c++ - Android JNI bridge Toast C++ 不工作——如何解决？

Question

我正在尝试解决我的 hpp 装置的一个小问题。我在互联网上找到了一些示例，展示了如何使用 Android JNI 桥在屏幕上 toast 信息，但它只是在 pascal (delphi) 中，所以我决定使用相同的 pas 文件，但使用 hpp 文件进行转换。到现在我明白了:

#ifndef Android_Jni_ToastHPP
#define Android_Jni_ToastHPP

#pragma delphiheader begin
#pragma option push
#pragma option -w-                                        // All warnings off
#pragma option -Vx                                        // Zero-length empty class member 
#pragma pack(push,8)
#include <FMX.Helpers.Android.hpp>                        // Pascal unit
#include <Androidapi.JNIBridge.hpp>                       // Pascal unit
#include <Androidapi.JNI.JavaTypes.hpp>                   // Pascal unit
#include <Androidapi.JNI.GraphicsContentViewText.hpp>     // Pascal unit
#include <Androidapi.JNI.Util.hpp>                        // Pascal unit
#include <Androidapi.JNI.App.hpp>                         // Pascal unit
#include <FMX.Surfaces.hpp>                               // Pascal unit

//-- user supplied -----------------------------------------------------------

namespace Android
{
namespace Jni
{
namespace Toast
{
//-- type declarations -------------------------------------------------------

extern DELPHI_PACKAGE Androidapi::Jni::Toast __fastcall Toast(const System::UnicodeString Msg, TToastLength duration);

#pragma pack(pop)

//-- type declarations -------------------------------------------------------
//-- var, const, procedure ---------------------------------------------------

}   /* namespace Android */
}   /* namespace JNI     */
}   /* namespace Toast   */
#if !defined(DELPHIHEADER_NO_IMPLICIT_NAMESPACE_USE) && !defined(NO_USING_NAMESPACE_ANDROID_JNI_TOAST)
using namespace Android::Jni::Toast;
#endif
#if !defined(DELPHIHEADER_NO_IMPLICIT_NAMESPACE_USE) && !defined(NO_USING_NAMESPACE_ANDROID_JNI)
using namespace Android::Jni;
#endif
#if !defined(DELPHIHEADER_NO_IMPLICIT_NAMESPACE_USE) && !defined(NO_USING_NAMESPACE_ANDROID)
using namespace Android;
#endif
#pragma pack(pop)
#pragma option pop

#pragma delphiheader end.
//-- end unit ----------------------------------------------------------------
#endif  // Androidapi_Jni_ToastHPP

如果你想要帕斯卡单位，就在这里:

unit Android.JNI.Toast;

interface

{$IFDEF ANDROID}

uses
  Androidapi.JNIBridge,
  Androidapi.JNI.JavaTypes,
  Androidapi.JNI.GraphicsContentViewText;
{$ENDIF}
{$IFDEF ANDROID}

type
  TToastLength = (LongToast, ShortToast);

  JToast = interface;

  JToastClass = interface(JObjectClass)
    ['{69E2D233-B9D3-4F3E-B882-474C8E1D50E9}']
    { Property methods }
    function _GetLENGTH_LONG: Integer; cdecl;
    function _GetLENGTH_SHORT: Integer; cdecl;
    { Methods }
    function init(context: JContext): JToast; cdecl; overload;
    function makeText(context: JContext; text: JCharSequence; duration: Integer)
      : JToast; cdecl;
    { Properties }
    property LENGTH_LONG: Integer read _GetLENGTH_LONG;
    property LENGTH_SHORT: Integer read _GetLENGTH_SHORT;
  end;

  [JavaSignature('android/widget/Toast')]
  JToast = interface(JObject)
    ['{FD81CC32-BFBC-4838-8893-9DD01DE47B00}']
    { Methods }
    procedure cancel; cdecl;
    function getDuration: Integer; cdecl;
    function getGravity: Integer; cdecl;
    function getHorizontalMargin: Single; cdecl;
    function getVerticalMargin: Single; cdecl;
    function getView: JView; cdecl;
    function getXOffset: Integer; cdecl;
    function getYOffset: Integer; cdecl;
    procedure setDuration(value: Integer); cdecl;
    procedure setGravity(gravity, xOffset, yOffset: Integer); cdecl;
    procedure setMargin(horizontalMargin, verticalMargin: Single); cdecl;
    procedure setText(s: JCharSequence); cdecl;
    procedure setView(view: JView); cdecl;
    procedure show; cdecl;
  end;

  TJToast = class(TJavaGenericImport<JToastClass, JToast>)
  end;

procedure Toast(const Msg: string; duration: TToastLength = ShortToast);

{$ENDIF}

implementation

{$IFDEF ANDROID}

uses
  FMX.Helpers.Android, Androidapi.Helpers;

procedure Toast(const Msg: string; duration: TToastLength);
var
  ToastLength: Integer;
begin
  if duration = ShortToast then
    ToastLength := TJToast.JavaClass.LENGTH_SHORT
  else
    ToastLength := TJToast.JavaClass.LENGTH_LONG;
  CallInUiThread(
    procedure
    begin
      TJToast.JavaClass.makeText(SharedActivityContext, StrToJCharSequence(Msg),
        ToastLength).show
    end);
end;
{$ENDIF}

end.

但是在使用这个源进行编译时出现错误...我做什么？

PS.:我只是将 AppMetthod 源与我正在制作的进行比较...

日志:

Checking project dependencies...
Compiling WebBrowser.cbproj (Debug, Android)
bccaarm command line for "uMain.cpp"
  c:\program files (x86)\embarcadero\studio\15.0\bin\bccaarm.exe -cc1 -D _DEBUG -isysroot 
  C:\Users\Public\Documents\Embarcadero\Studio\15.0\PlatformSDKs\android-ndk-r9c\platforms\android-14\arch-arm -idirafter =\usr\include -idirafter 
  C:\Users\Public\Documents\Embarcadero\Studio\15.0\PlatformSDKs\android-ndk-r9c\sources\cxx-stl\gnu-libstdc++\4.8\include -idirafter 
  C:\Users\Public\Documents\Embarcadero\Studio\15.0\PlatformSDKs\android-ndk-r9c\sources\cxx-stl\gnu-libstdc++\4.8\libs\armeabi-v7a\include -idirafter 
  C:\Users\Public\Documents\Embarcadero\Studio\15.0\PlatformSDKs\android-ndk-r9c\sources\android\native_app_glue -I 
  "C:\Users\Public\Documents\Embarcadero\Studio\15.0\Samples\CPP\Mobile Snippets\WebBrowser" -isystem "c:\program files 
  (x86)\embarcadero\studio\15.0\include" -isystem "c:\program files (x86)\embarcadero\studio\15.0\include\android\rtl" -isystem "c:\program files 
  (x86)\embarcadero\studio\15.0\include\android\fmx" -isystem "c:\program files (x86)\embarcadero\studio\15.0\include\android\crtl" -g 
  -fno-limit-debug-info -fborland-extensions -fborland-auto-refcount -nobuiltininc -nostdsysteminc -triple thumbv7-none-linux-androideabi -emit-obj 
  -mconstructor-aliases -pic-level 2 -target-abi aapcs-linux  -nostdinc++ -fdeprecated-macro -fexceptions -fcxx-exceptions -munwind-tables 
  -mstackrealign -fno-spell-checking -fno-use-cxa-atexit -main-file-name uMain.cpp -x c++ -std=c++11 -O0 -tU -o .\Android\Debug\uMain.o 
  -dependency-file .\Android\Debug\uMain.d -MT .\Android\Debug\uMain.o uMain.cpp 
[bccaarm Error] Android.JNI.Toast.hpp(36): expected a class or namespace
[bccaarm Error] Android.JNI.Toast.hpp(36): reference to 'Android' is ambiguous
  Android.JNI.Toast.hpp(28): candidate found by name lookup is 'Android'
  FMX.Helpers.Android.hpp(28): candidate found by name lookup is 'Fmx::Helpers::Android'
[bccaarm Error] Android.JNI.Toast.hpp(36): expected unqualified-id
[bccaarm Error] Android.JNI.Toast.hpp(47): expected a class or namespace
[bccaarm Error] Android.JNI.Toast.hpp(47): reference to 'Android' is ambiguous
  Android.JNI.Toast.hpp(28): candidate found by name lookup is 'Android'
  FMX.Helpers.Android.hpp(28): candidate found by name lookup is 'Fmx::Helpers::Android'
[bccaarm Error] Android.JNI.Toast.hpp(47): expected namespace name
[bccaarm Error] Android.JNI.Toast.hpp(50): expected a class or namespace
[bccaarm Error] Android.JNI.Toast.hpp(50): reference to 'Android' is ambiguous
  Android.JNI.Toast.hpp(28): candidate found by name lookup is 'Android'
  FMX.Helpers.Android.hpp(28): candidate found by name lookup is 'Fmx::Helpers::Android'
[bccaarm Error] Android.JNI.Toast.hpp(50): expected namespace name
[bccaarm Error] Android.JNI.Toast.hpp(53): reference to 'Android' is ambiguous
  Android.JNI.Toast.hpp(28): candidate found by name lookup is 'Android'
  FMX.Helpers.Android.hpp(28): candidate found by name lookup is 'Fmx::Helpers::Android'
[bccaarm Error] uMain.cpp(32): use of undeclared identifier 'Toast'
Failed
Elapsed time: 00:00:05.8

编辑:

新日志文件:

[bccaarm Error] Androidapi.JNI.Toast.hpp(36): no type named 'Toast' in namespace 'Androidapi::Jni'
[bccaarm Error] Androidapi.JNI.Toast.hpp(36): expected unqualified-id
[bccaarm Error] uMain.cpp(32): unexpected namespace name 'Toast': expected expression
Failed

从现在开始，非常感谢。

Answer 1

.hpp 文件格式不正确。

.pas 文件的interface 部分中定义的公共(public)类型均未在.hpp 文件中定义。特别是缺少 TToastLength 枚举。并且 Toast() 在 .pas 文件中被声明为一个 procedure，因此没有返回值，但它在 .hpp 文件中有一个(错误的)返回值。

您(或其他人)是否手动创建了 .hpp 文件？我怀疑是这种情况，原因有两个:

1. 初始#ifndef/#define中定义的Android_JNI_ToastHPP与Fmx_Helpers_AndroidHPP不匹配在相应的#endif中。

2. Delphi 编译器总是通过将第一个字母大写并将其余字母小写来为 Pascal 单元名称命名 C++ 命名空间，但此 .hpp 文件具有全大写的 JNI 命名空间。

Delphi 编译器不会犯这些错误。

话虽如此，Android.JNI.Toast.pas 应该重命名为 Androidapi.JNI.Toast.pas(并且重命名 .hpp 文件并更新其命名空间相应地)为了与 Embarcadero 的其他 JNI 单元保持一致(并匹配 this article 中的示例)。这也应该有助于缓解 reference to 'Android' is ambiguous 错误。

我强烈建议您更正 .pas 文件，通过 Delphi 编译器运行一次以生成正确的 .hpp 文件，然后按原样在您的 C++ 代码中使用它。

Androidapi.JNI.Toast.pas:

unit Androidapi.JNI.Toast;

interface

{$IFDEF ANDROID}

uses
  Androidapi.JNIBridge,
  Androidapi.JNI.JavaTypes,
  Androidapi.JNI.GraphicsContentViewText;

type
  TToastLength = (LongToast, ShortToast);

  JToast = interface;

  JToastClass = interface(JObjectClass)
    ['{69E2D233-B9D3-4F3E-B882-474C8E1D50E9}']
    { Property methods }
    function _GetLENGTH_LONG: Integer; cdecl;
    function _GetLENGTH_SHORT: Integer; cdecl;
    { Methods }
    function init(context: JContext): JToast; cdecl; overload;
    function makeText(context: JContext; text: JCharSequence; duration: Integer)
      : JToast; cdecl;
    { Properties }
    property LENGTH_LONG: Integer read _GetLENGTH_LONG;
    property LENGTH_SHORT: Integer read _GetLENGTH_SHORT;
  end;

  [JavaSignature('android/widget/Toast')]
  JToast = interface(JObject)
    ['{FD81CC32-BFBC-4838-8893-9DD01DE47B00}']
    { Methods }
    procedure cancel; cdecl;
    function getDuration: Integer; cdecl;
    function getGravity: Integer; cdecl;
    function getHorizontalMargin: Single; cdecl;
    function getVerticalMargin: Single; cdecl;
    function getView: JView; cdecl;
    function getXOffset: Integer; cdecl;
    function getYOffset: Integer; cdecl;
    procedure setDuration(value: Integer); cdecl;
    procedure setGravity(gravity, xOffset, yOffset: Integer); cdecl;
    procedure setMargin(horizontalMargin, verticalMargin: Single); cdecl;
    procedure setText(s: JCharSequence); cdecl;
    procedure setView(view: JView); cdecl;
    procedure show; cdecl;
  end;

  TJToast = class(TJavaGenericImport<JToastClass, JToast>)
  end;

procedure Toast(const Msg: string; duration: TToastLength = ShortToast);

{$ENDIF}

implementation

{$IFDEF ANDROID}

uses
  FMX.Helpers.Android, Androidapi.Helpers;

procedure Toast(const Msg: string; duration: TToastLength);
var
  ToastLength: Integer;
begin
  if duration = ShortToast then
    ToastLength := TJToast.JavaClass.LENGTH_SHORT
  else
    ToastLength := TJToast.JavaClass.LENGTH_LONG;
  CallInUiThread(
    procedure
    begin
      TJToast.JavaClass.makeText(SharedActivityContext, StrToJCharSequence(Msg),
        ToastLength).show
    end);
end;
{$ENDIF}

end.

Androidapi.JNI.Toast.hpp:

// CodeGear C++Builder
// Copyright (c) 1995, 2014 by Embarcadero Technologies, Inc.
// All rights reserved

// (DO NOT EDIT: machine generated header) 'Androidapi.JNI.Toast.pas' rev: 28.00 (Android)

#ifndef Androidapi_Jni_ToastHPP
#define Androidapi_Jni_ToastHPP

#pragma delphiheader begin
#pragma option push
#pragma option -w-      // All warnings off
#pragma option -Vx      // Zero-length empty class member 
#pragma pack(push,8)
#include <System.hpp>   // Pascal unit
#include <SysInit.hpp>  // Pascal unit
#include <Androidapi.JNIBridge.hpp> // Pascal unit
#include <Androidapi.JNI.JavaTypes.hpp> // Pascal unit
#include <Androidapi.JNI.GraphicsContentViewText.hpp>   // Pascal unit
#include <System.Rtti.hpp>  // Pascal unit

//-- user supplied -----------------------------------------------------------

namespace Androidapi
{
namespace Jni
{
namespace Toast
{
//-- type declarations -------------------------------------------------------
enum DECLSPEC_DENUM TToastLength : unsigned char { LongToast, ShortToast };

__interface JToastClass;
typedef System::DelphiInterface<JToastClass> _di_JToastClass;
__interface JToast;
typedef System::DelphiInterface<JToast> _di_JToast;
__interface  INTERFACE_UUID("{69E2D233-B9D3-4F3E-B882-474C8E1D50E9}") JToastClass  : public Androidapi::Jni::Javatypes::JObjectClass 
{

public:
    virtual int __cdecl _GetLENGTH_LONG(void) = 0 ;
    virtual int __cdecl _GetLENGTH_SHORT(void) = 0 ;
    HIDESBASE virtual _di_JToast __cdecl init(Androidapi::Jni::Graphicscontentviewtext::_di_JContext context) = 0 /* overload */;
    virtual _di_JToast __cdecl makeText(Androidapi::Jni::Graphicscontentviewtext::_di_JContext context, Androidapi::Jni::Javatypes::_di_JCharSequence text, int duration) = 0 ;
    __property int LENGTH_LONG = {read=_GetLENGTH_LONG};
    __property int LENGTH_SHORT = {read=_GetLENGTH_SHORT};
};

__interface  INTERFACE_UUID("{FD81CC32-BFBC-4838-8893-9DD01DE47B00}") JToast  : public Androidapi::Jni::Javatypes::JObject 
{

public:
    virtual void __cdecl cancel(void) = 0 ;
    virtual int __cdecl getDuration(void) = 0 ;
    virtual int __cdecl getGravity(void) = 0 ;
    virtual float __cdecl getHorizontalMargin(void) = 0 ;
    virtual float __cdecl getVerticalMargin(void) = 0 ;
    virtual Androidapi::Jni::Graphicscontentviewtext::_di_JView __cdecl getView(void) = 0 ;
    virtual int __cdecl getXOffset(void) = 0 ;
    virtual int __cdecl getYOffset(void) = 0 ;
    virtual void __cdecl setDuration(int value) = 0 ;
    virtual void __cdecl setGravity(int gravity, int xOffset, int yOffset) = 0 ;
    virtual void __cdecl setMargin(float horizontalMargin, float verticalMargin) = 0 ;
    virtual void __cdecl setText(Androidapi::Jni::Javatypes::_di_JCharSequence s) = 0 ;
    virtual void __cdecl setView(Androidapi::Jni::Graphicscontentviewtext::_di_JView view) = 0 ;
    virtual void __cdecl show(void) = 0 ;
};

class DELPHICLASS TJToast;
#pragma pack(push,4)
class PASCALIMPLEMENTATION TJToast : public Androidapi::Jnibridge::TJavaGenericImport__2<_di_JToastClass,_di_JToast> 
{
    typedef Androidapi::Jnibridge::TJavaGenericImport__2<_di_JToastClass,_di_JToast>  inherited;

public:
    /* TJavaImport.Create */ inline __fastcall TJToast(void * ID, void * ClsID, Androidapi::Jnibridge::TJavaVTable* VTable) : Androidapi::Jnibridge::TJavaGenericImport__2<_di_JToastClass,_di_JToast> (ID, ClsID, VTable) { }
    /* TJavaImport.Destroy */ inline __fastcall virtual ~TJToast(void) { }

};

#pragma pack(pop)

//-- var, const, procedure ---------------------------------------------------
extern DELPHI_PACKAGE void __fastcall Toast(const System::UnicodeString Msg, TToastLength duration = (TToastLength)(0x1));
}   /* namespace Toast */
}   /* namespace Jni */
}   /* namespace Androidapi */
#if !defined(DELPHIHEADER_NO_IMPLICIT_NAMESPACE_USE) && !defined(NO_USING_NAMESPACE_ANDROIDAPI_JNI_TOAST)
using namespace Androidapi::Jni::Toast;
#endif
#if !defined(DELPHIHEADER_NO_IMPLICIT_NAMESPACE_USE) && !defined(NO_USING_NAMESPACE_ANDROIDAPI_JNI)
using namespace Androidapi::Jni;
#endif
#if !defined(DELPHIHEADER_NO_IMPLICIT_NAMESPACE_USE) && !defined(NO_USING_NAMESPACE_ANDROIDAPI)
using namespace Androidapi;
#endif
#pragma pack(pop)
#pragma option pop

#pragma delphiheader end.
//-- end unit ----------------------------------------------------------------
#endif  // Androidapi_Jni_ToastHPP