如何在包含本机代码的Java应用程序中使用命令行执行Maven主类？

Question

I want to execute my maven project standalone class using command line.

JnetSampleTest.java -

import java.util.ArrayList;
import java.util.Date;
import java.util.List;

import org.jnetpcap.Pcap;
import org.jnetpcap.PcapIf;
import org.jnetpcap.packet.PcapPacket;
import org.jnetpcap.packet.PcapPacketHandler;

public class JnetSampleTest {

    public static void main(String[] args) {

        List<PcapIf> alldevs = new ArrayList<PcapIf>(); // Will be filled with NICs
        StringBuilder errbuf = new StringBuilder(); // For any error msgs

        int r = Pcap.findAllDevs(alldevs, errbuf);
        if (r == Pcap.NOT_OK || alldevs.isEmpty()) {
            System.err.printf("Can't read list of devices, error is %s", errbuf.toString());
            return;
        }

        System.out.println("Network devices found:");

        int i = 0;
        for (PcapIf device : alldevs) {
            String description = (device.getDescription() != null) ? device.getDescription()
                    : "No description available";
            System.out.printf("#%d: %s [%s]\n", i++, device.getName(), description);
        }

        PcapIf device = alldevs.get(8); // We know we have atleast 1 device
        PcapIf d = new PcapIf();

        System.out.printf("\nChoosing '%s' on your behalf:\n",
                (device.getDescription() != null) ? device.getDescription() : device.getName());

        int snaplen = 64 * 1024; // Capture all packets, no trucation
        int flags = Pcap.MODE_PROMISCUOUS; // capture all packets
        int timeout = 10 * 1000; // 10 seconds in millis
        Pcap pcap = Pcap.openLive(device.getName(), snaplen, flags, timeout, errbuf);

        if (pcap == null) {
            System.err.printf("Error while opening device for capture: " + errbuf.toString());
            return;
        }

        PcapPacketHandler<String> jpacketHandler = new PcapPacketHandler<String>() {
            public void nextPacket(PcapPacket packet, String user) {
                System.out.printf("Received packet at %s caplen=%-4d len=%-4d %s\n",
                        new Date(packet.getCaptureHeader().timestampInMillis()), packet.getCaptureHeader().caplen(), // Length
                        packet.getCaptureHeader().wirelen(), // Original length
                        user // User supplied object
                );
            }
        };

        pcap.loop(10, jpacketHandler, "jNetPcap rocks!");
        pcap.close();
    }
}

I created user library for jnetpcap by following this tutorial and added it to project.

In eclipse this code is running fine but I want to execute this code using command line so I added below sample code in pom.xml -

<build>
    <plugins>
        <plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>exec-maven-plugin</artifactId>
            <version>1.2.1</version>
            <executions>
                <execution>
                    <goals>
                        <goal>java</goal>
                    </goals>
                </execution>
            </executions>
            <configuration>
                <mainClass>com.JnetSampleTest.JnetSampleTest</mainClass>
            </configuration>
        </plugin>
    </plugins>
</build>

I tried this command to execute my main class -

mvn exec:java -Dexec.mainClass="com.JnetSampleTest.JnetSampleTest"

I'm getting this exception -

[WARNING] 
java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.codehaus.mojo.exec.ExecJavaMojo$1.run(ExecJavaMojo.java:297)
    at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.UnsatisfiedLinkError: com.slytechs.library.NativeLibrary.dlopen(Ljava/lang/String;)J
    at com.slytechs.library.NativeLibrary.dlopen(Native Method)
    at com.slytechs.library.NativeLibrary.<init>(Unknown Source)
    at com.slytechs.library.JNILibrary.<init>(Unknown Source)
    at com.slytechs.library.JNILibrary.loadLibrary(Unknown Source)
    at com.slytechs.library.JNILibrary.register(Unknown Source)
    at com.slytechs.library.JNILibrary.register(Unknown Source)
    at com.slytechs.library.JNILibrary.register(Unknown Source)
    at org.jnetpcap.Pcap.<clinit>(Unknown Source)

How I can execute this class using command line?

Answer 1

The native library is missing. Could be a x86 vs. x64 issue.

Answer 2

this type of error occurs, when the so/dll file that the code is looking for is not found. please ensure you have the .dll file for jnetpcap saved in the windows system32 folder.

The process for IntelliJ should be similar to that on jnetpcap.com/?q=eclipse (or for NetBeans). I'm not familiar with IntelliJ, but ... you could just try copying the native library (.so file on linux, .dll file on windows, .dylib file on Mac) into the main directory of your project.