爪哇從MIDI鍵盤獲取輸入

Question

我已經設計了我自己的合成器在java中，我現在想要連接它與MIDI鍵盤。我的課程通過所有有變送器的MIDI設備進行搜索。它成功找到我的midi鍵盤。我爲每個設備添加自己的接收器到每個發射器，以便它可以接收所有可能的東西。從閱讀所有的幫助文檔和java文檔，我知道發送器將MidiEvent發送給接收器，然後使用發送方法處理它們。所以我編寫了自己的實現Receiver的內部類，並使用println語句來檢查send方法中是否檢測到任何東西。然而，沒有任何東西被拿起。似乎沒有什麼幫助做這樣一個簡單的事情，我已經看過每個幫助文件，javadoc和論壇。我敢肯定，這肯定是一件非常明顯的事情，我不知何故錯過了。

我的合成器不應該與界面合成器混淆，它不是一個MIDI設備。它使用合成算法並具有播放方法。基本上我只需要讓midi鍵盤發送關於將調用播放方法的事件的註釋。

import javax.sound.midi.*; 
import java.util.ArrayList; 
import java.util.List; 
import java.io.*; 
public class MidiHandler 
{ 
    //ArrayList of MidiDevices 
    private ArrayList<MidiDevice> devices = new ArrayList<MidiDevice>(); 

    public MidiHandler() 
    { 
     MidiDevice device; 
     MidiDevice.Info[] infos = MidiSystem.getMidiDeviceInfo(); 
     for (int i = 0; i < infos.length; i++) { 
      try { 
       device = MidiSystem.getMidiDevice(infos[i]); 
       //does the device have any transmitters? 
       if (device.getTransmitters().size() > 0) { 
        //if it does, add it to the device list 
        System.out.println(infos[i] + ": " + device.getTransmitters().size()); 
        devices.add(device); 
       } 
      } catch (MidiUnavailableException e) {} 
     } 
     //if any transmitting devices were found 
     if(devices.size()>0) { 
      //for each device 
      for(int i = 0; i<devices.size(); i++) { 
       try { 
        //get all transmitters 
        List<Transmitter> transmitters = devices.get(i).getTransmitters(); 
        //and for each transmitter 
        for(int j = 0; j<transmitters.size();j++) { 
         //create a new receiver 
         transmitters.get(i).setReceiver(
          //using my own MidiInputReceiver 
          new MidiInputReceiver(devices.get(i).getDeviceInfo().toString()) 
         ); 
        } 
        //open each device 
        devices.get(i).open(); 
        //if code gets this far without throwing an exception 
        //print a success message 
        System.out.println(devices.get(i).getDeviceInfo()+" Was Opened"); 
       } catch (MidiUnavailableException e) {} 
      } 
     } 
    } 
    //tried to write my own class. I thought the send method handles an MidiEvents sent to it 
    public class MidiInputReceiver implements Receiver { 
     public String name; 
     public MidiInputReceiver(String name) { 
      this.name = name; 
     } 
     public void send(MidiMessage msg, long timeStamp) { 
      System.out.println("midi received"); 
     } 
     public void close() {} 
    } 
} 

注： 我已經看到了這一點：Java MIDI - getting data from piano?。

這：http://www.jsresources.org/examples/MidiInDump.html

接口音序看着方式複雜，我想也是。

Answer 1

我發現MidiDevice的getTransmitters（）似乎返回當前已經開發射器，而不是發射是可要打開的列表。我相信打開一個新的發射器的方式是通過getTransmitter（）方法。我已經修改了你的代碼要做到這一點：

import javax.sound.midi.*; 
import java.util.ArrayList; 
import java.util.List; 
import java.io.*; 
    public class MidiHandler 
{ 

    public MidiHandler() 
    { 
     MidiDevice device; 
     MidiDevice.Info[] infos = MidiSystem.getMidiDeviceInfo(); 
     for (int i = 0; i < infos.length; i++) { 
      try { 
      device = MidiSystem.getMidiDevice(infos[i]); 
      //does the device have any transmitters? 
      //if it does, add it to the device list 
      System.out.println(infos[i]); 

      //get all transmitters 
      List<Transmitter> transmitters = device.getTransmitters(); 
      //and for each transmitter 

      for(int j = 0; j<transmitters.size();j++) { 
       //create a new receiver 
       transmitters.get(j).setReceiver(
         //using my own MidiInputReceiver 
         new MidiInputReceiver(device.getDeviceInfo().toString()) 
       ); 
      } 

      Transmitter trans = device.getTransmitter(); 
      trans.setReceiver(new MidiInputReceiver(device.getDeviceInfo().toString())); 

      //open each device 
      device.open(); 
      //if code gets this far without throwing an exception 
      //print a success message 
      System.out.println(device.getDeviceInfo()+" Was Opened"); 


     } catch (MidiUnavailableException e) {} 
    } 


} 
//tried to write my own class. I thought the send method handles an MidiEvents sent to it 
public class MidiInputReceiver implements Receiver { 
    public String name; 
    public MidiInputReceiver(String name) { 
     this.name = name; 
    } 
    public void send(MidiMessage msg, long timeStamp) { 
     System.out.println("midi received"); 
    } 
    public void close() {} 
    } 
} 

在我的硬件（我已經插入一個簡單的USB MIDI控制器），代碼正確地打印出「MIDI收到」創建MidiHandler的實例後。

希望這會有所幫助！

Answer 2

我發現你必須在調用setRecceiver（）之前打開設備，否則接收者的send（）方法會被上次運行應用程序時的任何垃圾MIDI數據調用。

device.open(); 

Transmitter trans = device.getTransmitter();  
// set new receiver after opening so that the input buffer will be flushed 
trans.setReceiver(new MidiInputReceiver(device.getDeviceInfo().toString()));