软件设计之状态机 - JAVA

RESS_RUNNING: do_change_running(); break; case PRESS_PAUSE: do_change_pause(); break; default: printf("CD's state not change\n"); break; } break; case PAUSE: switch(event) { case PRESS_RUNNING: do_change_running(); break; case PRESS_STOP: do_change_stop(); break; default: printf("CD's state not change\n"); break; } break; case RUNNING: switch(event) { case PRESS_PAUSE: do_change_pause(); break; case PRESS_STOP: do_change_stop(); break; default: printf("CD's state not change\n"); break; } break; default: printf("Error! no such status!\n"); break; } } int main () { char ch = '0'; printf ("请输入数字操作CD机(0:RUNNING, 1:PAUSE, 2:STOP):\n"); while (1) { ch = getchar(); if (ch == '\n') { } else if ((ch < '0') || (ch > '3')) { printf ("非法输入，请重新输入!\n"); continue; } else { char event = ch; dispather(current_state, event); printf ("请输入数字操作CD机(0:RUNNING, 1:PAUSE, 2:STOP):\n"); } } return 0; }

3. 函数指针法，这种方法是我最常用的，也是最喜欢的。所以这里我会分别贴出C和python的代码，详细讲解。

仔细观察第一章中的“CD机状态转换图”，它其实就是一个二维矩阵结构，二维矩阵结构对应到数据结构中，无非就是二维数组。在状态转换时，都有对应的逻辑处理，所以，我们完全可以使用 “二维函数指针”来实现状态转换图。这里我没有使用二维数组，使用了结构体数组，这种实现更为直观。

如果有新的状态加入，只需要在state_mechine这个数组中加入新的状态，事件以及处理函数即可。

#include 
  
   
#include 
   
     #include 
    
      typedef enum { STOP = 0, RUNNING, PAUSE, MAX_STATE, } CD_STATE; typedef enum { PRESS_RUNNING = 0, PRESS_PAUSE, PRESS_STOP, MAX_EVENT, } CD_EVENT; char state_to_str[3][100] = {"STOP", "RUNNING", "PAUSE"}; struct CD_STATE_MECHINE { int state; int event; void (*func)(unsigned char *); }; void do_change_running(unsigned char * user_data); void do_change_stop(unsigned char * user_data); void do_change_pause(unsigned char * user_data); struct CD_STATE_MECHINE state_mechine[] = { {RUNNING, PRESS_RUNNING, NULL}, {RUNNING, PRESS_STOP, do_change_stop}, {RUNNING, PRESS_PAUSE, do_change_pause}, {PAUSE, PRESS_RUNNING, do_change_running}, {PAUSE, PRESS_STOP, do_change_stop}, {PAUSE, PRESS_PAUSE, NULL}, {STOP, PRESS_RUNNING, do_change_running}, {STOP, PRESS_STOP, NULL}, {STOP, PRESS_PAUSE, do_change_pause}, {-1, -1, NULL}, }; //全局变量，用来存储CD当前状态 int current_state = STOP; void do_change_running(unsigned char * user_data) { printf("CD Status from %s to RUNING\n", state_to_str[current_state]); current_state = RUNNING; } void do_change_stop(unsigned char * user_data) { printf("CD Status from '%s' to STOP\n", state_to_str[current_state]); current_state = STOP; } void do_change_pause(unsigned char * user_data) { printf("CD Status from '%s' to pause\n", state_to_str[current_state]); current_state = PAUSE; } int dispather(current_state, event) { int i = 0; for(i = 0; state_mechine[i].state != -1; i++) { if (current_state == state_mechine[i].state && event == state_mechine[i].event) { void (*func)(unsigned char *); func = state_mechine[i].func; if (func != NULL) { func(NULL); } else { printf("state not change!\n"); } break; } } } int main () { char ch = '0'; printf ("请输入数字操作CD机(0:RUNNING, 1:PAUSE, 2:STOP):\n"); while (1) { ch = getchar(); if (ch == '\n') { } else if ((ch < '0') || (ch > '3')) { printf ("非法输入，请重新输入!\n"); continue; } else { int event = ch - '0'; dispather(current_state, event); printf ("请输入数字操作CD机(0:RUNNING, 1:PAUSE, 2:STOP):\n"); } } return 0; }

暂时写到这里，回头儿有空了，再补上python版本的状态机实现。

软件设计之状态机(二)