java - JNI、C++ 将字符串压入堆栈

Question

我的C++代码，将字符串推送到mystack

#include <iostream>
#include <stack>
#include "NativeLogger.h"


std::stack<std::string> mystack;


JNIEXPORT void JNICALL
Java_NativeLogger_push(JNIEnv *env, jobject obj,jstring name)
{

  std::string s = env->GetStringUTFChars(name, 0);

  mystack.push(s);

  return;
}

JNIEXPORT void JNICALL
Java_NativeLogger_pop(JNIEnv *env, jobject obj)
{

  mystack.pop();
  return;
}

使用 Java 运行时，我收到了以下崩溃报告，知道如何修复它吗？

A fatal error has been detected by the Java Runtime Environment:

SIGSEGV (0xb) at pc=0x00007f29421a0207, pid=18007, tid=0x00007f2942d3e700

JRE version: Java(TM) SE Runtime Environment (8.0_144-b01) (build 1.8.0_144-b01) Java VM: Java HotSpot(TM) 64-Bit Server VM (25.144-b01 mixed mode linux-amd64 compressed oops) Problematic frame: C [libc.so.6+0x97207] __libc_malloc+0x197

Answer 1

Java代码:

package recipeNo025;

public class HelloWorld {

  public static native void pushString(String s);
  public static native String popString();

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

  public static void main(String[] args) {
    HelloWorld.pushString("Hello");
    System.out.println(HelloWorld.popString());
  }
}

C++代码

#include <iostream>
#include <stack>
#include "jni.h"
#include "recipeNo025_HelloWorld.h"

std::stack<std::string> mystack;

JNIEXPORT void JNICALL Java_recipeNo025_HelloWorld_pushString
  (JNIEnv *env, jclass obj, jstring str) {

    // we have to get string bytes into C string
    const char *c_str;
    c_str = env->GetStringUTFChars(str, NULL);
    if(c_str == NULL) {
        return;
    }

    std::cout << "Passed string: " << c_str << std::endl;

    std::string my_string(c_str);
    mystack.push(my_string);

    // after using it, remember to release the memory
    env->ReleaseStringUTFChars(str, c_str);
}

JNIEXPORT jstring JNICALL Java_recipeNo025_HelloWorld_popString
  (JNIEnv *env, jclass obj) {

    std::string s = mystack.top();
    mystack.pop();
    return env->NewStringUTF(s.c_str());
}

执行:

> java -Djava.library.path=:./lib -cp target recipeNo025.HelloWorld
Passed string: Hello
Hello

此外，我还考虑过使用单例模式而不是使用堆栈的全局变量。