Merge branch 'dev-practice-10' into 'master'

.gitignore

README.md

practice-10/.gitignore

practice-10/README.md

practice-10/build.gradle

practice-10/gradle/wrapper/gradle-wrapper.jar

practice-10/gradle/wrapper/gradle-wrapper.properties

practice-10/gradlew

practice-10/gradlew.bat

practice-10/settings.gradle

...java/csui/adpro2021/practice10/Practice10Application.java

.../csui/adpro2021/practice10/controller/BookController.java

...10/src/main/java/csui/adpro2021/practice10/core/Book.java

...ui/adpro2021/practice10/core/bookcontent/BookContent.java

...2021/practice10/core/bookcontent/GrimoireBookContent.java

...pro2021/practice10/core/bookcontent/ImageBookContent.java

.../adpro2021/practice10/core/bookcontent/NoBookContent.java

...dpro2021/practice10/core/bookcontent/TextBookContent.java

...ui/adpro2021/practice10/core/bookcover/BookCoverType.java

...dpro2021/practice10/core/bookcover/GrimoireCoverType.java