JNI_learn/c/reference/JNI_weakGlobalReference.c

#include <stdint.h>
#include "space_anyi_jni_reference_WeakGlobalReferenceTest.h"
JNIEXPORT jlong JNICALL Java_space_anyi_jni_reference_WeakGlobalReferenceTest_getPersonHandler(JNIEnv *env, jobject this){
        //1.获取对应的jclass
        jclass class_Person = (*env)->FindClass(env, "Lspace/anyi/jni/reference/Person;");
        //2.获取对应的构造方法
        jmethodID constructor = (*env)->GetMethodID(env, class_Person, "<init>", "(Ljava/lang/String;I)V");
        //3.创建对象
        jstring name = (*env)->NewStringUTF(env, "杨逸-弱引用");
        jobject person = (*env)->NewObject(env, class_Person, constructor,name,18);
        //4.获取全局弱引用
        jobject weakGlobalReference = (*env)->NewWeakGlobalRef(env, person);
        //5.转换为句柄,使用intptr_t类型作为中间类型,避免精度丢失
        jlong handler = (jlong)(intptr_t)weakGlobalReference;
        return handler;
}

JNIEXPORT jobject JNICALL Java_space_anyi_jni_reference_WeakGlobalReferenceTest_getPerson(JNIEnv *env, jobject this, jlong handler){
    //1.通过句柄获取全局弱引用,使用intptr_t类型作为中间类型
    jobject person = (jobject)(intptr_t)handler;
    return person;
}

JNIEXPORT void JNICALL Java_space_anyi_jni_reference_WeakGlobalReferenceTest_freePerson(JNIEnv *env, jobject this, jlong handler){
    //1.通过句柄获取全局弱引用,使用intptr_t类型作为中间类型
    jobject weakGlobalReference = (jobject)(intptr_t)handler;
    //2.释放全局弱引用
    (*env)->DeleteWeakGlobalRef(env, weakGlobalReference);
}