Android设计模式（十）－－生成器模式

回头看自己写的东西，大概Android当自己控制的定义，编写代码适用性比较高。但是，看看没有什么技术含量，因此，当在学习设计模式，想想有些东西是否可以改善，例如：

自己定义Dialog是Android应用必须的，系统的控件实在是太难看了。

在构建中，全然是，new完对象之后，须要什么构建什么。这样写没有问题。可读性也还行，就是看上去不咋的。

下面是小部分代码片段：

package com.example.demo.Builder;

/**
 *
 * @author qubian
 * @data 2015年6月10日
 * @email naibbian@163.com
 *
 */
public class BuilderDialog extends Dialog implements View.OnClickListener {
	private Context mContext;
	private View view;
	private View lineView;
	private TextView titleTv;
	private TextView contentTv;
	private Button sureBtn;
	private Button cancelBtn;
	private String sureTitle;
	private String cancelTitle;
	private String title;
	private String content;
	private boolean sureVisible = true;
	private boolean cancelVisible = true;
	private View.OnClickListener sureListener;
	private View.OnClickListener cancelListener;

	public BuilderDialog(Context context, String title, String content) {
		super(context, R.style.base_dialog_style);
		this.mContext = context;
		this.title = title;
		this.content = content;
		view = LayoutInflater.from(mContext).inflate(R.layout.dialog_normal,
				null);
		addContentView(view, Utils.getDialogLayoutParams(mContext));
	}

	public void setSureTitle(String title) {
		sureTitle = title;
	}

	public void setCancelTitle(String title) {
		cancelTitle = title;
	}

	public void setCancelVisible(boolean visible) {
		cancelVisible = visible;
	}

	public void setSureListener(View.OnClickListener listener) {
		if (listener != null) {
			sureListener = listener;
		}
	}

	public void setCancelListener(View.OnClickListener listener) {

	}

	/**
	 * 能否够返回
	 *
	 * @param canBack
	 */
	public void setCanBack(boolean canBack) {

	}
       //初始化
	private void initView() {
		lineView = view.findViewById(R.id.line_view);
		titleTv = (TextView) view.findViewById(R.id.title_tv);
		contentTv = (TextView) view.findViewById(R.id.content_tv);
		contentTv.setText((content.replace("\\r","\r").replace("\\n", "\n")));
		sureBtn = (Button) view.findViewById(R.id.sure_btn);
		cancelBtn = (Button) view.findViewById(R.id.cancel_btn);
	}

	@Override
	public void show() {
		initView();
		titleTv.setText(title);
		if (sureVisible) {
			if (sureListener == null) {
				sureBtn.setOnClickListener(this);
			} else {
				sureBtn.setOnClickListener(sureListener);
			}
			if (sureTitle != null) {
				sureBtn.setText(sureTitle);
			}
		} else {
			sureBtn.setVisibility(View.GONE);
		}
		if (cancelVisible) {

		} else {

		}
		super.show();
	}

	@Override
	public void onClick(View v) {
		if (v.getId() == sureBtn.getId()) {
			this.cancel();
		} else if (v.getId() == cancelBtn.getId()) {
			this.cancel();
		}
	}

}

使用。和适用都没问题，而且逻辑也比較简单，那么怎样优化呢？

言归正传：

建造者模式

1、定义：

将一个复杂的构建与其表示分离，使得同样的构建有了不同的表示。

2、目的：

建造者模式是讲复杂的内部构建封装在内部，对于其它外部成员来说，仅仅须要传递构建者和构建工具。便能够得到所需。不须要关心怎样构建，以及内部构建过程。

3、使用：

3.1、在构建的过程中，同意不同的构建过程。产生不同表示的构建对象；

3.2、在复杂的对象时，其复杂的构建算法应当独立于对象的组成部分，或者是独立于装配方式时；

4、一个简单的demo：

核心：抽象建造者，详细建造者，实体类

package com.example.demo.Builder;

import android.util.Log;
/**
 * 建造者模式
 * @author qubian
 * @data 2015年6月10日
 * @email naibbian@163.com
 *
 */
public class Product {

	Builder mBuilder ;
	public Builder getBuilder()
	{
		if (mBuilder==null) {
			mBuilder = new ProductBuilder();
		}
		return mBuilder;
	}

	/**
	 * 抽象建造者
	 * @author qubian
	 * @data 2015年6月10日
	 * @email naibbian@163.com
	 *
	 */
	public interface Builder
	{
		public Builder buildPart1();

		public Builder buildPart2();

		public Product getProduct();
	}
	/**
	 * 详细的建造者
	 * @author qubian
	 * @data 2015年6月10日
	 * @email naibbian@163.com
	 *
	 */
	public class ProductBuilder implements Builder
	{
		private static final String TAG= "ProductBuilder";
		Product mProduct = new Product();
		@Override
		public Builder buildPart1() {
			Log.i(TAG, "buildPart1");
			return this;

		}

		@Override
		public Builder buildPart2() {
			Log.i(TAG, "buildPart2");
			return this;

		}

		@Override
		public Product getProduct() {

			return mProduct;
		}

	}

}

使用：

package com.example.demo.Builder;

/**
 *  使用
 * @author qubian
 * @data 2015年6月10日
 * @email naibbian@163.com
 *
 */
public class UseProduct {

	public void use()
	{
		Product p = new Product().getBuilder().buildPart1().buildPart2().getProduct();
	}

}

5、在Android的源代码中。建造者模式。肯定是不可缺少的；

当中最为代表的就是AlertDialog,在其构建过程中，便是构建与表示分离。

其内部的Builder便是他的构建者。

public class AlertDialog extends Dialog implements DialogInterface {
    private AlertController mAlert;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mAlert.installContent();
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (mAlert.onKeyDown(keyCode, event)) return true;
        return super.onKeyDown(keyCode, event);
    }

    @Override
    public boolean onKeyUp(int keyCode, KeyEvent event) {
        if (mAlert.onKeyUp(keyCode, event)) return true;
        return super.onKeyUp(keyCode, event);
    }

    public static class Builder {
        private final AlertController.AlertParams P;
        private int mTheme;

        /**
         * Constructor using a context for this builder and the {@link AlertDialog} it creates.
         */
        public Builder(Context context) {
            this(context, resolveDialogTheme(context, 0));
        }

        /**
         * Set the title displayed in the {@link Dialog}.
         *
         * @return This Builder object to allow for chaining of calls to set methods
         */
        public Builder setTitle(CharSequence title) {
            P.mTitle = title;
            return this;
        }

        /**
         * Set the message to display using the given resource id.
         *
         * @return This Builder object to allow for chaining of calls to set methods
         */
        public Builder setMessage(int messageId) {
            P.mMessage = P.mContext.getText(messageId);
            return this;
        }

        /**
         * Set the message to display.
          *
         * @return This Builder object to allow for chaining of calls to set methods
         */
        public Builder setMessage(CharSequence message) {
            P.mMessage = message;
            return this;
        }

        /**
         * Set the resource id of the {@link Drawable} to be used in the title.
         *
         * @return This Builder object to allow for chaining of calls to set methods
         */
        public Builder setIcon(int iconId) {
            P.mIconId = iconId;
            return this;
        }

        /**
         * Set a listener to be invoked when the positive button of the dialog is pressed.
         * @param textId The resource id of the text to display in the positive button
         * @param listener The {@link DialogInterface.OnClickListener} to use.
         *
         * @return This Builder object to allow for chaining of calls to set methods
         */
        public Builder setPositiveButton(int textId, final OnClickListener listener) {
            P.mPositiveButtonText = P.mContext.getText(textId);
            P.mPositiveButtonListener = listener;
            return this;
        }

        /**
         * Set a listener to be invoked when the positive button of the dialog is pressed.
         * @param text The text to display in the positive button
         * @param listener The {@link DialogInterface.OnClickListener} to use.
         *
         * @return This Builder object to allow for chaining of calls to set methods
         */
        public Builder setPositiveButton(CharSequence text, final OnClickListener listener) {
            P.mPositiveButtonText = text;
            P.mPositiveButtonListener = listener;
            return this;
        }

        /**
         * Set a listener to be invoked when the negative button of the dialog is pressed.
         * @param textId The resource id of the text to display in the negative button
         * @param listener The {@link DialogInterface.OnClickListener} to use.
         *
         * @return This Builder object to allow for chaining of calls to set methods
         */
        public Builder setNegativeButton(int textId, final OnClickListener listener) {
            P.mNegativeButtonText = P.mContext.getText(textId);
            P.mNegativeButtonListener = listener;
            return this;
        }

        /**
         * Set a listener to be invoked when the negative button of the dialog is pressed.
         * @param text The text to display in the negative button
         * @param listener The {@link DialogInterface.OnClickListener} to use.
         *
         * @return This Builder object to allow for chaining of calls to set methods
         */
        public Builder setNegativeButton(CharSequence text, final OnClickListener listener) {
            P.mNegativeButtonText = text;
            P.mNegativeButtonListener = listener;
            return this;
        }

        /**
         * Set a listener to be invoked when the neutral button of the dialog is pressed.
         * @param textId The resource id of the text to display in the neutral button
         * @param listener The {@link DialogInterface.OnClickListener} to use.
         *
         * @return This Builder object to allow for chaining of calls to set methods
         */
        public Builder setNeutralButton(int textId, final OnClickListener listener) {
            P.mNeutralButtonText = P.mContext.getText(textId);
            P.mNeutralButtonListener = listener;
            return this;
        }
        /**
         * Set a custom view to be the contents of the Dialog. If the supplied view is an instance
         * of a {@link ListView} the light background will be used.
         *
         * @param view The view to use as the contents of the Dialog.
         *
         * @return This Builder object to allow for chaining of calls to set methods
         */
        public Builder setView(View view) {
            P.mView = view;
            P.mViewSpacingSpecified = false;
            return this;
        }

        /**
         * Creates a {@link AlertDialog} with the arguments supplied to this builder. It does not
         * {@link Dialog#show()} the dialog. This allows the user to do any extra processing
         * before displaying the dialog. Use {@link #show()} if you don't have any other processing
         * to do and want this to be created and displayed.
         */
        public AlertDialog create() {
            final AlertDialog dialog = new AlertDialog(P.mContext, mTheme, false);
            P.apply(dialog.mAlert);
            dialog.setCancelable(P.mCancelable);
            if (P.mCancelable) {
                dialog.setCanceledOnTouchOutside(true);
            }
            dialog.setOnCancelListener(P.mOnCancelListener);
            dialog.setOnDismissListener(P.mOnDismissListener);
            if (P.mOnKeyListener != null) {
                dialog.setOnKeyListener(P.mOnKeyListener);
            }
            return dialog;
        }

        /**
         * Creates a {@link AlertDialog} with the arguments supplied to this builder and
         * {@link Dialog#show()}'s the dialog.
         */
        public AlertDialog show() {
            AlertDialog dialog = create();
            dialog.show();
            return dialog;
        }
    }

}

也许它的开放性，AlterView也有自己的构建过程，这种使用AlterView建设者Builder要构建视图，他对象可以自行操作。