JNI各类型参数互相调用示例(二)__臣本布衣

http://blog.sina.com.cn/u/1920717142

首页博文目录关于我

个人资料

微博

加好友发纸条

写留言加关注

博客等级：
博客积分：

博客访问：
关注人气：
获赠金笔：0支
赠出金笔：0支
荣誉徽章：

正文字体大小：大中小

JNI各类型参数互相调用示例(二)

(2013-01-09 21:40:58)

标签：

ndk

jni

android

it

jni和java之间字符串的转换方法。
　　C的实现:
　　JNIEXPORT jstring JNICALL Java_Android123_CwjC (JNIEnv env, jobject obj, jstring string)
　　{
　　　char szBuffer[255];
　　　return (env)->NewStringUTF(env, szBuffer);
　　}
　　C++的实现:
　　JNIEXPORT jstring JNICALL Java_Android123_CwjCpp (JNIEnv env, jobject obj, jstring string)
　　{
　　const char strUTF = env->GetStringUTFChars(string, 0);
　　char szBuffer[255];
　　strcpy(szBuffer, strUTF);
　　env->ReleaseStringUTFChars(string, strUTF);
　　return env->NewStringUTF(szBuffer);
　　}

java中string与byte[]的转换

1.string 转 byte[]

byte[] midbytes=isoString.getBytes("UTF8");

//为UTF8编码

byte[] isoret = srt2.getBytes("ISO-8859-1");

//为ISO-8859-1编码

其中ISO-8859-1为单字节的编码

2.byte[]转string

String isoString = new String(bytes,"ISO-8859-1");

String srt2=new String(midbytes,"UTF-8");

//jbytearray转c++byte数组
	jbyte * arrayBody = env->GetByteArrayElements(data,0);

3	jsize theArrayLengthJ = env->GetArrayLength(data);
4	BYTE * starter = (BYTE *)arrayBody;

1	//jbyteArray 转 c++中的BYTE[]
2	//jbytearray array

3	jbyte * olddata = (jbyte*)env->GetByteArrayElements(array, 0);
4	jsize oldsize = env->GetArrayLength(array);

5	BYTE* bytearr = (BYTE*)olddata;
6	int len = (int)oldsize;

1	//C++中的BYTE[]转jbyteArray
2	//nOutSize是BYTE数组的长度 BYTE pData[]

3	jbyte by = (jbyte)pData;
4	jbyteArray jarray = env->NewByteArray(nOutSize);

5	env->SetByteArrayRegin(jarray, 0, nOutSize, by);

1	//jbyteArray 转 char *
2	char* data = (char*)env->GetByteArrayElements(strIn, 0);

1	//char* 转jstring
2	jstring WindowsTojstring(JNIEnv* env, char* str_tmp)

3	{
4	jstring rtn=0;

5	int slen = (int)strlen(str_tmp);
6	unsigned short* buffer=0;

7	if(slen == 0)
8	{

9	rtn = env->NewStringUTF(str_tmp);
10		}

11	else
12	{

13	int length = MultiByteToWideChar(CP_ACP, 0, (LPCSTR)str_tmp, slen, NULL, 0);
14	buffer = (unsigned short)malloc(length2+1);

15	if(MultiByteToWideChar(CP_ACP, 0, (LPCSTR)str_tmp, slen, (LPWSTR)buffer, length) > 0)
16	{

17	rtn = env->NewString((jchar*)buffer, length);
18	}

19	}
20	if(buffer)

21	{
22	free(buffer);

23	}
24	return rtn;

}

1	//jstring 转 char* 或者 const char*
2	// jstring str

3	const char *key = env->GetStringUTFChars(str, 0);
4	//jboolean isOffer

5	jsClient->modify(key, isOffer);
6	//需要释放，否则容易内存泄露

7	env->ReleaseStringUTFChars(str, key);

1	//JNI 返回 jbyteArray
2	JNIEXPORT jbyteArray JNICALL Java_Test_getByteArray(JNIEnv *env, jobject obj)

3	{
4	jbyteArray firstMacArray = env->NewByteArray( 6 );

5	......
6	jbyte *bytes = env->GetByteArrayElements( firstMacArray, 0);

7	for ( int i = 0; i < sizeof( pAdapterInfo->Address ); i++ )
8	{

9	bytes[ i ] = pAdapterInfo->Address[ i ];
10		}

11
12	env->SetByteArrayRegion(firstMacArray, 0, 6, bytes );

13		return firstMacArray;
14		}
1	//jstring to char*

2	char* jstringTostring(JNIEnv* env, jstring jstr)
3	{

4	char* rtn = NULL;
5	jclass clsstring = env->FindClass("java/lang/String");

6	jstring strencode = env->NewStringUTF("utf-8");
7	jmethodID mid = env->GetMethodID(clsstring, "getBytes", "(Ljava/lang/String;)[B");

8	jbyteArray barr= (jbyteArray)env->CallObjectMethod(jstr, mid, strencode);
9	jsize alen = env->GetArrayLength(barr);

10	jbyte* ba = env->GetByteArrayElements(barr, JNI_FALSE);
11	if (alen > 0)

12	{
13	rtn = (char*)malloc(alen + 1);

14	memcpy(rtn, ba, alen);
15	rtn[alen] = 0;

16	}
17	env->ReleaseByteArrayElements(barr, ba, 0);

18	return rtn;
19	}

1	*////char to jstring**
2	jstring stoJstring(JNIEnv* env, const char* pat)

3	{
4	jclass strClass = env->FindClass("Ljava/lang/String;");

5	jmethodID ctorID = env->GetMethodID(strClass, "", "([BLjava/lang/String;)V");
6	jbyteArray bytes = env->NewByteArray(strlen(pat));

7	env->SetByteArrayRegion(bytes, 0, strlen(pat), (jbyte*)pat);
8	jstring encoding = env->NewStringUTF("utf-8");

9	return (jstring)env->NewObject(strClass, ctorID, bytes, encoding);
10		}

1	//将jstring类型转换成windows类型
2	char* jstringToWindows( JNIEnv *env, jstring jstr )

3	{
4	int length = (env)->GetStringLength(jstr );

5	const jchar* jcstr = (env)->GetStringChars(jstr, 0 );
6	char* rtn = (char)malloc( length2+1 );

7	int size = 0;
8	size = WideCharToMultiByte( CP_ACP, 0, (LPCWSTR)jcstr, length, rtn,(length*2+1), NULL, NULL );

9	if( size <= 0 )
10		return NULL;

11	(env)->ReleaseStringChars(jstr, jcstr );
12	rtn[size] = 0;

13	return rtn;
14	}

1	//将windows类型转换成jstring类型
2	jstring WindowsTojstring( JNIEnv* env, char* str )

3	{
4	jstring rtn = 0;

5	int slen = strlen(str);
6	unsigned short * buffer = 0;

7	if( slen == 0 )
8	rtn = (env)->NewStringUTF(str );

9	else
10		{

11	int length = MultiByteToWideChar( CP_ACP, 0, (LPCSTR)str, slen, NULL, 0 );
12	buffer = (unsigned short )malloc( length2 + 1 );

13	if( MultiByteToWideChar( CP_ACP, 0, (LPCSTR)str, slen, (LPWSTR)buffer, length ) >0 )
14	rtn = (env)->NewString( (jchar*)buffer, length );

15	}
16	if( buffer )

17	free( buffer );
18	return rtn;

19	}
20

1	//从传进来的对象中取出byte[]
2	jfieldID byteData = (env)->GetFieldID(clazz,"bData","[B");

3	jbyteArray pDataIn = (jbyteArray) (env)->GetObjectField(objDataIn, byteData);
4	jsize theArrayLeng = env->GetArrayLength(pDataIn);

1	//byte[]转为BYTE[]
2	jbyte * arrayBody = env->GetByteArrayElements(pDataIn,0);

3	BYTE * jDataIn = (BYTE *)arrayBody;

JNI开发交流 C/C++,JAVA，android，linux/unix QQ群：25093009

1	//将BYTE数组转为jarray
2	jbyte* byte = (jbyte*)jDataOut;

3	jbyteArray jarray = env->NewByteArray(theArrayLeng);
4	env->SetByteArrayRegion(jarray, 0, theArrayLeng, byte);

1	//给每一个实例的变量付值
2	(env)->SetObjectField(objDataIn,byteData,jarray);

3	(env)->SetIntField(objDataIn,pDataInLen,jDataInLen);
4	(env)->ReleaseByteArrayElements(pDataIn, arrayBody, 0);

阅读┊ 收藏 ┊ 喜欢 ▼ ┊打印┊举报/Report

前一篇：JNI各类型参数互相调用示例

后一篇：Linux下使用netbeans开发JNI官方教程

新浪BLOG意见反馈留言板　欢迎批评指正