完成顶部标题栏和ViewPager的功能
来源：互联网 发布：大屏幕切换软件 编辑：程序博客网 时间：2024/06/05 00:27
我们顶部的标题栏用的是一个PagerTab的类来做的代码如下
public class PagerTab extends ViewGroup { private ViewPager mViewPager; private PageListener mPageListener = new PageListener();//用于注册给ViewPager监听状态和滚动 private OnPageChangeListener mDelegatePageListener;//用于通知外界ViewPager的状态和滚动 private BaseActivity mActivity; private int mDividerPadding = 12;// 分割线上下的padding private int mDividerWidth = 1;// 分割线的宽度 private int mDividerColor = 0x1A000000;//分割线颜色 private Paint mDividerPaint;//分割线的画笔 private int mIndicatorHeight = 4;//指示器的高度 private int mIndicatorWidth;//指示器的宽度，是动态的随着tab的宽度变化 private int mIndicatorLeft;//指示器的距离左边的距离 private int mIndicatorColor = 0xFF0084FF;//指示器颜色 private Paint mIndicatorPaint; //指示器的画笔 private int mContentWidth;//记录自身内容的宽度 private int mContentHeight;//记录自身内容的高度 private int mTabPadding = 24;// tab左右的内边距 private int mTabTextSize = 16; //tab文字大小 private int mTabBackgroundResId = R.drawable.bg_tab_text;// tab背景资源 private int mTabTextColorResId = R.color.bg_text_color; //tab文字颜色 private int mTabCount;//tab的个数 private int mCurrentPosition = 0;//当前光标所处的tab，规则是以光标的最左端所在的item的position private float mCurrentOffsetPixels;//光标左边距离当前光标所处的tab的左边距离 private int mSelectedPosition = 0; //当前被选中的tab，用于记录手指点击tab的position private boolean mIsBeingDragged = false;//是否处于拖动中 private float mLastMotionX;//上一次手指触摸的x坐标 private VelocityTracker mVelocityTracker;//用于记录速度的帮助类 private int mMinimumVelocity;//系统默认的最小满足fling的速度 private int mMaximumVelocity;//系统默认最大的fling速度 private int mTouchSlop;//系统默认满足滑动的最小位移 private ScrollerCompat mScroller;//处理滚动的帮助者 private int mLastScrollX;//记录上一次滚动的x位置，这是用于处理overScroll，实际位置可能会受到限制 private int mMaxScrollX = 0;// 控件最大可滚动的距离 private int mSplitScrollX = 0;// 根据item的个数，计算出每移动一个item控件需要移动的距离 private EdgeEffectCompat mLeftEdge;//处理overScroll的反馈效果 private EdgeEffectCompat mRightEdge; public PagerTab(Context context) { this(context, null); } public PagerTab(Context context, AttributeSet attrs) { this(context, attrs, 0); } public PagerTab(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); if (context instanceof BaseActivity) { mActivity = (BaseActivity) context; } init(); initPaint(); } /** 初始化一些常量 */ private void init() { //把一个值从dip转换成px mIndicatorHeight = UIUtils.dip2px(mIndicatorHeight); mDividerPadding = UIUtils.dip2px(mDividerPadding); mTabPadding = UIUtils.dip2px(mTabPadding); mDividerWidth = UIUtils.dip2px(mDividerWidth); mTabTextSize = UIUtils.dip2px(mTabTextSize); //创建一个scroller mScroller = ScrollerCompat.create(mActivity); //获取一个系统关于View的常量配置类 final ViewConfiguration configuration = ViewConfiguration.get(mActivity); //获取滑动的最小距离 mTouchSlop = configuration.getScaledTouchSlop(); //获取fling的最小速度 mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); //获取fling的最大速度 mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); mLeftEdge = new EdgeEffectCompat(mActivity); mRightEdge = new EdgeEffectCompat(mActivity); } /** 初始化笔 */ private void initPaint() { mIndicatorPaint = new Paint(); mIndicatorPaint.setAntiAlias(true); mIndicatorPaint.setStyle(Paint.Style.FILL); mIndicatorPaint.setColor(mIndicatorColor); mDividerPaint = new Paint(); mDividerPaint.setAntiAlias(true); mDividerPaint.setStrokeWidth(mDividerWidth); mDividerPaint.setColor(mDividerColor); } /** 设置ViewPager */ public void setViewPager(ViewPager viewPager) { if (viewPager == null || viewPager.getAdapter() == null) { throw new IllegalStateException("ViewPager is null or ViewPager does not have adapter instance."); } mViewPager = viewPager; onViewPagerChanged(); } private void onViewPagerChanged() { mViewPager.setOnPageChangeListener(mPageListener);//给ViewPager设置监听 mTabCount = mViewPager.getAdapter().getCount();//有多少个tab需要看ViewPager有多少个页面 for (int i = 0; i < mTabCount; i++) { if (mViewPager.getAdapter() instanceof IconTabProvider) {//如果想要使用icon作为tab，则需要adapter实现IconTabProvider接口 addIconTab(i, ((IconTabProvider) mViewPager.getAdapter()).getPageIconResId(i)); } else { addTextTab(i, mViewPager.getAdapter().getPageTitle(i).toString()); } } ViewTreeObserver viewTreeObserver = getViewTreeObserver(); if (viewTreeObserver != null) {//监听第一个的全局layout事件，来设置当前的mCurrentPosition，显示对应的tab viewTreeObserver.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() { @Override public void onGlobalLayout() { getViewTreeObserver().removeGlobalOnLayoutListener(this);//只需要监听一次，之后通过listener回调即可 mCurrentPosition = mViewPager.getCurrentItem(); if (mDelegatePageListener != null) { mDelegatePageListener.onPageSelected(mCurrentPosition); } } }); } } /** 设置监听，因为Tab会监听ViewPager的状态，所以不要给ViewPager设置监听了，设置给Tab，由Tab转发 */ public void setOnPageChangeListener(OnPageChangeListener listener) { mDelegatePageListener = listener; } /** 添加文字tab */ private void addTextTab(final int position, String title) { TextView tab = new TextView(mActivity); tab.setText(title); tab.setGravity(Gravity.CENTER); tab.setSingleLine(); tab.setTextSize(TypedValue.COMPLEX_UNIT_PX, mTabTextSize); tab.setTypeface(Typeface.defaultFromStyle(Typeface.BOLD)); tab.setTextColor(UIUtils.getColorStateList(mTabTextColorResId)); tab.setBackgroundDrawable(UIUtils.getDrawable(mTabBackgroundResId)); tab.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.MATCH_PARENT)); addTab(position, tab); } /** 添加图片icon */ private void addIconTab(final int position, int resId) { ImageButton tab = new ImageButton(mActivity); tab.setImageResource(resId); tab.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT)); addTab(position, tab); } private void addTab(final int position, View tab) { tab.setFocusable(true); //设置tab的点击事件，当tab被点击时候切换pager的页面 tab.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { mViewPager.setCurrentItem(position); } }); tab.setPadding(mTabPadding, 0, mTabPadding, 0); addView(tab, position); } /** 测量时的回调 */ @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { // 获取控件自身的宽高,模式 int widthSize = MeasureSpec.getSize(widthMeasureSpec) - getPaddingLeft() - getPaddingRight(); int heightSize = MeasureSpec.getSize(heightMeasureSpec) - getPaddingBottom() - getPaddingBottom(); int widthMode = MeasureSpec.getMode(widthMeasureSpec); int heightMode = MeasureSpec.getMode(heightMeasureSpec); int totalWidth = 0; int highest = 0; int goneChildCount = 0; for (int i = 0; i < mTabCount; i++) { final View child = getChildAt(i); if (child == null || child.getVisibility() == View.GONE) { goneChildCount--; continue; } int childWidthMeasureSpec; int childHeightMeasureSpec; LayoutParams childLayoutParams = child.getLayoutParams(); if (childLayoutParams == null) { childLayoutParams = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT); } if (childLayoutParams.width == LayoutParams.MATCH_PARENT) { childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(widthSize, MeasureSpec.EXACTLY); } else if (childLayoutParams.width == LayoutParams.WRAP_CONTENT) { childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(widthSize, MeasureSpec.AT_MOST); } else { childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(childLayoutParams.width, MeasureSpec.EXACTLY); } if (childLayoutParams.height == LayoutParams.MATCH_PARENT) { childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(heightSize, MeasureSpec.EXACTLY); } else if (childLayoutParams.height == LayoutParams.WRAP_CONTENT) { childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(heightSize, MeasureSpec.AT_MOST); } else { childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(childLayoutParams.height, MeasureSpec.EXACTLY); } child.measure(childWidthMeasureSpec, childHeightMeasureSpec); int childWidth = child.getMeasuredWidth(); int childHeight = child.getMeasuredHeight(); totalWidth += childWidth; highest = highest < childHeight ? childHeight : highest; } if (totalWidth <= widthSize) {//如果子Tab的总宽度小于PagerTab，则采用平分模式 int splitWidth = (int) (widthSize / (mTabCount - goneChildCount + 0.0f) + 0.5f); for (int i = 0; i < mTabCount; i++) { final View child = getChildAt(i); if (child == null || child.getVisibility() == View.GONE) { continue; } int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(splitWidth, MeasureSpec.EXACTLY); int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(child.getMeasuredHeight(), MeasureSpec.EXACTLY); child.measure(childWidthMeasureSpec, childHeightMeasureSpec); } mMaxScrollX = 0; mSplitScrollX = 0; } else {//如果所有子View大于控件的宽度 mMaxScrollX = totalWidth - widthSize; mSplitScrollX = (int) (mMaxScrollX / (mTabCount - goneChildCount - 1.0f) + 0.5f); } if (widthMode == MeasureSpec.EXACTLY) { mContentWidth = widthSize; } else { mContentWidth = totalWidth; } if (heightMode == MeasureSpec.EXACTLY) { mContentHeight = heightSize; } else { mContentHeight = highest; } int measureWidth = mContentWidth + getPaddingLeft() + getPaddingRight(); int measureHeight = mContentHeight + getPaddingTop() + getPaddingBottom(); setMeasuredDimension(measureWidth, measureHeight); } /** 布局时的回调 */ @Override protected void onLayout(boolean changed, int l, int t, int r, int b) {//这里简化了，没有考虑margin的情况 if (changed) { int height = b - t;//控件供子View显示的高度 int left = l; for (int i = 0; i < mTabCount; i++) { final View child = getChildAt(i); if (child == null || child.getVisibility() == View.GONE) { continue; } int top = (int) ((height - child.getMeasuredHeight()) / 2.0f + 0.5f);//如果控件比tab要高，则居中显示 int right = left + child.getMeasuredWidth(); child.layout(left, top, right, top + child.getMeasuredHeight());//摆放tab left = right;//因为是水平摆放的，所以为下一个准备left值 } } } /** 绘制时的回调 */ @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); final int height = getHeight(); //画指示器 canvas.drawRect(mIndicatorLeft, height - mIndicatorHeight, mIndicatorLeft + mIndicatorWidth, height, mIndicatorPaint); // 画分割线 for (int i = 0; i < mTabCount - 1; i++) {//分割线的个数比tab的个数少一个 final View child = getChildAt(i); if (child == null || child.getVisibility() == View.GONE) { continue; } if (child != null) { canvas.drawLine(child.getRight(), mDividerPadding, child.getRight(), mContentHeight - mDividerPadding, mDividerPaint); } } // 因为overScroll效果是一个持续效果，所以需要持续画 boolean needsInvalidate = false; if (!mLeftEdge.isFinished()) {//如果效果没停止 final int restoreCount = canvas.save();//先保存当前画布 final int heightEdge = getHeight() - getPaddingTop() - getPaddingBottom(); final int widthEdge = getWidth(); canvas.rotate(270); canvas.translate(-heightEdge + getPaddingTop(), 0); mLeftEdge.setSize(heightEdge, widthEdge); needsInvalidate |= mLeftEdge.draw(canvas); canvas.restoreToCount(restoreCount); } if (!mRightEdge.isFinished()) { final int restoreCount = canvas.save(); final int widthEdge = getWidth(); final int heightEdge = getHeight() - getPaddingTop() - getPaddingBottom(); canvas.rotate(90); canvas.translate(-getPaddingTop(), -(widthEdge + mMaxScrollX)); mRightEdge.setSize(heightEdge, widthEdge); needsInvalidate |= mRightEdge.draw(canvas); canvas.restoreToCount(restoreCount); } if (needsInvalidate) { postInvalidate(); } } /** 触摸事件是否拦截的方法 */ @Override public boolean onInterceptTouchEvent(MotionEvent ev) { final int action = ev.getAction(); if (mIsBeingDragged && action == MotionEvent.ACTION_MOVE) {//当已经处于拖动，并且当前事件是MOVE，直接消费掉 return true; } switch (action) { case MotionEvent.ACTION_DOWN: { final float x = ev.getX(); mLastMotionX = x; //记录住当前的x坐标 mIsBeingDragged = !mScroller.isFinished();//如果按下的时候还在滚动，则把状态处于拖动状态 break; } case MotionEvent.ACTION_MOVE: { final float x = ev.getX(); final int xDiff = (int) Math.abs(x - mLastMotionX);//计算两次的差值 if (xDiff > mTouchSlop) {//如果大于最小移动的距离，则把状态改变为拖动状态 mIsBeingDragged = true; mLastMotionX = x; ViewParent parent = getParent();//并请求父View不要再拦截自己触摸事件，交给自己处理 if (parent != null) { parent.requestDisallowInterceptTouchEvent(true); } } break; } case MotionEvent.ACTION_CANCEL://当手指离开或者触摸事件取消的时候，把拖动状态取消掉 case MotionEvent.ACTION_UP: mIsBeingDragged = false; break; } return mIsBeingDragged;//如果是拖动状态，则拦截事件，交给自己的onTouch处理 } /** 触摸事件的处理方法 */ public boolean onTouchEvent(MotionEvent ev) { if (mVelocityTracker == null) { mVelocityTracker = VelocityTracker.obtain(); } mVelocityTracker.addMovement(ev); final int action = ev.getAction(); switch (action) { case MotionEvent.ACTION_DOWN: {//如果是down事件，记录住当前的x坐标 final float x = ev.getX(); if (!mScroller.isFinished()) { mScroller.abortAnimation(); } mLastMotionX = x; break; } case MotionEvent.ACTION_MOVE: { final float x = ev.getX(); final float deltaX = x - mLastMotionX; if (!mIsBeingDragged) {//如果还没有处于拖动，则判断两次的差值是否大于最小拖动的距离 if (Math.abs(deltaX) > mTouchSlop) { mIsBeingDragged = true; } } if (mIsBeingDragged) {//如果处于拖动状态，记录住x坐标 mLastMotionX = x; onMove(deltaX); } break; } case MotionEvent.ACTION_UP: { if (mIsBeingDragged) { final VelocityTracker velocityTracker = mVelocityTracker; //先对速度进行一个调整，第一个参数是时间单位，1000毫秒，第二个参数是最大速度。 velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); float velocity = velocityTracker.getXVelocity();//获取水平方向上的速度 onUp(velocity); } } case MotionEvent.ACTION_CANCEL: { mIsBeingDragged = false; if (mVelocityTracker != null) { mVelocityTracker.recycle(); mVelocityTracker = null; } break; } } return true; } private void onMove(float x) { if (mMaxScrollX <= 0) { if (mViewPager.isFakeDragging() || mViewPager.beginFakeDrag()) { mViewPager.fakeDragBy(x); } } else { int scrollByX = -(int) (x + 0.5); if (getScrollX() + scrollByX < 0) { scrollByX = 0 - getScrollX(); mLeftEdge.onPull(Math.abs(x) / getWidth()); } if (getScrollX() + scrollByX > mMaxScrollX) { scrollByX = mMaxScrollX - getScrollX(); mRightEdge.onPull(Math.abs(x) / getWidth()); } scrollBy(scrollByX, 0); ViewCompat.postInvalidateOnAnimation(this); } } private void onUp(float velocity) { if (mMaxScrollX <= 0) { if (mViewPager.isFakeDragging()) mViewPager.endFakeDrag(); } else { if (Math.abs(velocity) <= mMinimumVelocity) { return; } mScroller.fling(getScrollX(), 0, -(int) (velocity + 0.5), 0, 0, mMaxScrollX, 0, 0, 270, 0); ViewCompat.postInvalidateOnAnimation(this); } } @Override public void computeScroll() { if (mScroller.computeScrollOffset()) { int oldX = mLastScrollX; mLastScrollX = mScroller.getCurrX(); if (mLastScrollX < 0 && oldX >= 0) { mLeftEdge.onAbsorb((int) mScroller.getCurrVelocity()); } else if (mLastScrollX > mMaxScrollX && oldX <= mMaxScrollX) { mRightEdge.onAbsorb((int) mScroller.getCurrVelocity()); } int x = mLastScrollX; if (mLastScrollX < 0) { x = 0; } else if (mLastScrollX > mMaxScrollX) { x = mMaxScrollX; } scrollTo(x, 0); } ViewCompat.postInvalidateOnAnimation(this); } /** 检测mIndicatorOffset的合法性，并计算出其他有关tab的属性值 */ private void checkAndcalculate() { // 如果指示器起始位置比第一个tab的起始位置还要小，纠正为第一个tab的起始位置，指示器宽度就是第一个tab的宽度 final View firstTab = getChildAt(0); if (mIndicatorLeft < firstTab.getLeft()) { mIndicatorLeft = firstTab.getLeft(); mIndicatorWidth = firstTab.getWidth(); } // 如果指示器起始位置比最后一个tab的起始位置还要大，纠正为最后一个tab的起始位置，指示器宽度就是最后一个tab的宽度 View lastTab = getChildAt(mTabCount - 1); if (mIndicatorLeft > lastTab.getLeft()) { mIndicatorLeft = lastTab.getLeft(); mIndicatorWidth = lastTab.getWidth(); } // 通过指示器的起始位置计算出当前处于第几个position，并且计算出已经偏移了多少，偏移量是以当前所处的tab的宽度的百分比 for (int i = 0; i < mTabCount; i++) { View tab = getChildAt(i); if (mIndicatorLeft < tab.getLeft()) { mCurrentPosition = i - 1; View currentTab = getChildAt(mCurrentPosition); mCurrentOffsetPixels = (mIndicatorLeft - currentTab.getLeft()) / (currentTab.getWidth() + 0.0f); break; } } } /** 滚动到指定的child */ public void scrollSelf(int position, float offset) { if (position >= mTabCount) { return; } final View tab = getChildAt(position); mIndicatorLeft = (int) (tab.getLeft() + tab.getWidth() * offset + 0.5); int rightPosition = position + 1; if (offset > 0 && rightPosition < mTabCount) { View rightTab = getChildAt(rightPosition); mIndicatorWidth = (int) (tab.getWidth() * (1 - offset) + rightTab.getWidth() * offset + 0.5); } else { mIndicatorWidth = tab.getWidth(); } checkAndcalculate(); int newScrollX = position * mSplitScrollX + (int) (offset * mSplitScrollX + 0.5); if (newScrollX < 0) { newScrollX = 0; } if (newScrollX > mMaxScrollX) { newScrollX = mMaxScrollX; } //scrollTo(newScrollX, 0);//滑动 int duration = 100; if (mSelectedPosition != -1) { duration = (Math.abs(mSelectedPosition - position)) * 100; } mScroller.startScroll(getScrollX(), 0, (newScrollX - getScrollX()), 0, duration); ViewCompat.postInvalidateOnAnimation(this); } /** 选中指定位置的Tab */ private void selectTab(int position) { for (int i = 0; i < mTabCount; i++) { View tab = getChildAt(i); if (tab != null) { tab.setSelected(position == i); } } } /** ViewPager的OnPageChangeListener实现类，因为我们需要在PagerTab中获取PagerView的监听，以便可以调整tab */ private class PageListener implements OnPageChangeListener { @Override public void onPageScrolled(int position, float positionOffset, final int positionOffsetPixels) { //根据VierPager的偏移值来滚动tab scrollSelf(position, positionOffset); if (mDelegatePageListener != null) {//这个是提供给外部的 mDelegatePageListener.onPageScrolled(position, positionOffset, positionOffsetPixels); } } @Override public void onPageScrollStateChanged(int state) { if (state == ViewPager.SCROLL_STATE_IDLE) { mSelectedPosition = -1; } if (mDelegatePageListener != null) { mDelegatePageListener.onPageScrollStateChanged(state); } } @Override public void onPageSelected(int position) { System.out.println("onPageSelected:" + position); mSelectedPosition = position; selectTab(position); if (mDelegatePageListener != null) { mDelegatePageListener.onPageSelected(position); } } } /** 如果指示器希望是图片，则继承该接口 */ public interface IconTabProvider { public int getPageIconResId(int position); public int getPageSelectedIconResId(); }}在ViewPager中载入我们的fragment
public class MainActivity extends BaseActivity { private PagerTab mPagerTab; private ViewPager mViewPager; private MyAdapter mAdapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mPagerTab = (PagerTab) findViewById(R.id.pager_tab); mViewPager = (ViewPager) findViewById(R.id.viewpager); mAdapter = new MyAdapter(getSupportFragmentManager());//得到一个fragment传进去Activity要继承FragmentActivity mViewPager.setAdapter(mAdapter); mPagerTab.setViewPager(mViewPager);//将指针和viewpager绑定在一起 mPagerTab.setOnPageChangeListener(new ViewPager.OnPageChangeListener() { @Override public void onPageSelected(int position) { BaseFragment fragment = FragmentFactory.createFragment(position); //开始加载数据 fragment.loadData(); } @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { } @Override public void onPageScrollStateChanged(int state) { } }); } class MyAdapter extends FragmentPagerAdapter{ private String[] mTabNames; public MyAdapter(FragmentManager fm) { super(fm); mTabNames = UIUtils.getStringArray(R.array.tab_names);//加载页面标题数组 } @Override public CharSequence getPageTitle(int position) { return mTabNames[position]; } //返回当前页面位置的fragment对象 @Override public Fragment getItem(int position) { BaseFragment fragment = FragmentFactory.createFragment(position); return fragment; } //fragment数量 @Override public int getCount() { return mTabNames.length; } }}我们的Fragment是通过一个工厂类来进行生产的
/** * 生产fragment工厂 * Created by matri on 2017/5/11. */public class FragmentFactory { private static HashMap<Integer,BaseFragment> mFragmentMap = new HashMap<Integer,BaseFragment>(); public static BaseFragment createFragment(int pos){ //先从集合中取，如果没有，才创建对象，提高性能 BaseFragment fragment = mFragmentMap.get(pos); if(fragment == null) { switch (pos) { case 0: fragment = new HomeFragment(); break; case 1: fragment = new AppFragment(); break; case 2: fragment = new GameFragment(); break; case 3: fragment = new SubjectFragment(); break; case 4: fragment = new RecommendFragment(); break; case 5: fragment = new CategoryFragment(); break; case 6: fragment = new HotFragment(); break; default: break; } mFragmentMap.put(pos, fragment);//将fragment保存在集合中 } return fragment; }}这些Fragment都继承了BaseFragment
public abstract class BaseFragment extends Fragment{ @Nullable private LoadingPage mLoadingPage; @Override public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) { //使用textview显示当前类的类名// TextView view = new TextView(UIUtils.getContext());// view.setText(getClass().getSimpleName()); mLoadingPage = new LoadingPage(UIUtils.getContext()){ @Override public View onCreateSuccessView() { //注意：此处一定要调用BaseFragment的onCreateView，否则栈溢出 return BaseFragment.this.onCreateSuccessView(); } @Override public ResultState onLoad() { return BaseFragment.this.onLoad(); } }; return mLoadingPage; } //加载成功的布局，必须由子类来实现 public abstract View onCreateSuccessView(); //加载网络数据必须由子类实现 public abstract LoadingPage.ResultState onLoad(); //开始加载数据 public void loadData(){ if(mLoadingPage != null){ mLoadingPage.loadData(); } }}
虽然看上去各个Fragment的展示页面是不同的但其实细分还有这么几种状态：
-未加载 -加载中 -加载失败 -数据为空 -加载成功
所以我们可以写一个LoadingPage类来根据不同的情况展现不同的页面
有两个抽象方法需要我们注意它需要子类来实现，这样才能在数据请求成功后回调这些方法展示我们想要看到的页面
/** * 根据当前状态来显示不同页面的自定义控件 * * - 未加载 - 加载中 - 加载失败 - 数据为空 - 加载成功 * * @author Kevin * @date 2015-10-27 */public abstract class LoadingPage extends FrameLayout { private static final int STATE_LOAD_UNDO = 1;// 未加载 private static final int STATE_LOAD_LOADING = 2;// 正在加载 private static final int STATE_LOAD_ERROR = 3;// 加载失败 private static final int STATE_LOAD_EMPTY = 4;// 数据为空 private static final int STATE_LOAD_SUCCESS = 5;// 加载成功 private int mCurrentState = STATE_LOAD_UNDO;// 当前状态 private View mLoadingPage; private View mErrorPage; private View mEmptyPage; private View mSuccessPage; public LoadingPage(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); initView(); } public LoadingPage(Context context, AttributeSet attrs) { super(context, attrs); initView(); } public LoadingPage(Context context) { super(context); initView(); } private void initView() { // 初始化加载中的布局 if (mLoadingPage == null) { mLoadingPage = UIUtils.inflate(R.layout.page_loading); addView(mLoadingPage);// 将加载中的布局添加给当前的帧布局 } // 初始化加载失败布局 if (mErrorPage == null) { mErrorPage = UIUtils.inflate(R.layout.page_error); addView(mErrorPage); } // 初始化数据为空布局 if (mEmptyPage == null) { mEmptyPage = UIUtils.inflate(R.layout.page_empty); addView(mEmptyPage); } showRightPage(); } // 根据当前状态,决定显示哪个布局 private void showRightPage() { // if (mCurrentState == STATE_LOAD_UNDO // || mCurrentState == STATE_LOAD_LOADING) { // mLoadingPage.setVisibility(View.VISIBLE); // } else { // mLoadingPage.setVisibility(View.GONE); // } mLoadingPage .setVisibility((mCurrentState == STATE_LOAD_UNDO || mCurrentState == STATE_LOAD_LOADING) ? View.VISIBLE : View.GONE); mErrorPage .setVisibility(mCurrentState == STATE_LOAD_ERROR ? View.VISIBLE : View.GONE); mEmptyPage .setVisibility(mCurrentState == STATE_LOAD_EMPTY ? View.VISIBLE : View.GONE); // 当成功布局为空,并且当前状态为成功,才初始化成功的布局 if (mSuccessPage == null && mCurrentState == STATE_LOAD_SUCCESS) { mSuccessPage = onCreateSuccessView(); if (mSuccessPage != null) { addView(mSuccessPage); } } if (mSuccessPage != null) { mSuccessPage .setVisibility(mCurrentState == STATE_LOAD_SUCCESS ? View.VISIBLE : View.GONE); } } // 开始加载数据 public void loadData() { if (mCurrentState != STATE_LOAD_LOADING) {// 如果当前没有加载, 就开始加载数据 mCurrentState = STATE_LOAD_LOADING; new Thread() { @Override public void run() { final ResultState resultState = onLoad(); // 运行在主线程 UIUtils.runOnUIThread(new Runnable() { @Override public void run() { if (resultState != null) { mCurrentState = resultState.getState();// 网络加载结束后,更新网络状态 // 根据最新的状态来刷新页面 showRightPage(); } } }); } }.start(); } } // 加载成功后显示的布局, 必须由调用者来实现 public abstract View onCreateSuccessView(); // 加载网络数据, 返回值表示请求网络结束后的状态 public abstract ResultState onLoad(); public enum ResultState { STATE_SUCCESS(STATE_LOAD_SUCCESS), STATE_EMPTY(STATE_LOAD_EMPTY), STATE_ERROR( STATE_LOAD_ERROR); private int state; private ResultState(int state) { this.state = state; } public int getState() { return state; } } public static class Person { public static Person P1 = new Person(10); public static Person P2 = new Person(12); public static Person P3 = new Person(19); public Person(int age) { } } // public enum Person { // P1,P2,P3; // }}结构示意图如下 
上面BaseFragment的代码已经给出以HomeFragment为例
/** * 首页 * Created by matri on 2017/5/11. */public class HomeFragment extends BaseFragment { //如果加载数据成功，回调此方法,在主线程运行 @Override public View onCreateSuccessView() { TextView view = new TextView(UIUtils.getContext()); view.setText(getClass().getSimpleName()); return view; } //运行在子线程，可以直接执行耗时网络操作 @Override public LoadingPage.ResultState onLoad() { //请求网络 return LoadingPage.ResultState.STATE_SUCCESS; }}数据请求部分我们在后面的文章中学习完成
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