GetWindowTextA，GetWindowText在Edit Control上返回空值 [英] GetWindowTextA, GetWindowText returns empty value on Edit Control

问题描述

当我调用GetWindowText或者调用GetWindowText时，我会尝试从C ++ / Java中的外部窗口列出并获取编辑控件的内容。 GetWindowTextA它返回一个空的值在Edit Controls，我知道GetWindowText / GetWindowTextW和GetWindowTextA之间有一些差异，但我不知道我做错了，因为它适用于所有其他控件。

这里是C ++代码：

  BOOL CALLBACK EnumChildProc（HWND hwnd，LPARAM lParam）
 {
 cout<<---------- CHILD ------------<< endl; 
 char class_name [80]; 
 char title [80]; 
 GetClassName（hwnd，class_name，sizeof（class_name））; 
 GetWindowText（hwnd，title，sizeof（title））; 
 cout<<\tWindow title：<< title<< endl; 
 cout<<\tClass name：<< class_name<< endl<< endl; 
 return TRUE; 
} 
  

Java代码：

  User32.INSTANCE.EnumChildWindows（hWnd，new User32.WNDENUMPROC（）{
 @Override 
 public boolean callback（Pointer hWnd，Pointer arg）{
 byte [] windowClassx = new byte [512]; 
 User32.INSTANCE.GetClassNameA（hWnd，windowClassx，512）; 
 String wClass = Native.toString（windowClassx）; 
 System.out .println（ -  Found sub window / control class：+ new String（windowClassx）.trim（））; 
 if（wClass.toLowerCase（）。equals（edit））{
 byte [] windowTextx = new byte [128]; 
 user32.GetWindowText（hWnd，windowTextx，128）; 
 String wText = Native.toString（windowTextx）; 
 System.out.println ）; 
} 
 
 return true; 
} 
}，null）; 
  

解决方案

我不知道是什么原因导致你的问题，但这对我来说很好：

  byte [] windowText = new byte [512] 
 User32.INSTANCE.GetWindowTextA（hWnd，windowText，512）; 
 String wText = Native.toString（windowText）.trim（）; 
  
 
 
 
 
 
 
 编辑 > 
您应该使用不同的方式获得编辑文本，通过
  User32.SendMessageA（editHwnd，User32.WM_GETTEXT， paramWPARAM，lParamStr）; 
  
例如
 code> import com.sun.jna.Native; 
 import com.sun.jna.platform.win32.WinDef.HWND; 
 import com.sun.jna.platform.win32.WinDef.LPARAM; 
 import com.sun.jna.platform.win32.WinDef.LRESULT; 
 import com.sun.jna.platform.win32.WinDef.WPARAM; 
 import com.sun.jna.win32.StdCallLibrary; 
 
 public class GetTextInNotePad {
 public static final String NOTEPAD_CLASS =Notepad; 
 public static final String EDIT_CLASS =Edit; 
 
接口User32扩展StdCallLibrary {
 User32 INSTANCE =（User32）Native.loadLibrary（user32，User32.class）; 
 int WM_SETTEXT = 0x000c; 
 int WM_GETTEXT = 0x000D; 
 
 HWND FindWindowA（String lpClassName，String lpWindowName）; 
 HWND FindWindowExA（HWND hwndParent，HWND hwndChildAfter，String lpClassName，
 String lpWindowName）; 
 LRESULT SendMessageA（HWND paramHWND，int paramInt，WPARAM paramWPARAM，LPARAM paramLPARAM）; 
 LRESULT SendMessageA（HWND editHwnd，int wmGettext，long l，byte [] lParamStr）; 
 int GetClassNameA（HWND hWnd，byte [] lpString，int maxCount）; 
} 
 
 public static void main（String [] args）{
 User32 user32 = User32.INSTANCE; 
 String lpClassName =Notepad; 
 HWND notePadHwnd = user32.FindWindowA（lpClassName，null）; 
 HWND editHwnd = user32.FindWindowExA（notePadHwnd，null，EDIT_CLASS，null）; 
 byte [] lParamStr = new byte [512]; 
 LRESULT resultBool = user32.SendMessageA（editHwnd，User32.WM_GETTEXT，512，lParamStr）; 
 
 System.out.println（lParamStr：+ Native.toString（lParamStr））; 
} 
} 
  
 
I'm trying to list and get the content of Edit Controls from an external Window in C++ / Java, unfortunately with no success.

When I call GetWindowText or GetWindowTextA it returns an empty value on Edit Controls, I know there are some differences between GetWindowText / GetWindowTextW and GetWindowTextA but I don't know What I'm doing wrong since it works on all other controls.

Here the C++ Code:
BOOL CALLBACK EnumChildProc(HWND hwnd, LPARAM lParam)
{
    cout <<"----------CHILD------------"<<endl;
    char class_name[80];
    char title[80];
    GetClassName(hwnd,class_name, sizeof(class_name));
    GetWindowText(hwnd,title,sizeof(title));
    cout <<"\tWindow title: "<<title<<endl;
    cout <<"\tClass name: "<<class_name<<endl<<endl;
     return TRUE;
}
Java Code:
User32.INSTANCE.EnumChildWindows(hWnd, new User32.WNDENUMPROC() {
    @Override
    public boolean callback(Pointer   hWnd, Pointer   arg) {
        byte[] windowClassx = new byte[512];
        User32.INSTANCE.GetClassNameA(hWnd, windowClassx, 512);
        String wClass = Native.toString(windowClassx);
        System.out.println(" - Found sub window / control class: " + new String(windowClassx).trim());
        if (wClass.toLowerCase().equals("edit")){
            byte[] windowTextx = new byte[128];
            user32.GetWindowText(hWnd, windowTextx, 128);
            String wText = Native.toString(windowTextx);
            System.out.println(wText);
        }

        return true;
    }
}, null);  

解决方案
I'm not sure what is causing your problem, but this has worked just fine for me:
byte[] windowText = new byte[512];
User32.INSTANCE.GetWindowTextA(hWnd, windowText, 512);
String wText = Native.toString(windowText).trim();




Edit

You should get the edit text a different way, via
User32.SendMessageA(editHwnd, User32.WM_GETTEXT, paramWPARAM, lParamStr);
e.g.,
import com.sun.jna.Native;
import com.sun.jna.platform.win32.WinDef.HWND;
import com.sun.jna.platform.win32.WinDef.LPARAM;
import com.sun.jna.platform.win32.WinDef.LRESULT;
import com.sun.jna.platform.win32.WinDef.WPARAM;
import com.sun.jna.win32.StdCallLibrary;

public class GetTextInNotePad {
   public static final String NOTEPAD_CLASS = "Notepad";
   public static final String EDIT_CLASS = "Edit";

   interface User32 extends StdCallLibrary {
      User32 INSTANCE = (User32) Native.loadLibrary("user32", User32.class);
      int WM_SETTEXT = 0x000c;
      int WM_GETTEXT = 0x000D;

      HWND FindWindowA(String lpClassName, String lpWindowName);
      HWND FindWindowExA(HWND hwndParent, HWND hwndChildAfter, String lpClassName,
            String lpWindowName);
      LRESULT SendMessageA(HWND paramHWND, int paramInt, WPARAM paramWPARAM, LPARAM paramLPARAM);
      LRESULT SendMessageA(HWND editHwnd, int wmGettext, long l, byte[] lParamStr);
      int GetClassNameA(HWND hWnd, byte[] lpString, int maxCount);
   }

   public static void main(String[] args) {
      User32 user32 = User32.INSTANCE;
      String lpClassName = "Notepad";
      HWND notePadHwnd = user32.FindWindowA(lpClassName , null);
      HWND editHwnd = user32.FindWindowExA(notePadHwnd, null, EDIT_CLASS, null); 
      byte[] lParamStr = new byte[512];
      LRESULT resultBool = user32.SendMessageA(editHwnd, User32.WM_GETTEXT, 512, lParamStr);

      System.out.println("lParamStr: " + Native.toString(lParamStr));
   }
}


                        
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