java - 创建 TessBaseAPI 时出现 UnsatisfiedLinkError : no jnilept in java. library.path

Question

我是 java cpp 和 tesseract-ocr 的新手。我在几个小时内遇到了一个问题。我在创建 TessBaseAPI 时收到 UnsatisfiedLinkError: no jnilept in java.library.path。下面是我的代码片段。

public static void tesseractForPdf(String filePath) throws Exception {
    BytePointer outText;

    TessBaseAPI api = new TessBaseAPI();//getting the UnsatisfiedLinkError exception here.
    // Initialize tesseract-ocr with English, without specifying tessdata path
    if (api.Init(".", "ENG") != 0) {
        System.err.println("Could not initialize tesseract.");
        System.exit(1);
    }

    // Open input image with leptonica library
    PIX image = pixRead(filePath);
    api.SetImage(image);
    // Get OCR result
    outText = api.GetUTF8Text();
    String string = outText.getString();
    System.out.println("OCR output:\n" + string);

    // Destroy used object and release memory
    api.End();
    outText.deallocate();
    pixDestroy(image);
}

异常我正在使用 TessBaseAPI api = new TessBaseAPI();行

Exception in thread "main" java.lang.UnsatisfiedLinkError: no jnilept in java.library.path
at java.lang.ClassLoader.loadLibrary(Unknown Source)
at java.lang.Runtime.loadLibrary0(Unknown Source)
at java.lang.System.loadLibrary(Unknown Source)
at org.bytedeco.javacpp.Loader.loadLibrary(Loader.java:702)
at org.bytedeco.javacpp.Loader.load(Loader.java:500)
at org.bytedeco.javacpp.Loader.load(Loader.java:417)
at org.bytedeco.javacpp.lept.<clinit>(lept.java:10)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at org.bytedeco.javacpp.Loader.load(Loader.java:472)
at org.bytedeco.javacpp.Loader.load(Loader.java:417)
at org.bytedeco.javacpp.tesseract$TessBaseAPI.<clinit>(tesseract.java:3648)
at om.practiceproblems.BasicTesseractExampleTest.givenTessBaseApi_whenImageOcrd_thenTextDisplayed(BasicTesseractExampleTest.java:35)
at com.practiceproblems.BasicTesseractExampleTest.main(BasicTesseractExampleTest.java:22)
Caused by: java.lang.UnsatisfiedLinkError: no liblept in java.library.path
at java.lang.ClassLoader.loadLibrary(Unknown Source)
at java.lang.Runtime.loadLibrary0(Unknown Source)
at java.lang.System.loadLibrary(Unknown Source)
at org.bytedeco.javacpp.Loader.loadLibrary(Loader.java:702)
at org.bytedeco.javacpp.Loader.load(Loader.java:491)
... 9 more

在我的示例中，我使用 java 预设库 tesseract-3.04.01-1.2 和 leptonica-1.73-1.2.jar 以及 javacpp-1.2.1。我有 Windows 操作系统。 我确实看到了这个https://github.com/bytedeco/javacpp-presets/issues/46以及关于 SO 和 github 的一些讨论指出这个问题在 jacacpp-1.1 本身中已修复。但我使用的是 javacpp1.2。
如果能帮助解决问题或找到根本原因，我将不胜感激。

Answer 1

您可以克隆或下载该项目:

https://github.com/bytedeco/javacpp-presets#the-cppbuildsh-scripts

然后构建模块:Tesseract 的 JavaCPP 预设和 Leptonica 的 JavaCPP 预设；

(要构建 leptonica 项目，您可能需要安装 nasm https://www.nasm.us/ )

(要构建整个 javacpp-presets 项目，您还必须安装 cmake)

这将创建原生库:

libjnilept.so 和 libjnitesseract.so

然后你必须指定jni.library.path

你可以这样做:

System.setProperty(JAVA_LIBRARY_PATH, tmpDirName);
/* Optionally add these two lines */
System.setProperty("jna.library.path", tmpDirName);
System.setProperty("jni.library.path", tmpDirName);
final Field fieldSysPath;

fieldSysPath = ClassLoader.class.getDeclaredField(SYS_PATHS);

fieldSysPath.setAccessible(true);
fieldSysPath.set(null, null);

(您可以改为在虚拟机选项上指定 -Djava.library.path=)

你只需要把生成的文件:libjnilept.so 和 libjnitesseract.so 在某个文件夹中并设置此路径:jni.library.path

<dependency>
    <groupId>org.bytedeco.javacpp-presets</groupId>
    <artifactId>tesseract</artifactId>           
    <version>4.0.0-1.4.4</version>            
</dependency>

<dependency>
    <groupId>org.bytedeco.javacpp-presets</groupId>
    <artifactId>leptonica</artifactId>
    <version>1.77.0-1.4.4</version> 
</dependency>

你也可以尝试添加

<dependency>    
    <groupId>org.bytedeco.javacpp-presets</groupId>
    <artifactId>leptonica-platform</artifactId> 
    <version>1.77.0-1.4.4</version>
</dependency> 

<dependency>
    <groupId>org.bytedeco.javacpp-presets</groupId>
    <artifactId>tesseract-platform</artifactId>
    <version>4.0.0-1.4.4</version>
</dependency>

并在构建中添加一个 maven-assembly-plugin

<build>
        <plugin>
            <artifactId>maven-assembly-plugin</artifactId>
            <configuration>
                <archive>
                    <manifest>
                         mainClass>fully.qualified.MainClass</mainClass>
                    </manifest>
                </archive>
                <descriptorRefs>
                    <descriptorRef>jar-with-dependencies</descriptorRef>
                </descriptorRefs>
            </configuration>
            <!-- new -->
            <executions>
                <execution>
                    <id>make-assembly</id> 
                    <phase>package</phase> 
                    <goals>
                        <goal>single</goal> 
                    </goals>
                </execution>
            </executions>
        </plugin>   
</build>

---

此外，您还可能会遇到这样的错误:

sscanf(line, "%" QUOTED_TOKENSIZE "s %" QUOTED_TOKENSIZE "s %f %f",
linear_token, essential_token, &ParamDesc[i].Min, &ParamDesc[i].Max) == 4
:Error:Assert failed:in file clusttool.cpp, line 73
#
# A fatal error has been detected by the Java Runtime Environment:

Due to Tesseract's locale requirements, export LC_ALL=C is required before running any client programs.

所以:

       <plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>exec-maven-plugin</artifactId>
            <version>1.6.0</version>
            <executions>
                <execution>
                    <goals>
                        <goal>exec</goal>
                    </goals>
                </execution>
            </executions>
            <configuration> 
                <environmentVariables>  
                    <LC_ALL>C</LC_ALL>
                </environmentVariables>
                <executable>java</executable>
                <arguments>
                    <argument>-classpath</argument>
                    <classpath />
                    <argument>${classpath}</argument>
                </arguments>
            </configuration>
        </plugin> 

source:
    - https://github.com/nguyenq/tess4j/issues/106
    - https://github.com/sirfz/tesserocr/issues/165