问Android Tabview + Webview

EN

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        SectionsPagerAdapter sectionsPagerAdapter = new SectionsPagerAdapter(this, getSupportFragmentManager());
        final ViewPager viewPager = findViewById(R.id.view_pager);
        viewPager.setAdapter(sectionsPagerAdapter);
        TabLayout tabs = findViewById(R.id.tabs);
        tabs.setupWithViewPager(viewPager);
        tabs.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {

            }

            @Override
            public void onTabUnselected(TabLayout.Tab tab) {

            }

            @Override
            public void onTabReselected(TabLayout.Tab tab) {

            }
        });


    }
}

/**
 * A [FragmentPagerAdapter] that returns a fragment corresponding to
 * one of the sections/tabs/pages.
 */
public class SectionsPagerAdapter extends FragmentPagerAdapter {

    @StringRes
    private static final int[] TAB_TITLES = new int[]{R.string.tab_text_1, R.string.tab_text_2, R.string.tab_text_3, R.string.tab_text_4, R.string.tab_text_5, R.string.tab_text_6, R.string.tab_text_7};
    private final Context mContext;

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

    @Override
    public Fragment getItem(int position) {
        // getItem is called to instantiate the fragment for the given page.
        // Return a PlaceholderFragment (defined as a static inner class below).
        return PlaceholderFragment.newInstance(position + 1);

    }

    @Nullable
    @Override
    public CharSequence getPageTitle(int position) {
        return mContext.getResources().getString(TAB_TITLES[position]);
    }

    @Override
    public int getCount() {
        // Show 2 total pages.
        return 7;
    }
}

/**
 * A placeholder fragment containing a simple view.
 */
public class PlaceholderFragment extends Fragment {

    String type;

    private static final String ARG_SECTION_NUMBER = "section_number";

    private PageViewModel pageViewModel;

    public static PlaceholderFragment newInstance(int index) {
        PlaceholderFragment fragment = new PlaceholderFragment();
        Bundle bundle = new Bundle();
        bundle.putInt(ARG_SECTION_NUMBER, index);
        fragment.setArguments(bundle);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        pageViewModel = ViewModelProviders.of(this).get(PageViewModel.class);
        int index = 1;
        if (getArguments() != null) {
            index = getArguments().getInt(ARG_SECTION_NUMBER);
        }
        pageViewModel.setIndex(index);
    }


    @Override
    public View onCreateView(
            @NonNull LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View root = inflater.inflate(R.layout.fragment_main, container, false);
        final WebView webView = (WebView)root.findViewById(R.id.webView);
        webView.setWebViewClient( new WebViewClient(){
            @Override
            public boolean shouldOverrideUrlLoading(WebView view, String url){
                webView.loadUrl(url);
                return true;
            }

        });
        webView.getSettings().setJavaScriptEnabled(true);
        webView.getSettings().setRenderPriority(WebSettings.RenderPriority.HIGH);


        pageViewModel.getText().observe(this, new Observer<String>() {
            @Override
            public void onChanged(@Nullable String s) {
                type = s;
            }
        });

        if(type == null)
        {
            type="1";
        }

        webView.loadUrl("https://my.domain/list.php?type="+type);
        return root;
    }
}

public class PageViewModel extends ViewModel {

    private MutableLiveData<Integer> mIndex = new MutableLiveData<>();
    private LiveData<String> mText = Transformations.map(mIndex, new Function<Integer, String>() {
        @Override
        public String apply(Integer input) {
            return input.toString();
        }
    });

    public void setIndex(int index) {
        mIndex.setValue(index);
    }

    public LiveData<String> getText() {
        return mText;
    }
}