程序的主框架

michaelye1988

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OsChina Android客户端研究

通过对OsChina的Android客户端的代码分析，从里面抠出程序的主框架。下面是效果图：

这个框架和我想的不一样，它还是很不错的。因为它的页面可以通过左右滑动和底部按钮进行切换。这点很值得借鉴。如果通过Android提供的控件。能够支持左右滑动的，有ViewPager。但是ViewPager有一点不好，就是不能让它取消左右滑动。界面切换在3.0以后加入了Fragment，这也是Google推荐的做法，但是这也存在一个问题，Fragment不支持左右滑动切换界面。可以说鱼和熊掌不可得兼。那么今天我整理出的这个框架就能很好的解决这个问题。

下面简要分析下框架的布局：

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@color/white">
    
	<include layout="@layout/main_header" />   
    
    <net.oschina.app.widget.ScrollLayout   
	  android:id="@+id/main_scrolllayout"    
	  android:layout_width="fill_parent"    
	  android:layout_height="0dip"
   	  android:layout_weight="1">    
  
 	  <include layout="@layout/frame_news" />
      
	  <include layout="@layout/frame_question" />
	  
	  <include layout="@layout/frame_tweet" />
	      
	  <include layout="@layout/frame_active" />
       
	</net.oschina.app.widget.ScrollLayout> 
    
    <include layout="@layout/main_footer" />   

</LinearLayout>

从布局文件和上图就可以看出他的框架结构了。中间自定义了一个ScrollView，可以左右切换，并实时改变底部的按钮显示情况以及头部的显示内容切换。而底部的按钮被点击时也会触发界面切换的事件。

下面看代码：

public class Main extends Activity 
{
	
	private ScrollLayout mScrollLayout;	
	private RadioButton[] mButtons;
	private String[] mHeadTitles;
	private int mViewCount;
	private int mCurSel;//记录底部当前选中的按钮的索引
	
	/**
	 * Header
	 * */
	private ImageView mHeadLogo;
	private TextView mHeadTitle;
	private ProgressBar mHeadProgress;
	private ImageButton mHead_search;
	private ImageButton mHeadPub_post;
	private ImageButton mHeadPub_tweet;
	
	/**
	 * Footer
	 * */
	private RadioButton fbNews;
	private RadioButton fbQuestion;
	private RadioButton fbTweet;
	private RadioButton fbactive;
	private ImageView fbSetting;

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        initHeadView();
        initFootBar();
        initPageScroll();
    }

    /**
     * 初始化头部视图(最顶端)
     */
    private void initHeadView()
    {
    	mHeadLogo = (ImageView)findViewById(R.id.main_head_logo);
    	mHeadTitle = (TextView)findViewById(R.id.main_head_title);
    	mHeadProgress = (ProgressBar)findViewById(R.id.main_head_progress);
    	mHead_search = (ImageButton)findViewById(R.id.main_head_search);
    	mHeadPub_post = (ImageButton)findViewById(R.id.main_head_pub_post);
    	mHeadPub_tweet = (ImageButton)findViewById(R.id.main_head_pub_tweet);
    	
    	mHead_search.setOnClickListener(new View.OnClickListener() {
			public void onClick(View v) {
			}
		});
    	mHeadPub_post.setOnClickListener(new View.OnClickListener() {
			public void onClick(View v) {
			}
		});
    	mHeadPub_tweet.setOnClickListener(new View.OnClickListener() {
			public void onClick(View v) {
			}
		});
    }
    /**
     * 初始化底部栏
     * 
     */
    private void initFootBar()
    {
    	fbNews = (RadioButton)findViewById(R.id.main_footbar_news);
    	fbQuestion = (RadioButton)findViewById(R.id.main_footbar_question);
    	fbTweet = (RadioButton)findViewById(R.id.main_footbar_tweet);
    	fbactive = (RadioButton)findViewById(R.id.main_footbar_active);
    	fbSetting = (ImageView)findViewById(R.id.main_footbar_setting);
    }
    
    
    /**
     * 初始化水平滚动翻页
     * 
     * 并设置底部按钮的点击事件的监听
     * 
     */
    private void initPageScroll()
    {
    	mScrollLayout = (ScrollLayout) findViewById(R.id.main_scrolllayout);
    	
    	LinearLayout linearLayout = (LinearLayout) findViewById(R.id.main_linearlayout_footer);
    	mHeadTitles = getResources().getStringArray(R.array.head_titles);
    	mViewCount = mScrollLayout.getChildCount();
    	mButtons = new RadioButton[mViewCount];
    	
    	for(int i = 0; i < mViewCount; i++)
    	{
    		mButtons[i] = (RadioButton) linearLayout.getChildAt(i*2);
    		mButtons[i].setTag(i);
    		mButtons[i].setChecked(false);
    		mButtons[i].setOnClickListener(new View.OnClickListener() {
				public void onClick(View v) {
					int pos = (Integer)(v.getTag());
					//点击当前项刷新
	    			if(mCurSel == pos) {
		    			switch (pos) {
						case 0://资讯+博客
							break;	
						case 1://问答
							break;
						case 2://动弹
							break;
						case 3://动态+留言
							break;
						}
	    			}
					setCurPoint(pos);
					mScrollLayout.snapToScreen(pos);
				}
			});
    	}
    	
    	//设置第一显示屏
    	mCurSel = 0;
    	mButtons[mCurSel].setChecked(true);
    	
    	mScrollLayout.SetOnViewChangeListener(new ScrollLayout.OnViewChangeListener() {
			public void OnViewChange(int viewIndex) {
				//切换列表视图-如果列表数据为空：加载数据
				switch (viewIndex) {
				case 0://资讯
					break;	
				case 1://问答
					break;
				case 2://动弹
					break;
				case 3://动态
					break;
				}
				setCurPoint(viewIndex);
			}
		});
    }
    
    /**
     * 设置底部栏当前焦点
     * 并且改变头部的内容
     * @param index
     */
    private void setCurPoint(int index)
    {
    	if (index < 0 || index > mViewCount - 1 || mCurSel == index)
    		return;
   	
    	mButtons[mCurSel].setChecked(false);
    	mButtons[index].setChecked(true);    	
    	mHeadTitle.setText(mHeadTitles[index]);    	
    	mCurSel = index;
    	
    	mHead_search.setVisibility(View.GONE);
    	mHeadPub_post.setVisibility(View.GONE);
    	mHeadPub_tweet.setVisibility(View.GONE);
		//头部logo、发帖、发动弹按钮显示
    	if(index == 0){
    		mHeadLogo.setImageResource(R.drawable.frame_logo_news);
    		mHead_search.setVisibility(View.VISIBLE);
    	}
    	else if(index == 1){
    		mHeadLogo.setImageResource(R.drawable.frame_logo_post);
    		mHeadPub_post.setVisibility(View.VISIBLE);
    	}
    	else if(index == 2){
    		mHeadLogo.setImageResource(R.drawable.frame_logo_tweet);
    		mHeadPub_tweet.setVisibility(View.VISIBLE);
    	}
    	//处理通知信息
    	else if(index == 3){
    		mHeadLogo.setImageResource(R.drawable.frame_logo_active);
    		mHeadPub_tweet.setVisibility(View.VISIBLE);
		}
    }
    
}

代码很清晰，可以看出，主要就是初始化所有的控件，以及设置监听。

中间部分的自定义的ScrollLayout:

/**
 * 左右滑动切换屏幕控件
 * @author Yao.GUET date: 2011-05-04
 * @modify liux (http://my.oschina.net/liux)
 */
public class ScrollLayout extends ViewGroup {
	private static final String TAG = "ScrollLayout";
	private Scroller mScroller;
	private VelocityTracker mVelocityTracker;
	private int mCurScreen;
	private int mDefaultScreen = 0;
	private static final int TOUCH_STATE_REST = 0;
	private static final int TOUCH_STATE_SCROLLING = 1;
	private static final int SNAP_VELOCITY = 600;
	private int mTouchState = TOUCH_STATE_REST;
	private int mTouchSlop;
	private float mLastMotionX;
	private float mLastMotionY;
    private OnViewChangeListener mOnViewChangeListener;

    /**
     * 设置是否可左右滑动
     * @author liux
     */
    private boolean isScroll = true;
    public void setIsScroll(boolean b) {
    	this.isScroll = b;
    }
    
	public ScrollLayout(Context context, AttributeSet attrs) {
		this(context, attrs, 0);
	}

	public ScrollLayout(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		mScroller = new Scroller(context);
		mCurScreen = mDefaultScreen;
		mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
	}

	@Override
	protected void onLayout(boolean changed, int l, int t, int r, int b) {
		int childLeft = 0;
		final int childCount = getChildCount();
		for (int i = 0; i < childCount; i++) {
			final View childView = getChildAt(i);
			if (childView.getVisibility() != View.GONE) {
				final int childWidth = childView.getMeasuredWidth();
				childView.layout(childLeft, 0, childLeft + childWidth,
						childView.getMeasuredHeight());
				childLeft += childWidth;
			}
		}
	}

	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		//Log.e(TAG, "onMeasure");
		super.onMeasure(widthMeasureSpec, heightMeasureSpec);
		final int width = MeasureSpec.getSize(widthMeasureSpec);
		final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
		if (widthMode != MeasureSpec.EXACTLY) {
			throw new IllegalStateException(
					"ScrollLayout only canmCurScreen run at EXACTLY mode!");
		}
		final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
		if (heightMode != MeasureSpec.EXACTLY) {
			throw new IllegalStateException(
					"ScrollLayout only can run at EXACTLY mode!");
		}

		// The children are given the same width and height as the scrollLayout
		final int count = getChildCount();
		for (int i = 0; i < count; i++) {
			getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);
		}
		// Log.e(TAG, "moving to screen "+mCurScreen);
		scrollTo(mCurScreen * width, 0);
	}

	/**
	 * According to the position of current layout scroll to the destination
	 * page.
	 */
	public void snapToDestination() {
		final int screenWidth = getWidth();
		final int destScreen = (getScrollX() + screenWidth / 2) / screenWidth;
		snapToScreen(destScreen);
	}

	public void snapToScreen(int whichScreen) {
		//是否可滑动
		if(!isScroll) {
			this.setToScreen(whichScreen);
			return;
		}
		
		scrollToScreen(whichScreen);
	}

	public void scrollToScreen(int whichScreen) {		
		// get the valid layout page
		whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1));
		if (getScrollX() != (whichScreen * getWidth())) {
			final int delta = whichScreen * getWidth() - getScrollX();
			mScroller.startScroll(getScrollX(), 0, delta, 0,
					Math.abs(delta) * 1);//持续滚动时间 以毫秒为单位
			mCurScreen = whichScreen;
			invalidate(); // Redraw the layout
            
			if (mOnViewChangeListener != null)
            {
            	mOnViewChangeListener.OnViewChange(mCurScreen);
            }
		}
	}
	
	public void setToScreen(int whichScreen) {
		whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1));
		mCurScreen = whichScreen;
		scrollTo(whichScreen * getWidth(), 0);
		
        if (mOnViewChangeListener != null)
        {
        	mOnViewChangeListener.OnViewChange(mCurScreen);
        }
	}

	public int getCurScreen() {
		return mCurScreen;
	}

	@Override
	public void computeScroll() {
		if (mScroller.computeScrollOffset()) {
			scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
			postInvalidate();
		}
	}

	@Override
	public boolean onTouchEvent(MotionEvent event) {
		//是否可滑动
		if(!isScroll) {
			return false;
		}
		
		if (mVelocityTracker == null) {
			mVelocityTracker = VelocityTracker.obtain();
		}
		mVelocityTracker.addMovement(event);
		final int action = event.getAction();
		final float x = event.getX();
		final float y = event.getY();
		switch (action) {
		case MotionEvent.ACTION_DOWN:
			//Log.e(TAG, "event down!");
			if (!mScroller.isFinished()) {
				mScroller.abortAnimation();
			}
			mLastMotionX = x;
			
			//---------------New Code----------------------
			mLastMotionY = y;
			//---------------------------------------------
			
			break;
		case MotionEvent.ACTION_MOVE:
			int deltaX = (int) (mLastMotionX - x);
			
			//---------------New Code----------------------
			int deltaY = (int) (mLastMotionY - y);
			if(Math.abs(deltaX) < 200 && Math.abs(deltaY) > 10)
				break;
			mLastMotionY = y;
			//-------------------------------------
			
			mLastMotionX = x;
			scrollBy(deltaX, 0);
			break;
		case MotionEvent.ACTION_UP:
			//Log.e(TAG, "event : up");
			// if (mTouchState == TOUCH_STATE_SCROLLING) {
			final VelocityTracker velocityTracker = mVelocityTracker;
			velocityTracker.computeCurrentVelocity(1000);
			int velocityX = (int) velocityTracker.getXVelocity();
			//Log.e(TAG, "velocityX:" + velocityX);
			if (velocityX > SNAP_VELOCITY && mCurScreen > 0) {
				// Fling enough to move left
				//Log.e(TAG, "snap left");
				snapToScreen(mCurScreen - 1);
			} else if (velocityX < -SNAP_VELOCITY
					&& mCurScreen < getChildCount() - 1) {
				// Fling enough to move right
				//Log.e(TAG, "snap right");
				snapToScreen(mCurScreen + 1);
			} else {
				snapToDestination();
			}
			if (mVelocityTracker != null) {
				mVelocityTracker.recycle();
				mVelocityTracker = null;
			}
			// }
			mTouchState = TOUCH_STATE_REST;
			break;
		case MotionEvent.ACTION_CANCEL:
			mTouchState = TOUCH_STATE_REST;
			break;
		}
		return true;
	}

	@Override
	public boolean onInterceptTouchEvent(MotionEvent ev) {
		//Log.e(TAG, "onInterceptTouchEvent-slop:" + mTouchSlop);
		final int action = ev.getAction();
		if ((action == MotionEvent.ACTION_MOVE)
				&& (mTouchState != TOUCH_STATE_REST)) {
			return true;
		}
		final float x = ev.getX();
		final float y = ev.getY();
		switch (action) {
		case MotionEvent.ACTION_MOVE:
			final int xDiff = (int) Math.abs(mLastMotionX - x);
			if (xDiff > mTouchSlop) {
				mTouchState = TOUCH_STATE_SCROLLING;
			}
			break;
		case MotionEvent.ACTION_DOWN:
			mLastMotionX = x;
			mLastMotionY = y;
			mTouchState = mScroller.isFinished() ? TOUCH_STATE_REST
					: TOUCH_STATE_SCROLLING;
			break;
		case MotionEvent.ACTION_CANCEL:
		case MotionEvent.ACTION_UP:
			mTouchState = TOUCH_STATE_REST;
			break;
		}
		return mTouchState != TOUCH_STATE_REST;
	}
	
	/**
	 * 设置屏幕切换监听器
	 * @param listener
	 */
	public void SetOnViewChangeListener(OnViewChangeListener listener)
	{
		mOnViewChangeListener = listener;
	}

	/**
	 * 屏幕切换监听器
	 * @author liux
	 */
	public interface OnViewChangeListener {
		public void OnViewChange(int view);
	}
}

上面是主要的代码：

下面我将这个demo放到github上面，欢迎下载研究，并再次感谢OsChina：

https://github.com/michaelye/OsChinaMainLayout