设计模式---建造者模式

定义：
将一个负责的对象的构建与它的表示分离，使得同样的构建过程可以创建不同的表示
适用场景：
1、如果一个对象有非常复杂的内部结构（很多属性）
2、想把复杂对象的创建和使用分离
优点：
封装性好，创建和使用分离
扩展性好、建造类之间独立、一定程度上解耦
缺点：
产生多余的Builder对象
产品内部发生变化，建造者都要修改，成本较大

Coding：

public class Course {

    private String courseName;

    private String coursePPT;

    private String courseVideo;

    private String courseArticle;

    private String courseQA;

    public String getCourseName() {
        return courseName;
    }

    public void setCourseName(String courseName) {
        this.courseName = courseName;
    }

    public String getCoursePPT() {
        return coursePPT;
    }

    public void setCoursePPT(String coursePPT) {
        this.coursePPT = coursePPT;
    }

    public String getCourseVideo() {
        return courseVideo;
    }

    public void setCourseVideo(String courseVideo) {
        this.courseVideo = courseVideo;
    }

    public String getCourseArticle() {
        return courseArticle;
    }

    public void setCourseArticle(String courseArticle) {
        this.courseArticle = courseArticle;
    }

    public String getCourseQA() {
        return courseQA;
    }

    public void setCourseQA(String courseQA) {
        this.courseQA = courseQA;
    }

    @Override
    public String toString() {
        return "Course{" +
                "courseName='" + courseName + ''' +
                ", coursePPT='" + coursePPT + ''' +
                ", courseVideo='" + courseVideo + ''' +
                ", courseArticle='" + courseArticle + ''' +
                ", courseQA='" + courseQA + ''' +
                '}';
    }
}

public abstract class CourseBuilder {

    public abstract void buildCourseName(String courseName);

    public abstract void buildCoursePPT(String coursePPT);

    public abstract void buildCourseVideo(String courseVideo);

    public abstract void buildCourseArticle(String courseArticle);

    public abstract void buildCourseQA(String courseQA);

    public abstract Course makeCourse();

}

public class CourseActualBuilder extends CourseBuilder {

    private Course course = new Course();

    @Override
    public void buildCourseName(String courseName) {
        this.course.setCourseName(courseName);
    }

    @Override
    public void buildCoursePPT(String coursePPT) {
        this.course.setCoursePPT(coursePPT);
    }

    @Override
    public void buildCourseVideo(String courseVideo) {
        this.course.setCourseVideo(courseVideo);
    }

    @Override
    public void buildCourseArticle(String courseArticle) {
        this.course.setCourseArticle(courseArticle);
    }

    @Override
    public void buildCourseQA(String courseQA) {
        this.course.setCourseQA(courseQA);
    }

    @Override
    public Course makeCourse() {
        return this.course;
    }
}

public class Coach {

    private CourseBuilder courseBuilder;

    public void setCourseBuilder(CourseBuilder courseBuilder) {
        this.courseBuilder = courseBuilder;
    }

    public Course makeCourse(String courseName, String coursePPT, String courseVideo, String courseArticle, String courseQA){
        this.courseBuilder.buildCourseName(courseName);
        this.courseBuilder.buildCoursePPT(coursePPT);
        this.courseBuilder.buildCourseVideo(courseVideo);
        this.courseBuilder.buildCourseArticle(courseArticle);
        this.courseBuilder.buildCourseQA(courseQA);
        return this.courseBuilder.makeCourse();
    }
}

public class Test {

    public static void main(String[] args) {
        CourseBuilder courseBuilder = new CourseActualBuilder();
        Coach coach = new Coach();
        coach.setCourseBuilder(courseBuilder);
        Course course = coach.makeCourse("java设计模式", "java设计模式PPT", "java设计模式视频", "java设计模式手记", "java设计问题");
        System.out.println(course);
    }

}

常规写法

public class Course {

    private String courseName;

    private String coursePPT;

    private String courseVideo;

    private String courseArticle;

    private String courseQA;

    public Course(CourseBuilder courseBuilder) {
        this.courseName = courseBuilder.courseName;
        this.coursePPT = courseBuilder.courseName;
        this.courseVideo = courseBuilder.courseVideo;
        this.courseArticle = courseBuilder.courseArticle;
        this.courseQA = courseBuilder.courseQA;
    }


    @Override
    public String toString() {
        return "Course{" +
                "courseName='" + courseName + ''' +
                ", coursePPT='" + coursePPT + ''' +
                ", courseVideo='" + courseVideo + ''' +
                ", courseArticle='" + courseArticle + ''' +
                ", courseQA='" + courseQA + ''' +
                '}';
    }

    public static class CourseBuilder {

        private String courseName;

        private String coursePPT;

        private String courseVideo;

        private String courseArticle;

        private String courseQA;

        public CourseBuilder buildCourseName(String courseName) {
            this.courseName = courseName;
            return this;
        }

        public CourseBuilder buildCoursePPT(String coursePPT) {
            this.coursePPT = coursePPT;
            return this;
        }

        public CourseBuilder buildCourseVideo(String courseVideo) {
            this.courseVideo = courseVideo;
            return this;
        }

        public CourseBuilder buildCourseArticle(String courseArticle) {
            this.courseArticle = courseArticle;
            return this;
        }

        public CourseBuilder buildCourseQA(String courseQA) {
            this.courseQA = courseQA;
            return this;
        }

        public Course build() {
            return new Course(this);
        }
    }
}

public class Test {

    public static void main(String[] args) {
        Course course = new Course.CourseBuilder().buildCourseName("java设计模式")
                .buildCoursePPT("java设计模式PPT").buildCourseVideo("java设计模式视频")
                .buildCourseArticle("java设计模式手记").buildCourseQA("java设计问题").build();
        System.out.println(course);
    }

}