java.lang.IllegalArgumentException: Service Intent must be explicit问题研究

Android5.0中service的intent一定要显性声明，当这样绑定的时候不会报错。

以下可以将隐性调用变成显性调用。先定义一个函数：

/***
* Android L (lollipop, API 21) introduced a new problem when trying to invoke implicit intent,
* "java.lang.IllegalArgumentException: Service Intent must be explicit"
*
* If you are using an implicit intent, and know only 1 target would answer this intent,
* This method will help you turn the implicit intent into the explicit form.
*
* Inspired from SO answer: http://stackoverflow.com/a/26318757/1446466
* @param context
* @param implicitIntent - The original implicit intent
* @return Explicit Intent created from the implicit original intent
*/
public static Intent createExplicitFromImplicitIntent(Context context, Intent implicitIntent) {
// Retrieve all services that can match the given intent
PackageManager pm = context.getPackageManager();
List resolveInfo = pm.queryIntentServices(implicitIntent, 0);

    // Make sure only one match was found  
    if (resolveInfo == null || resolveInfo.size() != 1) {  
        return null;  
    }  

    // Get component info and create ComponentName  
    ResolveInfo serviceInfo = resolveInfo.get(0);  
    String packageName = serviceInfo.serviceInfo.packageName;  
    String className = serviceInfo.serviceInfo.name;  
    ComponentName component = new ComponentName(packageName, className);  

    // Create a new intent. Use the old one for extras and such reuse  
    Intent explicitIntent = new Intent(implicitIntent);  

    // Set the component to be explicit  
    explicitIntent.setComponent(component);  

    return explicitIntent;  
}  

然后调用
final Intent intent = new Intent();
intent.setAction("com.example.user.firstapp.FIRST_SERVICE");
final Intent eintent = new Intent(createExplicitFromImplicitIntent(this,intent));
bindService(eintent,conn, Service.BIND_AUTO_CREATE);