java - 使用 JNA 的 C 回调使 JRE 崩溃

Question

我在处理 JNA 中的回调时遇到问题。

我正在尝试使用一个使用回调来处理多个 session 事件(登录、注销、连接问题...)的 C API。
session 对象(称为 sp_session)是一个不透明的结构。所有回调都在 sp_session_callbacks 结构中注册。根据 API，我应该声明回调对象，并将其放入我将在创建 sp_session 对象时提供的 Config 对象中。如果我不想使用某些回调，我应该用 null 初始化它们。 API 使用 __stdcall 调用约定。

这是与我的问题相关的 C header 片段:

#define SP_CALLCONV __stdcall

typedef struct sp_session sp_session; ///< Representation of a session

typedef enum sp_error {
    SP_ERROR_OK                        = 0,  
    SP_ERROR_BAD_API_VERSION           = 1,
        /* More errors */
} sp_error;

typedef struct sp_session_callbacks {
    /**
     * Called when login has been processed and was successful
     */
    void (SP_CALLCONV *logged_in)(sp_session *session, sp_error error);

    /**
     * Called when logout has been processed. Either called explicitly
     * if you initialize a logout operation, or implicitly if there
     * is a permanent connection error
     *
     * @param[in]  session    Session
     */
    void (SP_CALLCONV *logged_out)(sp_session *session);

    /**
     * Called when there is a connection error, and the library has problems
     * reconnecting to the Spotify service. Could be called multiple times (as
     * long as the problem is present) 
     */
    void (SP_CALLCONV *connection_error)(sp_session *session, sp_error error);

    /* More callbacks */
} sp_session_callbacks;

/**
 * Initialize a session. The session returned will be initialized, but you will need
 * to log in before you can perform any other operation
 */
SP_LIBEXPORT(sp_error) sp_session_create(const sp_session_config *config, sp_session **sess);

这是我等效的 JNA 代码:

sp_session 对象

public class sp_session extends PointerType{

    public sp_session(Pointer address) {
        super(address);
    }
    public sp_session() {
        super();
    }
}

sp_session_callbacks 对象，包含所有回调

public class sp_session_callbacks extends Structure{
    public LoggedIn logged_in;
    public LoggedOut logged_out;
    public ConnectionError connection_error;
}

回调对象(这里是LoggedIn，当然我每个回调都有一个)

public interface LoggedIn extends StdCallCallback {
    public void logged_in(sp_session session, int error);
}

原生库，包含所有方法的声明

public interface JLibspotify extends StdCallLibrary{
    int sessionCreate(sp_session_config config, PointerByReference sess);
    int sessionLogin(sp_session session, String username, String password);
    // All the other methods defined by the API
}

还有我的主类，将它们绑定(bind)在一起

public class Test{
    static{
        System.loadLibrary("libspotify");
    }

    public static void main(String[] args){
        JLibspotify lib = (JLibspotify)Native.loadLibrary("libspotify", JLibspotify.class);
        sp_session_config cfg = new sp_session_config();
        }
        sp_session_callbacks sessCallbacks = new sp_session_callbacks();
        LoggedIn loggedInCallback = new LoggedIn(){
        public void logged_in(sp_session session, int error) {
             System.out.println("logged_in() called");
            }

        };
        sessCallbacks.logged_in = loggedInCallback;

        cfg.session_callbacks = sessCallbacks;

        PointerByReference sessionPbr = new PointerByReference();

        int error_id = sessionCreate(cfg, sessionPbr); // CRASHES HERE

        sp_session mySession = new sp_session(sessionPbr.getValue());
    }
}

因此，sessionCreate 函数调用使 JRE 崩溃，并在 EXCEPTION_ACCESS_VIOLATION (0xc0000005) 有问题的框架:C [jna3666290841889849729.dll+0xa3f4] 的末尾跟踪。

看起来是 logged_in 回调导致的，因为当我将它设置为 null 时它运行正常。另外，如果我初始化具有完全相同签名的 connection_error 回调，它也不会崩溃。

我正在运行 JNA 3.2.7 版。我尝试使用较早版本 (3.0.9)，但也失败了。我运行的是 JDK 1.7 beta 版，但我尝试使用 1.6，但也失败了。

谢谢!

#
# A fatal error has been detected by the Java Runtime Environment:
#
#  EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x0499a3f4, pid=1368, tid=1344
#
# JRE version: 7.0-b129
# Java VM: Java HotSpot(TM) Client VM (21.0-b01 mixed mode, sharing windows-x86 )
# Problematic frame:
# C  [jna3666290841889849729.dll+0xa3f4]
#
# If you would like to submit a bug report, please visit:
#   http://java.sun.com/webapps/bugreport/crash.jsp
# The crash happened outside the Java Virtual Machine in native code.
# See problematic frame for where to report the bug.
#

---------------  T H R E A D  ---------------

Current thread (0x01b79400):  JavaThread "main" [_thread_in_native, id=1344, stack(0x00340000,0x00390000)]

siginfo: ExceptionCode=0xc0000005, reading address 0x1993053a

Registers:
EAX=0x19930522, EBX=0x100dc77c, ECX=0x00010004, EDX=0x1008d3e0
ESP=0x0038f58c, EBP=0x0038f5b4, ESI=0x0038f5a4, EDI=0x100b79b0
EIP=0x0499a3f4, EFLAGS=0x00210212

Top of Stack: (sp=0x0038f58c)
0x0038f58c:   100dc77c 0038f5a4 00010004 0038f688
0x0038f59c:   05983de0 05981330 0598289c 05983de0
0x0038f5ac:   05983de0 00000014 0038f688 1008d3ea
0x0038f5bc:   05983de0 10030d77 0038fc44 100b79b0
0x0038f5cc:   ffffffff 1008d334 00000000 05983de0
0x0038f5dc:   1008d3e0 05983fc4 1008d9fd 0038f770
0x0038f5ec:   00000000 00000000 7275016a 055310b0
0x0038f5fc:   00000000 00010001 00000000 00000000 

Instructions: (pc=0x0499a3f4)
0x0499a3d4:   01 00 89 e5 57 56 8d 75 f0 53 83 ec 1c 8b 7d 14
0x0499a3e4:   8b 5f 4c 8b 03 89 4c 24 08 89 74 24 04 89 1c 24
0x0499a3f4:   ff 50 18 83 ec 0c 85 c0 0f 94 c0 0f b6 c0 85 c0
0x0499a404:   89 45 ec 75 19 8b 03 31 d2 89 54 24 08 89 74 24 


Register to memory mapping:

EAX=0x19930522 is an unknown value
EBX=0x100dc77c is an unknown value
ECX=0x00010004 is an unknown value
EDX=0x1008d3e0 is an unknown value
ESP=0x0038f58c is pointing into the stack for thread: 0x01b79400
EBP=0x0038f5b4 is pointing into the stack for thread: 0x01b79400
ESI=0x0038f5a4 is pointing into the stack for thread: 0x01b79400
EDI=0x100b79b0 is an unknown value


Stack: [0x00340000,0x00390000],  sp=0x0038f58c,  free space=317k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
C  [jna3666290841889849729.dll+0xa3f4]  Java_com_sun_jna_Native_initialize_1ffi_1type+0x1054
C  [libspotify.dll+0x8d3ea]  sp_error_message+0x35a
C  [jna3666290841889849729.dll+0xcb77]  Java_com_sun_jna_Native_initialize_1ffi_1type+0x37d7
C  [jna3666290841889849729.dll+0xc7c2]  Java_com_sun_jna_Native_initialize_1ffi_1type+0x3422
C  [jna3666290841889849729.dll+0x4561]  Java_com_sun_jna_Pointer__1getString+0xa31
C  [jna3666290841889849729.dll+0x4d2e]  Java_com_sun_jna_Function_invokeInt+0x2e
j  com.sun.jna.Function.invokeInt(I[Ljava/lang/Object;)I+0
j  com.sun.jna.Function.invoke([Ljava/lang/Object;Ljava/lang/Class;Z)Ljava/lang/Object;+315
j  com.sun.jna.Function.invoke(Ljava/lang/Class;[Ljava/lang/Object;Ljava/util/Map;)Ljava/lang/Object;+214
j  com.sun.jna.Library$Handler.invoke(Ljava/lang/Object;Ljava/lang/reflect/Method;[Ljava/lang/Object;)Ljava/lang/Object;+341
j  $Proxy0.sp_session_create(Lcom/nbarraille/jspotify/model/sp_session_config;Lcom/sun/jna/ptr/PointerByReference;)I+20
j  com.nbarraille.jspotify.main.Test.main([Ljava/lang/String;)V+273
v  ~StubRoutines::call_stub
V  [jvm.dll+0x115f6d]
V  [jvm.dll+0x1b788e]
V  [jvm.dll+0x115fed]
V  [jvm.dll+0xa2507]
V  [jvm.dll+0xac867]
C  [javaw.exe+0x209e]
C  [javaw.exe+0xa23b]
C  [javaw.exe+0xa2c5]
C  [kernel32.dll+0x51194]  BaseThreadInitThunk+0x12
C  [ntdll.dll+0x5b429]  RtlInitializeExceptionChain+0x63
C  [ntdll.dll+0x5b3fc]  RtlInitializeExceptionChain+0x36

Java frames: (J=compiled Java code, j=interpreted, Vv=VM code)
j  com.sun.jna.Function.invokeInt(I[Ljava/lang/Object;)I+0
j  com.sun.jna.Function.invoke([Ljava/lang/Object;Ljava/lang/Class;Z)Ljava/lang/Object;+315
j  com.sun.jna.Function.invoke(Ljava/lang/Class;[Ljava/lang/Object;Ljava/util/Map;)Ljava/lang/Object;+214
j  com.sun.jna.Library$Handler.invoke(Ljava/lang/Object;Ljava/lang/reflect/Method;[Ljava/lang/Object;)Ljava/lang/Object;+341
j  $Proxy0.sp_session_create(Lcom/nbarraille/jspotify/model/sp_session_config;Lcom/sun/jna/ptr/PointerByReference;)I+20
j  com.nbarraille.jspotify.main.Test.main([Ljava/lang/String;)V+273
v  ~StubRoutines::call_stub

---------------  P R O C E S S  ---------------

Java Threads: ( => current thread )
  0x0182fc00 JavaThread "Low Memory Detector" daemon [_thread_blocked, id=4664, stack(0x04170000,0x041c0000)]
  0x0182ac00 JavaThread "C1 CompilerThread0" daemon [_thread_blocked, id=1728, stack(0x01b20000,0x01b70000)]
  0x01829800 JavaThread "Attach Listener" daemon [_thread_blocked, id=112, stack(0x04020000,0x04070000)]
  0x01826400 JavaThread "Signal Dispatcher" daemon [_thread_blocked, id=5836, stack(0x03ea0000,0x03ef0000)]
  0x01819800 JavaThread "Finalizer" daemon [_thread_blocked, id=4724, stack(0x03f80000,0x03fd0000)]
  0x01817800 JavaThread "Reference Handler" daemon [_thread_blocked, id=3940, stack(0x01ad0000,0x01b20000)]
=>0x01b79400 JavaThread "main" [_thread_in_native, id=1344, stack(0x00340000,0x00390000)]

Other Threads:
  0x01816400 VMThread [stack: 0x01a30000,0x01a80000] [id=3876]
  0x01843000 WatcherThread [stack: 0x040d0000,0x04120000] [id=4636]

VM state:not at safepoint (normal execution)

VM Mutex/Monitor currently owned by a thread: None

Heap
 def new generation   total 4928K, used 3630K [0x23450000, 0x239a0000, 0x289a0000)
  eden space 4416K,  82% used [0x23450000, 0x237db858, 0x238a0000)
  from space 512K,   0% used [0x238a0000, 0x238a0000, 0x23920000)
  to   space 512K,   0% used [0x23920000, 0x23920000, 0x239a0000)
 tenured generation   total 10944K, used 0K [0x289a0000, 0x29450000, 0x33450000)
   the space 10944K,   0% used [0x289a0000, 0x289a0000, 0x289a0200, 0x29450000)
 compacting perm gen  total 12288K, used 860K [0x33450000, 0x34050000, 0x37450000)
   the space 12288K,   7% used [0x33450000, 0x33527190, 0x33527200, 0x34050000)
    ro space 10240K,  43% used [0x37450000, 0x3789ce40, 0x3789d000, 0x37e50000)
    rw space 12288K,  53% used [0x37e50000, 0x384c2710, 0x384c2800, 0x38a50000)

Code Cache  [0x01e90000, 0x01f20000, 0x03e90000)
 total_blobs=234 nmethods=82 adapters=88 free_code_cache=32972224 largest_free_block=0

Dynamic libraries:
0x00880000 - 0x008b0000     C:\Program Files\Java\jdk1.7.0\bin\javaw.exe
0x778f0000 - 0x77a2d000     C:\Windows\SYSTEM32\ntdll.dll
0x77070000 - 0x77144000     C:\Windows\system32\kernel32.dll
0x75cf0000 - 0x75d3a000     C:\Windows\system32\KERNELBASE.dll
0x60000000 - 0x60041000     C:\Program Files\BitDefender\BitDefender 2011\Active Virus Control\Midas_00078_002\midas32.dll
0x61000000 - 0x61028000     C:\Program Files\BitDefender\BitDefender 2011\Active Virus Control\Midas_00078_002\plugin_base.m32
0x67000000 - 0x67048000     C:\Program Files\BitDefender\BitDefender 2011\Active Virus Control\Midas_00078_002\plugin_nt.m32
0x64000000 - 0x64021000     C:\Program Files\BitDefender\BitDefender 2011\Active Virus Control\Midas_00078_002\plugin_registry.m32
0x62000000 - 0x6202d000     C:\Program Files\BitDefender\BitDefender 2011\Active Virus Control\Midas_00078_002\plugin_extra.m32
0x65000000 - 0x6501a000     C:\Program Files\BitDefender\BitDefender 2011\Active Virus Control\Midas_00078_002\plugin_net.m32
0x63000000 - 0x630a6000     C:\Program Files\BitDefender\BitDefender 2011\Active Virus Control\Midas_00078_002\plugin_fragments.m32
0x75e10000 - 0x75eb0000     C:\Windows\system32\ADVAPI32.dll
0x775c0000 - 0x7766c000     C:\Windows\system32\msvcrt.dll
0x75d50000 - 0x75d69000     C:\Windows\SYSTEM32\sechost.dll
0x77670000 - 0x77711000     C:\Windows\system32\RPCRT4.dll
0x76f00000 - 0x76fc9000     C:\Windows\system32\USER32.dll
0x77a50000 - 0x77a9e000     C:\Windows\system32\GDI32.dll
0x77a30000 - 0x77a3a000     C:\Windows\system32\LPK.dll
0x75d70000 - 0x75e0d000     C:\Windows\system32\USP10.dll
0x74830000 - 0x749ce000     C:\Windows\WinSxS\x86_microsoft.windows.common-controls_6595b64144ccf1df_6.0.7600.16661_none_420fe3fa2b8113bd\COMCTL32.dll
0x772f0000 - 0x77347000     C:\Windows\system32\SHLWAPI.dll
0x775a0000 - 0x775bf000     C:\Windows\system32\IMM32.DLL
0x75eb0000 - 0x75f7c000     C:\Windows\system32\MSCTF.dll
0x72740000 - 0x727fe000     C:\Program Files\Java\jdk1.7.0\jre\bin\msvcr100.dll
0x01b80000 - 0x01e89000     C:\Program Files\Java\jdk1.7.0\jre\bin\client\jvm.dll
0x746c0000 - 0x746f2000     C:\Windows\system32\WINMM.dll
0x73920000 - 0x7392c000     C:\Program Files\Java\jdk1.7.0\jre\bin\verify.dll
0x73330000 - 0x73350000     C:\Program Files\Java\jdk1.7.0\jre\bin\java.dll
0x75d40000 - 0x75d45000     C:\Windows\system32\PSAPI.DLL
0x733a0000 - 0x733b3000     C:\Program Files\Java\jdk1.7.0\jre\bin\zip.dll
0x10000000 - 0x10259000     C:\Windows\System32\libspotify.dll
0x77150000 - 0x77185000     C:\Windows\system32\WS2_32.dll
0x77a40000 - 0x77a46000     C:\Windows\system32\NSI.dll
0x75ba0000 - 0x75cbc000     C:\Windows\system32\CRYPT32.dll
0x75ab0000 - 0x75abc000     C:\Windows\system32\MSASN1.dll
0x74ee0000 - 0x74f38000     C:\Windows\system32\WINHTTP.dll
0x74e90000 - 0x74edf000     C:\Windows\system32\webio.dll
0x754c0000 - 0x754d6000     C:\Windows\system32\CRYPTSP.dll
0x75260000 - 0x7529b000     C:\Windows\system32\rsaenh.dll
0x750a0000 - 0x750b7000     C:\Windows\system32\USERENV.dll
0x75a40000 - 0x75a4b000     C:\Windows\system32\profapi.dll
0x75a30000 - 0x75a3c000     C:\Windows\system32\CRYPTBASE.dll
0x728a0000 - 0x728b6000     C:\Program Files\Java\jdk1.7.0\jre\bin\net.dll
0x75480000 - 0x754bc000     C:\Windows\system32\mswsock.dll
0x75470000 - 0x75476000     C:\Windows\System32\wship6.dll
0x73950000 - 0x73960000     C:\Windows\system32\NLAapi.dll
0x75340000 - 0x75384000     C:\Windows\system32\DNSAPI.dll
0x71030000 - 0x71038000     C:\Windows\System32\winrnr.dll
0x71020000 - 0x71030000     C:\Windows\system32\napinsp.dll
0x71000000 - 0x71012000     C:\Windows\system32\pnrpnsp.dll
0x74fd0000 - 0x74fd5000     C:\Windows\System32\wshtcpip.dll
0x74d30000 - 0x74d4c000     C:\Windows\system32\IPHLPAPI.DLL
0x74d20000 - 0x74d27000     C:\Windows\system32\WINNSI.DLL
0x70c60000 - 0x70c66000     C:\Windows\system32\rasadhlp.dll
0x71ba0000 - 0x71bd8000     C:\Windows\System32\fwpuclnt.dll
0x73930000 - 0x7393f000     C:\Program Files\Java\jdk1.7.0\jre\bin\nio.dll
0x04990000 - 0x049e5000     C:\Users\nbarraille\AppData\Local\Temp\jna3666290841889849729.dll

VM Arguments:
jvm_args: -Djava.library.path=C:\Windows\System32 -Dfile.encoding=Cp1252 
java_command: com.nbarraille.jspotify.main.Test
Launcher Type: SUN_STANDARD

Environment Variables:
PATH=C:/Program Files/Java/jdk1.7.0/bin/../jre/bin/client;C:/Program Files/Java/jdk1.7.0/bin/../jre/bin;C:/Program Files/Java/jdk1.7.0/bin/../jre/lib/i386;C:\Windows\System32
USERNAME=nbarraille
OS=Windows_NT
PROCESSOR_IDENTIFIER=x86 Family 6 Model 23 Stepping 10, GenuineIntel



---------------  S Y S T E M  ---------------

OS: Windows 7 Build 7600 

CPU:total 2 (2 cores per cpu, 1 threads per core) family 6 model 23 stepping 10, cmov, cx8, fxsr, mmx, sse, sse2, sse3, ssse3, sse4.1

Memory: 4k page, physical 3624108k(885020k free), swap 7246452k(3637664k free)

vm_info: Java HotSpot(TM) Client VM (21.0-b01) for windows-x86 JRE (1.7.0-ea-b129), built on Feb 10 2011 07:43:39 by "java_re" with unknown MS VC++:1600

time: Mon Mar 07 14:25:08 2011
elapsed time: 0 seconds

编辑:*用 C 语言测试 API 的代码*

#include "api.h"


/* --- Data --- */
const uint8_t g_appkey[] = {/*My appkey*/};


/* ---------------------------  SESSION CALLBACKS  ------------------------- */
static void logged_in(sp_session *sess, sp_error error){
    printf("logged_in() called: \n");
}

static void log_message(sp_session *sess, const char *data){
    printf("log_message() called %s : \n", data);
}

static void notify_main_thread(sp_session *sess){
    printf("notify_main_thread() called \n");
}

static sp_session_callbacks session_callbacks = {
    //.logged_in = (void*)&logged_in,
    //.notify_main_thread = (void*)&notify_main_thread,
    //.log_message = (void*)&log_message,
};

static sp_session_config spconfig = {
    .api_version = 7,
    .cache_location = "tmp",
    .settings_location = "tmp",
    .application_key = g_appkey,
    .application_key_size = sizeof(g_appkey),
    .user_agent = "jspotify",
    .callbacks = &session_callbacks,
    .userdata = NULL
};

int main(int argc, char **argv)
{
    sp_session *sp;

    const char *username = "foo";
    const char *password = "bar";

    spconfig.application_key_size = sizeof(g_appkey);


    printf("Creating session \n");

    sp_error err = sp_session_create(&spconfig, &sp);

    if(err != 0){
        printf("Error occured: %d \n", err);
        return 0;
    }

    printf("Login\n");
    sp_session_login(sp, username, password);

    Sleep(10000);
    return 0;
}

当我这样运行它(没有回调)时，输出是:

Creating session 
Login

当我注册回调(取消注释行)时，它甚至不打印任何东西!

看起来它在调用回调时不会打印任何内容，因为如果我注释 sp_session_login 行，只有 notify_main_thread 的声明(这是唯一的一个打印)将阻止程序打印...

Answer 1

当你有一个像这样的 C 结构时:

struct Foo {
   Bar* bar
}

即一个包含指向另一个结构的指针的 Bar (class Bar extends Structure) 的 JNA 实现也必须实现 Structure.ByReference 接口(interface)——否则 JNA 会认为 struct Foo 包含 struct Bar 的实例而不是指向 struct Bar 的指针，当 C 代码解释 a 时，将导致非法内存访问Bar 实例中的值作为指针。

您需要将 implements Structure.ByReference 添加到 sp_session_callbacks 类。

感谢您鼓励我关注 JNA——它非常酷!

这段代码的输出是:

sp_session_create returned 0
sp_session_login returned 0
log_message() called:14:16:53.825 I [ap:1388] Connecting to AP ap.spotify.com:4070

log_message() called:14:16:54.061 I [ap:938] Connected to AP: 193.182.8.11:4070

log_message() called:14:16:54.765 E [ap:3396] Connection error:  401

进程结束，退出代码为 0

import com.sun.jna.*;
import com.sun.jna.ptr.PointerByReference;

import java.sql.Connection;

public class JNATest {
//    static {
//        System.loadLibrary("libspotify");
//    }

    public interface JLibspotify extends Library {
        int sp_session_create(sp_session_config config, PointerByReference sess);

        int sp_session_login(sp_session session, String username, String password);
        // All the other methods defined by the API
    }

    public static class sp_session extends PointerType {

        public sp_session(Pointer address) {
            super(address);
        }

        public sp_session() {
            super();
        }
    }

    public static class sp_session_config extends Structure {
        public int api_version = 7; // The version of the Spotify API your application is compiled with.
        public String cache_location = ".";
        public String settings_location = ".";
        public Pointer application_key; // Your application key.
        public int application_key_size; // The size of the application key in bytes
        public String user_agent = "jspotify";
        public sp_session_callbacks callbacks; // Delivery callbacks for session events. NULL if not interested in any callbacks
        public Pointer userdata; // User supplied data for your application
        public boolean compress_playlists;
        public boolean dont_save_metadata_for_playlists;
        public boolean initially_unload_playlists;
    }

    public interface LoggedIn extends Callback {
        public void logged_in(sp_session session, int error);
    }

    public interface LoggedOut extends Callback {
        public void logged_out(sp_session session, int error);
    }

    public interface ConnectionError extends Callback {
        public void connection_error(sp_session session, int error);
    }

    public static class sp_session_callbacks extends Structure implements Structure.ByReference{
    public LoggedIn logged_in; // Called when login has been processed and was successful
    public LoggedOut logged_out; // Called when logout has been processded. Either called explicitly if you initialize a logout operation, or implicitly if there is a permanent connection error.
    public Callback metadata_updated; // Called whenever metadata has been updated. If you have metadata cached outside of libspotify, you should purge your caches and fetch new versions.
    public ConnectionError connection_error; // Called when there is a connection error, and the library has problems reconnecting to the Spotify service. Could be called multiple times (as long as the problem is present)
    public Callback message_to_user; // Called when the acces point wants to display a message to the user. In the desktop client, these are shown in a blueish toolbar just below the search box.
    public Callback notify_main_thread; // Called when processing needs to take place on the main thread. You need to call sp_session_process_events() in the main thread to get libspotify to do more work. Failure to do so may cause request timeouts, or a lost connections.
    public Callback music_delivery; // Called when there is decompressed audio data available.
    public Callback play_token_lost; // Music has been paused because only one account may play music at the same time.
    public Callback log_message; // Logging callback
    public Callback end_of_track; // End of track. Called when the currently played track has reached its end.
    public Callback streaming_error; // Streaming error. Called when streaming cannot start or continue.
    public Callback userinfo_updated; // Called after user info (anything related to sp_user objects) have been updated.
    public Callback start_playback; // Called when audio playback should start. For this to work correctly the application must also implement get_audio_buffer_stats(). This function is called from an internal session thread - you need to have proper synchronization. This function must never block.
    public Callback stop_playback; // Called when audio playback should stop. For this to work correctly the application must also implement get_audio_buffer_stats(). This function is called from an internal session thread - you need to have proper synchronization. This function must never block.
    public Callback get_audio_buffer_stats; // Called to query application about its audio buffer. This function is called from an internal session thread - you need to have proper synchronization! This function must never block.
}

    private static final char[] APP_KEY ={/* Appkey here**/;

    public static void main(String[] args) throws InterruptedException {
        JLibspotify lib = (JLibspotify) Native.loadLibrary("spotify", JLibspotify.class);
        sp_session_config cfg = new sp_session_config();
        Pointer ptr = new Memory(APP_KEY.length);
        ptr.write(0, toBytes(APP_KEY), 0, APP_KEY.length);
        cfg.application_key = ptr;
        cfg.application_key_size = APP_KEY.length;
        sp_session_callbacks sessCallbacks = new sp_session_callbacks();
        LoggedIn loggedInCallback = new LoggedIn() {
            public void logged_in(sp_session session, int error) {
                System.out.println("logged_in() called");
            }

        };
        ConnectionError connectionErrorCallback = new ConnectionError() {

            public void connection_error(sp_session session, int error) {
                System.out.println("connection_error() called");
            }
        };
        LoggedOut loggedOutCallback = new LoggedOut() {

            public void logged_out(sp_session session, int error) {
                System.out.println("logged_out() called");
            }
        };

        sessCallbacks.logged_in = loggedInCallback;
        sessCallbacks.connection_error = connectionErrorCallback;
        sessCallbacks.logged_out = loggedOutCallback;
        sessCallbacks.log_message = new Callback() {
            public void callback(sp_session session, String message) {
                System.out.println("log_message() called:" + message);
            }
        };
        cfg.callbacks = sessCallbacks;
        PointerByReference sessionPbr = new PointerByReference();

        int error_id = lib.sp_session_create(cfg, sessionPbr); // CRASHES HERE
        System.out.println("sp_session_create returned " + error_id);
//
        sp_session mySession = new sp_session(sessionPbr.getValue());
        error_id = lib.sp_session_login(mySession, "foo", "bar");
        System.out.println("sp_session_login returned " + error_id);
        Thread.sleep(1000);
    }

    public static byte[] toBytes(char[] key){
        byte[] b = new byte[key.length];
        for(int i =0; i < key.length; i++){
            if(key[i] > 127){
                b[i] = (byte)(key[i] - 256);
            }else{
                b[i] = (byte)key[i];
            }
        }
        return b;
    }
}

这是一个执行相同操作的 C 程序(回调较少——您需要添加更多回调)。它适用于 OS X，因此您可能需要更改 #include。由于我无法在澳大利亚获得 spotify，因此我无法对其进行测试以查看成功登录是否会触发回调，但日志记录回调有效。

#include <stdio.h>
#include <libspotify/api.h>

void SP_CALLCONV log_message(sp_session *session, const char *data) {
        fprintf(stderr,"log_message: %s\n", data);
        fflush(stderr);
}

void SP_CALLCONV connection_error(sp_session *session, sp_error error) {
        fprintf(stderr,"connection_error: %d\n", error);
        fflush(stderr);
}

int main(int argc, char** argv) {

        static byte APP_KEY[] = {
                /*the API key */};
        static sp_session_callbacks callbacks;
        callbacks.log_message = log_message;
        callbacks.connection_error = connection_error;
        static sp_session_config cfg;
        cfg.callbacks = &callbacks;
        cfg.api_version = 7;
        cfg.cache_location = ".";
        cfg.settings_location = ".";
        cfg.user_agent = "jspotify";
        cfg.application_key = APP_KEY;
        cfg.application_key_size = sizeof(APP_KEY);

        sp_session* mySession;
        int code = sp_session_create(&cfg, &mySession);
        printf("sp_session_create returned %d\n", code);
        sp_session_login(mySession, "foo", "bar");
        printf("sp_session_login returned %d\n", code);
        sleep(10);
}

如果 C 程序调用 Java 版本不调用的回调，那么 jna 的使用可能有问题——如果不是，则可能需要了解更多有关 spotify 及其调用回调的信息。我同意文档似乎说成功登录会调用回调，但也许它们已经过时了？