java設計模式精講 Debug 方式+記憶體分析 第7章 建造者模式
阿新 • • 發佈:2018-11-23
建造者模式
7-1 建造者模式講解
7-2 建造者模式coding
我們來建造一個視訊課程:
首先,建立一個課程類:
public class Course {
private String courseName;
private String coursePPT;
private String courseVideo;
private String courseArticle;
/** 問題和答案 */
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 + '\'' +
'}';
}
}
我們再來建立一個抽象類:
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();
}
我們再來建立一個實現CourseBuilder 的子類:
public class CourseActualBuilder extends CourseBuilder {
/** 這裡把課程組合到實際的Builde當中 */
private Course course = new Course();
@Override
public void buildCourseName(String courseName) {
course.setCourseName(courseName);
}
@Override
public void buildCoursePPT(String coursePPT) {
course.setCoursePPT(coursePPT);
}
@Override
public void buildCourseVideo(String courseVideo) {
course.setCourseVideo(courseVideo);
}
@Override
public void buildCourseArticle(String courseArticle) {
course.setCourseArticle(courseArticle);
}
@Override
public void buildCourseQA(String courseQA) {
course.setCourseQA(courseQA);
}
@Override
public Course makeCourse() {
return course;
}
}
這裡還引入了一個教練類:
public class Coach {
private CourseBuilder courseBuilder;
/** 這裡的CourseBuilder通過set的方式給注入進來 */
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();
}
}
這個就是類圖:
測試:
public class Test {
public static void main(String[]args){
/** 利用多型,抽象類的引用指向子類的實現 */
CourseBuilder courseBuilder = new CourseActualBuilder();
Coach coach = new Coach();
/** 這裡利用set方法注入進去 */
coach.setCourseBuilder(courseBuilder);
Course course = coach.makeCourse("Java設計模式", "Java設計模式PPT", "Java設計模式視訊", "Java設計模式手記", "Java設計模式問答");
System.out.println(course);
}
}
執行結果:
Course{courseName=‘Java設計模式’, coursePPT=‘Java設計模式PPT’, courseVideo=‘Java設計模式視訊’, courseArticle=‘Java設計模式手記’, courseQA=‘Java設計模式問答’}
我們可以打個斷點來看看執行過程:
我們再來演進一下:使用靜態內部類
把具體的實體類和實體類對應的Builder寫在一個類裡面:
這裡一個很關鍵的地方就是this和靜態內部類的使用:
public class Course {
private String courseName;
private String coursePPT;
private String courseVideo;
private String courseArticle;
/** 問題和答案 */
private String courseQA;
public Course(CourseBuilder courseBuilder) {
this.courseName = courseBuilder.courseName;
this.coursePPT = courseBuilder.coursePPT;
this.courseVideo = courseBuilder.courseVideo;
this.courseArticle = courseBuilder.courseArticle;
this.courseQA = courseBuilder.courseQA;
}
public static class CourseBuilder{
private String courseName;
private String coursePPT;
private String courseVideo;
private String courseArticle;
/** 問題和答案 */
private String courseQA;
public CourseBuilder builderCourseName(String courseName) {
this.courseName = courseName;
return this;
}
public CourseBuilder builderCoursePPT(String coursePPT) {
this.coursePPT = coursePPT;
return this;
}
public CourseBuilder builderCourseVideo(String courseVideo) {
this.courseVideo = courseVideo;
return this;
}
public CourseBuilder builderCourseArticle(String courseArticle) {
this.courseArticle = courseArticle;
return this;
}
public CourseBuilder builderCourseQA(String courseQA) {
this.courseQA = courseQA;
return this;
}
public Course build() {
return new Course(this);
}
}
@Override
public String toString() {
return "Course{" +
"courseName='" + courseName + '\'' +
", coursePPT='" + coursePPT + '\'' +
", courseVideo='" + courseVideo + '\'' +
", courseArticle='" + courseArticle + '\'' +
", courseQA='" + courseQA + '\'' +
'}';
}
}
我們再來寫上一個測試類來測試:
public class Test {
public static void main(String[]args){
Course course = new Course.CourseBuilder()
.builderCourseName("Java設計模式")
.builderCoursePPT("Java設計模式PPT")
.builderCourseVideo("Java設計模式視訊")
.builderCourseArticle("Java設計模式手記")
.builderCourseQA("Java設計模式問答").build();
System.out.println(course);
}
}
執行結果:
Course{courseName=‘Java設計模式’, coursePPT=‘Java設計模式PPT’, courseVideo=‘Java設計模式視訊’, courseArticle=‘Java設計模式手記’, courseQA=‘Java設計模式問答’}
這個就是現在的類圖:
7-3 建造者模式原始碼解析(jdk+guava+spring+mybatis)
StringBuilder
而StringBuffer裡面同樣也是如此,只不過方法裡面加入了synchronized關鍵字
Guava裡面的 :
測試:
public static void main(String[]args){
Set<String> set = ImmutableSet.<String>builder().add("a").add("b").build();
System.out.println(set);
}
執行結果:
[a, b]