运行 jar 应用程序时无法显示启动图像

Question

package misc;

import java.awt.*;
import java.awt.event.*;

public class SplashDemo extends Frame implements ActionListener {

static void renderSplashFrame(Graphics2D g, int frame) {
    final String[] comps = {"foo", "bar", "baz"};
    g.setComposite(AlphaComposite.Clear);
    g.fillRect(120,140,200,40);
    g.setPaintMode();
    g.setColor(Color.BLACK);
    g.drawString("Loading "+comps[(frame/5)%3]+"...", 120, 150);
}
public SplashDemo() {
    super("SplashScreen demo");
    setSize(300, 200);
    setLayout(new BorderLayout());
    Menu m1 = new Menu("File");
    MenuItem mi1 = new MenuItem("Exit");
    m1.add(mi1);
    mi1.addActionListener(this);
    this.addWindowListener(closeWindow);

    MenuBar mb = new MenuBar();
    setMenuBar(mb);
    mb.add(m1);
    
    //
    final SplashScreen splash = SplashScreen.getSplashScreen();
    if (splash == null) {
        System.out.println("SplashScreen.getSplashScreen() returned null");
        return;
    }
    Graphics2D g = splash.createGraphics();
    if (g == null) {
        System.out.println("g is null");
        return;
    }
    for(int i=0; i<50; i++) {
        renderSplashFrame(g, i);
        splash.update();
        try {
            Thread.sleep(90);
        }
        catch(InterruptedException e) {
        }
    }
    splash.close();
    
    // setVisible(true);
    // toFront();
}
public void actionPerformed(ActionEvent ae) {
    System.exit(0);
}

private static WindowListener closeWindow = new WindowAdapter(){
    public void windowClosing(WindowEvent e){
        e.getWindow().dispose();
    }
};
}

在jar的主类中：

public static void main(String[] args) {
    new SplashDemo(); //splash with image
    ...

当我从控制台运行它时，我得到

SplashScreen.getSplashScreen() 返回 null

项目文件夹如下

project root > src > misc > SplashDemo.java
project root > src > main > resources > META-INF > MANIFEST.MF
// made a few locations for the picture to pick up from somewhere.
project root > src > main > resources > images > `image here`
project root > images > `image here`
project root > src > images > `image here`

和清单文件

Manifest-Version: 1.0
Main-Class: main.MainClassName
SplashScreen-Image: images/splash.gif

pom 文件

<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://maven.apache.org/POM/4.0.0"
    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>com.creator</groupId>
    <artifactId>myapp</artifactId>
    <version>0.1.0-SNAPSHOT</version>
    <packaging>jar</packaging>

    <dependencies> ... </dependencies>

    <build>
        <sourceDirectory>src</sourceDirectory>

        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.7.0</version>
                <configuration>
                    <source>${project.java.version}</source>
                    <target>${project.java.version}</target>
                    <encoding>${project.build.sourceEncoding}</encoding>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-dependency-plugin</artifactId>
                <executions>
                    <execution>
                        <id>copy-dependencies</id>
                        <phase>prepare-package</phase>
                        <goals>
                            <goal>copy-dependencies</goal>
                        </goals>
                        <configuration>
                            <outputDirectory>
                                ${project.build.directory}/libs
                            </outputDirectory>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <version>3.3.0</version>
                <configuration>
                    <archive>
                        <manifest>
                            <addClasspath>true</addClasspath>
                            <classpathPrefix>libs/</classpathPrefix>
                            <mainClass>main.MainClassName</mainClass>
                        </manifest>
                    </archive>
                </configuration>
            </plugin>
        </plugins>

    </build>
</project>

但是，应用程序在通过清单文件选项启动时并未创建启动屏幕，即 getSplashScreen 方法返回 null。怎么解决？

创建的 jar 文件包含一个 images 文件夹，根目录中有图像。

Answer 1

以下内容适用于您似乎正在使用的

tutorial

中的 SplashDemo 类：

                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-jar-plugin</artifactId>
                    <version>3.3.0</version>
                    <configuration>
                        <archive>
                            <manifest>
                                <addClasspath>true</addClasspath>
                                <classpathPrefix>libs/</classpathPrefix>
                                <mainClass>misc.SplashDemo</mainClass>
                            </manifest>
                            <manifestEntries>
                                <SplashScreen-Image>splash.gif</SplashScreen-Image>
                            </manifestEntries>
                        </archive>
                    </configuration>
                </plugin>

演示 zip 位于 此处 (

mvn package && java -jar target/misc-1.0-SNAPSHOT.jar

)