java實現銀行家演算法
阿新 • • 發佈:2020-01-07
本文例項為大家分享了java實現銀行家演算法的具體程式碼,供大家參考,具體內容如下
import java.util.Arrays; import javax.swing.JOptionPane; public class Banker_Dijkstra { static int available[]={3,3,2}; //可利用資源數 static int max[][]={{7,5,3},{3,2,2},{9,{2,{4,3}};; //每執行緒最大需求 static int allocation[][]={{0,1,0},1},{0,2}}; //已分配資源 static int need[][]={{7,4,{1,{6,1}}; //需求 static int request[]=new int[3]; //存放請求資源 static int thread; //執行緒號 static JOptionPane jpane = new JOptionPane(); // static boolean m; public static void main(String[] argv){ int n = 0 ; Banker_Dijkstra bd = new Banker_Dijkstra(); for(int i=0;i<5;i++){ if(bd.safeState(i)){ JOptionPane.showMessageDialog(jpane,"系統狀態安全"); n=1; break; }else{ n=2; continue; } } if(n==1){ bd.getThread(); } else if(n==2){ JOptionPane.showMessageDialog(jpane,"系統狀態不安全"); } } protected void getThread(){//輸入測試執行緒號且輸出結果 try{ String xiancheng = JOptionPane.showInputDialog(jpane,"請輸入申請資源的執行緒:"); thread = (int) Integer.parseInt(xiancheng); }catch(Exception e){ int response = JOptionPane.showConfirmDialog(jpane,"請輸入0~4:",null,JOptionPane.YES_NO_OPTION); // 處理異常 if(response==0){ getThread(); }else if(response ==1){ System.exit(0); } } if(thread<0||thread>4){ JOptionPane.showMessageDialog(jpane,"請輸入0~4:"); getThread(); }else{ for(int i=0;i<3;i++){ String requestR = JOptionPane.showInputDialog(jpane,"請輸入申請的第"+(i+1)+"種資源(若不申請則填0)"); try{ request[i]=Integer.parseInt(requestR);} catch(Exception e){ JOptionPane.showConfirmDialog(jpane,"請輸入申請的第"+(i+1)+"種資源(若不申請則填0)",JOptionPane.YES_NO_OPTION); } } if(request[0]>need[thread][0]||request[1]>need[thread][1]||request[2]>need[thread][2]){ JOptionPane.showMessageDialog(jpane,thread+"執行緒申請的資源超出其需要的資源,請重新輸入"); getThread(); }else{ if(request[0]> available[0]||request[1]> available[1]||request[2]> available[2]){ JOptionPane.showMessageDialog(jpane,thread+"執行緒申請的資源大於系統資源,請重新輸入"); getThread(); } } // 分配資源 allocateData(thread); // 判斷 繼續模擬選擇與處理 int tag=0; if(check(thread)){ try{ String str = JOptionPane.showInputDialog(jpane,"是/否 繼續模擬?( 1/0 ):"); tag = Integer.parseInt(str); }catch(Exception e){ JOptionPane.showMessageDialog(jpane,"繼續 輸入(數值) 1,不繼續 輸入(數值) 0 !"); } if(tag==1){ recoverData(thread); getThread(); } else{ if( (JOptionPane.YES_NO_OPTION)==JOptionPane.CANCEL_OPTION)System.exit(0); if((JOptionPane.YES_NO_OPTION)==JOptionPane.YES_OPTION) recoverData(thread); } }else{ recoverData(thread); getThread(); } } } // 安全演算法 private boolean check(int thread2) { boolean[] finish = new boolean[5]; Arrays.fill(finish,false); int[] work = new int[3]; int[] queue = new int[5]; int q=0;//安全序列下標 for(int i = 0;i<3;i++){ work[i] = available[i]; } int tT = thread2; while(tT<5){ for(int R=0;R<3;R++){ if((!(finish[tT]==false))||(!(work[R]>=need[tT][R]))){ tT++; break; }else{ if(R==2){ for(int m =0;m<3;m++){ work[m] += allocation[tT][m]; } for(int s:work){ System.out.print(s+" "); } System.out.println(""); finish[tT] = true; queue[q] = tT; q++; tT =0; } } } } for(int p =0;p<5;p++){ if(finish[p]==false){ JOptionPane.showMessageDialog(jpane,"安全序列生成失敗"); return false; } } JOptionPane.showMessageDialog(jpane,"安全序列:"+queue[0]+","+queue[1]+"," +queue[2]+","+queue[3]+","+queue[4]); return true; } private boolean safeState(int thread3){ boolean[] finish = new boolean[5]; Arrays.fill(finish,false); int[] work = new int[3]; int[] queue = new int[5]; int q=0;//安全序列下標 for(int i = 0;i<3;i++){ work[i] = available[i]; } int tT = thread3; while(tT<5){ for(int R=0;R<3;R++){ if((!(finish[tT]==false))||(!(work[R]>=need[tT][R]))){ tT++; break; } else{ if(R==2){ for(int m =0;m<3;m++){ work[m] += allocation[tT][m]; } finish[tT] = true; queue[q] = tT; q++; tT =0; } } // if((finish[tT]==false)&&(work[R]>=need[tT][R])){ // for(int m =0;m<3;m++){ // work[m] += allocation[tT][m];} // finish[tT] = true; // queue[q] = tT; // q++; // tT=0; // }else{ // tT++; // break; // } } } for(int p =0;p<5;p++){ if(finish[p]==false){ return false; } } return true; } private void recoverData(int thread2) { // 生成失敗則重置已分配資源 for(int i=0;i<3;i++){ //重新調整系統資源數 available[i]+=request[i]; //計算各個執行緒擁有資源 allocation[thread2][i]-=request[i]; //重新計算需求 need[thread2][i]+=request[i]; } } private void allocateData(int thread2) { //分配 for(int i=0;i<3;i++){ //重新調整可用系統資源數 available[i]-=request[i]; //計算各個執行緒分配後擁有資源 allocation[thread2][i]+=request[i]; //重新計算需求 need[thread2][i]-=request[i]; } } }
以上就是本文的全部內容,希望對大家的學習有所幫助,也希望大家多多支援我們。