Tips/JNI_HWND のバックアップ(No.13)

概要

JNI Windowsでウィンドウハンドルを取得する - Memo of Masterの方法２を参考にして、JNI(Java Native Interface)でJFrame(SunAwtFrame)のHWND(ウィンドウハンドル)を取得します。

JNI_HWND.png

環境

  • Microsoft Windows XP [Version 5.1.2600]
  • JDK 1.6.0_04
  • Microsoft Visual Studio .NET 2003\vc7

サンプルコード

import java.awt.*;
import javax.swing.*;

public class windowHandler{
  public native static int getHWND(Object obj);
  static {
    System.loadLibrary("hwndTest");
  }
  public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
      @Override public void run() {
        createAndShowGUI();
      }
    });
  }
  public static void createAndShowGUI() {
    try{
      //UIManager.getInstalledLookAndFeels();
      UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
    }catch(Exception e) {
      e.printStackTrace();
    }
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    frame.setSize(320, 240);
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
    int hwnd = getHWND(frame);
    frame.setTitle("HWND: 0x"+Integer.toHexString(hwnd).toUpperCase());
  }
}

#include "windowHandler.h"
#include "jawt_md.h"
#include <windows.h>
JNIEXPORT jint JNICALL Java_windowHandler_getHWND(
            JNIEnv *env, jobject jobj, jobject jframe) {
  JAWT awt;
  JAWT_DrawingSurface* ds;
  JAWT_DrawingSurfaceInfo* dsi;
  JAWT_Win32DrawingSurfaceInfo* dsi_win;
  jint lock;
  HWND hWnd;
  awt.version = JAWT_VERSION_1_4;
  if (JAWT_GetAWT(env, &awt) == JNI_FALSE) {
    return 0;
  }
  ds = awt.GetDrawingSurface(env, jframe);
  if (ds == NULL) {
    return 0;
  }

  lock = ds->Lock(ds);
  if ((lock & JAWT_LOCK_ERROR) != 0) {
    awt.FreeDrawingSurface(ds);
    return 0;
  }

  dsi = ds->GetDrawingSurfaceInfo(ds);
  if (dsi == NULL) {
    ds->Unlock(ds);
    awt.FreeDrawingSurface(ds);
    return 0;
  }
  dsi_win = (JAWT_Win32DrawingSurfaceInfo*)dsi->platformInfo;
  hWnd = dsi_win->hwnd;

  /* Free the drawing surface info */
  ds->FreeDrawingSurfaceInfo(dsi);

  /* Unlock the drawing surface */
  ds->Unlock(ds);

  /* Free the drawing surface */
  awt.FreeDrawingSurface(ds);

  return (jint)hWnd;
}

解説

以下のようにコンパイル、実行するとJFrameのタイルトバーにHWNDが表示されます。

@echo off
SETLOCAL

"%JAVA_HOME%\bin\javac" windowHandler.java
"%JAVA_HOME%\bin\javah" -jni windowHandler

set SDK=C:\Program Files\Microsoft Visual Studio .NET 2003\vc7
"%SDK%\bin\cl.exe" /c -I"%SDK%\include" -I"%SDK%\PlatformSDK\include" -I"%JAVA_HOME%\include" -I"%JAVA_HOME%\include\win32" -IhwndTest.h hwndTest.c

set LIB=%SDK%\lib;%SDK%\PlatformSDK\lib
"%SDK%\bin\link.exe" /DLL hwndTest.obj "%JAVA_HOME%\lib\jawt.lib"

set Path=%Path%;%JAVA_HOME%\jre\bin

"%JAVA_HOME%\bin\java" windowHandler

JNIを使用せず、以下のようにHWNDを取得する方法もあります。

import java.awt.*;
import javax.swing.*;
import sun.awt.windows.WComponentPeer;
public class WComponentPeerTest {
  public static long getHWnd(Frame f) {
    return f.getPeer()!=null ? ((WComponentPeer)f.getPeer()).getHWnd() : 0;
  }
  public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
      @Override public void run() { createAndShowGUI(); }
    });
  }
  public static void createAndShowGUI() {
    JFrame f = new JFrame();
    f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    f.setSize(320, 240);
    f.setLocationRelativeTo(null);
    f.setVisible(true);
    f.setTitle("HWnd: "+getHWnd(f));
  }
}

参考リンク

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