具有包时的 JNI 致命错误

JNI fatal error when having a package

本文关键字:JNI 致命错误 包时      更新时间:2023-10-16

如果我把java文件放在一个包里(比如jni/test/),执行时会出现致命错误。但是如果我不将文件放在包中,一切正常。

拥有包裹时:

javac jni/test/Main.java 
javah -jni jni.test.Main
g++ -shared -o libfoo.so -I/usr/lib/jvm/java-7-openjdk-i386/include -I/usr/lib/jvm/java-7-openjdk-i386/include/linux Main.cpp 
java -Djava.library.path=. jni/test/Main
#
# A fatal error has been detected by the Java Runtime Environment:
#
#  SIGSEGV (0xb) at pc=0xb6c1ce3c, pid=3704, tid=3060386624
#
# JRE version: 7.0_25-b30
# Java VM: OpenJDK Server VM (23.7-b01 mixed mode linux-x86 )
# Problematic frame:
# V  [libjvm.so+0x436e3c]  get_method_id(JNIEnv_*, _jclass*, char const*, char const*, bool, Thread*) [clone .isra.106]+0x7c
#
# Failed to write core dump. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
#
# An error report file with more information is saved as:
# /home/idle/workspace/JNITest/src/hs_err_pid3704.log
#
# If you would like to submit a bug report, please include
# instructions on how to reproduce the bug and visit:
#   https://bugs.launchpad.net/ubuntu/+source/openjdk-7/
#
Aborted

没有包时:

javac Main.java
javah -jni Main
g++ -shared -o libfoo.so -I/usr/lib/jvm/java-7-openjdk-i386/include -I/usr/lib/jvm/java-7-openjdk-i386/include/linux Main.cpp 
java -Djava.library.path=. Main
//This executes fine

我有 2 个 Java 类

public class Animal {
    public String name = null;
    public int age = 0;
}
public class Main {    
    public native Animal nativeFoo();    
    static {
        System.loadLibrary("foo");
    }        
    public void print () {
        Animal a = nativeFoo();
        System.out.println(a.name + " " + a.age);
    }
    public static void main(String[] args) {
    (new Main()).print();
    }
}

c++ 部分

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class Main */
#ifndef _Included_Main
#define _Included_Main
#ifdef __cplusplus
extern "C" {
#endif
/*
 * Class:     Main
 * Method:    nativeFoo
 * Signature: ()LAnimal;
 */
//if the java file in a package
//JNIEXPORT jobject JNICALL Java_jni_test_Main_nativeFoo (JNIEnv *env, jobject obxj)
JNIEXPORT jobject JNICALL Java_Main_nativeFoo
  (JNIEnv *, jobject);
#ifdef __cplusplus
}
#endif
#endif

cpp 文件

#include "Main.h"
//if the java file in a package
//JNIEXPORT jobject JNICALL Java_jni_test_Main_nativeFoo (JNIEnv *env, jobject obxj)
JNIEXPORT jobject JNICALL Java_Main_nativeFoo (JNIEnv *env, jobject obxj){
    jclass animal = env->FindClass("Animal");
    jmethodID cons = env->GetMethodID(animal, "<init>", "()V");
    jobject obj = env->NewObject(animal, cons);
    jfieldID age = env->GetFieldID(animal, "age", "I");
    jfieldID name = env->GetFieldID(animal, "name", "Ljava/lang/String;");
    env->SetObjectField(obj, name, env->NewStringUTF("awww"));
    env->SetIntField(obj, age, 23);
    return obj;
}

基于错误,即当通过env->GetMethodID()调用get_method_id(JNIEnv_*, _jclass*, char const*, char const*, bool, Thread*)时,您的 jclass 变量animal为空。

FindClass 调用失败,因为它找不到类"动物"。

验证类名和包定义是否正确。

请参阅此处用相同的 sigsegv 回答的类似问题

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