如何使用Gradle访问Java项目中的资源？

Question

我有一个javafx项目,我正在使用Gradle文件构建,我正在Intellij中编写所有内容.在其中,我使用javafx.scene.media.Media和javafx.scene.media.MediaPlayer播放一些音乐.

public SoundPlayer(String filename) {
    String soundLocation = "\\src\\main\\resources\\sound\\" + fileName;
    String absolute = new File("").getAbsolutePath() + soundLocation;
    System.out.println(absolute);
    Media soundMedia = new Media(new File(absolute).toURI().toString());
    mediaPlayer = new MediaPlayer(soundMedia);
}

我一直在努力的项目目录是:

SRC /

| ---主/

| --- | ---爪哇/

| --- | --- | --- sound.SoundPlayer

| --- | ---资源/

| --- | --- | ---声音/

| --- | --- | --- | --- click.mp3

| --- | --- | --- | --- bgm.mp3

然而,当我去编译并将其转换为jar文件时,Gradle将目录更改为此(在jar文件中,顶级):

声音/

| --- SoundPlayer.class

| --- click.mp3

| --- bgm.mp3

这使得它引发媒体异常:MEDIA UNAVAILABLE.我已经尝试将文件更改为以下两个:

Media soundMedia = new Media(new File("sound\\" + fileName).toURI().toString());

和

Media soundMedia = new Media(new File(fileName).toURI().toString());

......但我总是得到同样的例外.这是怎么回事？

Answer 1

Gradle做了什么是完全可以预料到的.该的src/main/JAVA和SRC /主/资源目录分别存储代码和资源.resources文件夹包含所有非java代码,如图像,声音等.

创建jar文件时,资源目录的内容将按原样复制(维护包结构).请注意,click.mp3和bgm.mp3是声音包的成员.

因此,当您要加载资源时,应该(通常)不使用文件路径来完成.而是使用包结构来做到这一点.在这里,作为声音和SoundPlayer具有相同的包,即sound,您可以使用SoundPlayer该类来加载如下资源:

public SoundPlayer(String filename) {
    URL resource = SoundPlayer.class.getResource(filename);
    Media soundMedia = new Media(resource.toExternalForm());
    mediaPlayer = new MediaPlayer(soundMedia);
}

来自Javadocs

public String toExternalForm()
构造此URL的字符串表示形式.通过调用此对象的流协议处理程序的toExternalForm方法来创建该字符串.

本质上,toExternalForm()函数为给定资源创建适当的URL.

这是一个完整的例子.

// build.gradle
apply plugin: 'java'
apply plugin: 'application'

sourceCompatibility = '1.8'
[compileJava, compileTestJava]*.options*.encoding = 'UTF-8'


mainClassName = 'sound.Main'

repositories {
    mavenCentral()
}

dependencies {
    testCompile group: 'junit', name: 'junit', version: '4.10'
}

jar { manifest { attributes 'Main-Class': 'sound.Main' } } 

和修改后的SoundPlayer

//sound.SoundPlayer
package sound;

import java.net.URL;
import javafx.scene.media.Media;
import javafx.scene.media.MediaPlayer;

public class SoundPlayer {

    private MediaPlayer mediaPlayer;

    public SoundPlayer(String filename) {
        URL resource = SoundPlayer.class.getResource(filename);
        Media soundMedia = new Media(resource.toExternalForm());
        mediaPlayer = new MediaPlayer(soundMedia);
    }

    public void play(){
        mediaPlayer.play();
    }
}

和Main类使用SoundPlayer

// sound.Main
// This class does not actually create a JavaFX UI. Instead, it is
// only creating a JavaFX application to use Media
package sound;

import javafx.application.Application;
import javafx.stage.Stage;

/**
 *
 * @author aga53
 */
public class Main extends Application{

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage primaryStage) throws Exception {
        SoundPlayer s = new SoundPlayer("test.mp3");
        System.out.println("Hello World");
        s.play();
    }

}