外观模式

参考《设计模式的艺术软件开发人员内功修炼之道》-刘伟 著

实验目的

外观模式作为调用者和系统之间的接口，屏蔽了系统的具体细节，简化调用

实验代码

package Facade;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.IOException;class ReadFile {    public static String readFile(String filename) throws IOException {        File file = new File(filename);        if (!(file.exists() && file.canRead() && file.isFile())) {            System.out.println("source file not satisfy requirement");            return null;        }        StringBuffer sb = new StringBuffer();        FileInputStream is = new FileInputStream(filename);        int data;        while ((data = is.read()) != -1) {            sb.append((char) data);        }        System.out.println("return string of readFile is " + sb.toString());        return sb.toString();    }}class EncryFile {    public static String encryFile(String str) {        StringBuffer sb = new StringBuffer();        int len = str.length();        for (int i = 0; i < len; i++) {            char c = (char) (str.charAt(i) + 0);            sb.append(c);        }        System.out.println("return string of encryFile is " + sb.toString());        return sb.toString();    }}class WriteFile {    public static void writeFile(String encryContent, String filename) throws IOException {        File file = new File(filename);        if (file.exists() && !file.canWrite()) {            System.out.println("dest file not satisfy requirement");            return;        }        if (!file.exists())            file.createNewFile();        FileOutputStream os = new FileOutputStream(filename);        os.write(encryContent.getBytes());        System.out.println("return string of writeFile is " + encryContent);    }}interface AbstractInterface {    public void encryptFile(String filesrc, String filedest) throws IOException;}class ConcreteImpletation implements AbstractInterface {    @Override    public void encryptFile(String filesrc, String filedest) throws IOException {        // TODO Auto-generated method stub        String content = ReadFile.readFile(filesrc);        String encryContent = EncryFile.encryFile(content);        WriteFile.writeFile(encryContent, filedest);    }}public class FacadeTest {    public static void main(String[] args) throws IOException {        // TODO Auto-generated method stub        AbstractInterface intf = new ConcreteImpletation();        intf.encryptFile("D:/src.txt", "D:/dest.txt");        return;    }}

结果输出

return string of readFile is abcdefghijklmnreturn string of encryFile is abcdefghijklmnreturn string of writeFile is abcdefghijklmn

结论

• 外观模式解耦客户端和系统，减少复杂依赖关系
• 改变接口只需要增加具体的外观实现类即可