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在王道操作系统复习上学习了银行家算法

public class Resources {
       //可用各资源数量    private int A;    private int B;    private int C;    public Resources(int a, int b, int c) {
           A = a;        B = b;        C = c;    }    public int getA() {
           return A;    }    public void setA(int a) {
           A = a;    }    public int getB() {
           return B;    }    public void setB(int b) {
           B = b;    }    public int getC() {
           return C;    }    public void setC(int c) {
           C = c;    }    public synchronized void update(int a,int b,int c){
           setA(this.A+a);        setB(this.B+b);        setC(this.C+c);        //System.out.println("当前可用资源数：A："+A+",B:"+B+",C:"+C);    }}

线程1：

public class P0 extends Thread{
       private Resources resources;    //需要各类资源的最大值    private int maxA;    private int maxB;    private int maxC;    //已分配各类资源个数    private int alloA;    private int alloB;    private int alloC;    //需要各资源的个数    private int needA;    private int needB;    private int needC;    //构造方法    public P0(int maxA, int maxB, int maxC, int alloA, int alloB, int alloC,Resources resources) {
           this.maxA = maxA;        this.maxB = maxB;        this.maxC = maxC;        this.alloA = alloA;        this.alloB = alloB;        this.alloC = alloC;        needA=maxA-alloA;        needB=maxB-alloB;        needC=maxC-alloC;        this.resources=resources;    }    @Override    public void run() {
           System.out.println("P0需要资源个数分别为：A:"+needA+",B:"+needB+",C:"+needC);        try {
               Thread.sleep(200);        } catch (InterruptedException e) {
               e.printStackTrace();        }        while (true){
               if(resources.getA()>=needA&&resources.getB()>=needB&&resources.getC()>=needC){
                   System.out.println("P0执行完毕，归还资源");                resources.update(alloA,alloB,alloC);                break;            }        }    }}

线程2：

public class P1 extends Thread{
       private Resources resources;    //需要各类资源的最大值    private int maxA;    private int maxB;    private int maxC;    //已分配各类资源个数    private int alloA;    private int alloB;    private int alloC;    //需要各资源的个数    private int needA;    private int needB;    private int needC;    //构造方法    public P1(int maxA, int maxB, int maxC, int alloA, int alloB, int alloC, Resources resources) {
           this.maxA = maxA;        this.maxB = maxB;        this.maxC = maxC;        this.alloA = alloA;        this.alloB = alloB;        this.alloC = alloC;        needA=maxA-alloA;        needB=maxB-alloB;        needC=maxC-alloC;        this.resources=resources;    }    @Override    public void run() {
           System.out.println("P1需要资源个数分别为：A:"+needA+",B:"+needB+",C:"+needC);        try {
               Thread.sleep(200);        } catch (InterruptedException e) {
               e.printStackTrace();        }        while (true){
               if(resources.getA()>=needA&&resources.getB()>=needB&&resources.getC()>=needC){
                   System.out.println("P1执行完毕，归还资源");                resources.update(alloA,alloB,alloC);                break;            }        }    }}

其余都大同小异

public class Test {
       public static void main(String[] args) {
           Resources resources=new Resources(3,3,2);        P0 p0=new P0(7,5,3,0,1,0,resources);        P1 p1=new P1(3,2,2,2,0,0,resources);        P2 p2=new P2(9,0,2,3,0,2,resources);        P3 p3=new P3(2,2,2,2,1,1,resources);        P4 p4=new P4(4,3,3,0,0,2,resources);        p0.start();        p1.start();        p2.start();        p3.start();        p4.start();    }}

运行结果：

P0需要资源个数分别为：A:7,B:4,C:3P3需要资源个数分别为：A:0,B:1,C:1P4需要资源个数分别为：A:4,B:3,C:1P2需要资源个数分别为：A:6,B:0,C:0P1需要资源个数分别为：A:1,B:2,C:2P1执行完毕，归还资源P3执行完毕，归还资源P2执行完毕，归还资源P0执行完毕，归还资源P4执行完毕，归还资源

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