Java C中使用JNI未定义CallXXXMethod
因此,我尝试使用JNI接口从C调用Java方法。 调用静态方法没有问题,但是当我想调用对象上的方法时,我会陷入困境。代码如下:Java C中使用JNI未定义CallXXXMethod,java,c,java-native-interface,Java,C,Java Native Interface,因此,我尝试使用JNI接口从C调用Java方法。 调用静态方法没有问题,但是当我想调用对象上的方法时,我会陷入困境。代码如下: #include <stdio.h> #include <string.h> #include <jni.h> int main() { JavaVMOption options[1]; JNIEnv *env; JavaVM *jvm; JavaVMInitArgs vm_args; lo
#include <stdio.h>
#include <string.h>
#include <jni.h>
int main()
{
JavaVMOption options[1];
JNIEnv *env;
JavaVM *jvm;
JavaVMInitArgs vm_args;
long status;
jclass cls, cls2;
jmethodID mid;
jint square;
jboolean not;
jobject person;
options[0].optionString ="-Djava.class.path=.";
memset(&vm_args, 0, sizeof(vm_args));
vm_args.version = JNI_VERSION_1_8;
vm_args.nOptions = 1;
vm_args.options = options;
status = JNI_CreateJavaVM(&jvm, (void **)&env, &vm_args);
if (status != JNI_ERR) {
cls = (*env)->FindClass(env, "Test");
if (cls != 0) {
mid = (*env)->GetStaticMethodID(env, cls, "square", "(I)I");
if (mid != 0) {
square = (*env)->CallStaticIntMethod(env, cls, mid, 7);
printf("Square: %i\n", square);
}
/*mid = (*env)->GetStaticMethodID(env, cls, "newWindow", "()V");
if (mid) {
(*env)->CallStaticVoidMethod(env, cls, mid, NULL);
}*/
mid = (*env)->GetStaticMethodID(env, cls, "newPerson", "(ILjava/lang/String;)LPerson;");
if (mid) {
person = (*env)->CallStaticObjectMethod(env, cls, mid, 23, "Nox");
cls2 = (*env)->FindClass(env, "Person");
mid = (*env)->GetMethodID(env, cls2, "getAge", "()I");
jint age = (*env)->CallIntMethod(env, cls2, mid, NULL);
printf("age: %i\n", age);
}
}
(*jvm)->DestroyJavaVM(jvm);
return 0;
}
}
我的Java代码非常简单:
class Person {
private int age;
private String name;
public Person(int age, String name) {
this.age = age;
this.name = name;
}
public int getAge() {
return this.age;
}
public String getName() {
return this.name;
}
}
class Test {
public static int square(int n) {
return n * n;
}
public static boolean not(boolean bool) {
return !bool;
}
public static Person newPerson(int age, String name) {
return new Person(age, name);
}
}
代码中需要的修复程序很少:
CallIntMethod
应该是(*env)->CallIntMethod
类测试
应该是公共测试
jint age=(*env)->CallIntMethod(env,mod_obj,mid,NULL)代码>
它不应该是
(*env)->CallIntMethod(…)
?耶稣。。是的,你说得对。我已经在代码上扮演主角太久了。谢谢<代码>类测试应该是公共的
可以,但这并不能解决问题:(你必须测试每个JNI方法的结果。不仅仅是其中的一些。例如,你不是在测试最终的GetMethodID()
结果。啊,一个简单的输入。非常感谢!=)如果它有帮助,我很高兴
class Person {
private int age;
private String name;
public Person(int age, String name) {
this.age = age;
this.name = name;
}
public int getAge() {
return this.age;
}
public String getName() {
return this.name;
}
}
class Test {
public static int square(int n) {
return n * n;
}
public static boolean not(boolean bool) {
return !bool;
}
public static Person newPerson(int age, String name) {
return new Person(age, name);
}
}
mid = (*env)->GetStaticMethodID(env, cls, "newPerson", "(ILjava/lang/String;)LPerson;");
mod_obj = mid;
if (mid) {
person = (*env)->CallStaticObjectMethod(env, cls, mid, 23, "Nox");
cls2 = (*env)->FindClass(env, "Person");
mid = (*env)->GetMethodID(env, cls2, "getAge", "()I");
jint age = (*env)->CallIntMethod(env, mid_obj, mid, NULL);
printf("age: %i\n", age);
}