public class WorkExcuse implements Excuse {
private String[] excuses = {"in an incredible confluence of circumstances, I ran out of hot water and had to wait until sunlight, focused using a magnifying glass, heated a mug of water so that I could wash.",
"the artificial intelligence in my alarm clock failed me, waking me up an hour earlier than normal. Because it is winter, I thought it was still nighttime and I fell back asleep. Everything after that is a bit hazy.",
"my pre-holiday mood slows metabolic processes in my body, leading to depression and insomnia."};
private String [] apologies = {"This will not happen again, of course. I'm very sorry.", "I apologize for my unprofessional behavior.", "There is no excuse for my actions. I am not worthy of this position."};
@Override
public String generateExcuse() { // Randomly select an excuse from the array
String result = "I was late today because " + excuses[(int) Math.round(Math.random() + 1)] + "\\n" +
apologies[(int) Math.round(Math.random() + 1)];
return result;
}
@Override
public void likeExcuse(String excuse) {
// Duplicate the element in the array so that its chances of being chosen are higher
}
@Override
public void dislikeExcuse(String excuse) {
// Remove the item from the array
}
}
この例をテストしてみましょう。
Excuse excuse = new WorkExcuse();
System.out.println(excuse.generateExcuse());
出力：
"I was late today because my pre-holiday mood slows metabolic processes in my body, leading to depression and insomnia.
I apologize for my unprofessional behavior.
public class SuperStudentExcuse implements StudentExcuse {
@Override
public String generateExcuse() {
// Logic for the new functionality
return "An incredible excuse adapted to the current weather conditions, traffic jams, or delays in public transport schedules.";
}
@Override
public void dislikeExcuse(String excuse) {
// Adds the reason to a blacklist
}
}
public class Middleware implements Excuse { // 1. Middleware becomes compatible with WorkExcuse objects via the Excuse interface
private StudentExcuse superStudentExcuse;
public Middleware(StudentExcuse excuse) { // 2. Get a reference to the object being adapted
this.superStudentExcuse = excuse;
}
@Override
public String generateExcuse() {
return superStudentExcuse.generateExcuse(); // 3. The adapter implements an interface method
}
@Override
public void dislikeExcuse(String excuse) {
// The method first adds the excuse to the blacklist,
// Then passes it to the dislikeExcuse method of the superStudentExcuse object.
}
// The likeExcuse method will appear later
}
テスト (クライアント コード内):
public class Test {
public static void main(String[] args) {
Excuse excuse = new WorkExcuse(); // We create objects of the classes
StudentExcuse newExcuse = new SuperStudentExcuse(); // that must be compatible.
System.out.println("An ordinary excuse for an employee:");
System.out.println(excuse.generateExcuse());
System.out.println("\n");
Excuse adaptedStudentExcuse = new Middleware(newExcuse); // Wrap the new functionality in the adapter object
System.out.println("Using new functionality with the adapter:");
System.out.println(adaptedStudentExcuse.generateExcuse()); // The adapter calls the adapted method
}
}
出力：
An ordinary excuse for an employee:
I was late today because my pre-holiday mood slows metabolic processes in my body, leading to depression and insomnia.
There is no excuse for my actions. I am not worthy of this position.
Using new functionality with the adapter:
public class Middleware implements Excuse {
private StudentExcuse superStudentExcuse;
public Middleware(StudentExcuse excuse) {
this.superStudentExcuse = excuse;
}
@Override
public String generateExcuse() {
return superStudentExcuse.generateExcuse();
}
@Override
public void likeExcuse(String excuse) {
throw new UnsupportedOperationException("The likeExcuse method is not supported by the new functionality");
}
@Override
public void dislikeExcuse(String excuse) {
// The method accesses a database to fetch additional information,
// and then passes it to the superStudentExcuse object's dislikeExcuse method.
}
}
この場合どうすればよいでしょうか? コードを書き換えますか? システムの分析に時間がかかるか、アプリケーションの内部ロジックに違反する可能性があるため、それはできません。この問題を解決するために、アダプター パターンが作成されました。これは、互換性のないインターフェイスを持つオブジェクトが連携して動作するのに役立ちます。使い方を見てみましょう！
このバージョンのシステムは Excuse インターフェイスでのみ動作します。コードを書き直すことはできません。大規模なアプリケーションでは、そのような変更を行うと時間がかかるプロセスになったり、アプリケーションのロジックが壊れたりする可能性があります。基本インターフェイスを導入して階層を拡張できます。 
これを行うには、インターフェイスの名前を変更する必要があります
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