如何在 Java 中模拟按下媒体键？

Question

如何在 Java 中模拟按下媒体键？如播放/暂停、下一个/上一个、音量控制。

C#有VK_MEDIA_PLAY_PAUSE、VK_MEDIA_NEXT_TRACK等等。

Java 有类Robot 用于处理密钥，但没有媒体密钥。

Answer 1

我使用 JNI 库使用 C 编写的代码模拟按键。我创建了一个 .dll 文件和 .java 文件来点击“降低音量”、“提高音量”、“静音”、“ Previous Track”、“Next Track”和“Play/Pause Track”媒体键。

这是完整存储库的link，但是，我将在下面更详细地解释它。

MediaKeys.java 必须在名为“commands”的包中才能工作。

MediaKeys.dll 必须与“src”文件夹位于同一路径，或编译时与.class 文件位于同一路径。

MediaKeys.java 文件包含以下内容：

package commands

public class MediaKeys {

    //loads library from "MediaKeys.dll"
    static {
        System.loadLibrary("MediaKeys");
    }



    public static native void volumeMute();

    public static native void volumeDown();

    public static native void volumeUp();


    public static native void songPrevious();

    public static native void songNext();

    public static native void songPlayPause();



    //test driver
    public static void main(String[] args) {

        //volumeMute();

    }

}

静态块加载 .dll 文件，然后使用 native 关键字声明用 C 编写的函数。

如果您只需要这些功能，那么您可以使用适用于 Windows 的 .dll 文件。如果您需要.dll 的源代码，它包含在上面的link 中，我将在下面更详细地解释它。

.dll 由两个文件组成，一个用于函数源代码的 C 文件和一个头文件。 （命名为 MediaKeys.c 和 MediaKeys.h）

MediaKeys.c 包含按下所需键的代码。为了节省空间，C 和头文件的以下代码块仅针对“下一曲目”、“上一曲目”和“暂停/播放曲目”功能进行了格式化。

头文件： MediaKeys.h

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class MediaKeys */

#ifndef _Included_MediaKeys
#define _Included_MediaKeys
#ifdef __cplusplus
extern "C" {
#endif
/*
 * Class:     MediaKeys
 * Method:    songPrevious
 * Signature: ()V
 */
JNIEXPORT void JNICALL Java_commands_MediaKeys_songPrevious
  (JNIEnv *, jclass);

/*
 * Class:     MediaKeys
 * Method:    songNext
 * Signature: ()V
 */
JNIEXPORT void JNICALL Java_commands_MediaKeys_songNext
  (JNIEnv *, jclass);

/*
 * Class:     MediaKeys
 * Method:    songPlayPause
 * Signature: ()V
 */
JNIEXPORT void JNICALL Java_commands_MediaKeys_songPlayPause
  (JNIEnv *, jclass);

#ifdef __cplusplus
}
#endif
#endif

头文件包含每个方法所需的声明，格式如下：

JNIEXPORT void JNICALL Java_{package_name}_{class_name}_{method_name}
  (JNIEnv *, jclass);

C 文件必须与头文件相对应。 MediaKeys.c

//standard dependencies for C and the JNI Library
#include <jni.h>
#include <stdio.h>
#include "MediaKeys.h"

//dependencies required to hit the media keys
#define WINVER 0x0500
#include <windows.h>


//hits the previous track key
JNIEXPORT void JNICALL Java_commands_MediaKeys_songPrevious (JNIEnv *env, jobject thisObj) {

    KEYBDINPUT kbi;

    //specific keycode
    kbi.wVk = VK_MEDIA_PREV_TRACK; //this can be changed depending on the key

    kbi.wScan = 0;
    kbi.dwFlags = 0;
    kbi.time = 0;
    kbi.dwExtraInfo = (ULONG_PTR) GetMessageExtraInfo();

    INPUT input;
    input.type = INPUT_KEYBOARD;
    input.ki   = kbi;

    SendInput(1, &input, sizeof(INPUT));

    return;

}


//hits the next track key
JNIEXPORT void JNICALL Java_commands_MediaKeys_songNext (JNIEnv *env, jobject thisObj) {

    KEYBDINPUT kbi;

    //specific keycode
    kbi.wVk = VK_MEDIA_NEXT_TRACK;

    kbi.wScan = 0;
    kbi.dwFlags = 0;
    kbi.time = 0;
    kbi.dwExtraInfo = (ULONG_PTR) GetMessageExtraInfo();

    INPUT input;
    input.type = INPUT_KEYBOARD;
    input.ki   = kbi;

    SendInput(1, &input, sizeof(INPUT));

    return;

}


//hits the play/pause key
JNIEXPORT void JNICALL Java_commands_MediaKeys_songPlayPause (JNIEnv *env, jobject thisObj) {

    KEYBDINPUT kbi;

    //specific keycode
    kbi.wVk = VK_MEDIA_PLAY_PAUSE;

    kbi.wScan = 0;
    kbi.dwFlags = 0;
    kbi.time = 0;
    kbi.dwExtraInfo = (ULONG_PTR) GetMessageExtraInfo();

    INPUT input;
    input.type = INPUT_KEYBOARD;
    input.ki   = kbi;

    SendInput(1, &input, sizeof(INPUT));

    return;

}

C 文件包含每个标题语句的对应函数，格式如下：

JNIEXPORT void JNICALL Java_{package_name}_{class_name}_{method_name} (JNIEnv *env, jobject thisObj) {

    //specific code goes here
    return;

}

如代码中所述，您可以通过更改：kbi.wVk = specific_key_goes_here; 来更改特定键。可以找到可用密钥列表here。

一旦创建了 C 和头文件，就可以将它们编译成 dll 文件。为此，我使用 Code::Blocks 创建了一个新的动态链接库项目，添加了 MediaKeys.c 和 MediaKeys.h 文件，然后单击了构建。

由于我的 JVM 是 64 位并且 Code::Blocks 默认编译器是 32 位，我不得不将 install a 64-bit compiler 转换为 Code::Blocks。

您还必须添加指向jni.h 库的链接。要在 Code::Blocks 中执行此操作，请转到 Settings>Compiler>Search Directories 并添加目录 C:\Program Files\Java\jdk1.8.0_171\include 和 C:\Program Files\Java\jdk1.8.0_171\include\win32。您很可能必须根据您的 jdk 版本更改文件路径。

构建完成后，将 dll 文件复制到 java 程序所需的位置。

有关设置 Java 原生接口的更多信息，我发现 this link 非常有用。

我知道这篇文章有点旧，但我认为这些信息可能对其他人有所帮助。

Answer 2

您可以使用https://github.com/kwhat/jnativehook 实现它，然后监视密钥。在my question我写了一些示例方法：

public static void MediaKeyForward(){
    GlobalScreen.postNativeEvent(new NativeKeyEvent(2401,0,176,57369,org.jnativehook.keyboard.NativeKeyEvent.CHAR_UNDEFINED));

}
public static void MediaKeyBack(){
    GlobalScreen.postNativeEvent(new NativeKeyEvent(2401,0,177,57360,org.jnativehook.keyboard.NativeKeyEvent.CHAR_UNDEFINED));

}
public static void MediaKeyPause(){
 GlobalScreen.postNativeEvent(new NativeKeyEvent(2401,0,179,57378,org.jnativehook.keyboard.NativeKeyEvent.CHAR_UNDEFINED));

}

要做的就是将库包含到您的项目中。可以在here 找到如何监视键并获取必要参数以创建键事件的示例。

Answer 3

创建您自己的 keylistener 和 spy，然后使用这个值。 这是简单的 KeySpy 类：

import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;

import javax.swing.JFrame;
import javax.swing.JLabel;


public class KeySpy {
    JLabel label=new JLabel("Enter the key");
    public KeySpy() {
        JFrame frame=new JFrame("KeySpy");
        frame.add(label);

        frame.addKeyListener(new KeyListener() {

            @Override
            public void keyTyped(KeyEvent e) {
            }

            @Override
            public void keyReleased(KeyEvent e) {
            }

            @Override
            public void keyPressed(KeyEvent e) {
                label.setText(e.toString());
                System.out.println(e.toString());
            }
        });

        frame.setSize(200, 200);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        new KeySpy();

    }

}

这是我键盘上 2 个按钮的结果

   [Stop] = java.awt.event.KeyEvent[KEY_PRESSED,keyCode=0,keyText=Unknown keyCode: 0x0,keyChar=Undefined keyChar,keyLocation=KEY_LOCATION_STANDARD,rawCode=178,primaryLevelUnicode=0,scancode=36,extendedKeyCode=0x0] on frame0

   [Mute] = java.awt.event.KeyEvent[KEY_PRESSED,keyCode=0,keyText=Unknown keyCode: 0x0,keyChar=Undefined keyChar,keyLocation=KEY_LOCATION_STANDARD,rawCode=173,primaryLevelUnicode=0,scancode=32,extendedKeyCode=0x0] on frame0

如您所见，他们没有 keyCode，但他们有 rawCode - 所以使用它。

Answer 4

我改进了Alex's KeySpy application。 JFrame 保持焦点，因此您可以最小化或最大化应用程序，并且在应用程序处于焦点时仍然可以按任意键。

这是图形用户界面。

我将信息放在标签/值网格中，以便更轻松地找到您感兴趣的值。

这是代码。这是 GridBagLayout 的一个很好的例子。

package com.ggl.testing;

import java.awt.Component;
import java.awt.Container;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;

public class KeySpy implements Runnable {

    private KeySpyPanel keySpyPanel;

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new KeySpy());
    }

    @Override
    public void run() {
        final JFrame frame = new JFrame("Key Spy");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocationByPlatform(true);
        frame.addWindowFocusListener(new WindowAdapter() {
            public void windowGainedFocus(WindowEvent e) {
                frame.requestFocusInWindow();
            }
        });

        keySpyPanel = new KeySpyPanel();
        frame.add(keySpyPanel.getPanel());
        frame.addKeyListener(new KeyPressedListener(this));

        frame.pack();
        frame.setVisible(true);
    }

    public KeySpyPanel getKeySpyPanel() {
        return keySpyPanel;
    }

    public class KeySpyPanel {

        private final Insets bottomInsets = new Insets(10, 10, 10, 10);
        private final Insets normalInsets = new Insets(10, 10, 0, 10);

        private JPanel panel;

        private JTextField keyCodeField;
        private JTextField keyTextField;
        private JTextField keyCharField;
        private JTextField keyLocationField;
        private JTextField modifiersField;
        private JTextField extModifiersField;
        private JTextField rawCodeField;
        private JTextField primaryLevelUnicodeField;
        private JTextField scancodeField;
        private JTextField extendedKeyCodeField;

        public KeySpyPanel() {
            createPartControl();
        }

        private void createPartControl() {
            panel = new JPanel();
            panel.setLayout(new GridBagLayout());

            int gridy = 0;

            JLabel anyKeyLabel = new JLabel("Press any key");
            anyKeyLabel.setFont(anyKeyLabel.getFont().deriveFont(36F));
            anyKeyLabel.setHorizontalAlignment(JLabel.CENTER);
            addComponent(panel, anyKeyLabel, 0, gridy++, 2, 1, normalInsets,
                    GridBagConstraints.CENTER, GridBagConstraints.HORIZONTAL);

            JLabel keyCodeLabel = new JLabel("KeyCode:");
            addComponent(panel, keyCodeLabel, 0, gridy, 1, 1, normalInsets,
                    GridBagConstraints.LINE_START,
                    GridBagConstraints.HORIZONTAL);

            keyCodeField = new JTextField(20);
            keyCodeField.setEditable(false);
            addComponent(panel, keyCodeField, 1, gridy++, 1, 1, normalInsets,
                    GridBagConstraints.LINE_START,
                    GridBagConstraints.HORIZONTAL);

            JLabel keyTextLabel = new JLabel("KeyText:");
            addComponent(panel, keyTextLabel, 0, gridy, 1, 1, normalInsets,
                    GridBagConstraints.LINE_START,
                    GridBagConstraints.HORIZONTAL);

            keyTextField = new JTextField(20);
            keyTextField.setEditable(false);
            addComponent(panel, keyTextField, 1, gridy++, 1, 1, normalInsets,
                    GridBagConstraints.LINE_START,
                    GridBagConstraints.HORIZONTAL);

            JLabel keyCharLabel = new JLabel("KeyChar:");
            addComponent(panel, keyCharLabel, 0, gridy, 1, 1, normalInsets,
                    GridBagConstraints.LINE_START,
                    GridBagConstraints.HORIZONTAL);

            keyCharField = new JTextField(20);
            keyCharField.setEditable(false);
            addComponent(panel, keyCharField, 1, gridy++, 1, 1, normalInsets,
                    GridBagConstraints.LINE_START,
                    GridBagConstraints.HORIZONTAL);

            JLabel keyLocationLabel = new JLabel("KeyLocation:");
            addComponent(panel, keyLocationLabel, 0, gridy, 1, 1, normalInsets,
                    GridBagConstraints.LINE_START,
                    GridBagConstraints.HORIZONTAL);

            keyLocationField = new JTextField(20);
            keyLocationField.setEditable(false);
            addComponent(panel, keyLocationField, 1, gridy++, 1, 1,
                    normalInsets, GridBagConstraints.LINE_START,
                    GridBagConstraints.HORIZONTAL);

            JLabel modifiersLabel = new JLabel("Modifiers:");
            addComponent(panel, modifiersLabel, 0, gridy, 1, 1, normalInsets,
                    GridBagConstraints.LINE_START,
                    GridBagConstraints.HORIZONTAL);

            modifiersField = new JTextField(20);
            modifiersField.setEditable(false);
            addComponent(panel, modifiersField, 1, gridy++, 1, 1, normalInsets,
                    GridBagConstraints.LINE_START,
                    GridBagConstraints.HORIZONTAL);

            JLabel extModifiersLabel = new JLabel("ExtModifiers:");
            addComponent(panel, extModifiersLabel, 0, gridy, 1, 1,
                    normalInsets, GridBagConstraints.LINE_START,
                    GridBagConstraints.HORIZONTAL);

            extModifiersField = new JTextField(20);
            extModifiersField.setEditable(false);
            addComponent(panel, extModifiersField, 1, gridy++, 1, 1,
                    normalInsets, GridBagConstraints.LINE_START,
                    GridBagConstraints.HORIZONTAL);

            JLabel rawCodeLabel = new JLabel("RawCode:");
            addComponent(panel, rawCodeLabel, 0, gridy, 1, 1, normalInsets,
                    GridBagConstraints.LINE_START,
                    GridBagConstraints.HORIZONTAL);

            rawCodeField = new JTextField(20);
            rawCodeField.setEditable(false);
            addComponent(panel, rawCodeField, 1, gridy++, 1, 1, normalInsets,
                    GridBagConstraints.LINE_START,
                    GridBagConstraints.HORIZONTAL);

            JLabel primaryLevelUnicodeLabel = new JLabel("PrimaryLevelUnicode:");
            addComponent(panel, primaryLevelUnicodeLabel, 0, gridy, 1, 1,
                    normalInsets, GridBagConstraints.LINE_START,
                    GridBagConstraints.HORIZONTAL);

            primaryLevelUnicodeField = new JTextField(20);
            primaryLevelUnicodeField.setEditable(false);
            addComponent(panel, primaryLevelUnicodeField, 1, gridy++, 1, 1,
                    normalInsets, GridBagConstraints.LINE_START,
                    GridBagConstraints.HORIZONTAL);

            JLabel scancodeLabel = new JLabel("Scancode:");
            addComponent(panel, scancodeLabel, 0, gridy, 1, 1, normalInsets,
                    GridBagConstraints.LINE_START,
                    GridBagConstraints.HORIZONTAL);

            scancodeField = new JTextField(20);
            scancodeField.setEditable(false);
            addComponent(panel, scancodeField, 1, gridy++, 1, 1, normalInsets,
                    GridBagConstraints.LINE_START,
                    GridBagConstraints.HORIZONTAL);

            JLabel extendedKeyCodeLabel = new JLabel("ExtendedKeyCode:");
            addComponent(panel, extendedKeyCodeLabel, 0, gridy, 1, 1,
                    bottomInsets, GridBagConstraints.LINE_START,
                    GridBagConstraints.HORIZONTAL);

            extendedKeyCodeField = new JTextField(20);
            extendedKeyCodeField.setEditable(false);
            addComponent(panel, extendedKeyCodeField, 1, gridy++, 1, 1,
                    bottomInsets, GridBagConstraints.LINE_START,
                    GridBagConstraints.HORIZONTAL);
        }

        private void addComponent(Container container, Component component,
                int gridx, int gridy, int gridwidth, int gridheight,
                Insets insets, int anchor, int fill) {
            GridBagConstraints gbc = new GridBagConstraints(gridx, gridy,
                    gridwidth, gridheight, 1.0D, 1.0D, anchor, fill, insets, 0,
                    0);
            container.add(component, gbc);
        }

        public JPanel getPanel() {
            return panel;
        }

        public void setKeyPressed(KeyEvent event) {
            String s = event.toString();

            keyCodeField.setText(getValue("keyCode", s));
            keyTextField.setText(getValue("keyText", s));
            keyCharField.setText(getValue("keyChar", s));
            keyLocationField.setText(getValue("keyLocation", s));
            modifiersField.setText(getValue("modifiers", s));
            extModifiersField.setText(getValue("extModifiers", s));
            rawCodeField.setText(getValue("rawCode", s));
            primaryLevelUnicodeField
                    .setText(getValue("primaryLevelUnicode", s));
            scancodeField.setText(getValue("scancode", s));
            extendedKeyCodeField.setText(getValue("extendedKeyCode", s));
        }

        private String getValue(String key, String line) {
            int sPos = line.indexOf(key);
            if (sPos >= 0) {
                int nPos = sPos + key.length() + 1;
                int ePos = line.indexOf(",", nPos);
                if (ePos < 0) {
                    ePos = line.indexOf("]", nPos);
                }
                if (ePos >= 0) {
                    return line.substring(nPos, ePos);
                }
            }

            return "";
        }

    }

    public class KeyPressedListener extends KeyAdapter {

        private KeySpy keySpyFrame;

        public KeyPressedListener(KeySpy keySpyFrame) {
            this.keySpyFrame = keySpyFrame;
        }

        @Override
        public void keyPressed(KeyEvent event) {
            keySpyFrame.getKeySpyPanel().setKeyPressed(event);
        }
    }

}