Android仿京东客户端选择收货地址小Demo

记录一下最近项目中有一个类似于京东客户端选择收货地址的需求。

实现结果如下：

实现思路：

1. ViewPager+Fragment+TabLayout
2. 在Fragment里面的listview的点击事件里面发送广播
3. 在Activity里面接收发来的广播，进行逻辑处理

本次实现主要用到ViewPager、Fragment、TabLayout 主要代码：TabActivity.java

public class TabActivity extends AppCompatActivity {

    private ViewPager mViewPager;
    private TabLayout mTab;
    private List mFragments;
    private List mTitles;
    private FragmentPagerAdapter mAdapter;

    private CustomBroadcast mReceiver;
    private String mRecordBuildingName = null;
    private String mRecordUnitName = null;


    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_tablayout);

        mReceiver = new CustomBroadcast();
        IntentFilter filter = new IntentFilter();
        filter.addAction("lpf1");
        filter.addAction("lpf2");
        filter.addAction("lpf3");
        registerReceiver(mReceiver, filter);

        mTitles = new ArrayList<>();
        mFragments = new ArrayList<>();
        mTab = findViewById(R.id.tablayout);
        mViewPager = findViewById(R.id.vp_viewpager);

        initViewPager();
        initTabData();
    }

    private void initViewPager() {

        mTitles.add("请选择");
        mFragments.add(0, new FirstFragment());


        mAdapter = new FragmentPagerAdapter(getSupportFragmentManager()) {
            @Override
            public Fragment getItem(int position) {
                return mFragments.get(position);
            }

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

            @Override
            public CharSequence getPageTitle(int position) {

                return mTitles.get(position);
            }
        };

        mViewPager.setAdapter(mAdapter);

        /*
        * 将TabLayout、ViewPager 的监听事件同步
        * 对TabLayout 的适配器进行重置
        * 对TabLayout 的 TabItem 进行重置
        * 从ViewPager 的 Adapter 中读取到每一页的标题，并为之创建 TabItem 添加到 TabLayout 中
        */
        mTab.setupWithViewPager(mViewPager);
    }

    private void initTabData() {

        mTab.setSelectedTabIndicatorColor(getResources().getColor(R.color.colorAccent));
        mTab.setTabTextColors(getResources().getColor(R.color.white),
                getResources().getColor(R.color.colorAccent));

        mTab.setTabMode(TabLayout.MODE_SCROLLABLE);
        mTab.setBackgroundResource(R.color.colorPrimaryDarkNew);

    }

    @Override
    protected void onDestroy() {
        super.onDestroy();

        unregisterReceiver(mReceiver);
    }

    class CustomBroadcast extends BroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {

            mTitles.clear();
            mFragments.clear();
            mFragments.add(0, new FirstFragment());
            mFragments.add(1, new SecondFragment());

            if (Objects.equals(intent.getAction(), "lpf1")) {

                String buildingName = intent.getStringExtra("FirstFragment");
                mRecordBuildingName = buildingName;
                if (buildingName != null) {

                    mTitles.add(0, buildingName);
                    mTitles.add(1, "请选择");
                    mAdapter.notifyDataSetChanged();
                    mViewPager.setCurrentItem(1);
                }

            } else if (Objects.equals(intent.getAction(), "lpf2")) {

                String unitName = intent.getStringExtra("SecondFragment");
                mRecordUnitName = unitName;
                Log.e("spspsp", "单元名称：" + unitName);
                if (unitName != null) {

                    mTitles.add(0, mRecordBuildingName);
                    mTitles.add(1, unitName);
                    mTitles.add(2, "请选择");
                    mFragments.add(2, new ThirdFragment());
                    mAdapter.notifyDataSetChanged();
                    mViewPager.setCurrentItem(2);
                }
            } else if (Objects.equals(intent.getAction(), "lpf3")) {

                String roomName = intent.getStringExtra("ThirdFragment");
                Log.e("spspsp", "房屋名称：" + roomName);
                if (roomName != null) {

                    mTitles.add(0, mRecordBuildingName);
                    mTitles.add(1, mRecordUnitName);
                    mTitles.add(2, roomName);
                    mFragments.add(2, new ThirdFragment());
                    mAdapter.notifyDataSetChanged();
                }
            }
        }
    }
}

注意：这里当时在重写ViewPager适配器的时候，上面的Tab标签字样不能正常显示，
原因在于 mTab.setupWithViewPager(mViewPager)，点进去看源码发现如下：

• TabLayout.java

void populateFromPagerAdapter() {
        removeAllTabs();

        if (mPagerAdapter != null) {
            final int adapterCount = mPagerAdapter.getCount();
            for (int i = 0; i < adapterCount; i++) {
                addTab(newTab().setText(mPagerAdapter.getPageTitle(i)), false);
            }

            // Make sure we reflect the currently set ViewPager item
            if (mViewPager != null && adapterCount > 0) {
                final int curItem = mViewPager.getCurrentItem();
                if (curItem != getSelectedTabPosition() && curItem < getTabCount()) {
                    selectTab(getTabAt(curItem));
                }
            }
        }
    }

可以发现进入到if语句内的第一个for循环就是在为Tab标签赋值，具体值是通过ViewPager的getPageTitle方法，那么继续看getPageTitle方法，如下：

• PagerAdapter.java

 /**
     * This method may be called by the ViewPager to obtain a title string
     * to describe the specified page. This method may return null
     * indicating no title for this page. The default implementation returns
     * null.
     *
     * @param position The position of the title requested
     * @return A title for the requested page
     */
    @Nullable
    public CharSequence getPageTitle(int position) {
        return null;
    }

可以看到在默认情况下，该方法的默认值都是null，这样就解释了Tab标签不能正常显示的原因了。