在X-Cross平台库上使用JsonCpp [英] Using JsonCpp on X-Cross platform library

问题描述

我在C ++中使用OpenCV和JsonCpp制作了一个库，用于为Android和iOS构建库。

在测试我的库时， JNI文件，但是当我尝试加载库我正在获取

java.lang.UnsatisfiedLinkError：dlopen失败：找不到符号
libXYZ.so引用的_ZN4Json6WriterD2Ev...

这是因为我认为我不是Json库非常好。

我使用的库是这样的： https://github.com/open-source-parsers/jsoncpp

我的Android.mk是：

  LOCAL_PATH：= $（call my-dir）
 
 include $（CLEAR_VARS）
 $ b b OPENCV_CAMERA_MODULES：= off 
 OPENCV_INSTALL_MODULES：= on 
 
 include $（LOCAL_PATH）/jsoncpp/Android.mk 
 include /Users/localmac/Desktop/AndroidDevelopment/OpenCV-2.4。 9-android-sdk / sdk / native / jni / OpenCV.mk 
 
 OPENCV_LIB_TYPE：= SHARED 
 
 LOCAL_C_INCLUDES + = $（LOCAL_PATH）
 LOCAL_C_INCLUDES + = / Users / localmac / mylibrary / OpenCVtry / 
 LOCAL_C_INCLUDES + = / Users / localmac / Desktop / RD / OpenCVtry / Libraries / jsoncpp-master / include 
 
 LOCAL_ALLOW_UNDEFINED_SYMBOLS：= true 
 LOCAL_MODULE ：= libXYZ 
 LOCAL_SRC_FILES：= androidClass.cpp main.cpp utils.cpp 
 LOCAL_LDLIBS + = -llog -ldl 
 
 include $（BUILD_SHARED_LIBRARY）
  

我不知道如何做。

。

---

EDIT 不是NDK Compiling的错误。

即使我编译JsonCpp，我得到

java.lang.UnsatisfiedLinkError：dlopen failed：can not找到由libXYZ.so引用的符号_ZN4Json6WriterD2Ev...

EDIT 我的jsoncpp / Android .mk：

LOCAL_PATH：= $（call my-dir）

include $（CLEAR_VARS）

LOCAL_CPP_EXTENSION：= .cpp LOCAL_MODULE：= libJsoncpp

LOCAL_C_INCLUDES：= $（LOCAL_PATH ）/ jsoncpp / include

LOCAL_SRC_FILES：= src / lib_json / json_reader.cpp \
src / lib_json / json_value.cpp \
src /lib_json/json_writer.cpp

包含$（BUILD_SHARED_LIBRARY）

解决方案

你不是在你的makefile中链接Jsoncpp。您应该添加以下行：

  LOCAL_SHARED_LIBRARIES：= libJsoncpp 
  

之前包含$（BUILD_SHARED_LIBRARY）。

您必须为此变量（及其姐妹 LOCAL_STATIC_LIBRARIES ）指定模块名称，即您为 LOCAL_MODULE 变量。

此外，它使您无法指定 LOCAL_C_INCLUDE 变量中的包含（因为makefile将包括

编辑：为了完整起见，我将您可以指定多个库：

  LOCAL_SHARED_LIBRARIES = libJsoncpp \ 
 libOpenCV \ 
 ... 
  

，同样适用于 LOCAL_STATIC_LIBRARIES 。

I'm making a library in C++ with OpenCV and JsonCpp towards building a library for Android and iOS.

On testing my library for Android, I'm making the JNI files but when I try to load the library I'm getting

java.lang.UnsatisfiedLinkError: dlopen failed: cannot locate symbol "_ZN4Json6WriterD2Ev" referenced by "libXYZ.so"...

and that's because I think I'm not building my Json library very well.

The library that I use is this one: https://github.com/open-source-parsers/jsoncpp

My Android.mk is:

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

OPENCV_CAMERA_MODULES:=off
OPENCV_INSTALL_MODULES:=on

include $(LOCAL_PATH)/jsoncpp/Android.mk
include /Users/localmac/Desktop/AndroidDevelopment/OpenCV-2.4.9-android-sdk/sdk/native/jni/OpenCV.mk

OPENCV_LIB_TYPE:=SHARED

LOCAL_C_INCLUDES += $(LOCAL_PATH)
LOCAL_C_INCLUDES += /Users/localmac/mylibrary/OpenCVtry/
LOCAL_C_INCLUDES += /Users/localmac/Desktop/RD/OpenCVtry/Libraries/jsoncpp-master/include

LOCAL_ALLOW_UNDEFINED_SYMBOLS := true
LOCAL_MODULE    := libXYZ
LOCAL_SRC_FILES := androidClass.cpp main.cpp utils.cpp
LOCAL_LDLIBS     += -llog -ldl

include $(BUILD_SHARED_LIBRARY)

I have no idea of how to do this.

Thank you in advance.

---

EDIT it's not the NDK Compiling's fault.

Even if I compile the JsonCpp, I get the

java.lang.UnsatisfiedLinkError: dlopen failed: cannot locate symbol "_ZN4Json6WriterD2Ev" referenced by "libXYZ.so"...

EDIT My jsoncpp/Android.mk :

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_CPP_EXTENSION := .cpp LOCAL_MODULE := libJsoncpp

LOCAL_C_INCLUDES := $(LOCAL_PATH)/jsoncpp/include

LOCAL_SRC_FILES := src/lib_json/json_reader.cpp \ src/lib_json/json_value.cpp \ src/lib_json/json_writer.cpp

include $(BUILD_SHARED_LIBRARY)

解决方案

You're not linking against Jsoncpp in your makefile. You should add the following line:

LOCAL_SHARED_LIBRARIES := libJsoncpp

before the last include $(BUILD_SHARED_LIBRARY).

You must specify module names for this variable (and its sister LOCAL_STATIC_LIBRARIES), that is, what you specified for the LOCAL_MODULE variable.

Also, that spares you from specifiying the includes in the LOCAL_C_INCLUDE variable (as the makefile will include them directly when specifying the library in the variable I mentioned at the top of my post).

EDIT: For the sake of completeness, I'll add that you can specify multiple libraries like that:

LOCAL_SHARED_LIBRARIES = libJsoncpp \
                         libOpenCV \
                         ...

and the same goes for LOCAL_STATIC_LIBRARIES.

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