Android中跨包访问Preferences

我们可以在一个应用程序中创建并编辑一个 Preferences ，然后在另外一个应用程序中读取它。当然有个前提是 该Preferences 的权限至少是 Context.MODE_WORLD_READABLE 。

比如在包名为 com.teleca 应用程序A中有一个名叫 com.teleca_prefer 的Preferences：

final static String preferName=" com.teleca_prefer ";

final static String KEY_TIP="tip";

.......................................................

        prefsWorldRead = getSharedPreferences(preferName,

                 Context.MODE_WORLD_READABLE) ;

        Editor prefsWorldReadEditor = prefsWorldRead.edit();

        prefsWorldReadEditor.putString(KEY_TIP, "Are you fine?");

        prefsWorldReadEditor.commit();

我们可以在包名为com.teleca.robin应用程序B中这样读取它：

private SharedPreferences prefsWorldRead;

final static String preferName=" com.teleca_prefer ";

final static String KEY_TIP="tip";

....................................................................

          if(prefsWorldRead ==null)

          {

          Context otherContext=null;

          try {

otherContext =createPackageContext(" com.teleca ",  Context.CONTEXT_IGNORE_SECURITY  );

} catch (NameNotFoundException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

             prefsWorldRead = otherContext.getSharedPreferences(preferName,

                     Context.MODE_WORLD_READABLE);

          }

             String tip=prefsWorldRead.getString(KEY_TIP, "null2");

createPackageContext 为Context的方法， " com.teleca " 为A应用程序的包名， " com.teleca_prefer " 为你要读取的A应用程序的 Preferences 名字。

public abstract Context createPackageContext (String packageName, int flags)

Since:  API Level 1

Return a new Context object for the given application name. This Context is the same as what the named application gets when it is launched, containing the same resources and class loader. Each call to this method returns a new instance of a Context object; Context objects are not shared, however they share common state (Resources, ClassLoader, etc) so the Context instance itself is fairly lightweight.

Throws PackageManager.NameNotFoundException if there is no application with the given package name.

Throws SecurityException if the Context requested can not be loaded into the caller's process for security reasons (see CONTEXT_INCLUDE_CODE for more information}.

Parameters

packageName	Name of the application's package.
flags	Option flags, one of CONTEXT_INCLUDE_CODE or CONTEXT_IGNORE_SECURITY.

Returns

• A Context for the application.

Throws

	java.lang.SecurityException
	if there is no application with the given package name
PackageManager.NameNotFoundException