1.原型模式的定義及使用場景

3）一個對象需要提供給其他對象訪問，而且各個調(diào)用者可能都需要修改其值時，可以考慮使用原型模式拷貝多個對象供調(diào)用者使用，即保護(hù)性拷貝

2.原型模式的優(yōu)缺點(diǎn)

2.1優(yōu)點(diǎn)

2.2缺點(diǎn)

3.注意實(shí)現(xiàn)

4.原型模式的實(shí)現(xiàn)方式

PRotoType：public class ProtoType implements Cloneable {    public ProtoType() {        System.out.println("ProtoType is excute...");    }    private int id;    private String name;    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;    }    @Override    protected ProtoType clone() {        ProtoType protoType = null;        try {            protoType = (ProtoType) super.clone();        } catch (CloneNotSupportedException e) {            e.printStackTrace();        }        return protoType;    }    @Override    public String toString() {        return "ProtoType{" +                "id=" + id +                ", name='" + name + '/'' +                '}';    }}Text：public class Test {    public static void main(String args[]) {        ProtoType type = new ProtoType();        type.setId(1);        type.setName("張三");        System.out.println(type);        ProtoType clone = type.clone();        clone.setId(2);        clone.setName("李四");        System.out.println(clone);    }}
Objec的clone源碼：  /**  * Creates and returns a copy of this {@code Object}. The default  * implementation returns a so-called "shallow" copy: It creates a new  * instance of the same class and then copies the field values (including  * object references) from this instance to the new instance. A "deep" copy,  * in contrast, would also recursively clone nested objects. A subclass that  * needs to implement this kind of cloning should call {@code super.clone()}  * to create the new instance and then create deep copies of the nested,  * mutable objects.  *  * @return a copy of this object.  * @throws CloneNotSupportedException  * if this object's class does not implement the {@code  * Cloneable} interface.  */  protected Object clone() throws CloneNotSupportedException {  if (!(this instanceof Cloneable)) {  throw new CloneNotSupportedException("Class " + getClass().getName() +  " doesn't implement Cloneable");  }  return internalClone();  }  /*  * Native helper method for cloning.  */  private native Object internalClone();可見執(zhí)行了一個native方法執(zhí)行二進(jìn)制流的拷貝
5.原型模式在Android中的實(shí)際應(yīng)用
Intent：  @Override  public Object clone() {  return new Intent(this);  } /**  * Copy constructor.  */  public Intent(Intent o) {  this.mAction = o.mAction;  this.mData = o.mData;  this.mType = o.mType;  this.mPackage = o.mPackage;  this.mComponent = o.mComponent;  this.mFlags = o.mFlags;  this.mContentUserHint = o.mContentUserHint;  if (o.mCategories != null) {  this.mCategories = new ArraySet<String>(o.mCategories);  }  if (o.mExtras != null) {  this.mExtras = new Bundle(o.mExtras);  }  if (o.mSourceBounds != null) {  this.mSourceBounds = new Rect(o.mSourceBounds);  }  if (o.mSelector != null) {  this.mSelector = new Intent(o.mSelector);  }  if (o.mClipData != null) {  this.mClipData = new ClipData(o.mClipData);  }  }