JNA:找不到指定的程序 [英] JNA: The specified procedure could not be found

问题描述

我试图了解 JNA 的工作原理，所以我决定使用 spotify API(libspotify 0.0.7).我设法正确加载了我的 dll，但看起来我的代码没有找到 API 中定义的任何方法.

I was trying to learn how JNA works, so I decided to use the spotify API (libspotify 0.0.7). I managed to load my dll correctly, but then it looks like my code is not finding any of the method defined in the API.

这是我的代码:

我的主文件:

public class Test{
    private static final int SPOTIFY_API_VERSION = 7;
private static final char[] APP_KEY = { /* MY APP KEY HERE */ };

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

    public static void main(String[] args){
    JLibspotify libs = JLibspotify.INSTANCE;

    sp_session mySession = new sp_session();
    sp_session_config cfg = new sp_session_config();
    cfg.api_version = SPOTIFY_API_VERSION;
    cfg.cache_location = "tmp";
    cfg.settings_location = "tmp";
    cfg.application_key = APP_KEY;
    cfg.application_key_size = APP_KEY.length;
    cfg.user_agent = "spshell";
    cfg.callbacks = null;

    libs.sp_session_create(cfg, mySession);
}
}

我的图书馆界面:

public interface JLibspotify extends Library {  
    JLibspotify INSTANCE = (JLibspotify)Native.loadLibrary("libspotify", JLibspotify.class);

    // Methods definitions
    sp_error sp_session_create(sp_session_config config, sp_session sess);
}

我的 sp_session 对象(不透明的 C 结构)

public class sp_session extends PointerType{
    public sp_session(Pointer address) {
        super(address);
    }
    public sp_session() {
        super();
    }
}

我的 sp_session_config 对象

public class sp_session_config extends Structure{
    public int api_version; // The version of the Spotify API your application is compiled with.
    public String cache_location;
    public String settings_location;
    public char[] application_key}; // Your application key.
    public int application_key_size; // The size of the application key in bytes
    public String user_agent;
    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;
}

我的 sp_error 枚举

public enum sp_error {
    SP_ERROR_OK, 
    SP_ERROR_BAD_API_VERSION, 
    SP_ERROR_API_INITIALIZATION_FAILED, 
    SP_ERROR_TRACK_NOT_PLAYABLE, 
    SP_ERROR_RESOURCE_NOT_LOADED, 
    SP_ERROR_BAD_APPLICATION_KEY, 
    SP_ERROR_BAD_USERNAME_OR_PASSWORD, 
    SP_ERROR_USER_BANNED, 
    SP_ERROR_UNABLE_TO_CONTACT_SERVER, 
    SP_ERROR_CLIENT_TOO_OLD, 
    SP_ERROR_OTHER_PERMANENT, 
    SP_ERROR_BAD_USER_AGENT, 
    SP_ERROR_MISSING_CALLBACK, 
    SP_ERROR_INVALID_INDATA, 
    SP_ERROR_INDEX_OUT_OF_RANGE, 
    SP_ERROR_USER_NEEDS_PREMIUM, 
    SP_ERROR_OTHER_TRANSIENT, 
    SP_ERROR_IS_LOADING, 
    SP_ERROR_NO_STREAM_AVAILABLE, 
    SP_ERROR_PERMISSION_DENIED, 
    SP_ERROR_INBOX_IS_FULL, 
    SP_ERROR_NO_CACHE, 
    SP_ERROR_NO_SUCH_USER
}

我的异常堆栈跟踪

Exception in thread "main" java.lang.UnsatisfiedLinkError: Error looking up function 'sp_session_create': The specified procedure could not be found.

at com.sun.jna.Function.<init>(Function.java:129)
at com.sun.jna.NativeLibrary.getFunction(NativeLibrary.java:250)
at com.sun.jna.Library$Handler.invoke(Library.java:191)
at $Proxy0.sp_session_create(Unknown Source)
at com.nbarraille.jspotify.main.Test.main(Test.java:49)

我尝试运行的方法的 C++ 声明

/**
 * Initialize a session. The session returned will be initialized, but you will need
 * to log in before you can perform any other operation
 *
 * Here is a snippet from \c spshell.c:
 * @dontinclude spshell.c
 * @skip config.api_version
 * @until }
 *
 * @param[in]   config    The configuration to use for the session
 * @param[out]  sess      If successful, a new session - otherwise NULL
 *
 * @return                One of the following errors, from ::sp_error
 *                        SP_ERROR_OK
 *                        SP_ERROR_BAD_API_VERSION
 *                        SP_ERROR_BAD_USER_AGENT
 *                        SP_ERROR_BAD_APPLICATION_KEY
 *                        SP_ERROR_API_INITIALIZATION_FAILED
 */
SP_LIBEXPORT(sp_error) sp_session_create(const sp_session_config *config, sp_session **sess);

推荐答案

我终于通过使用 Dependency Walker 打开 libspotify.dll 找到了解决方案:编译器向方法名称添加了一些额外信息(下划线前缀和@4 或@8 后缀).

I finally found the solution by opening the libspotify.dll with Dependency Walker: The compiler added some extra information to the method name (a underscore prefix and a @4 or @8 suffix).

我不得不:

• 创建一个 FunctionMapper 实现，根据真实名称重命名我的所有方法(在 Dependency Walker 中可用)
• 在选项映射中使用此映射器的实例实例化我的库.

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