JavaH 无法为 JNI 创建 C 头文件 class

Question

这真的让我感到困惑，因为我已经尝试了关于 classpath 和其他各种事情的一切可能。我在 windows、linux 和 IDE 中尝试了各种不同的命令提示，但似乎无济于事。总是同样的错误。任何见解都会在这里有所帮助。

尝试使用以下命令运行 javah 时出现以下错误：

javah -jni -cp jna-3.0.9.jar:java.nio.*:java.util.* CameraInterfaceLibrary
Error: Could not find class file for 'CameraInterfaceLibrary'.

我真的卡在这里了。我只是不明白为什么它拒绝生成头文件。无论我做什么，它总是说找不到 class 文件。我只是很困惑。我已经尝试了更简单的示例，但使用真实代码它无法正常工作。

代码如下：

import com.sun.jna.Native;
import com.sun.jna.NativeLibrary;
import com.sun.jna.Pointer;
import com.sun.jna.Structure;
import com.sun.jna.win32.StdCallLibrary;
import java.nio.ByteBuffer;
import java.util.Arrays;
import java.util.List;
/**
 * JNA Wrapper for library <b>CameraInterface</b><br>
 * This file was autogenerated by <a href="http://jnaerator.googlecode.com/">JNAerator</a>,<br>
 * a tool written by <a href="http://ochafik.com/">Olivier Chafik</a> that <a href="http://code.google.com/p/jnaerator/wiki/CreditsAndLicense">uses a few opensource projects.</a>.<br>
 * For help, please visit <a href="http://nativelibs4java.googlecode.com/">NativeLibs4Java</a> , <a href="http://rococoa.dev.java.net/">Rococoa</a>, or <a href="http://jna.dev.java.net/">JNA</a>.
 */
public class CameraInterfaceLibrary implements StdCallLibrary {
    public static final String JNA_LIBRARY_NAME = "CameraInterface";
    public static final NativeLibrary JNA_NATIVE_LIB = NativeLibrary.getInstance(CameraInterfaceLibrary.JNA_LIBRARY_NAME);
    static {
        Native.loadLibrary(CameraInterfaceLibrary.JNA_LIBRARY_NAME, CameraInterfaceLibrary.class);
    }
    public static class DV_TM extends Structure {
        /**
         * Second.interval is [0.59] * /<br>
         * int tm_min; /* To the value interval [0.59]
         */
        public int tm_sec;
        /** Value seconds interval [0.23] */
        public int tm_hour;
        /** The value date of the month interval [1.31] */
        public int tm_mday;
        /** The value date of the month interval [1.31] */
        public int tm_mon;
        /** Month (from the beginning of January, o behalf of the month) value interval [0.11] */
        public int tm_year;
        /** Year, its value is equal to the actual year as 2010 */
        public int tm_wday;
        /** The value range for the week [0.6], where O stands for Sunday, 1 for Monday, and so on */
        public int tm_yday;
        /** Number of days from the beginning of January 1 each year ranging from [0.365], where 0 represents January 1, 1 represents January 2, and so on, can be set to 0 */
        public int tm_isdst;
        public DV_TM() {
            super();
        }
        protected List<? > getFieldOrder() {
            return Arrays.asList("tm_sec", "tm_hour", "tm_mday", "tm_mon", "tm_year", "tm_wday", "tm_yday", "tm_isdst");
        }
        /**
         * @param tm_sec Second.interval is [0.59] * /<br>
         * int tm_min; /* To the value interval [0.59]<br>
         * @param tm_hour Value seconds interval [0.23]<br>
         * @param tm_mday The value date of the month interval [1.31]<br>
         * @param tm_mon The value date of the month interval [1.31]<br>
         * @param tm_year Month (from the beginning of January, o behalf of the month) value interval [0.11]<br>
         * @param tm_wday Year, its value is equal to the actual year as 2010<br>
         * @param tm_yday The value range for the week [0.6], where O stands for Sunday, 1 for Monday, and so on<br>
         * @param tm_isdst Number of days from the beginning of January 1 each year ranging from [0.365], where 0 represents January 1, 1 represents January 2, and so on, can be set to 0
         */
        public DV_TM(int tm_sec, int tm_hour, int tm_mday, int tm_mon, int tm_year, int tm_wday, int tm_yday, int tm_isdst) {
            super();
            this.tm_sec = tm_sec;
            this.tm_hour = tm_hour;
            this.tm_mday = tm_mday;
            this.tm_mon = tm_mon;
            this.tm_year = tm_year;
            this.tm_wday = tm_wday;
            this.tm_yday = tm_yday;
            this.tm_isdst = tm_isdst;
        }

        /* JR - Removed as no deemed necessary at this point
        public DV_TM(com.sun.jna.Pointer peer) {
            super(peer);
        }*/

        public static class ByReference extends DV_TM implements Structure.ByReference {

        };
        public static class ByValue extends DV_TM implements Structure.ByValue {

        };
    };
    /**
     * Connected devices (connect with camera)<br>
     * Original signature : <code>int CConnectDV()</code><br>
     * <i>native declaration : line 18</i>
     */
    public static native int CConnectDV();
    /**
     * Disconnect the device (disconnect with camera)<br>
     * Original signature : <code>int CDisconnectDV()</code><br>
     * <i>native declaration : line 20</i>
     */
    public static native int CDisconnectDV();
    /**
     * Landing equipment parameters: password (connect and open the camera parameter: password)<br>
     * Original signature : <code>int CLogin(char*)</code><br>
     * <i>native declaration : line 22</i><br>
     * @deprecated use the safer methods {@link #CLogin(java.nio.ByteBuffer)} and {@link #CLogin(com.sun.jna.Pointer)} instead
     */
    public static native int CLogin(com.sun.jna.Pointer Password);
    /**
     * Landing equipment parameters: password (connect and open the camera parameter: password)<br>
     * Original signature : <code>int CLogin(char*)</code><br>
     * <i>native declaration : line 22</i>
     */
    public static native int CLogin(ByteBuffer Password);
    /**
     * The school parameters: see DV-TM structure (timing parameter: look at the DV-TM structure)<br>
     * Original signature : <code>int CSetTime(DV_TM*)</code><br>
     * <i>native declaration : line 24</i>
     */
    public static native int CSetTime(CameraInterfaceLibrary.DV_TM ptm);
    /**
     * Read machine time parameters: see DV-TM structure (read the machine time parameter: look at the DV-TM structure)<br>
     * Original signature : <code>int CGetTime(DV_TM*)</code><br>
     * <i>native declaration : line 26</i>
     */
    public static native int CGetTime(CameraInterfaceLibrary.DV_TM ptm);
    /**
     * Set password parameters: password new password 6 (set password parameter: password 6 new password)<br>
     * Original signature : <code>int CSetPassword(char*)</code><br>
     * <i>native declaration : line 28</i><br>
     * @deprecated use the safer methods {@link #CSetPassword(java.nio.ByteBuffer)} and {@link #CSetPassword(com.sun.jna.Pointer)} instead
     */
    public static native int CSetPassword(com.sun.jna.Pointer Password);
    /**
     * Set password parameters: password new password 6 (set password parameter: password 6 new password)<br>
     * Original signature : <code>int CSetPassword(char*)</code><br>
     * <i>native declaration : line 28</i>
     */
    public static native int CSetPassword(ByteBuffer Password);
    /**
     * Set the number parameter: ID Number 13 (set ID number parameter: 13 ID number)<br>
     * Original signature : <code>int CSetID(char*)</code><br>
     * <i>native declaration : line 30</i><br>
     * @deprecated use the safer methods {@link #CSetID(java.nio.ByteBuffer)} and {@link #CSetID(com.sun.jna.Pointer)} instead
     */
    public static native int CSetID(com.sun.jna.Pointer ID);
    /**
     * Set the number parameter: ID Number 13 (set ID number parameter: 13 ID number)<br>
     * Original signature : <code>int CSetID(char*)</code><br>
     * <i>native declaration : line 30</i>
     */
    public static native int CSetID(ByteBuffer ID);
    /**
     * Read the number parameter: ID Number 13 (read ID number parameter: 13 ID number)<br>
     * Original signature : <code>int CGetID(char*)</code><br>
     * <i>native declaration : line 32</i><br>
     * @deprecated use the safer methods {@link #CGetID(java.nio.ByteBuffer)} and {@link #CGetID(com.sun.jna.Pointer)} instead
     */
    public static native int CGetID(com.sun.jna.Pointer ID);
    /**
     * Read the number parameter: ID Number 13 (read ID number parameter: 13 ID number)<br>
     * Original signature : <code>int CGetID(char*)</code><br>
     * <i>native declaration : line 32</i>
     */
    public static native int CGetID(ByteBuffer ID);
    /**
     * Enter the U disk mode (Enter the U disk mode)<br>
     * Original signature : <code>int CIntoUDiskMode()</code><br>
     * <i>native declaration : line 34</i>
     */
    public static native int CIntoUDiskMode();
}

Answer 1

当您使用 JNA 时，不再需要生成 C 头文件或编译任何本机代码。

使用直接映射时，声明的方法 native 会自动绑定到目标共享库中的相应方法。

JNA 使用方法签名和 StdCall 标记接口来确定如何将您的 Java 调用转换为具有适当类型转换的本机调用。

编辑

确保在静态初始化程序中调用 Native.register()，而不是 Native.loadLibrary()。如果您已经实现了工作模型，请在您的问题中添加注释。

您可以通过编写一个简单的 main 函数来测试执行情况，该函数会调用您的一个或多个方法。

Answer 2

其他人是正确的（如果您使用的是 JPA，则不需要 javah）。

但是为了彻底（并帮助您处理您可能运行进行 Java 开发的其他事情），我怀疑您问题的答案是您没有指定class路径正确。

这里是 javah 的文档：http://docs.oracle.com/javase/7/docs/technotes/tools/windows/javah.html

我在您的命令行中看到的问题：

合适的参数是-classpath（不是-cp）
您需要使用分号而不是冒号分隔条目
您必须指定 classes 的根路径（如果这恰好是当前目录，您仍然必须使用“.”包含它）
必须指定依赖jar文件的路径
在任何情况下都不会向 class 路径添加类似导入的标识符（即 java.nio.* 是一个导入 - 与此处无关）
如果您的 class 在包裹中（您应该这样做！），那么您需要将其包含在 classname

在普通项目中（其中 classes 和依赖的 jar 存储在单独的文件夹中），我会使用这样的东西：

javah -jni -classpath C:\MyApp\Classes;C:\MyApp\lib\* com.myapp.MyAppLibrary

注意使用通配符加载 lib\ 文件夹中的所有 jar 文件。

JavaH 无法为 JNI 创建 C 头文件 class

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