[工作积累] Android system dialog with native callback

JNI: invoke java dialog with native callback:

store native function address in java, and invoke native another method to this function.

key points:

1.Store callback function pointer(address) in java: to support multiple calls, use data block for each call.

2.Use primitive long(64bit) in Java to store native callback pointer, for 64 bit native compatibility

3.intptr_t for pointer in native.

4.Show dialog  in UI thread (Activity.runOnUiThread )

5.optional: Let the native code to handle localization (minimize Java code)

Java:

 1 public static native void nativeOnSystemDialogResult(long nativeFuncAddr);
 2
 3
 4     class DialogRunnable implements Runnable {
 5         public String mTitle;
 6         public String mMessage;
 7         public String mYes;
 8         public String mNo;
 9         public long mOnYesAddr;
10         public long mOnNoAddr;
11         public boolean mTwoButton;
12
13         //////////////////////////////////////////////////////////////////////////
14         ///title, message, localized Yes No
15         DialogRunnable(String tittle, String message, String locYes, String locNo, long onYesAddr, long onNoAddr, boolean twoButton)
16         {
17             mTitle = tittle;
18             mMessage = message;
19             mYes = locYes;
20             mNo = locNo;
21             mOnYesAddr = onYesAddr;
22             mOnNoAddr = onNoAddr;
23             mTwoButton = twoButton;
24         }
25
26         //////////////////////////////////////////////////////////////////////////
27         public void run() {
28
29             if( mTwoButton ) {
30                 Dialog dialog = new AlertDialog.Builder( GameActivity.getInstance() )
31                 .setTitle(mTitle)
32                 .setMessage(mMessage)
33                 .setPositiveButton( mYes, new DialogInterface.OnClickListener() {
34                                                     public void onClick(DialogInterface dialog, int whichButton) {
35                                                         GameActivity.getInstance().nativeOnSystemDialogResult( mOnYesAddr );
36                                                     }
37                                                 })
38                 .setNegativeButton( mNo, new DialogInterface.OnClickListener() {
39                                                     public void onClick(DialogInterface dialog, int whichButton) {
40                                                         GameActivity.getInstance().nativeOnSystemDialogResult( mOnNoAddr );
41                                                     }
42                                                 })
43                 .setCancelable(false)
44                 .create();
45                 dialog.show();
46             }else {
47                 Dialog dialog = new AlertDialog.Builder( GameActivity.getInstance() )
48                 .setTitle(mTitle)
49                 .setMessage(mMessage)
50                 .setPositiveButton( mNo, new DialogInterface.OnClickListener() {
51                                                     public void onClick(DialogInterface dialog, int whichButton) {
52                                                         GameActivity.getInstance().nativeOnSystemDialogResult( mOnYesAddr );
53                                                     }
54                                                 })
55                 .setCancelable(false)
56                 .create();
57                 dialog.show();
58             }
59         }
60     }
61
62
63     //////////////////////////////////////////////////////////////////////////
64     //Cooperate with native code. DO NOT call on Java
65     //////////////////////////////////////////////////////////////////////////
66     public void showDialogYesNo(String title, String showText, String locYes, String locNo, long onYesAddr, long onNoAddr) {
67         this.runOnUiThread( new DialogRunnable(title, showText, locYes, locNo, onYesAddr, onNoAddr, true) );
68     }
69
70
71
72     

C (for C++, JNI calls are simpler & different)

1 JNIEXPORT void JNICALL Java_com_org_package_GameActivity_nativeOnSystemDialogResult(JNIEnv *env, jobject thiz, jlong functionAddr)
2 {
3     typedef void(*FUNCPTR)(void);
4     FUNCPTR ptr = (FUNCPTR)(void*)function;
5     if( ptr != null )
6         ptr();
7 }

 1 //////////////////////////////////////////////////////////////////////////
 2 //Note: onOK & onCancel can be NULL
 3 void    Android_SystemDialog(const char* title, const char* message, const char* yes, const char* no, void(*onOK)(void), void(*onCancel)(void) )
 4 {
 5     android_app* app = GetApp();
 6     JNIEnv* env = app->activity->env;
 7     //note: we need to attach dalvik VM to current thread, as it is not main thread
 8     JavaVM* vm = app->activity->vm;
 9     if ( (*vm)->GetEnv(vm, (void **)&env, JNI_VERSION_1_6) < 0 )
10         (*vm)->AttachCurrentThread(vm, &env, NULL);
11
12     jclass ActivityClass = (*env)->GetObjectClass(env, app->activity->clazz);
13     jmethodID java_method = (*env)->GetMethodID(env, ActivityClass,
14         (char8*)"showDialogYesNo",
15         (char8*)"(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;JJ)V");
16     assert( java_method != NULL );
17
18     jstring jTitle = (*env)->NewStringUTF(env, title, strlen(title) );
19     jstring jMsg = (*env)->NewStringUTF(env, message, strlen(message) );
20     jstring jOK = (*env)->NewStringUTF(env, yes, strlen(yes) );
21     jstring jCancel = (*env)->NewStringUTF(env, no, strlen(no) );
22     //Note: jlong is 64 bit
23     jlong jOnOK = (intptr_t)onOK;
24     jlong jOnCancel = (intptr_t)onCancel;
25     //invoke UI Dialog in another thread
26     (*env)->CallVoidMethod(env, app->activity->clazz , java_method, jTitle, jMsg, jOK, jCancel, jOnOK, jOnCancel);
27
28     (*env)->DeleteLocalRef(env, jTitle);
29     (*env)->DeleteLocalRef(env, jMsg);
30     (*env)->DeleteLocalRef(env, jOK);
31     (*env)->DeleteLocalRef(env, jCancel);
32     (*env)->DeleteLocalRef(env, ActivityClass);
33 }

native usage sample:

 1 static void OnExit()
 2 {
 3     exit(0);
 4 }
 5
 6 void Android_Confirm_Exit()
 7 {
 8     const char* title = "Quit";
 9     const char* message = "Unsaved progress will be lost.\nAre you sure you want to quit game?";
10     const char* yes = "Ok";
11     const char* no = "Cancel";
12     Android_SystemDialog(title, message, yes, no, &OnExit, NULL);
13 }