仿微博发现界面

仿微博发现界面

先上效果图：

这里用到了 LayoutTransition动画，在我的博客中有一节专门介绍

public class MainActivity extends AppCompatActivity {

    //fragment的适配器
    private MainTabFragmentAdapter mainTabFragmentAdapter;

    //viewpager
    private ViewPager mViewPager;

    //左上角的退出ICON
    private ImageView exit;
    //AppBarLayout
    private AppBarLayout mAppBarLayout;

    //顶部HeaderLayout
    private LinearLayout headerLayout,title5;

    //大头部标题的高度
    int title5Height;

    //小头部的标题
    private SmartTabLayout mTabs;

    //是否隐藏了头部
    private boolean isHideHeaderLayout = false;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        init();
    }

    //初始化方法
    private void init(){
        exit= (ImageView) findViewById(R.id.exit);
        title5= (LinearLayout) findViewById(R.id.title5);
        title5Height= title5.getMeasuredHeight();
        mTabs = (SmartTabLayout) findViewById(R.id.tabs);
        mViewPager = (ViewPager) findViewById(R.id.viewpager);


        mainTabFragmentAdapter = new MainTabFragmentAdapter(getSupportFragmentManager(),this);

        mViewPager.setAdapter(mainTabFragmentAdapter);
        mTabs.setViewPager(mViewPager);


        mViewPager.setOffscreenPageLimit(mainTabFragmentAdapter.getCount());
        headerLayout = (LinearLayout) findViewById(R.id.guanggao);
        initAppBarLayout();

        exit.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if ( isHideHeaderLayout ){
                    isHideHeaderLayout = false;
                    ((MainTabFragment)mainTabFragmentAdapter.getFragments().get(0)).getRvList().scrollToPosition(0);
                    headerLayout.setVisibility(View.VISIBLE);

                    new Handler().postDelayed(new Runnable() {
                        @Override
                        public void run() {
                            AppBarLayout.LayoutParams mParams = (AppBarLayout.LayoutParams) headerLayout.getLayoutParams();
                            mParams.setScrollFlags(AppBarLayout.LayoutParams.SCROLL_FLAG_SCROLL|
                                    AppBarLayout.LayoutParams.SCROLL_FLAG_EXIT_UNTIL_COLLAPSED);
                            headerLayout.setLayoutParams(mParams);
                            title5.setVisibility(View.VISIBLE);
                            mTabs.setVisibility(View.GONE);
                        }
                    },300);
                }else {
                    finish();
                }
            }
        });
    }

    // 初始化AppBarLayout
    private void initAppBarLayout(){
        LayoutTransition mTransition = new LayoutTransition();
        /**
         * 添加View时过渡动画效果
         */
        ObjectAnimator addAnimator = ObjectAnimator.ofFloat(null, "translationY", 0, 1.f).
                setDuration(mTransition.getDuration(LayoutTransition.APPEARING));
        mTransition.setAnimator(LayoutTransition.APPEARING, addAnimator);

        //header layout height
        final int headerHeight = getResources().getDimensionPixelOffset(R.dimen.header_height)+title5Height;
        mAppBarLayout = (AppBarLayout) findViewById(R.id.appbar);
        mAppBarLayout.setLayoutTransition(mTransition);

        mAppBarLayout.addOnOffsetChangedListener(new AppBarLayout.OnOffsetChangedListener() {
            @Override
            public void onOffsetChanged(AppBarLayout appBarLayout, int verticalOffset) {
                verticalOffset = Math.abs(verticalOffset);
                if ( verticalOffset >= headerHeight ){
                    isHideHeaderLayout = true;
                    //当偏移量超过顶部layout的高度时，我们认为他已经完全移动出屏幕了
                    new Handler().postDelayed(new Runnable() {
                        @Override
                        public void run() {
                            title5.setVisibility(View.GONE);
                            mTabs.setVisibility(View.VISIBLE);
                            AppBarLayout.LayoutParams mParams = (AppBarLayout.LayoutParams) headerLayout.getLayoutParams();
                            mParams.setScrollFlags(0);
                            headerLayout.setLayoutParams(mParams);
                            headerLayout.setVisibility(View.GONE);

                        }
                    },100);
                }
            }
        });
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if ( keyCode == KeyEvent.KEYCODE_BACK ){
            //监听返回键
            if ( isHideHeaderLayout ){
                isHideHeaderLayout = false;
                ((MainTabFragment)mainTabFragmentAdapter.getFragments().get(0)).getRvList().scrollToPosition(0);
                headerLayout.setVisibility(View.VISIBLE);

                new Handler().postDelayed(new Runnable() {
                    @Override
                    public void run() {
                        AppBarLayout.LayoutParams mParams = (AppBarLayout.LayoutParams) headerLayout.getLayoutParams();
                        mParams.setScrollFlags(AppBarLayout.LayoutParams.SCROLL_FLAG_SCROLL|
                                AppBarLayout.LayoutParams.SCROLL_FLAG_EXIT_UNTIL_COLLAPSED);
                        headerLayout.setLayoutParams(mParams);
                        title5.setVisibility(View.VISIBLE);
                        mTabs.setVisibility(View.GONE);
                    }
                },300);
            }else {
                finish();
            }
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }
}

MainTabFragment

public class MainTabFragment extends Fragment {

    public static MainTabFragment newInstance() {
        return new MainTabFragment();
    }

    private RecyclerView mRvList;

    private View rootView;

    private TestRvAdapter adapter;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        rootView = inflater.inflate(R.layout.fragment_main_tab,container,false);
        initWidget();
        return rootView;
    }

    public void initWidget(){
        adapter = new TestRvAdapter(getActivity());
        mRvList = (RecyclerView) rootView.findViewById(R.id.rv_list);
        mRvList.setLayoutManager(new LinearLayoutManager(getActivity()));
        mRvList.setAdapter(adapter);
    }

    public RecyclerView getRvList(){
        return mRvList;
    }

}

MainTabFragmentAdapte

public class MainTabFragmentAdapter extends FragmentStatePagerAdapter {

    public ArrayList<Fragment> fragments;

    public Context mContext;

    private String[] titles;

    public MainTabFragmentAdapter(FragmentManager fm, Context context) {
        super(fm);
        mContext = context;
        initFragments();
    }

    public ArrayList<Fragment> getFragments() {
        return fragments;
    }

    @Override
    public Fragment getItem(int position) {
        return fragments.get(position);
    }

    @Override
    public int getCount() {
        return fragments.size();
    }

    private void initFragments() {
        titles = new String[]{
                mContext.getResources().getString(R.string.test_1),
                mContext.getResources().getString(R.string.test_2),
                mContext.getResources().getString(R.string.test_3),
                mContext.getResources().getString(R.string.test_4),
                mContext.getResources().getString(R.string.test_5),
        };

        fragments = new ArrayList<>();
        for ( int i=0; i < titles.length; i++ ){
            Fragment fragment = MainTabFragment.newInstance();
            fragments.add(fragment);
        }
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return titles[position];
    }
}

TestRvAdapter

public class TestRvAdapter extends RecyclerView.Adapter<TestRvAdapter.TestViewHolder> {

    private Context context;

    public TestRvAdapter(Context context){
        this.context = context;
    }

    @Override
    public TestViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(context).inflate(R.layout.item_layout,parent,false);
        return new TestViewHolder(view);
    }

    @Override
    public void onBindViewHolder(TestViewHolder holder, int position) {
       // holder.tv_test.setText("测试数据" + position);
    }

    @Override
    public int getItemCount() {
        return 10;
    }

    class TestViewHolder extends RecyclerView.ViewHolder {

        //TextView tv_test;

        TestViewHolder(View itemView) {
            super(itemView);
           // tv_test = (TextView) itemView.findViewById(R.id.tv_test);
        }
    }
}