JNA - JVM致命錯誤 - XGetInputFocus - Ubuntu的

操作系統：Ubuntu的16.04
JNA：4.2.2
JDK：1.8.0u111JNA - JVM致命錯誤 - XGetInputFocus - Ubuntu的

我試圖在JavaFX應用程序來檢索使用JNA當前焦點窗口在Ubuntu上運行。

爲了實現我的目標，我使用X11 API，更精確的功能XGetInputFocus那樣：

if (Platform.isLinux()) { 

    System.err.println("Linux platform"); 

    final X11 x11 = X11.INSTANCE; 
    final XLib xlib = XLib.INSTANCE; 

    X11.Display display = x11.XOpenDisplay(null); 

    //X11.Window window = new X11.Window(); 
    X11.WindowByReference winRef = new X11.WindowByReference(); 

    Pointer pointer = Pointer.NULL; 

    xlib.XGetInputFocus(display, winRef, pointer); 

    /*X11.XTextProperty name = new X11.XTextProperty(); 
    x11.XGetWMName(display, window, name); 
    System.out.println(name.toString());*/ 
}

public interface XLib extends X11 { 
    XLib INSTANCE = (XLib) Native.loadLibrary("X11", XLib.class); 
    //void XGetInputFocus(X11.Display display, X11.Window focus_return, Pointer revert_to_return); 
    void XGetInputFocus(X11.Display display, X11.WindowByReference focus_return, Pointer revert_to_return); 
}

不幸的是，我得到了以下異常，我試過X11.WindowByReference和X11.Window有參數，但它什麼都沒有改變，例外是一樣的。

Linux platform 
Looking in classpath from [email protected] for /com/sun/jna/linux-x86-64/libjnidispatch.so 
Found library resource at jar:file:/home/puglic/eclipse/jna-4.2.2.jar!/com/sun/jna/linux-x86-64/libjnidispatch.so 
Looking for library 'X11' 
Adding paths from jna.library.path: null 
Trying libX11.so 
Found library 'X11' at libX11.so 
# 
# A fatal error has been detected by the Java Runtime Environment: 
# 
# SIGSEGV (0xb) at pc=0x00007f4063178e47, pid=21693, tid=0x00007f405423a700 
# 
# JRE version: Java(TM) SE Runtime Environment (8.0_111-b14) (build 1.8.0_111-b14) 
# Java VM: Java HotSpot(TM) 64-Bit Server VM (25.111-b14 mixed mode linux-amd64 compressed oops) 
# Problematic frame: 
# C [libX11.so.6+0x22e47] XGetInputFocus+0x57

此外，它會生成一個巨大的錯誤文件，名爲hs_err_pid21693.log。在這裏我們可以找到這樣的行：

... 
Internal exceptions (10 events): 
Event: 0,223 Thread 0x00007f213000a000 Exception <a 'java/lang/NoSuchFieldError': method resolution failed> (0x00000000d7b0ded8) thrown at [/HUDSON3/workspace/8-2-build-linux-amd64/jdk8u111/7883/hotspot/src/share/vm/prims/methodHandles.cpp, line 1146] 
Event: 0,262 Thread 0x00007f213000a000 Exception <a 'java/security/PrivilegedActionException'> (0x00000000d7b98008) thrown at [/HUDSON3/workspace/8-2-build-linux-amd64/jdk8u111/7883/hotspot/src/share/vm/prims/jvm.cpp, line 1386] 
Event: 0,262 Thread 0x00007f213000a000 Exception <a 'java/security/PrivilegedActionException'> (0x00000000d7b98218) thrown at [/HUDSON3/workspace/8-2-build-linux-amd64/jdk8u111/7883/hotspot/src/share/vm/prims/jvm.cpp, line 1386] 
Event: 0,263 Thread 0x00007f213000a000 Exception <a 'java/security/PrivilegedActionException'> (0x00000000d7b9a7e8) thrown at [/HUDSON3/workspace/8-2-build-linux-amd64/jdk8u111/7883/hotspot/src/share/vm/prims/jvm.cpp, line 1386] 
Event: 0,263 Thread 0x00007f213000a000 Exception <a 'java/security/PrivilegedActionException'> (0x00000000d7b9a9f8) thrown at [/HUDSON3/workspace/8-2-build-linux-amd64/jdk8u111/7883/hotspot/src/share/vm/prims/jvm.cpp, line 1386] 
Event: 0,263 Thread 0x00007f213000a000 Exception <a 'java/lang/NullPointerException'> (0x00000000d7b9afd0) thrown at [/HUDSON3/workspace/8-2-build-linux-amd64/jdk8u111/7883/hotspot/src/share/vm/interpreter/linkResolver.cpp, line 1178] 
Event: 0,621 Thread 0x00007f21302c1800 Exception <a 'java/lang/NullPointerException'> (0x00000000d8349f68) thrown at [/HUDSON3/workspace/8-2-build-linux-amd64/jdk8u111/7883/hotspot/src/share/vm/interpreter/linkResolver.cpp, line 1178] 
Event: 0,621 Thread 0x00007f21302c1800 Exception <a 'java/lang/NullPointerException'> (0x00000000d8349f68) thrown at [/HUDSON3/workspace/8-2-build-linux-amd64/jdk8u111/7883/hotspot/src/share/vm/prims/jvm.cpp, line 1390] 
Event: 0,871 Thread 0x00007f21302c1800 Exception <a 'java/io/FileNotFoundException'> (0x00000000d87dc6d8) thrown at [/HUDSON3/workspace/8-2-build-linux-amd64/jdk8u111/7883/hotspot/src/share/vm/prims/jni.cpp, line 709] 
Event: 1,041 Thread 0x00007f21302c1800 Implicit null exception at 0x00007f212120d176 to 0x00007f212120d531 
...

來源

2017-01-23 puglic

請注意'Pointer.NULL'和'null'是等價的。前者僅適用於那些使用'null'的情況，可能會引入一些含糊或類型混淆的情況。 – technomage

我不認爲XGetInputFocus給你傳遞NULL作爲最後一個參數的選項。您需要傳入有效內存位置的地址，函數可以在其中寫入其revert_to「返回」值。

您應該使用非空IntByReference對象而不是NULL。

來源

2017-01-23 15:26:33 technomage

謝謝，它的工作原理！那麼，我應該怎麼做來檢索窗口名稱？ – puglic

'x11.XGetWMName（display，winRef.getValue（），name）;''name.value'給我標題。但對於Firefox等其他應用，它給了我'null'。我做錯什麼了嗎？ – puglic

您應該爲'XTextProperty *'參數傳遞'PointerByReference'，然後使用「返回」指針值初始化新的'XTextProperty'。 – technomage

JNA - JVM致命錯誤 - XGetInputFocus - Ubuntu的

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