导航抽屉和ViewPager冲突

Question

我目前正在开发一个Android应用程序，我使用导航抽屉以及使用viewPager浏览片段的滑动手势。

基本上，我希望用户能够使用导航抽屉选择页面（片段），并能够滑动到下一页（片段）。

我现在的问题是他们重叠了。滑动手势按预期工作，但当我在导航抽屉上选择另一个页面时，它们的底层页面不会消失。我需要一些东西来刷新＆＃34;每个片段。

这是我在MainActivity.java页面中的代码

package com.example.home.cloud;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Toast;

public class MainActivity extends ActionBarActivity implements FragmentDrawer.FragmentDrawerListener {

    private static String TAG = MainActivity.class.getSimpleName();

    private static final int NUM_PAGES = 10;

    private Toolbar mToolbar;
    private FragmentDrawer drawerFragment;

    private ViewPager mPager;
    private PagerAdapter mPagerAdapter;

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

        mPager = (ViewPager) findViewById(R.id.pager);
        mPagerAdapter = new MyFragmentStatePagerAdapter(getSupportFragmentManager());
        mPager.setAdapter(mPagerAdapter);

        mToolbar = (Toolbar) findViewById(R.id.toolbar);

        setSupportActionBar(mToolbar);
        getSupportActionBar().setDisplayShowHomeEnabled(true);

        drawerFragment = (FragmentDrawer)
         getSupportFragmentManager().findFragmentById(R.id.fragment_navigation_drawer);
        drawerFragment.setUp(R.id.fragment_navigation_drawer, (DrawerLayout) findViewById(R.id.drawer_layout), mToolbar);
        drawerFragment.setDrawerListener(this);

        // display the first navigation drawer view on app launch
        displayView(0);
    }

    @Override
    public void onBackPressed() {
        if (mPager.getCurrentItem() == 0) {
            super.onBackPressed();
        } else {
            mPager.setCurrentItem(mPager.getCurrentItem() - 1);
        }
    }

    private class MyFragmentStatePagerAdapter extends FragmentStatePagerAdapter
    {
        public MyFragmentStatePagerAdapter(FragmentManager fm)
        {
            super(fm);
        }

        @Override
        public Fragment getItem(int position) {
            final Fragment result;
            switch (position) {
                case 0:
                    result= new HomeFragment();
                   break;
                case 1:
                    result= new OverviewFragment();
                    break;
                case 2:
                    result= new BenFragment();
                    break;
                case 3:
                    result= new TechFragment();
                    break;
                case 4:
                    result= new ArcFragment();
                    break;
                case 5:
                    result= new DmodFragment();
                    break;
                case 6:
                    result= new SmodFragment();
                    break;
                case 7:
                    result= new VirtFragment();
                    break;
                case 8:
                    result= new StorageFragment();
                    break;
                case 9:
                    result= new SecurityFragment();
                    break;
                default: result=null;
                    break;
            }
         /*   if (result != null) {
                FragmentManager fragmentManager = getSupportFragmentManager();
                FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
                fragmentTransaction.replace(R.id.container_body, result);
                fragmentTransaction.commit();

            }*/
            return result;

        }


        @Override
        public int getCount() {
            return NUM_PAGES;
        }
    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        if(id == R.id.action_search){
            Toast.makeText(getApplicationContext(), "Search action is selected!", Toast.LENGTH_SHORT).show();
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @Override
    public void onDrawerItemSelected(View view, int position) {
        displayView(position);
    }

    private void displayView(int position) {
        Fragment fragment = null;
        String title = getString(R.string.app_name);
        switch (position) {
            case 0:
                fragment = new HomeFragment();
                title = getString(R.string.title_home);
                break;
            case 1:
                fragment = new OverviewFragment();
                title = getString(R.string.title_overview);
                break;
            case 2:
                fragment=new BenFragment();
                title="Benefits and Risks";
                break;
            case 3:
                fragment=new TechFragment();
                title="Technologies behind Cloud Computing";
                break;
            case 4:
                fragment = new ArcFragment();
                title="Architecture";
                break;
            case 5:
                fragment= new DmodFragment();
                title="Deployment Models";
                break;
            case 6:
                fragment = new SmodFragment();
                title="Service Models";
                break;
            case 7:
                fragment = new VirtFragment();
                title="Virtualization";
                break;
            case 8:
                fragment = new StorageFragment();
                title="Data Storage";
                break;
            case 9:
                fragment = new SecurityFragment();
                title="Security";
                break;
            default:
                break;
        }

        if (fragment != null) {
            FragmentManager fragmentManager = getSupportFragmentManager();
            FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
            fragmentTransaction.replace(R.id.container_body, fragment);
            fragmentTransaction.commit();

            // set the toolbar title
            getSupportActionBar().setTitle(title);
        }
    }
}

Answer 1

问题在于您以两种不同的方式显示片段。您的displayView()方法正在创建新片段并显示它们，而不是显示ViewPager中已加载的片段。要解决此问题，您需要displayView()来设置ViewPager位置。

private void displayView(int position) {
    mPager.setCurrentItem(position);
    getSupportActionBar().setTitle(mPagerAdapter.getPageTitle(position));
}