原型模式-設計模式

原型模型經過拷貝建立對象，也可歸結爲的建立型的設計模式。

原型模式的示例：

public class Prototype {

    public static void main(String[] args) {
        Field field = new Field("code");
        System.out.println("field=[" + field + "]");
        field.setCode("codedes");
        Field fieldCopy = field.clone();
        System.out.println("fieldCopy=[" + fieldCopy + "]");
    }
}

class Field implements Cloneable {

    private String code;

    public Field(String code) {
        this.code = code;
    }
    
    public void setCode(String code) {
        this.code = code;
    }

    @Override
    public String toString() {
        return "Field{" +
                "code='" + code + '\'' +
                '}';
    }

    public Field clone() {

        Field field = null;
        try {
            field = (Field) super.clone();

        } catch (CloneNotSupportedException e) {
            throw new RuntimeException(e);
        }
        return field;
    }
}

一、實現Cloneable接口
二、調用object父類的clone方法進行拷貝。這裏的拷貝是淺拷貝。

實現深拷貝：

public class Prototype {

    public static void main(String[] args) {
        Field field = new Field("code", new Type("string"));
        System.out.println("field=[" + field + "]");
        field.setCode("codedes");
        Field fieldCopy = field.clone();
        System.out.println("fieldCopy=[" + fieldCopy + "]");
    }
}

class Type implements Cloneable {
    private String typeName;

    public Type(String typeName) {
        this.typeName = typeName;
    }

    public Type clone(){
        Type type = null;
        try {
            type = (Type) super.clone();
        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
        }
        return type;
    }
}

class Field implements Cloneable {

    private String code;

    private Type type;

    public Field(String code, Type type) {
        this.code = code;
        this.type = type;
    }

    public void setCode(String code) {
        this.code = code;
    }

    @Override
    public String toString() {
        return "Field{" +
                "code='" + code + '\'' +
                ", type=" + type +
                '}';
    }

    public Field clone() {

        Field field = null;
        try {
            field = (Field) super.clone();
            field.type = type.clone();

        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
        }
        return field;
    }
}

clone這種方式是先分配內存大小，而後經過內存塊的複製操做來實現賦值的，效率可能會比new出來一個對象的效率高點。