获取UnsatisfiedLinkError：创建TessBaseAPI时java.library.path中没有jnilept

Question

我是java cpp和tesseract-ocr的新手。 几个小时后我就遇到了一个问题。 when I create TessBaseAPI. 我创建TessBaseAPI时得到了 jnilept。 下面是我的代码。

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);
}

我遇到的例外情况TessBaseAPI api = new TessBaseAPI（）; 线

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

我在我的例子中使用java-presets libraries tesseract-3.04.01-1.2和leptonica-1.73-1.2.jar和javacpp-1.2.1。我有windows OS。 我确实看到了这个https://github.com/bytedeco/javacpp-presets/issues/46以及关于SO和github的几个讨论，指出这个问题在jacacpp-1.1本身已得到修复。但我使用的是javacpp1.2。
我真的很感激在解决问题或找到根本原因方面的任何帮助。

Answer 1

你可以克隆或下载项目：

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

然后构建模块：用于Leptonica的Tesseract和JavaCPP预设的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，还必须安装cmake ）

这将创建本机库：

libjnilept.so和libjnitesseract.so

那么你必须指定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);

（您可以在虚拟机选项上指定-Djava.library.path =）

您只需将生成的文件：libjnilept.so和libjnitesseract.so放在某个文件夹中，并将此路径设置为：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，您还可能会收到如下错误：

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:

由于Tesseract的区域设置要求，在运行任何客户端程序之前需要导出LC_ALL = C.

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> 

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