Downloaded 35 times
![public class ScoreRepository {
private String url;
private HttpClient client;
public ScoreRepository() {
this.url = “http://localhost:3000/scores”
this.client = new HttpClient(
new MultiThreadedHttpConnectionManager());
}
public int [] getScores() {
GetMethod get = new GetMethod(url);
try {
if (client.executeMethod(get) == HttpStatus.SC_OK) {
return new Gson().fromJson(get.getResponseBodyAsString(),
int [].class);
} else {
return new int [0];
}
} catch (Exception e) {
throw new RuntimeException(e);
} finally {
get.releaseConnection();
}
}
}
ScoreRepository](https://image.slidesharecdn.com/jwpaweek02-140714104419-phpapp02/75/JWAP-2-DI-Spring-22-2048.jpg)
Uploaded byYoung-Ho Cho
[JWAP-2] DI & Spring
The document discusses dependency injection and loose coupling in Java applications. It describes how tightly coupling the Lecture class to the ScoreRepository class caused testability and dependency issues. To address this, the document suggests using dependency injection by modifying the Lecture constructor to accept the dependencies rather than creating them internally. This loosens the coupling and allows mocking dependencies for testing. It provides an example using Mockito to mock the ScoreRepository and test grading behavior without depending on the real implementation or external services.
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[JWAP-2] DI & Spring
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- 21. class Lecture interface Grader class ScoreRepository Score Server 2) HTTP 1)score 조회 3) JSON 4) score 전달
- 22. public class ScoreRepository{ private String url; private HttpClient client; public ScoreRepository() { this.url = “http://localhost:3000/scores” this.client = new HttpClient( new MultiThreadedHttpConnectionManager()); } public int [] getScores() { GetMethod get = new GetMethod(url); try { if (client.executeMethod(get) == HttpStatus.SC_OK) { return new Gson().fromJson(get.getResponseBodyAsString(), int [].class); } else { return new int [0]; } } catch (Exception e) { throw new RuntimeException(e); } finally { get.releaseConnection(); } } } ScoreRepository
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- 24. public class Lecture{ private ScoreRepository scoreRepository; private Grader grader; public Lecture(Grader grader) { this.grader = grader; this.scoreRepository = new ScoreRepository(); } public String grade() { return grader.grade(scoreRepository.getScores()); } } Lecture
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- 54. public class Lecture{ private ScoreRepository scoreRepository; private Grader grader; public Lecture(Grader grader) { this.grader = grader; this.scoreRepository = new ScoreRepository(); } public String grade() { return grader.grade(scoreRepository.getScores()); } } Lecture
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- 61. public class Lecture{ private ScoreRepository scoreRepository; private Grader grader; public Lecture(Grader grader) { this.grader = grader; this.scoreRepository = new ScoreRepository(); } public String grade() { return grader.grade(scoreRepository.getScores()); } } Hidden Dependency
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- 64. @Test public void starndardGrade(){ Lecture lecture = new Lecture(new StandardGrader()); String grade = lecture.grade(); assertEquals(A:1 B:1 C:1 D:0 F:2 , grade); } assertEquals
- 65. “A:1 B:1 C:1D:0 F:2” ?
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- 88. public class Lecture{ private ScoreRepository scoreRepository; private Grader grader; public Lecture(Grader grader) { this.grader = grader; this.scoreRepository = new ScoreRepository(); } public String grade() { return grader.grade(scoreRepository.getScores()); } } Tight Coupling
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- 90. public class Lecture{ private ScoreRepository scoreRepository; private Grader grader; public Lecture(Grader grader, ScoreRepository scoreRepository) { this.grader = grader; this.scoreRepository = scoreRepository; } Loose Coupling
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- 93. {50,20,70,80,90} =“A:1 B:1C:1 D:0 F:2”
- 94. @RunWith(MockitoJUnitRunner.class) public class LectureTest{ @Mock private ScoreRepository repository; @Test public void starndardGrade() { when(repository.getScores()) .thenReturn(new int [] {50,20,70,80,90}); Lecture lecture = new Lecture(new StandardGrader(), repository); String grade = lecture.grade(); assertEquals(A:1 B:1 C:1 D:0 F:2 , grade); }
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- 97. lecture = newLecture(new StandardGrader(), new HttpScoreRepository()); lecture = new Lecture(new PassFailGrader(), new HttpScoreRepository()); Loose Coupling = Complex Object Graph
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- 101. get Standard GradeLecture get Pass Fail Grade Lecture Container
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- 103. public class Score{ private static LectureRegistry lectureFactory = new LectureRegistry(); public static void main(String [] args) { Lecture lecture = null; Scanner scanner = new Scanner(System.in); try { System.out.print(grader? ); switch(scanner.next()) { case st: lecture = lectureFactory.getStandardGradeLecture(); break; case pf: lecture = lectureFactory.getPassFailGradeLecture(); break; default: return; } System.out.println(lecture.grade()); } finally { scanner.close(); } } } Score class
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- 106. lecture = lectureFactory.getStandardGradeLecture(); lecture= lectureFactory.getPassFailGradeLecture(); Dependency Lookup
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- 121. Spring 표준화된 Registry 메커니즘제공 Spring의
- 122. Registry = ApplicationContext Dependency Injection Framework IoC Container
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- 128. ?xml version=1.0 encoding=UTF-8? !DOCTYPEbeans PUBLIC -//SPRING//DTD BEAN 2.0//EN http://www.springframework.org/dtd/spring-beans-2.0.dtd beans /beans Scores.xml
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- 130. ?xml version=1.0 encoding=UTF-8? !DOCTYPEbeans PUBLIC -//SPRING//DTD BEAN 2.0//EN http://www.springframework.org/dtd/spring-beans-2.0.dtd beans bean id=httpScoreRepository class=com.nhnnext.score.scores.HttpScoreRepository / /beans Scores.xml
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- 132. ?xml version=1.0 encoding=UTF-8? !DOCTYPEbeans PUBLIC -//SPRING//DTD BEAN 2.0//EN http://www.springframework.org/dtd/spring-beans-2.0.dtd beans bean id=httpScoreRepository class=com.nhnnext.score.scores.HttpScoreRepository / bean id=standardGrader class=com.nhnnext.score.lecture.StandardGrader / bean id=passFailGrader class=com.nhnnext.score.lecture.PassFailGrader / /beans Scores.xml
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- 134. ?xml version=1.0 encoding=UTF-8? !DOCTYPEbeans PUBLIC -//SPRING//DTD BEAN 2.0//EN http://www.springframework.org/dtd/spring-beans-2.0.dtd beans bean id=httpScoreRepository class=com.nhnnext.score.scores.HttpScoreRepository / bean id=standardGrader class=com.nhnnext.score.lecture.StandardGrader / bean id=passFailGrader class=com.nhnnext.score.lecture.PassFailGrader / bean id=standardGradeLecture class=com.nhnnext.score.lecture.Lecture constructor-arg ref=standardGrader / constructor-arg ref=httpScoreRepository / /bean /beans Scores.xml
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- 136. ?xml version=1.0 encoding=UTF-8? !DOCTYPEbeans PUBLIC -//SPRING//DTD BEAN 2.0//EN http://www.springframework.org/dtd/spring-beans-2.0.dtd beans bean id=httpScoreRepository class=com.nhnnext.score.scores.HttpScoreRepository / bean id=standardGrader class=com.nhnnext.score.lecture.StandardGrader / bean id=passFailGrader class=com.nhnnext.score.lecture.PassFailGrader / bean id=standardGradeLecture class=com.nhnnext.score.lecture.Lecture constructor-arg ref=standardGrader / constructor-arg ref=httpScoreRepository / /bean bean id=passFailGradeLecture class=com.nhnnext.score.lecture.Lecture constructor-arg ref=passFailGrader / constructor-arg ref=httpScoreRepository / /bean /beans Sores.xml
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- 138. Load Application Context GenericXmlApplicationContextcontext = new GenericXmlApplicationContext(classpath:scores.xml”); Application Context object :Lecture object :Standard Grader object :PassFail Grader object :HttpScore Repository object :Lecture httpScore Repository passFail Grader standard Grader standard Grade Lecture passFail Grade Lecture
- 139. Dependency Lookup lecture =context.getBean(passFailGradeLecture, Lecture.class); Application Context object :Lecture object :Standard Grader object :PassFail Grader object :HttpScore Repository object :Lecture httpScore Repository passFail Grader passFail Grade Lecture id class
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- 156. Constructor Injection Discussion bean id=standardGradeLecture class=com.nhnnext.score.lecture.Lecture constructor-arg ref=standardGrader / constructor-arg ref=httpScoreRepository / /bean public Lecture(Grader grader, ScoreRepository scoreRepository) { this.grader = grader; this.scoreRepository = scoreRepository; }
- 157. Setter Injection Discussion bean id=standardGradeLecture class=com.nhnnext.score.lecture.Lecture property name=grader ref=standardGrader / property name=scoreRepository ref=httpScoreRepository / /bean public void setGrader(Grader grader) { this.grader = grader; } public void setScoreRepository(ScoreRepository scoreRepository) { this.scoreRepository = scoreRepository; }
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- 159. bean id=standardGrader class=com.nhnnext.score.lecture.StandardGrader scope=singleton / bean id=standardGrader class=com.nhnnext.score.lecture.StandardGrader scope=“prototype / Prototype Singletone Stateful Stateless