JNI的某些数组和字符串类型转换 (二)

//将windows类型转换成jstring类型
C代码 [c] view plaincopy jstring WindowsTojstring( JNIEnv* env, char* str )
{
jstring rtn = 0;
int slen = strlen(str);
unsigned short * buffer = 0;
if( slen == 0 )
rtn = (env)->NewStringUTF(str );
else
{
int length = MultiByteToWideChar( CP_ACP, 0, (LPCSTR)str, slen, NULL, 0 );
buffer = (unsigned short *)malloc( length*2 + 1 );
if( MultiByteToWideChar( CP_ACP, 0, (LPCSTR)str, slen, (LPWSTR)buffer, length ) >0 )
rtn = (env)->NewString( (jchar*)buffer, length );
}
if( buffer )
free( buffer );
return rtn;
}
/*JNIEXPORT jstring JNICALL Java_test_cs_web_SWIFTAlianceCASmfTest_strcal
(JNIEnv *env, jclass obj, jstring jstr1, jstring jstr2)
{
jbyteArray bytes = 0;
jthrowable exc;
char *pszResult = NULL;
char *pszSTR1 = NULL;
char *pszSTR2 = NULL;

pszSTR1 = jstringTostring(env, jstr1);
pszSTR2 = jstringTostring(env, jstr2);


int nlen = sizeof(char)*(strlen(pszSTR1)+strlen(pszSTR2));
pszResult = (char*)malloc(nlen);
strcpy(pszResult, pszSTR1);
strcat(pszResult, pszSTR2);

jstring jstrRe = stoJstring(env, pszResult);
free(pszSTR1);
free(pszSTR2);
free(pszResult);
return(jstrRe);
}
*/

jni object的使用

每一个jni格式的dll中的object对应该java里面的一个类。
如下例有一个 ObjData类，类中有成员bData ,Len
public class ObjData {
public byte[] bData;
public int Len;
}
//------------------------jni获得传过来的Object类型的变量objDataIn--------

jclass clazz =(env)->FindClass("ObjData");

//从传进来的对象中取出byte[]
C代码 [c]
jfieldID byteData = (env)->GetFieldID(clazz,"bData","[B");
jbyteArray pDataIn = (jbyteArray) (env)->GetObjectField(objDataIn, byteData);
jsize theArrayLeng = env->GetArrayLength(pDataIn);

//byte[]转为BYTE[]
C代码 [c]
jbyte * arrayBody = env->GetByteArrayElements(pDataIn,0);
BYTE * jDataIn = (BYTE *)arrayBody;

//将BYTE数组转为jarray
C代码 [c
jbyte* byte = (jbyte*)jDataOut;
jbyteArray jarray = env->NewByteArray(theArrayLeng);
env->SetByteArrayRegion(jarray, 0, theArrayLeng, byte);

//给每一个实例的变量付值
C代码 [c]
(env)->SetObjectField(objDataIn,byteData,jarray);
(env)->SetIntField(objDataIn,pDataInLen,jDataInLen);
(env)->ReleaseByteArrayElements(pDataIn, arrayBody, 0);