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[1]android 类似网易首页的图片切换（viewPager）

1.activity调用
private View viewImage() {
LinearLayout.LayoutParams mParams = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.WRAP_CONTENT,
LinearLayout.LayoutParams.WRAP_CONTENT);
viewPager = null;
View view = getLayoutInflater().inflate(R.layout.news_lstview_header,
null);
viewPager = (ViewPager) view.findViewById(R.id.news_layout_viewPager);
viewPager.setLayoutParams(new ListView.LayoutParams(
ListView.LayoutParams.FILL_PARENT, 300));
List<View> list = new ArrayList<View>();
for (int i = 0; i < 3; i++) {
ImageView imgView = new ImageView(this);
imgView.setLayoutParams(mParams);
imgView.setImageResource(pics[i]);
list.add(imgView);
}
viewPager.setAdapter(new MyPagerAdapter(list));
viewPager.setCurrentItem(0);

return viewPager;
}
2.适配器
package com.and.netease.utils;

import java.util.List;

import android.os.Parcelable;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.View;

public class MyPagerAdapter extends PagerAdapter {

List<View> views;
public MyPagerAdapter(List<View> v) {
super();
    views = v;
}
@Override
public void destroyItem(View v, int pos, Object arg2) {
((ViewPager) v).removeView(views.get(pos));
}

@Override
public void finishUpdate(View arg0) {

}

@Override
public int getCount() {
if (views != null)
        {
            return views.size();
        }
       
        return 0;
}

@Override
public Object instantiateItem(View v, int pos) {
((ViewPager) v).addView(views.get(pos));
return views.get(pos);
}

@Override
public boolean isViewFromObject(View arg0, Object arg1) {
return arg0==arg1;
}

@Override
public void restoreState(Parcelable arg0, ClassLoader arg1) {

}

@Override
public Parcelable saveState() {
return null;
}

@Override
public void startUpdate(View arg0) {

}
}


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[2]android 实现下拉刷新

1.布局文件 listview
<com.and.netease.utils.MyListView
            android:id="@+id/lv_b" android:layout_width="fill_parent"
            android:layout_height="fill_parent" android:layout_marginRight="10dip"
            />
2.刷新的header 布局
<?xml version="1.0" encoding="utf-8"?>
<!-- ListView的头部 -->
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  android:background="#ffffff"
>
  <!-- 内容 -->
  <RelativeLayout
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  android:id="@+id/head_contentLayout"
  android:paddingLeft="30dp"
  >
  <!-- 箭头图像、进度条 -->
  <FrameLayout
  android:layout_width="18dip"
  android:layout_height="wrap_content"
  android:layout_alignParentLeft="true"
  android:layout_centerVertical="true"
  >
  <!-- 箭头 -->
  <ImageView
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:layout_gravity="center"
  android:src="/blog_article/@drawable/arrow_down/index.html"
  android:id="@+id/head_arrowImageView"
  />
  <!-- 进度条 -->
  <ProgressBar
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
 
  android:layout_gravity="center"
  android:id="@+id/head_progressBar"
  android:visibility="gone"
  />
  </FrameLayout>
  <!-- 提示、最近更新 -->
  <LinearLayout
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:layout_centerHorizontal="true"
  android:orientation="vertical"
  android:gravity="center_horizontal"
  >
  <!-- 提示 -->
  <TextView
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="下拉刷新"
  android:textSize="15dp"
  android:id="@+id/head_tipsTextView"
  />
  <!-- 最近更新 -->
  <TextView
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:id="@+id/head_lastUpdatedTextView"
  android:text="上次更新"
  android:textSize="12dp"
  />
  </LinearLayout>
  </RelativeLayout>
</LinearLayout>
3.核心代码
package com.and.netease.utils;

import java.text.SimpleDateFormat;
import java.util.Date;

import com.and.netease.R;

import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.LinearInterpolator;
import android.view.animation.RotateAnimation;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.ProgressBar;
import android.widget.TextView;


public class MyListView extends ListView implements OnScrollListener {
private static final String TAG = "listview";

    private final static int RELEASE_To_REFRESH = 0;
    private final static int PULL_To_REFRESH = 1;
    private final static int REFRESHING = 2;
    private final static int DONE = 3;
    private final static int LOADING = 4;

    // 实际的padding的距离与界面上偏移距离的比例
    private final static int RATIO = 3;
    private LayoutInflater inflater;
    private LinearLayout headView;

    private TextView tipsTextview;
    private TextView lastUpdatedTextView;
    private ImageView arrowImageView;
    private ProgressBar progressBar;

    private RotateAnimation animation;
    private RotateAnimation reverseAnimation;

    // 用于保证startY的值在一个完整的touch事件中只被记录一次
    private boolean isRecored;

    private int headContentWidth;
    private int headContentHeight;

    private int startY;
    private int firstItemIndex;

    private int state;
    private boolean isBack;
    private OnRefreshListener refreshListener;
    private boolean isRefreshable;

    public MyListView(Context context) {
        super(context);
        init(context);
    }
    public MyListView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context);
    }
    private void init(Context context) {
    System.out.println("scroll");
        //setCacheColorHint(context.getResources().getColor(R.color.transparent));
        inflater = LayoutInflater.from(context);
        headView = (LinearLayout) inflater.inflate(R.layout.head, null);
        arrowImageView = (ImageView) headView.findViewById(R.id.head_arrowImageView);
        arrowImageView.setMinimumWidth(70);
        arrowImageView.setMinimumHeight(50);
        progressBar = (ProgressBar) headView.findViewById(R.id.head_progressBar);
        tipsTextview = (TextView) headView.findViewById(R.id.head_tipsTextView);
        lastUpdatedTextView = (TextView) headView.findViewById(R.id.head_lastUpdatedTextView);

        measureView(headView);
        headContentHeight = headView.getMeasuredHeight();
        headContentWidth = headView.getMeasuredWidth();

        headView.setPadding(0, -1 * headContentHeight, 0, 0);
        headView.invalidate();

        Log.v("size", "width:" + headContentWidth + " height:"+ headContentHeight);

        addHeaderView(headView, null, false);
        setOnScrollListener(this);

        animation = new RotateAnimation(0, -180,RotateAnimation.RELATIVE_TO_SELF, 0.5f,
                RotateAnimation.RELATIVE_TO_SELF, 0.5f);
        animation.setInterpolator(new LinearInterpolator());
        animation.setDuration(250);
        animation.setFillAfter(true);

        reverseAnimation = new RotateAnimation(-180, 0,
                RotateAnimation.RELATIVE_TO_SELF, 0.5f,
                RotateAnimation.RELATIVE_TO_SELF, 0.5f);
        reverseAnimation.setInterpolator(new LinearInterpolator());
        reverseAnimation.setDuration(200);
        reverseAnimation.setFillAfter(true);

        state = DONE;
        isRefreshable = false;
    }

    public void onScroll(AbsListView arg0, int firstVisiableItem, int arg2,
            int arg3) {

[3]设计模式-命令模式

命令(Command)模式属于对象的行为模式，把一个请求或者操作封装到一个对象中，允许系统使用不同的请求把客户端参数化，对请求排队或者记录到请求日志，可以提供命令的撤销和恢复功能。命令模式是对命令的封装，把发出的命令的责任和执行命令的责任分开，委派给不同的对象。

设计角色：

         客户(Client)角色：创建一个具体命令对象并确定接收者。

         命令(Command)角色：声明一个给所有具体命令的抽象接口。

         具体命令(ConcreteCommand)角色：定义一个接受者和行为之间的弱耦合；实现execute()方法，负责调用接受者的相应操作。execute方法通常叫做执行方法。

         请求者(Invoker)角色：负责调用命令对象执行请求，相关方法叫做行动方法。

         接收者(Reveiver)角色：负责具体实施和执行一个请求。任何一个类都可以成为接收者，实施和执行请求的方法叫做行动方法。

例子：

package cn.design.pattern.demo.command.client;

import cn.design.pattern.demo.command.command.Command;
import cn.design.pattern.demo.command.command.PlayCommand;
import cn.design.pattern.demo.command.command.RewindCommand;
import cn.design.pattern.demo.command.command.StopCommand;
import cn.design.pattern.demo.command.invoker.Keypad;
import cn.design.pattern.demo.command.reviever.AudioPlayer;

/**
 * 客户端：创建命令和确定接收者
 */
public class Client {

	private static Keypad keypad;
	private static AudioPlayer player = new AudioPlayer();		// 接收者
	
	public static void main(String[] args) {
		test1(); test2();
	}
	
	private static void test1() {
		// 创建三个命令并将接收者传入
		Command play = new PlayCommand(player);
		Command stop = new StopCommand(player);
		Command rewind = new RewindCommand(player);
		
		keypad = new Keypad(play, rewind, stop);
		keypad.play(); keypad.stop(); keypad.rewind();
	}
	
	private static void test2() {
		
		Command play = new Command() {
			@Override
			public void execute() {
				player.play();
			}
		};
		Command rewind = new Command() {
			@Override
			public void execute() {
				player.rewind();
			}
		};
		Command stop = new Command() {
			@Override
			public void execute() {
				player.stop();
			}
		};
		
		keypad = new Keypad(play, rewind, stop);
		keypad.play(); keypad.stop(); keypad.rewind();
	}
}

package cn.design.pattern.demo.command.command;

/**
 * 抽象命令角色
 */
public interface Command {

	/**
	 * 执行方法
	 */
	public void execute();
}

package cn.design.pattern.demo.command.command;

import cn.design.pattern.demo.command.reviever.AudioPlayer;

/**
 * 具体命令角色
 * 定义一个接受者和行为之间的弱耦合
 */
public class PlayCommand implements Command {

	private AudioPlayer audioPlayer;	// 接收者
	
	public PlayCommand(AudioPlayer audioPlayer) {
		this.audioPlayer = audioPlayer;
	}
	
	/**
	 * 执行方法
	 */
	@Override
	public void execute() {
		// 调用接收者相应方法，执行命令
		audioPlayer.play();
	}

}

package cn.design.pattern.demo.command.command;

import cn.design.pattern.demo.command.reviever.AudioPlayer;

/**
 * 具体命令角色
 */
public class RewindCommand implements Command {
	
	private AudioPlayer audioPlayer;
	
	public RewindCommand(AudioPlayer audioPlayer) {
		this.audioPlayer = audioPlayer;
	}

	@Override
	public void execute() {
		audioPlayer.rewind();
	}

}

package cn.design.pattern.demo.command.command;

import cn.design.pattern.demo.command.reviever.AudioPlayer;

/**
 * 具体命令角色
 */
public class StopCommand implements Command {

	private AudioPlayer audioPlayer;
	
	public StopCommand(AudioPlayer audioPlayer) {
		this.audioPlayer = audioPlayer;
	}
	
	@Override
	public void execute() {
		audioPlayer.stop();
	}

}

package cn.design.pattern.demo.command.invoker;

import cn.design.pattern.demo.command.command.Command;

/**
 * 请求者角色
 * 负责调用命令对象执行请求
 */
public class Keypad {

	private Command playCmd;		// 命令对象
	private Command rewindCmd;
	private Command stopCmd;

	public Keypad(Command play, Command rewind, Command stop) {
		this.playCmd = play;
		this.rewindCmd = rewind;
		this.stopCmd = stop;
	}

	/**
	 * 行动方法
	 */
	public void play() {
		// 执行命令请求
		playCmd.execute();
	}

	public void rewind() {
		rewindCmd.execute();
	}

	public void stop() {
		stopCmd.execute();
	}
}

package cn.design.pattern.demo.command.reviever;

/**
 * 接收者角色
 */
public class AudioPlayer {

	public void play() {
		System.out.println("播放");
	}
	
	public void rewind() {
		System.out.println("倒带");
	}
	
	public void stop() {
		System.out.println("停止");
	}
}

 特点：

        1.新的命令很容易地被加入到系统里.

        2.允许接受请求的一方决定是否要否决请求.

        3.可以方便地设置一个命令队列.

        4.实现对请求的Undo和Redo.

        5.比较容易地将命令计入日志.

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