM Jing Created. * */public interface IRead<T> { /** * * 方法说明：文件读取 * * Author： Jing * Create Date： Dec 24, 2014 10:52:28 AM * * @return * @throws Exception * @return T */ T read() throws Exception;}
/** * * @(#) TextRead.java * @Package pattern.chp06.bridge.read * * Copyright © JING Corporation. All rights reserved. * */package pattern.chp06.bridge.read;/** * 类描述：文本读取 * * @author: Jing * @version $Id: Exp$ * * History: Dec 24, 2014 10:04:08 AM Jing Created. * */public class TextRead implements IRead<String> { AbstractStream stream; public TextRead(AbstractStream stream) { this.stream = stream; } /** * 读取文本文件 */ public String read() throws Exception { byte[] buf = stream.readBytes(); String s = new String(buf); return s; }}
/** * * @(#) ImgRead.java * @Package pattern.chp06.bridge.read * * Copyright © JING Corporation. All rights reserved. * */package pattern.chp06.bridge.read;/** * 类描述：读取图像文件 * * @author: Jing * @version $Id: Exp$ * * History: Dec 24, 2014 10:51:58 AM Jing Created. * */public class ImgRead implements IRead<byte[]> { AbstractStream stream; public ImgRead(AbstractStream stream) { this.stream = stream; } public byte[] read() throws Exception { return stream.readBytes(); }}
/** * * @(#) AbstractStream.java * @Package pattern.chp06.bridge.read * * Copyright © JING Corporation. All rights reserved. * */package pattern.chp06.bridge.read;import java.io.InputStream;/** * 类描述：抽象基类流 * * @author: Jing * @version $Id: Exp$ * * History: Dec 24, 2014 10:05:54 AM Jing Created. * */public class AbstractStream { protected InputStream in; protected int size; /** * * 方法说明：读取对应输入流 * * Author： Jing Create Date： Dec 24, 2014 10:11:00 AM * * @return * @throws Exception * @return byte[] */ protected byte[] readBytes() throws Exception { byte[] buf = new byte[size]; in.read(buf); return buf; } /** * * 方法说明：关闭输入流 * * Author： Jing Create Date： Dec 24, 2014 10:11:24 AM * * @throws Exception * @return void */ public void close() throws Exception { in.close(); }}
/** * * @(#) NativeStream.java * @Package pattern.chp06.bridge.read * * Copyright © JING Corporation. All rights reserved. * */package pattern.chp06.bridge.read;import java.io.File;import java.io.FileInputStream;/** * 类描述：本地文件流读取 * * @author: Jing * @version $Id: Exp$ * * History: Dec 24, 2014 10:21:53 AM Jing Created. * */public class NativeStream extends AbstractStream{ public NativeStream(String fileName) throws Exception{ File f = new File(fileName); size = (int) f.length(); in = new FileInputStream(f); }}
/** * * @(#) URLStream.java * @Package pattern.chp06.bridge.read * * Copyright © JING Corporation. All rights reserved. * */package pattern.chp06.bridge.read;import java.net.HttpURLConnection;import java.net.URL;/** * 类描述：URl文件读取 * * @author: Jing * @version $Id: Exp$ * * History: Dec 24, 2014 10:27:09 AM Jing Created. * */public class URLStream extends AbstractStream { public URLStream(String fileName) throws Exception{ URL url = new URL(fileName); in = url.openStream(); HttpURLConnection urlCon = (HttpURLConnection) url.openConnection(); size = urlCon.getContentLength(); }}
/** * * @(#) AbstractThing.java * @Package pattern.chp06.bridge.read * * Copyright © JING Corporation. All rights reserved. * */package pattern.chp06.bridge.read;/** * 类描述：抽象事务类 * * @author: Jing * @version $Id: Exp$ * * History: Dec 24, 2014 10:54:09 AM Jing Created. * */public abstract class AbstractThing { IRead<?> read; public AbstractThing(IRead<?> read) { this.read = read; } Object read() throws Exception{ return read.read(); }}
/** * * @(#) NativeFile.java * @Package pattern.chp06.bridge.read * * Copyright © JING Corporation. All rights reserved. * */package pattern.chp06.bridge.read;/** * 类描述：本地文件读取 * * @author: Jing * @version $Id: Exp$ * * History: Dec 24, 2014 10:55:59 AM Jing Created. * */public class NativeFile extends AbstractThing{ public NativeFile(IRead<?> read) { super(read); }}
/** * * @(#) URLFile.java * @Package pattern.chp06.bridge.read * * Copyright © JING Corporation. All rights reserved. * */package pattern.chp06.bridge.read;/** * 类描述：URL文件读取 * * @author: Jing * @version $Id: Exp$ * * History: Dec 24, 2014 10:56:43 AM Jing Created. * */public class URLFile extends AbstractThing { public URLFile(IRead<?> read) { super(read); }}
/** * * @(#) Main.java * @Package pattern.chp06.bridge.read * * Copyright © JING Corporation. All rights reserved. * */package pattern.chp06.bridge.read;/** * 类描述： * * @author: Jing * @version $Id: Exp$ * * History: Dec 24, 2014 11:14:31 AM Jing Created. * */public class Main { public static void main(String[] args) throws Exception { //打开远程文件 AbstractStream in = new URLStream("http://js.t.sinajs.cn/t6/webim_prime/js/webim.js?v=1419389776378"); TextRead textRead = new TextRead(in); AbstractThing thing = new URLFile(textRead); String s = (String) thing.read(); in.close(); System.out.println(s); }}