Android JNI 使用的数据结构JNINativeMethod详解
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最近在做关于Android语音识别的东东。研究Recognizer源码的时候碰到个关于JNINativeMethod的结构体,不解,Google之在网上找到了片文章,见文后。结构体代码如下:
/* * Table of methods associated with a single class. */static JNINativeMethod gMethods[] = { /* name, signature, funcPtr */ // PMem {"PMemInit", "()V", (void*)Java_android_speech_srec_Recognizer_PMemInit}, {"PMemShutdown", "()V", (void*)Java_android_speech_srec_Recognizer_PMemShutdown}, // SR_Session {"SR_SessionCreate", "(Ljava/lang/String;)V", (void*)Java_android_speech_srec_Recognizer_SR_1SessionCreate}, {"SR_SessionDestroy", "()V", (void*)Java_android_speech_srec_Recognizer_SR_1SessionDestroy}, // SR_Recognizer {"SR_RecognizerStart", "(I)V", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerStart}, {"SR_RecognizerStop", "(I)V", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerStop}, {"SR_RecognizerCreate", "()I", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerCreate}, {"SR_RecognizerDestroy", "(I)V", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerDestroy}, {"SR_RecognizerSetup", "(I)V", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerSetup}, {"SR_RecognizerUnsetup", "(I)V", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerUnsetup}, {"SR_RecognizerIsSetup", "(I)Z", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerIsSetup}, {"SR_RecognizerGetParameter", "(ILjava/lang/String;)Ljava/lang/String;", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerGetParameter}, {"SR_RecognizerGetSize_tParameter", "(ILjava/lang/String;)I", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerGetSize_1tParameter}, {"SR_RecognizerGetBoolParameter", "(ILjava/lang/String;)Z", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerGetBoolParameter}, {"SR_RecognizerSetParameter", "(ILjava/lang/String;Ljava/lang/String;)V", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerSetParameter}, {"SR_RecognizerSetSize_tParameter", "(ILjava/lang/String;I)V", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerSetSize_1tParameter}, {"SR_RecognizerSetBoolParameter", "(ILjava/lang/String;Z)V", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerSetBoolParameter}, {"SR_RecognizerSetupRule", "(IILjava/lang/String;)V", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerSetupRule}, {"SR_RecognizerHasSetupRules", "(I)Z", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerHasSetupRules}, {"SR_RecognizerActivateRule", "(IILjava/lang/String;I)V", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerActivateRule}, {"SR_RecognizerDeactivateRule", "(IILjava/lang/String;)V", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerDeactivateRule}, {"SR_RecognizerDeactivateAllRules", "(I)V", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerDeactivateAllRules}, {"SR_RecognizerIsActiveRule", "(IILjava/lang/String;)Z", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerIsActiveRule}, {"SR_RecognizerCheckGrammarConsistency", "(II)Z", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerCheckGrammarConsistency}, {"SR_RecognizerPutAudio", "(I[BIIZ)I", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerPutAudio}, {"SR_RecognizerAdvance", "(I)I", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerAdvance}, {"SR_RecognizerIsSignalClipping", "(I)Z", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerIsSignalClipping}, {"SR_RecognizerIsSignalDCOffset", "(I)Z", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerIsSignalDCOffset}, {"SR_RecognizerIsSignalNoisy", "(I)Z", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerIsSignalNoisy}, {"SR_RecognizerIsSignalTooQuiet", "(I)Z", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerIsSignalTooQuiet}, {"SR_RecognizerIsSignalTooFewSamples", "(I)Z", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerIsSignalTooFewSamples}, {"SR_RecognizerIsSignalTooManySamples", "(I)Z", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerIsSignalTooManySamples}, // SR_AcousticState {"SR_AcousticStateReset", "(I)V", (void*)Java_android_speech_srec_Recognizer_SR_1AcousticStateReset}, {"SR_AcousticStateSet", "(ILjava/lang/String;)V", (void*)Java_android_speech_srec_Recognizer_SR_1AcousticStateSet}, {"SR_AcousticStateGet", "(I)Ljava/lang/String;", (void*)Java_android_speech_srec_Recognizer_SR_1AcousticStateGet}, // SR_Grammar {"SR_GrammarCompile", "(I)V", (void*)Java_android_speech_srec_Recognizer_SR_1GrammarCompile}, {"SR_GrammarAddWordToSlot", "(ILjava/lang/String;Ljava/lang/String;Ljava/lang/String;ILjava/lang/String;)V", (void*)Java_android_speech_srec_Recognizer_SR_1GrammarAddWordToSlot}, {"SR_GrammarResetAllSlots", "(I)V", (void*)Java_android_speech_srec_Recognizer_SR_1GrammarResetAllSlots}, {"SR_GrammarSetupVocabulary", "(II)V", (void*)Java_android_speech_srec_Recognizer_SR_1GrammarSetupVocabulary}, {"SR_GrammarSetupRecognizer", "(II)V", (void*)Java_android_speech_srec_Recognizer_SR_1GrammarSetupRecognizer}, {"SR_GrammarUnsetupRecognizer", "(I)V", (void*)Java_android_speech_srec_Recognizer_SR_1GrammarUnsetupRecognizer}, {"SR_GrammarCreate", "()I", (void*)Java_android_speech_srec_Recognizer_SR_1GrammarCreate}, {"SR_GrammarDestroy", "(I)V", (void*)Java_android_speech_srec_Recognizer_SR_1GrammarDestroy}, {"SR_GrammarLoad", "(Ljava/lang/String;)I", (void*)Java_android_speech_srec_Recognizer_SR_1GrammarLoad}, {"SR_GrammarSave", "(ILjava/lang/String;)V", (void*)Java_android_speech_srec_Recognizer_SR_1GrammarSave}, {"SR_GrammarAllowOnly", "(ILjava/lang/String;)V", (void*)Java_android_speech_srec_Recognizer_SR_1GrammarAllowOnly}, {"SR_GrammarAllowAll", "(I)V", (void*)Java_android_speech_srec_Recognizer_SR_1GrammarAllowAll}, // SR_Vocabulary {"SR_VocabularyLoad", "()I", (void*)Java_android_speech_srec_Recognizer_SR_1VocabularyLoad}, {"SR_VocabularyDestroy", "(I)V", (void*)Java_android_speech_srec_Recognizer_SR_1VocabularyDestroy}, {"SR_VocabularyGetPronunciation", "(ILjava/lang/String;)Ljava/lang/String;", (void*)Java_android_speech_srec_Recognizer_SR_1VocabularyGetPronunciation}, // SR_RecognizerResult {"SR_RecognizerResultGetWaveform", "(I)[B", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerResultGetWaveform}, {"SR_RecognizerResultGetSize", "(I)I", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerResultGetSize}, {"SR_RecognizerResultGetKeyCount", "(II)I", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerResultGetKeyCount}, {"SR_RecognizerResultGetKeyList", "(II)[Ljava/lang/String;", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerResultGetKeyList}, {"SR_RecognizerResultGetValue", "(IILjava/lang/String;)Ljava/lang/String;", (void*)Java_android_speech_srec_Recognizer_SR_1RecognizerResultGetValue},};
Andoird 中使用了一种不同传统Java JNI的方式来定义其native的函数。其中很重要的区别是Andorid使用了一种Java 和 C 函数的映射表数组,并在其中描述了函数的参数和返回值。这个数组的类型是JNINativeMethod,定义如下:
typedef struct {const char* name;const char* signature;void* fnPtr;} JNINativeMethod;
第一个变量name是Java中函数的名字。
第二个变量signature,用字符串是描述了函数的参数和返回值
第三个变量fnPtr是函数指针,指向C函数。
其中比较难以理解的是第二个参数,例如
"()V"
"(II)V"
"(Ljava/lang/String;Ljava/lang/String;)V"
实际上这些字符是与函数的参数类型一一对应的。
"()" 中的字符表示参数,后面的则代表返回值。例如"()V" 就表示void Func();
"(II)V" 表示 void Func(int, int);
具体的每一个字符的对应关系如下
字符 Java类型 C类型
V void void
Z jboolean boolean
I jint int
J jlong long
D jdouble double
F jfloat float
B jbyte byte
C jchar char
S jshort short
数组则以"["开始,用两个字符表示
[I jintArray int[]
[F jfloatArray float[]
[B jbyteArray byte[]
[C jcharArray char[]
[S jshortArray short[]
[D jdoubleArray double[]
[J jlongArray long[]
[Z jbooleanArray boolean[]
上面的都是基本类型。如果Java函数的参数是class,则以"L"开头,以";"结尾中间是用"/" 隔开的包及类名。而其对应的C函数名的参数则为jobject. 一个例外是String类,其对应的类为jstring
Ljava/lang/String; String jstring
Ljava/net/Socket; Socket jobject
如果JAVA函数位于一个嵌入类,则用$作为类名间的分隔符。
例如 "(Ljava/lang/String;Landroid/os/FileUtils$FileStatus;)Z"
文章出处:http://hi.baidu.com/leicejbgnndjrze/item/b87a4895e06a6c1c924f41f4
另供参考:http://blog.csdn.net/bigapple88/article/details/6756204
- Android JNI 使用的数据结构JNINativeMethod详解
- Android JNI 使用的数据结构JNINativeMethod详解
- Android JNI 使用的数据结构JNINativeMethod详解
- Android JNI 使用的数据结构JNINativeMethod详解
- Android JNI 使用的数据结构JNINativeMethod详解
- Android JNI 使用的数据结构JNINativeMethod详解
- Android JNI使用的数据结构JNINativeMethod详解
- Android JNI 使用的数据结构JNINativeMethod详解
- Android JNI 使用的数据结构JNINativeMethod详解
- Android JNI 使用的数据结构JNINativeMethod详解
- Android JNI 使用的数据结构JNINativeMethod详解
- Android JNI 使用的数据结构JNINativeMethod详解
- Android JNI 使用的数据结构JNINativeMethod详解
- Android JNI 使用的数据结构JNINativeMethod详解
- Android JNI 使用的数据结构JNINativeMethod详解
- Android JNI 使用的数据结构JNINativeMethod详解
- Android JNI 使用的数据结构JNINativeMethod详解
- Android JNI 使用的数据结构JNINativeMethod详解
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