使用sarxos拍摄网络摄像头快照

Question

我想在Sarxos的帮助下为网络摄像头拍摄快照

package org.rogatio.circlead.sunray.util.websnap;

import java.awt.Dimension;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

import org.slf4j.LoggerFactory;

import com.github.sarxos.webcam.Webcam;
import com.github.sarxos.webcam.WebcamPanel;

import ch.qos.logback.classic.Level;
import ch.qos.logback.classic.Logger;
import ch.qos.logback.classic.LoggerContext;

public class GuiSnap {

private static Webcam webcam = null;

public static void main(String[] args) throws IOException {

    webcam = Webcam.getDefault();

    if (webcam != null) {
        Dimension[] dimensions = webcam.getViewSizes();
        webcam.setViewSize(dimensions[dimensions.length - 1]);
        webcam.open();
    }

    JFrame window = createFrame();

    if (window != null) {
        JButton button = createButton(window);
        JPanel panel = createWebcamPanel();

        if (panel != null) {
            panel.add(button);
            if (window != null) {
                window.add(panel);
            }
        }
    }
}

private static WebcamPanel createWebcamPanel() {

    if (webcam == null) {
        return null;
    }

    WebcamPanel panel = new WebcamPanel(webcam);
    panel.setFPSDisplayed(true);
    panel.setDisplayDebugInfo(false);
    panel.setImageSizeDisplayed(true);
    panel.setMirrored(false);

    return panel;
}

private static JFrame createFrame() {

    if (webcam == null) {
        return null;
    }

    final JFrame window = new JFrame("Circlead Sunray (" + webcam.getName() + ")");

    Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();

    window.setSize(dim.width / 2, dim.height / 2);
    window.setPreferredSize(new Dimension(dim.width / 2, dim.height / 2));

    window.setLocation(dim.width / 2 - window.getSize().width / 2, dim.height / 2 - window.getSize().height / 2);

    window.setResizable(true);
    window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    window.pack();
    window.setVisible(true);

    return window;
}

private static JButton createButton(JFrame window) {
    JButton button = new JButton("Snap");
    button.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent event) {
            snap();

            System.exit(0);
            window.dispose();
            window.setVisible(false);
        }

    });

    return button;
}

private static String snap() {
    if (webcam != null) {
        BufferedImage image = webcam.getImage();

        String date = null;
        DateFormat format = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss", Locale.GERMANY);
        date = format.format(new Date());

        File img = new File("snap_" + date + ".png");
        if (img.exists()) {
            img.delete();
        }

        try {
            ImageIO.write(image, "PNG", img);
            System.out.println("" + img.toString());
            return img.toString();
        } catch (IOException e) {
        }
    }
    return null;
}

}

该代码在Ubuntu 18.04下的Eclipse内部运行良好。但是当我用maven编译并以

开头时

java -jar circlead-websnap-util-1.1.8-SNAPSHOT-jar-with-dependencies.jar 

那我只得到一个没有任何东西的白色窗户。日志显示没有错误，我不知道从命令行运行它时如何获得工作版本。有提示吗？

这是我的行家

  <?xml version="1.0" encoding="UTF-8"?>
  <project xmlns="http://maven.apache.org/POM/4.0.0"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0    http://maven.apache.org/xsd/maven-4.0.0.xsd">

  <modelVersion>4.0.0</modelVersion>

  <groupId>org.rogatio.circlead.sunray</groupId>
  <artifactId>circlead-websnap-util</artifactId>
  <name>Circlead :: Websnap :: Util</name>
  <version>1.1.8-SNAPSHOT</version>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <java-compiler.version>1.8</java-compiler.version>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>

    <maven-compiler-plugin.version>3.8.1</maven-compiler-plugin.version>
   </properties>

   <dependencies>
    <dependency>
        <groupId>com.github.sarxos</groupId>
        <artifactId>webcam-capture</artifactId>
        <version>0.3.12</version>
    </dependency>
    <dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-classic</artifactId>
        <version>1.0.13</version>
    </dependency>
</dependencies>

<build>
    <plugins>
        <plugin>
            <artifactId>maven-compiler-plugin</artifactId>
            <inherited>true</inherited>
            <version>${maven-compiler-plugin.version}</version>
            <configuration>
                <source>${java-compiler.version}</source>
                <target>${java-compiler.version}</target>
            </configuration>
        </plugin>
        <plugin>
            <artifactId>maven-assembly-plugin</artifactId>
            <executions>
                <execution>
                    <phase>package</phase>
                    <goals>
                        <goal>single</goal>
                    </goals>
                </execution>
            </executions>
            <configuration>
                <archive>
                    <manifest>
                        <mainClass>org.rogatio.circlead.sunray.util.websnap.GuiSnap</mainClass>
                    </manifest>
                </archive>
                <descriptorRefs>
                    <descriptorRef>jar-with-dependencies</descriptorRef>
                </descriptorRefs>
            </configuration>
        </plugin>
    </plugins>
 </build>

 </project>