Java设计模式-建造者模式

概念

将一个复杂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。

角色说明

Product 产品类 : 具体产品类。
Builder : 抽象接口类， 规范产品的组建。
ConcreteBuilder : 具体的建造者，实现Builder接口，构造和装配各个部件。.
Director : 指挥着，构建一个使用Builde接口的对象。

实例

具体产品（product）

/** * <pre> *     author : duyb *     time   : 2017/10/17 *     desc   : 具体产品类 *     version: 1.0 * </pre> */public class Computer {    public void setCpuCore(String partCore) {        Log.e("打印电脑cpu核数--->", partCore);    }    public void setRamSize(String partSize) {        Log.e("打印电脑内存大小--->", partSize);    }}

建造者（builder）接口

/** * <pre> *     author : duyb *     time   : 2017/10/17 *     desc   :建造者类接口 *     version: 1.0 * </pre> */public interface IComputerBuilder {    /**     * cpu核数     */    void BuilderCpuCore();    /**     * 内存大小     */    void BuilderRamSize();}

具体的建造者类

/** * <pre> *     author : duyb *     time   : 2017/10/17 *     desc   : 具体的建造者类1 *     version: 1.0 * </pre> */public class ConcreateBuilder1 implements IComputerBuilder {    private Computer computer = new Computer();    @Override    public void BuilderCpuCore() {        computer.setCpuCore("4");    }    @Override    public void BuilderRamSize() {        computer.setRamSize("2");    }}

/** * <pre> *     author : duyb *     time   : 2017/10/17 *     desc   : 具体的建造者类2 *     version: 1.0 * </pre> */public class ConcreateBuilder2 implements IComputerBuilder {    private Computer computer = new Computer();    @Override    public void BuilderCpuCore() {        computer.setCpuCore("8");    }    @Override    public void BuilderRamSize() {        computer.setRamSize("4");    }}

指挥着（Director）

/** * <pre> *     author : duyb *     time   : 2017/10/17 *     desc   : 指挥着，构建使用builder接口对象 *     version: 1.0 * </pre> */public class Director {    public void Construct(IComputerBuilder builder) {        builder.BuilderCpuCore();        builder.BuilderRamSize();    }}

测试代码

/** * <pre> *     author : duyb *     time   : 2017/10/17 *     desc   : 测试类 *     version: 1.0 * </pre> */public class TestMain {    public void Test() {        Director director = new Director();        IComputerBuilder b1 = new ConcreateBuilder1();        IComputerBuilder b2 = new ConcreateBuilder2();        director.Construct(b1);        director.Construct(b2);    }}

链式builder模式

/** * <pre> *     author : duyb *     time   : 2017/10/17 *     desc   :链式建造者 *     version: 1.0 * </pre> */public class Student {    //final修饰：必须在构造中初始化    private final int stuId;//必须    private final String name;//必须    private final int age;//可选    private final int gender;//可选    private final String address;//可选    //注意：此处构造私有    private Student(StudentBuilder builder) {        this.stuId = builder.stuId;        this.name = builder.name;        this.age = builder.age;        this.gender = builder.gender;        this.address = builder.address;    }    //此处省略各get方法（只提供get方法）.....    public static class StudentBuilder {        private final int stuId;        private final String name;        private int age;        private int gender;        private String address;        //必填属性        public StudentBuilder(int stuId, String name) {            this.stuId = stuId;            this.name = name;        }        public StudentBuilder setAge(int age) {            this.age = age;            return this;        }        public StudentBuilder setGender(int gender) {            this.gender = gender;            return this;        }        public StudentBuilder setAddress(String address) {            this.address = address;            return this;        }        //结束方法        public Student build() {            return new Student(this);        }    }}

public class TestMain {    public Student Test() {       return new Student.StudentBuilder(1,"duyb")               .setAge(25)               .setAddress("中国.北京")               .build();    }}

分析：

return new Student.StudentBuilder(1,”duyb”)
.setAge(25)
.setAddress(“中国.北京”)
.build();
—————————————
.build()返回student实例， 调用Student构造：
private Student(StudentBuilder builder) {
this.stuId = builder.stuId;
this.name = builder.name;
this.age = builder.age;
this.gender = builder.gender;
this.address = builder.address;
}，而Student(StudentBuilder builder)的参数是StudentBuilder 实例，故在调用.build()之前通过调用StudentBuilder 的构造Student.StudentBuilder(1,”duyb”)来初始化参数。

小结

使用场景：
相同的方法，不同的执行顺序，产生不同的执行效果
一个对象可以配置多个不同的零件，产生不同的效果
一个对象，参数方法极多，调用顺序不同则效果不同

参考
http://blog.csdn.net/nugongahou110/article/details/50395698