当无法加载本机库或尝试创建程序的 jar 文件时，这将发挥作用。由于 .dll 文件大多是用 c/c++ 编写的，因此当您尝试运行程序时，jvm 无法将它们包含在 jar 文件中或给出链接错误。但是对于 openCV，您可以使用这块成功加载 dll 文件。
只需创建一个java类并复制粘贴此代码并使用该方法成功加载dll文件
/**
* The minimum length a prefix for a file has to have according to {@link File#createTempFile(String, String)}}.
*/
private static final int MIN_PREFIX_LENGTH = 3;
public static final String NATIVE_FOLDER_PATH_PREFIX = "nativeutils";
/**
* Temporary directory which will contain the DLLs.
*/
private static File temporaryDir;
/**
* Private constructor - this class will never be instanced
*/
private NativeUtils() {
}
/**
* Loads library from current JAR archive
*
* The file from JAR is copied into system temporary directory and then loaded. The temporary file is deleted after
* exiting.
* Method uses String as filename because the pathname is "abstract", not system-dependent.
*
* @param path The path of file inside JAR as absolute path (beginning with '/'), e.g. /package/File.ext
* @throws IOException If temporary file creation or read/write operation fails
* @throws IllegalArgumentException If source file (param path) does not exist
* @throws IllegalArgumentException If the path is not absolute or if the filename is shorter than three characters
* (restriction of {@link File#createTempFile(java.lang.String, java.lang.String)}).
* @throws FileNotFoundException If the file could not be found inside the JAR.
*/
public static void loadLibraryFromJar(String path) throws IOException {
if (null == path || !path.startsWith("/")) {
throw new IllegalArgumentException("The path has to be absolute (start with '/').");
}
// Obtain filename from path
String[] parts = path.split("/");
String filename = (parts.length > 1) ? parts[parts.length - 1] : null;
// Check if the filename is okay
if (filename == null || filename.length() < MIN_PREFIX_LENGTH) {
throw new IllegalArgumentException("The filename has to be at least 3 characters long.");
}
// Prepare temporary file
if (temporaryDir == null) {
temporaryDir = createTempDirectory(NATIVE_FOLDER_PATH_PREFIX);
temporaryDir.deleteOnExit();
}
File temp = new File(temporaryDir, filename);
try (InputStream is = NativeUtils.class.getResourceAsStream(path)) {
Files.copy(is, temp.toPath(), StandardCopyOption.REPLACE_EXISTING);
} catch (IOException e) {
temp.delete();
throw e;
} catch (NullPointerException e) {
temp.delete();
throw new FileNotFoundException("File " + path + " was not found inside JAR.");
}
try {
System.load(temp.getAbsolutePath());
} finally {
if (isPosixCompliant()) {
// Assume POSIX compliant file system, can be deleted after loading
temp.delete();
} else {
// Assume non-POSIX, and don't delete until last file descriptor closed
temp.deleteOnExit();
}
}
}
private static boolean isPosixCompliant() {
try {
return FileSystems.getDefault()
.supportedFileAttributeViews()
.contains("posix");
} catch (FileSystemNotFoundException
| ProviderNotFoundException
| SecurityException e) {
return false;
}
}
private static File createTempDirectory(String prefix) throws IOException {
String tempDir = System.getProperty("java.io.tmpdir");
File generatedDir = new File(tempDir, prefix + System.nanoTime());
if (!generatedDir.mkdir())
throw new IOException("Failed to create temp directory " + generatedDir.getName());
return generatedDir;
}