重构之3.Replace Type Code with Subclasses(以子类取代类型码)

来源：互联网发布：人工智能人才培养编辑：程序博客网时间：2024/06/05 08:43

场景:

通常我们会在业务层判断类型码，执行不同的方法,可以使用子类来取代类型码

前提：

1.类型码不会被改变
2.类型码所属的类没有子类

修改前:

Student:

/** * @file Student.java *  *  * @author wumingkun * @version 1.0.0 * @Description */package com.refractor.subcode.before;/** * @author wumingkun * */public class Student {private int id;private String name;private int type;public static final int A =1;public static final int B =2;public Student(int id, String name, int type) {super();this.id = id;this.name = name;this.type = type;}public int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getType() {return type;}public void setType(int type) {this.type = type;}}

修改后:

Student:

/** * @file Student.java *  *  * @author wumingkun * @version 1.0.0 * @Description */package com.refractor.subcode.after;/** * @author wumingkun * */public abstract class Student {private int id;private String name;public static final int A =1;public static final int B =2;public Student(int id, String name) {super();this.id = id;this.name = name;}public static Student create(int type){switch (type) {case A:return new TypeA(1,"张三");case B:return new TypeB(2,"李四");default:throw new IllegalArgumentException();}}public abstract int getType();public int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}}

TypeA:

/** *  * @author wumingkun * @version 1.0.0 * @Description */package com.refractor.subcode.after;/** * @author wumingkun * */public class TypeA extends Student {/** * @param id * @param name */public TypeA(int id, String name) {super(id, name);}/* (non-Javadoc) * @see com.refractor.subcode.after.StudentManagement#getType() */@Overridepublic int getType() {return A;}@Overridepublic String toString() {return "TypeA [type=" + getType() + ", id=" + getId()+ ", name=" + getName() + "]";}}

TypeB:

/** *  * @author wumingkun * @version 1.0.0 * @Description */package com.refractor.subcode.after;/** * @author wumingkun * */public class TypeB extends Student {/** * @param id * @param name */public TypeB(int id, String name) {super(id, name);}/* (non-Javadoc) * @see com.refractor.subcode.after.StudentManagement#getType() */@Overridepublic int getType() {return B;}}

StudentTest:

/** * @file StudentTest.java *  * @author wumingkun * @version 1.0.0 * @Description */package com.refractor.subcode.after;/** * @author wumingkun * */public class StudentTest {/** * @param args */public static void main(String[] args) {Student student=Student.create(Student.A);System.out.println(student);}}

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