Android ndk solves the problem of mutual calls between the two so

From: http://blog.csdn.net/victoryckl/article/details/6832333

Modules A and B are mainly implemented in C and need to be compiled into two. so, B. so, but. so calls B. so function, B. so also called. so functions, and for some reason, A and B must be compiled separately. The problem is that no matter which module is compiled first, the compilation fails because they are mutually dependent.

This dependency must be canceled during compilation. In the following program, use dlopen to open so and dlsym to obtain the function pointer to avoid this dependency.

A. c

 

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1. # Include <stdio. h>
2. # Include <stdlib. h>
3. # Include <stdarg. h>
4. # Include <dlfcn. h>
5. # Include <JNI. h>
7. Char * getstringa (void)
8. {
9. Return "I am in A. So ";
10. }
12. Jstring java_com_ckl_socallso_socallsoactivity_fucntionina (jnienv * ENV, jobject thiz)
13. {
14. Return (* env)-> newstringutf (ENV, getstringa ());
15. }
17. Jstring java_com_ckl_socallso_socallsoactivity_acallb (jnienv * ENV, jobject thiz)
18. {
19. Jstring ret;
20. // So path:/data/package name of my program/lib/My so file name
21. Void * filehandle = dlopen ("/data/COM. CKL. socallso/lib/libb. So", rtld_lazy );
22. If (filehandle)
23. {
24. Char * (* funcptrb) (void) = NULL;
25. Funcptrb = dlsym (filehandle, "getstringb ");
26. If (funcptrb)
27. {
28. Ret = (* env)-> newstringutf (ENV, funcptrb ());
29. }
30. Else
31. {
32. Ret = (* env)-> newstringutf (ENV, "dlsym getstringb failed! ");
33. }
34. Dlclose (filehandle );
35. }
36. Else
37. {
38. Ret = (* env)-> newstringutf (ENV, "dlopen failed! ");
39. }
41. Return ret;
42. }

# Include <stdio. h> <br/> # include <stdlib. h> <br/> # include <stdarg. h> <br/> # include <dlfcn. h> <br/> # include <JNI. h> </P> <p> char * getstringa (void) <br/>{< br/> return "I am in. so "; <br/>}</P> <p> jstring java_com_ckl_socallso_socallsoactivity_fucntionina (jnienv * ENV, jobject thiz) <br/>{< br/> return (* env) -> newstringutf (ENV, getstringa (); <br/>}</P> <p> jstring java_com_ckl_socallso_socallsoactivity_ac Allb (jnienv * ENV, jobject thiz) <br/>{< br/> jstring ret; <br/> // so path: /data/package name of my program/lib/My so file name <br/> void * filehandle = dlopen ("/data/COM. CKL. socallso/lib/libb. so ", rtld_lazy); <br/> If (filehandle) <br/>{< br/> char * (* funcptrb) (void) = NULL; <br/> funcptrb = dlsym (filehandle, "getstringb"); <br/> If (funcptrb) <br/>{< br/> ret = (* env) -> newstringutf (ENV, funcptrb (); <br/>}< br/> else <br />{< Br/> ret = (* env)-> newstringutf (ENV, "dlsym getstringb failed! "); <Br/>}< br/> dlclose (filehandle ); <br/>}< br/> else <br/> {<br/> ret = (* env)-> newstringutf (ENV, "dlopen failed! "); <Br/>}</P> <p> return ret; <br/>}< br/>
B .C

 

 

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1. # Include <stdio. h>
2. # Include <stdlib. h>
3. # Include <stdarg. h>
4. # Include <dlfcn. h>
5. # Include <JNI. h>
7. Char * getstringb (void)
8. {
9. Return "I am in B. So ";
10. }
12. Jstring java_com_ckl_socallso_socallsoactivity_fucntioninb (jnienv * ENV, jobject thiz)
13. {
14. Return (* env)-> newstringutf (ENV, getstringb ());
15. }
17. Jstring java_com_ckl_socallso_socallsoactivity_bcalla (jnienv * ENV, jobject thiz)
18. {
19. Jstring ret;
20. // So path:/data/package name of my program/lib/My so file name
21. Void * filehandle = dlopen ("/data/COM. CKL. socallso/lib/LIBA. So", rtld_lazy );
22. If (filehandle)
23. {
24. Char * (* funcptra) (void) = NULL;
25. Funcptra = dlsym (filehandle, "getstringa ");
26. If (funcptra)
27. {
28. Ret = (* env)-> newstringutf (ENV, funcptra ());
29. }
30. Else
31. {
32. Ret = (* env)-> newstringutf (ENV, "dlsym getstringa failed! ");
33. }
34. Dlclose (filehandle );
35. }
36. Else
37. {
38. Ret = (* env)-> newstringutf (ENV, "dlopen failed! ");
39. }
40. Return ret;
41. }

# Include <stdio. h> <br/> # include <stdlib. h> <br/> # include <stdarg. h> <br/> # include <dlfcn. h> <br/> # include <JNI. h> </P> <p> char * getstringb (void) <br/>{< br/> return "I am in B. so "; <br/>}</P> <p> jstring java_com_ckl_socallso_socallsoactivity_fucntioninb (jnienv * ENV, jobject thiz) <br/>{< br/> return (* env) -> newstringutf (ENV, getstringb (); <br/>}</P> <p> jstring java_com_ckl_socallso_socallsoactivity_bc Alla (jnienv * ENV, jobject thiz) <br/>{< br/> jstring ret; <br/> // so path: /data/package name of my program/lib/My so file name <br/> void * filehandle = dlopen ("/data/COM. CKL. socallso/lib/LIBA. so ", rtld_lazy); <br/> If (filehandle) <br/>{< br/> char * (* funcptra) (void) = NULL; <br/> funcptra = dlsym (filehandle, "getstringa"); <br/> If (funcptra) <br/>{< br/> ret = (* env) -> newstringutf (ENV, funcptra (); <br/>}< br/> else <br />{< Br/> ret = (* env)-> newstringutf (ENV, "dlsym getstringa failed! "); <Br/>}< br/> dlclose (filehandle ); <br/>}< br/> else <br/> {<br/> ret = (* env)-> newstringutf (ENV, "dlopen failed! "); <Br/>}< br/> return ret; <br/>}
Android. mk

 

 

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1. Local_path: = $ (call my-DIR)
3. Include $ (clear_vars)
4. Local_module: =
5. Local_src_files: = A. C
6. Include $ (build_shared_library)
8. Include $ (clear_vars)
9. Local_module: = B
10. Local_src_files: = B. C
11. Include $ (build_shared_library)

Local_path: = $ (call my-DIR) </P> <p> include $ (clear_vars) <br/> local_module: = A <br/> local_src_files: =. c <br/> include $ (build_shared_library) </P> <p> include $ (clear_vars) <br/> local_module: = B <br/> local_src_files: = B. c <br/> include $ (build_shared_library)

 

A. c. B. c generate LIBA. so, libb. so, LIBA. so call libb. the getstringb () function in so, libb. so call LIBA. the getstringa () function in so.

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In addition, the path of the so file is/data/package name of my program/lib/My so file name.

Engineering source codeSocallso.7z

The running effect is as follows: