java - 文件操作JNI

Question

我是 android 和 JNI 的新手。我想访问设备中的文件。我已经向 list 添加了权限，但它不起作用。

Java 代码:

public class MainActivity extends ActionBarActivity {
public native String  setFilePath(String path);

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


    TextView  tv = new TextView(this);

    tv.setText( "1111" );


    setContentView(tv);
    String path = Environment.getExternalStorageDirectory().getPath()+"/xyz"; 
    Log.i("java ", path);
    setFilePath(path);

}
}

C 代码:

jint Java_package_MainActivity_setFilePath(JNIEnv* env, jobject this,jstring Path){



path = (*env)->GetStringUTFChars( env, Path , NULL ) ;
__android_log_print(ANDROID_LOG_DEBUG, "SO", "fopen(%s)", path);
FILE* file = fopen(path,"ab+");
(*env)->ReleaseStringUTFChars( env, Path , path );
fputs("Testing!\n", file);
fclose(file);
return 0;
}

出现错误:

Fatal signal 11 (SIGSEGV) at 0x0000000c (code=1), thread 16152 

Answer 1

// Path is an jstring passed as an arg of a function
char *path = (*env)->GetStringUTFChars( env, Path , NULL ) ;
__android_log_print(ANDROID_LOG_DEBUG, "SO", "fopen(%s)", path);
FILE* file = fopen(path,"ab+");
(*env)->ReleaseStringUTFChars( env, Path , path );
fputs("Testing!\n", file);
fclose(file);

如果不起作用，请将打印内容发布到 logcat。