Android 带有 FragmentStageAdapter 动态内容的选项卡视图

Question

我正在尝试通过使用 FragmentStageAdapter、片段和 android.support.v4.view.ViewPager 框架来实现选项卡式查看器。每个标签页应显示一个 X509 证书（动态内容），该证书是以前从网络上下载的。

我心中的程序如下：

下载证书并将它们存储在数组中
用标签填充标签activity，每个标签包含一个证书

什么是有效的：

我可以下载证书并将它们存储在数组中。
我可以实例化我的 FragmentActivity
我可以将与数组中的证书相同数量的选项卡添加到选项卡视图

什么不起作用

在我添加所有选项卡后，我调用了 FragmentStagePageAdapter 的方法 notifyDataSetChanged()，调试器在我的 Fragement 的 onCreateView 方法中停止，当我试图 infalte Fragment

View certView = inflater.inflate(R.layout.certificate_view, container, false);

之后我 return 在调试回 notifyDataSetChanged() 方法调用时我的 eclipse 调试器断开连接并抛出异常：

An internal error occurred during: "JDI Event Dispatch".

java.lang.NullPointerException

在 ADB 中 logcat 我可以看到多次出现以下异常：

java.lang.RuntimeException: Unable to instantiate application android.app.Application: java.lang.IllegalStateException: Unable to get package info for com.mydomain.mypackage; is package not installed?

我已经尝试清理我的项目，从我的设备上卸载 apk，但错误仍然存在。

下面我列出了一些我的来源，为了简单起见，我缩短了其中的一些。

问题

这是用“动态”数据在选项卡视图中填充片段的正确方法吗？据我了解，FragementStagePageAdapter 应用于未确定的选项卡数量，而不是用于 'static' 内容的 FragementAdapter。

这是我的 FragmentActivity

public class MyFragmentActivity extends FragmentActivity {
public static final String ARGUMENT_SERVER_URL = "URL";
private String mHostUrl;

private X509Certificate[] mX509Certificates;

private MyFragmentStagePageAdapter mCertPageAdapter;
private ActionBar mActionBar;
private ViewPager mViewPager;

private OnPageChangeListener onPageChangeListener = 
new ViewPager.SimpleOnPageChangeListener(){
    
    @Override
    public void onPageSelected(int position) {
        mActionBar = getActionBar();
        mActionBar.setSelectedNavigationItem(position);
    };
};

@Override
protected void onCreate(Bundle arg0) {
    super.onCreate(arg0);
    setContentView(R.layout.certificate_view_pager);
    
    // get the host url from the activity's received intent
    getHostUrlFromIntent();
    
    // instantiate the FragmentStatePagerAdapter 
    mCertPageAdapter = 
    new MyFragmentStagePageAdapter(getSupportFragmentManager());
    
    // create the ViewPager
    mViewPager = (ViewPager) findViewById(R.id.certificate_view_pager);
    
    // assign a onPageChangeListener
    mViewPager.addOnPageChangeListener(onPageChangeListener);
    // set the FragmentStatePagerAdapter
    mViewPager.setAdapter(mCertPageAdapter);
    
    mActionBar = getActionBar();
    mActionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
    
    startCertificateDownloadAsync();
}

private void getHostUrlFromIntent() {
    Intent intent = getIntent();
    Bundle serverCredentialsBundle = intent.getExtras();
    mHostUrl = serverCredentialsBundle.getString(ARGUMENT_SERVER_URL);
    if (mHostUrl == null) {
        throw new InvalidParameterException("URL must not be empty");
    }
}

private TabListener tabListener = new TabListener() {
    
    @Override
    public void onTabUnselected(Tab tab, FragmentTransaction ft) {
        
    }
    
    @Override
    public void onTabSelected(Tab tab, FragmentTransaction ft) {
        mViewPager.setCurrentItem(tab.getPosition());
    }
    
    @Override
    public void onTabReselected(Tab tab, FragmentTransaction ft) {
        
    }
};

private void startCertificateDownloadAsync(){
    new AsyncTask<Void, Void, Boolean>() {

        @Override
        protected Boolean doInBackground(Void... params) {
            // retreive certificates here 
            // (code is removed for the sake of simplicity)

        }
        
        @Override
        protected void onPostExecute(Boolean result) {
            super.onPostExecute(result);
            assignCertificatesToActionBarOnUiThread();
        }
    }.execute();
}

private void assignCertificatesToActionBarOnUiThread() {
    runOnUiThread(new Runnable() {
        
        @Override
        public void run() {
            if (mX509Certificates != null && 
            mX509Certificates.length >  0) {
                
                
                for (int i = 0; i < mX509Certificates.length; i++) {
                    Tab newTab = mActionBar.newTab();
                    X509Certificate cert = mX509Certificates[i];
                    newTab.setText(cert.getIssuerDN().getName());
                    newTab.setTabListener(tabListener);
                    mActionBar.addTab(newTab);
                }
                mCertPageAdapter.setCertificateArray(mX509Certificates);
                // call is required, when data was changed externally 
                mCertPageAdapter.notifyDataSetChanged();
            }
        }
        
    });
}

这是我的片段

public class MyCertificateFragment extends Fragment {
public static final String ARG_CERT = "CERTIFICATE";

private X509Certificate certificate;

private TextView commonName;


@Override
public View onCreateView(LayoutInflater inflater, 
        ViewGroup container, Bundle savedInstanceState) {
    // The last two arguments ensure LayoutParams are inflated properly.
    View certView = inflater.inflate(R.layout.certificate_view, 
container, false);
    
    Activity activity = getActivity();
    commonName = (TextView) 
activity.findViewById(R.id.certViewTextViewCnValue);
    
    byte[] certificateBytes = 
savedInstanceState.getByteArray(LoginActivity.INTENT_EXTRA_CERTIFICATE);
    certificate = CertUtils.toX509Certificate(certificateBytes);
    
    commonName.setText(certificate.getSubjectX500Principal().getName());
    return certView;
}
}

这就是我的 certificate_view.xml 的样子

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/certificate_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >

<LinearLayout
    android:id="@+id/certViewLinearLayoutCn"
    android:layout_width="fill_parent"
    android:layout_height="0dp"
    android:layout_gravity="end"
    android:layout_weight="1"
    android:gravity="fill_vertical|fill_horizontal"
    android:orientation="horizontal" >

    <TextView
        android:id="@+id/certViewTextViewCnLabel"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="start"
        android:text="Common Name:" />

    <TextView
        android:id="@+id/certViewTextViewCnValue"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="end"
        android:text="" />

</LinearLayout>

</LinearLayout>

寻呼机 activity

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.view.ViewPager 
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/certificate_view_pager"
android:layout_width="match_parent"
android:layout_height="match_parent" >

<android.support.v4.view.PagerTitleStrip
    android:id="@+id/pager_title_strip"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_gravity="top"
    android:background="#33b5e5"
    android:paddingBottom="4dp"
    android:paddingTop="4dp"
    android:textColor="#fff" />

</android.support.v4.view.ViewPager>

FrameStagePageAdapter

public class MyViewpageAdapter extends FragmentStatePagerAdapter {

private X509Certificate[] certificateArray;

public void setCertificateArray(X509Certificate[] array) {
    this.certificateArray = array;
}

public MyViewpageAdapter(FragmentManager fm) {
    super(fm);
}

@Override
public Fragment getItem(int i) {
    Fragment certFragment = null;
    if (i > -1 && i < certificateArray.length) {
        certFragment = new MyCertificateFragment();
        byte[] encodedCertificate = null;
        try {
            encodedCertificate = certificateArray[i].getEncoded();
        } catch (CertificateEncodingException e) {
            e.printStackTrace();
        }
        Bundle arguments = new Bundle();
        arguments.putByteArray(LoginActivity.INTENT_EXTRA_CERTIFICATE,
        encodedCertificate);
        certFragment.setArguments(arguments);
    }
    return certFragment;
}

@Override
public int getCount() {
    int count = 0;
    if (certificateArray != null){
        count = certificateArray.length;
    }
    return count;
}

}

Answer 1

我在 certificate_view.xml 中发现了这个问题。布局有误。我有一个线性布局的空高度。因此 certificate_view.xml 无法在 onCreateView 方法中加载。

Android 带有 FragmentStageAdapter 动态内容的选项卡视图

Android tab view with FragmentStageAdapter dynamic content

java

tabs

android

x509certificate

android-fragments

什么是有效的：

什么不起作用

问题