Android ndk Problems

Index:

 

Ndk compiles and uses static and dynamic libraries

JNI header file generation

Use Android log in nactive code of ndk

 

Analyze the stack information of ndk crash

Ndk-GDB debugging method

 

Ndk compiles and uses static and dynamic libraries

Too complicated. See the new article: http: // Android ndk for compiling and using static and dynamic libraries.

 

JNI header file generation:

 

1. Declare the Java Native Interface. (Defining Java Native interfaces can be declared in the main class of the android project, or by using independent classes .)

Static {system. loadlibrary ("libxxx ");}

Public native void Init ()

2. Compile the Java code.

Javah-classpath $ (bin_path) COM. x. y. Z. classname

 

3. Then, you can see the header file com_x_y_z_classname.h in the current path and implement it as OK.

Note: $ (bin_path) refers to the position of bin after class compilation. for Android development, it is generally under $ Project/bin.

 

Use Android log in nactive code of ndk

1. Add the following to the MK file:

Local_ldlibs: =-L $ (sysroot)/usr/lib-llog

2. Add the following to the CPP file:

# Include <Android/log. h>

# Define Logi (...) _ android_log_print (android_log_debug, "keymatch", _ va_args __)

3. Use:

Logi ("Some log here, % s, % d" ,__ file ,__ line __);

 

 

Analyze the stack information of ndk crash

1 Google provides a Python script that can be downloaded from the http://code.google.com/p/android-ndk-stacktrace-analyzer/, and then use ADB logcat-D> logfile to export the crash log, use arm-Eabi-objdump to convert so or EXE to assembly code under build/prebuilt/linux-x86/bin, such as arm-Eabi-objdump-s mylib. so> mylib. ASM, use the script Python parse_stack.py <ASM-File> <logcat-File>

2 directly use the arm-eabi-addr2line below ndk(Recommended)

Example: arm-eabi-addr2line-C-f-e libxxx. so 0x ###### (0x #### it is the top PC value in the address output log and can be traced back to the final function call sequence)

 

 

Ndk-GDB debugging method

1 androidmanifest. xml <Application> contains Android: debuggable = "true"

2. Run ndk-build ndk_debug = 1.

3. Add a breakpoint before Java code calls C, and then add B ***. C: main to the gdb command line.

Breakpoint addition method Android. OS. Debug. waitfordebugger ();

4. Run ndk-GDB.

Ndk-GDB -- start -- force -- verbose displays more information to view errors in the step.