java实现银行家算法

本文实例为大家分享了java实现银行家算法的具体代码，供大家参考，具体内容如下

import java.util.Arrays;
import javax.swing.JOptionPane;

public class Banker_Dijkstra {
 static int available[]={3,3,2};   //可利用资源数
 static int max[][]={{7,5,3},{3,2,2},{9,{2,{4,3}};;   //每线程最大需求
 static int allocation[][]={{0,1,0},1},{0,2}}; //已分配资源
 static int need[][]={{7,4,{1,{6,1}};  //需求
 static int request[]=new int[3];   //存放请求资源
 static int thread; //线程号
 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,"系统状态安全");
    n=1;
    break;
   }else{
    n=2;
    continue;
   }
  }
  if(n==1){
   bd.getThread();
   }
  else if(n==2){
   JOptionPane.showMessageDialog(jpane,"系统状态不安全");
  }
 }

 protected void getThread(){//输入测试线程号且输出结果
  try{
  String xiancheng = JOptionPane.showInputDialog(jpane,"请输入申请资源的线程:");
  thread = (int) Integer.parseInt(xiancheng);
  }catch(Exception e){
   int response = JOptionPane.showConfirmDialog(jpane,"请输入0～4:",null,JOptionPane.YES_NO_OPTION);
   // 处理异常
   if(response==0){
    getThread();
   }else if(response ==1){
    System.exit(0);
   }
  }

  if(thread<0||thread>4){
   JOptionPane.showMessageDialog(jpane,"请输入0～4:");
   getThread();
  }else{
   for(int i=0;i<3;i++){
    String requestR = JOptionPane.showInputDialog(jpane,"请输入申请的第"+(i+1)+"种资源(若不申请则填0)");
    try{
    request[i]=Integer.parseInt(requestR);}
    catch(Exception e){
     JOptionPane.showConfirmDialog(jpane,"请输入申请的第"+(i+1)+"种资源(若不申请则填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+"线程申请的资源超出其需要的资源，请重新输入");
    getThread();
   }else{
    if(request[0]> available[0]||request[1]> available[1]||request[2]> available[2]){
    JOptionPane.showMessageDialog(jpane,thread+"线程申请的资源大于系统资源，请重新输入");
     getThread();
    }
   }
   // 分配资源
   allocateData(thread);
   // 判断 继续模拟选择与处理
   int tag=0;
   if(check(thread)){
    try{
     String str = JOptionPane.showInputDialog(jpane,"是／否 继续模拟？( 1/0 ):");
     tag = Integer.parseInt(str);
     }catch(Exception e){
      JOptionPane.showMessageDialog(jpane,"继续 输入(数值) 1，不继续 输入(数值) 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;//安全序列下标
  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,"安全序列生成失败");
    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;//安全序列下标
   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) { // 生成失败则重置已分配资源
  for(int i=0;i<3;i++){
   //重新调整系统资源数
   available[i]+=request[i];
   //计算各个线程拥有资源
   allocation[thread2][i]-=request[i];
   //重新计算需求
   need[thread2][i]+=request[i];
  }
 }

 private void allocateData(int thread2) { //分配
  for(int i=0;i<3;i++){
   //重新调整可用系统资源数
   available[i]-=request[i];
   //计算各个线程分配后拥有资源
   allocation[thread2][i]+=request[i];
   //重新计算需求
   need[thread2][i]-=request[i];
  }
 }
}

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