JNI中的java类参数传递

public class testJNI {
public static final int a = 0;
public static final int b = 1;
public static final int c = 2;
public static final int d = 3;

public native int function1(javaclass1 param_in);
public native int function2(javaclass2 param_in);

static {
System.loadLibrary("exampleJNI");
}
}

<pre name="code" class="cpp">JNIEXPORT jint JNICALL Java_com_example_test_function1(JNIEnv *env, jobject obj, jobject objp)
{

javaclass1 param_in;
int flag = 0;
jclass objClass = (*env)->FindClass(env, "com/example/test/javaclass1");//这里必须直接指明参数类型
jfieldID membername1 = (*env)->GetFieldID(env, objClass, "member1", "I");
jfieldID membername2 = (*env)->GetFieldID(env, objClass, "member2", "I");
jfieldID membername3 = (*env)->GetFieldID(env, objClass, "member3", "I");
jfieldID membername4 = (*env)->GetFieldID(env, objClass, "member4", "I");
jint membervalue1 = (*env)->GetIntField(env, objp, membername1);
jint membervalue2 = (*env)->GetIntField(env, objp, membername2);
jint membervalue3 = (*env)->GetIntField(env, objp, membername3);
jint membervalue4 = (*env)->GetIntField(env, objp, membernane4);

//将解析出来的参数打包，传递给C function
param_in.member1 = membervalue1;
param_in.member2 = membervalue2;
param_in.member3 = membervalue3;
param_in.member4 = membervalue4;

handle = cfunctioncall1(¶m_in);//c 函数

if(handle == NULL)
{
flag = -1;
}

return((jint) flag);
}

<pre name="code" class="cpp">下面说说包含数组的java类参数传递

JNIEXPORT jint JNICALL Java_com_example_test_function2(JNIEnv *env, jobject obj, jint cmd, jobject objp){double* gx_data, *gy_data, *gz_data;javaclass2 g_data;// javaclass 里面包含三个大小一样double类型的数组jclass objClass = (*env)->FindClass(env, "com/example/testact/javaclass2");//获取参数的类型jfieldID gx_name = (*env)->GetFieldID(env, objClass, "gx", "[D");//获取域名jfieldID gy_name = (*env)->GetFieldID(env, objClass, "gy", "[D");jfieldID gz_name = (*env)->GetFieldID(env, objClass, "gz", "[D");jdoubleArray gx_objArray = (*env)->GetObjectField(env, objp, gx_name);//获取数组类型域，这个与int的成员不同，要进一步解析jdoubleArray gy_objArray = (*env)->GetObjectField(env, objp, gy_name);jdoubleArray gz_objArray = (*env)->GetObjectField(env, objp, gz_name);jdouble* gx_ptr = (*env)->GetDoubleArrayElements(env, gx_objArray, NULL);//获取数据指针jdouble* gy_ptr = (*env)->GetDoubleArrayElements(env, gy_objArray, NULL);jdouble* gz_ptr = (*env)->GetDoubleArrayElements(env, gz_objArray, NULL);jsize len = (*env)->GetArrayLength(env, gx_objArray);// 数组长度gx_data = (double*)Mymalloc(len, sizeof(double));//copy到本地用的buffergy_data = (double*)Mymalloc(len, sizeof(double));gz_data = (double*)Mymalloc(len, sizeof(double));if((gx_data == NULL)||(gy_data == NULL)||(gz_data == NULL)){LOGE("Err! malloc memory failed! %s %d\n", __FILE__, __LINE__);goto err;}memcpy(gx_data, gx_ptr, sizeof(double)*len);//copy到本地memcpy(gy_data, gy_ptr, sizeof(double)*len);memcpy(gz_data, gz_ptr, sizeof(double)*len);(*env)->ReleaseDoubleArrayElements(env, gx_objArray, gx_ptr, 0);//释放，这个是必须的，切勿忘记(*env)->ReleaseDoubleArrayElements(env, gy_objArray, gy_ptr, 0);(*env)->ReleaseDoubleArrayElements(env, gz_objArray, gz_ptr, 0);g_data.gx = gx_data;g_data.gy = gy_data;g_data.gz = gz_data;jint ret = cfunctioncall2(handle, cmd, (unsigned int)&g_data));Myfree(gx_data);Myfree(gy_data);Myfree(gz_data);return(ret);err:Myfree(gx_data);Myfree(gy_data);Myfree(gz_data);return((jint)(-1));}