我重新开始开发一款之前的应用程序，当时我把所有东西都建立在Android 2.2 Froyo环境下。
我更新了最新API的SDK并注意到我使用的ClipboardManager功能已经被弃用。我更新了代码，使用了更新的ClipData模型，并在我的Froyo手机上测试了一下，结果，在新代码中遇到了NoClassDefFoundError错误。
我在SO上搜索了一下，没有找到有关维护向后兼容性方面的实质性讨论。
我不太确定我应该如何处理这种情况和其他API不同的情况，因为我希望所有版本的用户都能够使用我的应用程序。
我应该按照以下方式进行检查吗？
if(version == old){
use old API;
} else {
use new API;
}
如果是这样，我的类中就有过时的代码，Eclipse 会一直显示警告。
另一方面，我可以只针对旧版本的API进行构建，并希望新版本可以正常处理它。但这样做存在一个风险，即在更好的替代方案可用时，构建可能会使用错误或低性能的代码。
应该如何处理这种情况最好？
您可以这样做（检查API版本）。
您还可以使用反射调用更新的类。
我不会担心使用已弃用的方法，因为所有Android版本都向后兼容，但如果您想要关注3.0 Honeycomb的事情，那么要注意一下，因为它们有些不同。
这里是如何使用反射的解释：（是的，它以前已经在SO上出现过，所以可能要搜索反射）
http://www.youtube.com/watch?v=zNmohaZYvPw&feature=player_detailpage#t=2087s
我希望能够将这个项目进行开放，但在此之前，请查看以下代码：
（你可以在扩展Application的类中执行此操作，即一次性设置）
public static Method getExternalFilesDir;
static {
try {
Class<?> partypes[] = new Class[1];
partypes[0] = String.class;
getExternalFilesDir = Context.class.getMethod("getExternalFilesDir", partypes);
} catch (NoSuchMethodException e) {
Log.e(TAG, "getExternalFilesDir isn't available in this devices api");
}
}
if(ClassThatExtendsApplication.getExternalFilesDir != null){
Object arglist[] = new Object[1];
arglist[0] = null;
File path = (File) ClassThatExtendsApplication.getExternalFilesDir.invoke(context, arglist);
// etc etc
} else {
// Not available do something else (like your deprecated methods / or load a different class / or notify they should get a newer version of Android to enhance your app ;-))
}
@SuppressWarnings("deprecation")注释。这将消除警告，并且你也因为尽可能使用最新的API而做到了正确的事情。这里有一个例子：
import android.os.Build;
public static int getWidth(Context mContext){
int width=0;
WindowManager wm = (WindowManager) mContext.getSystemService(Context.WINDOW_SERVICE);
Display display = wm.getDefaultDisplay();
if(VERSION.SDK_INT > VERSION_CODES.HONEYCOMB){
Point size = new Point();
display.getSize(size);
width = size.x;
}
else{
width = display.getWidth(); // deprecated, use only in Android OS<3.0.
}
return width;
}
正如您所看到的代码部分：
if(VERSION.SDK_INT > VERSION_CODES.HONEYCOMB){
Point size = new Point();
display.getSize(size);
width = size.x;
}
此代码仅适用于Android 3.0及更高版本，如果您想要至少在果冻豆（Android 4.1）上可用，请使用：
if(VERSION.SDK_INT > VERSION_CODES.JELLY_BEAN){
Point size = new Point();
display.getSize(size);
width = size.x;
}
/**
* Interface used to interact with the actual instance of MessageManager.
* This inteface allows will be the type of the reference that will point
* to the actual MessageMessenger, which will be loaded dynamically.
* @author steff
*
*/
public abstract class MessageManager {
/** Request code used to identify mail messages.*/
public final static int FOR_MAIL = 0x3689;
/** Request code used to identify SMS messages.*/
public final static int FOR_SMS = 0x3698;
/**
* Start an activity inside the given context. It will allow to pickup a contact
* and will be given an intent code to get contact pick up.
* *@param the request code. Has to be a constant : FOR_MAIL or FOR_SMS
*/
public abstract void pickupContact(int code);//met
/**
* Start an activity inside the given context. It will allow to pickup a contact
* and will be given an intent code to get contact pick up.
* *@param the request code. Has to be a constant : FOR_MAIL or FOR_SMS
*/
public abstract void sendMessage(int code, Intent data, final String body);//met
/**
* Static methode used as in factory design pattern to create an instance
* of messageManager. Here it is combined with the singleton pattern to
* get an instance of an inherited class that is supported by current android SDK.
* This singleton will be created bu reflexion.
* @param activity the activity that needs messaging capabilities.
* @return an instance of an inherited class that is supported by current android SDK or null, if not found.
*/
public static MessageManager getInstance( Activity activity )
{
MessageManager instance = null;
try {
Class<? extends MessageManager> messageManagerClass = (Class<? extends MessageManager>) activity.getClassLoader().loadClass( "ca.qc.webalterpraxis.cinedroid.message.MessageManagerSDK7" );
Method singletonMethod = messageManagerClass.getMethod("getInstance", Activity.class );
instance = (MessageManager) singletonMethod.invoke( null , activity);
} catch (Throwable e) {
Log.e( "CinemadroidMain", "Impossible to get an instance of class MessageManagerSDK7",e );
}//met
return instance;
}//met
}//interface
public class MessageManagerSDK7 extends MessageManager {
/** Used for logcat. */
private static final String LOG_TAG = "MessageManagerSDK7";
/** Singleton instance. */
private static MessageManagerSDK7 instance = null;
/** Activity that will call messaging actions. */
private Activity context;
/** Private constructor for singleton. */
private MessageManagerSDK7( Activity context )
{
if( instance != null )
throw new RuntimeException( "Should not be called twice. Singleton class.");
this.context = context;
}//cons
/**
* Static method that will be called by reflexion;
* @param context the activity that will enclose the call for messaging.
* @return an instance of this class (if class loader allows it).
*/
public static MessageManagerSDK7 getInstance( Activity context )
{
if( instance == null )
instance = new MessageManagerSDK7( context );
instance.context = context;
return instance;
}//met
/* (non-Javadoc)
* @see ca.qc.webalterpraxis.cinedroid.model.MessageManager#pickupContact(int)
*/
@Override
public void pickupContact( int code )
{
if( code != FOR_MAIL && code != FOR_SMS )
throw new RuntimeException( "Wrong request code, has to be either FOR_MAIL or FOR_SMS.");
Intent intentContact = new Intent(Intent.ACTION_PICK, ContactsContract.Contacts.CONTENT_URI);
context.startActivityForResult(intentContact, code );
}//met
/* (non-Javadoc)
* @see ca.qc.webalterpraxis.cinedroid.model.MessageManager#sendMessage(int, android.content.Intent, java.lang.String)
*/
@Override
public void sendMessage( int code, Intent data, final String body )
{
//System.out.println( "SendMessage");
if( code != FOR_MAIL && code != FOR_SMS )
throw new RuntimeException( "Wrong request code, has to be either FOR_MAIL or FOR_SMS.");
int icon = 0;
int noItemMessage = 0;
int title = 0;
//set the right icon and message for the dialog
if( code == FOR_MAIL )
{
icon=R.drawable.mail;
noItemMessage = R.string.no_email_found;
title = R.string.mail_error;
}//if
else if( code == FOR_SMS )
{
icon=R.drawable.sms;
noItemMessage = R.string.no_number_found;
title = R.string.sms_error;
}//if
//compose email or sms
//pick contact email address
final String[] emailsOrPhoneNumbers = (code == FOR_MAIL ) ? getContactsEmails( data ) : getContactPhoneNumber( data );
if( emailsOrPhoneNumbers == null )
{
new AlertDialog.Builder( context ).setIcon( icon ).setTitle(title).setMessage( noItemMessage ).show();
return;
}//if
//in case there are several addresses, we handle this using a dialog.
//modal dialog would be usefull but it's bad UI practice
//so we use an alert dialog, async ..
//all this is poorly coded but not very interesting, not worth having a dedicated inner class
if( emailsOrPhoneNumbers.length > 1 )
{
selectMultipleAndSend( emailsOrPhoneNumbers, body, code);
return;
}//if
if( code == FOR_MAIL )
sendMail( emailsOrPhoneNumbers, body );
else
sendSMS( emailsOrPhoneNumbers, body );
}//met
private void sendMail( String[] emails, String body )
{
if( body == null )
{
new AlertDialog.Builder( context ).setIcon( R.drawable.mail ).setTitle(R.string.mail_error).setMessage( R.string.impossible_compose_message ).show();
return;
}//if
//prepare email data
try {
Intent i = new Intent(Intent.ACTION_SEND);
i.setType("message/rfc822") ;
i.putExtra(Intent.EXTRA_EMAIL, emails );
//i.putExtra(Intent.EXTRA_EMAIL, emails);
i.putExtra(Intent.EXTRA_SUBJECT, context.getString( R.string.showtimes ) );
i.putExtra(Intent.EXTRA_TEXT,body);
context.startActivity(Intent.createChooser(i, context.getString( R.string.select_application ) ) );
} catch (Throwable e) {
new AlertDialog.Builder( context ).setIcon( R.drawable.mail ).setTitle(R.string.mail_error).setMessage( R.string.no_application_mail ).show();
Log.e( LOG_TAG, "No application found", e);
}//catch
}//met
private void sendSMS( String[] phoneNumbers, String body )
{
try {
Intent sendIntent= new Intent(Intent.ACTION_VIEW);
if( body == null )
{
new AlertDialog.Builder( context ).setIcon( R.drawable.sms ).setTitle(R.string.sms_error).setMessage( R.string.impossible_compose_message ).show();
return;
}//if
sendIntent.putExtra("sms_body", body);
String phones = "";
for( String phoneNumber : phoneNumbers )
phones += ((phones.length() == 0) ? "" : ";") + phoneNumber;
sendIntent.putExtra("address", phones );
sendIntent.setType("vnd.android-dir/mms-sms");
context.startActivity(sendIntent);
} catch (Throwable e) {
new AlertDialog.Builder( context ).setIcon( R.drawable.sms ).setTitle(R.string.sms_error).setMessage( R.string.no_application_sms ).show();
Log.e( LOG_TAG, "No application found", e);
}//catch
}//met
/**
* @param intent the intent returned by the pick contact activity
* @return the emails of selected people, separated by a comma or null if no emails has been found;
*/
protected String[] getContactsEmails(Intent intent)
{
List<String> resultList = new ArrayList<String>();
//https://dev59.com/Z3NA5IYBdhLWcg3wrf83
Cursor cursor = context.managedQuery(intent.getData(), null, null, null, null);
while (cursor.moveToNext())
{
String contactId = cursor.getString(cursor.getColumnIndex(ContactsContract.Contacts._ID));
// Find Email Addresses
Cursor emails = context.getContentResolver().query(ContactsContract.CommonDataKinds.Email.CONTENT_URI,null,ContactsContract.CommonDataKinds.Email.CONTACT_ID + " = " + contactId,null, null);
while (emails.moveToNext())
{
resultList.add( emails.getString(emails.getColumnIndex(ContactsContract.CommonDataKinds.Email.DATA)) );
}//while
emails.close();
} //while (cursor.moveToNext())
cursor.close();
if( resultList.size() == 0 )
return null;
else
return resultList.toArray( new String[ resultList.size() ] );
}//met
/**
* @param intent the intent returned by the pick contact activity
* @return the phoneNumber of selected people, separated by a comma or null if no phoneNumber has been found;
*/
protected String[] getContactPhoneNumber(Intent intent)
{
List<String> resultList = new ArrayList<String>();
//https://dev59.com/Z3NA5IYBdhLWcg3wrf83
Cursor cursor = context.managedQuery(intent.getData(), null, null, null, null);
while (cursor.moveToNext())
{
String contactId = cursor.getString(cursor.getColumnIndex(ContactsContract.Contacts._ID));
String name = cursor.getString(cursor.getColumnIndexOrThrow(ContactsContract.Contacts.DISPLAY_NAME));
String hasPhone = cursor.getString(cursor.getColumnIndex(ContactsContract.Contacts.HAS_PHONE_NUMBER));
if ( hasPhone.equalsIgnoreCase("1"))
hasPhone = "true";
else
hasPhone = "false" ;
if (Boolean.parseBoolean(hasPhone))
{
Cursor phones = context.getContentResolver().query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null,ContactsContract.CommonDataKinds.Phone.CONTACT_ID +" = "+ contactId,null, null);
while (phones.moveToNext())
{
resultList.add( phones.getString(phones.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER)) );
}
phones.close();
}
} //while (cursor.moveToNext())
cursor.close();
if( resultList.size() == 0 )
return null;
else
return resultList.toArray( new String[ resultList.size() ] );
}//met
private void selectMultipleAndSend( final String[] emailsOrPhoneNumbers, final String body, final int code )
{
int icon = 0;
int selectMessage = 0;
//set the right icon and message for the dialog
if( code == FOR_MAIL )
{
icon=R.drawable.mail;
selectMessage = R.string.select_email;
}//if
else if( code == FOR_SMS )
{
icon=R.drawable.sms;
selectMessage = R.string.select_phone;
}//if
final boolean[] selected = new boolean[ emailsOrPhoneNumbers.length ];
Arrays.fill( selected, true );
new AlertDialog.Builder( context ).setIcon( icon ).setTitle( selectMessage ).setMultiChoiceItems(emailsOrPhoneNumbers, selected, new OnMultiChoiceClickListener() {
@Override
public void onClick(DialogInterface dialog, int which, boolean isChecked) {
selected[ which ] = isChecked;
}
}).setPositiveButton( R.string.OK, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
int count = 0;
for( int s=0; s< selected.length; s ++ )
if( selected[s] )
count ++;
String[] selectedEmailsOrPhoneNumbers = new String[ count ];
int index = 0;
for( int s=0; s< selected.length; s ++ )
if( selected[s] )
selectedEmailsOrPhoneNumbers[ index ++ ] = emailsOrPhoneNumbers[ s ];
if( code == FOR_MAIL )
sendMail( selectedEmailsOrPhoneNumbers, body );
else if( code == FOR_SMS )
sendSMS( selectedEmailsOrPhoneNumbers, body );
}
}).setNegativeButton( R.string.cancel , null ).show();
}//met
}//class
你还可以提供其他替代方案。尝试按降序加载它们，即从较高的Android版本号开始。
使用您的消息服务非常简单：
MessageManager messageManager = MessageManager.getInstance( this );