銀行家算法課程設(shè)計(jì)

1、操作系統(tǒng)課程設(shè)計(jì)銀行家算法專 業(yè)：網(wǎng)絡(luò)工程學(xué) 號(hào)：110613119姓 名： 伊 兵指導(dǎo)老師： 姜 紅一、實(shí)驗(yàn)名稱： 模擬實(shí)現(xiàn)銀行家算法二、實(shí)驗(yàn)?zāi)康模河贸绦蛘Z(yǔ)言模擬實(shí)現(xiàn)銀行家算法。銀行家算法是避免死鎖的一種重要方法，通過(guò)編寫一個(gè)簡(jiǎn)單的銀行家算法程序，加深了解有關(guān)資源申請(qǐng)、避免死鎖等概念，并體會(huì)和了解死鎖和避免死鎖的具體實(shí)施方法。三、問(wèn)題分析與設(shè)計(jì)1、算法思路：先對(duì)用戶提出的請(qǐng)求進(jìn)行合法性檢查，即檢查請(qǐng)求是否大于需要的，是否大于可利用的。若請(qǐng)求合法，則進(jìn)行預(yù)分配，對(duì)分配后的狀態(tài)調(diào)用安全性算法進(jìn)行檢查。若安全，則分配；若不安全，則拒絕申請(qǐng)，恢復(fù)到原來(lái)的狀態(tài)，拒絕申請(qǐng)。2、銀行家算法步驟：（1）如果

2、Requestior =Need,則轉(zhuǎn)向步驟(2)；否則，認(rèn)為出錯(cuò)，因?yàn)樗枰馁Y源數(shù)已超過(guò)它所宣布的最大值。（2）如果Requestor=Available,則轉(zhuǎn)向步驟（3）；否則，表示系統(tǒng)中尚無(wú)足夠的資源，進(jìn)程必須等待。（3）系統(tǒng)試探把要求的資源分配給進(jìn)程Pi,并修改下面數(shù)據(jù)結(jié)構(gòu)中的數(shù)值：     Available=Available-Requesti;     Allocation=Allocation+Request;Need=Need-Request;(4)系統(tǒng)執(zhí)行安全性算法，檢查此次資源分配后，系統(tǒng)

3、是否處于安全狀態(tài)。3、安全性算法步驟：（1）設(shè)置兩個(gè)向量工作向量Work。它表示系統(tǒng)可提供進(jìn)程繼續(xù)運(yùn)行所需要的各類資源數(shù)目，執(zhí)行安全算法開(kāi)始時(shí)，Work=Allocation;布爾向量Finish。它表示系統(tǒng)是否有足夠的資源分配給進(jìn)程，使之運(yùn)行完成，開(kāi)始時(shí)先做Finishi=false，當(dāng)有足夠資源分配給進(jìn)程時(shí)，令Finishi=true。（2）從進(jìn)程集合中找到一個(gè)能滿足下述條件的進(jìn)程：Finishi=falseNeed<or=Work如找到，執(zhí)行步驟（3）；否則，執(zhí)行步驟（4）。（3）當(dāng)進(jìn)程P獲得資源后，可順利執(zhí)行，直至完成，并釋放出分配給它的資源，故應(yīng)執(zhí)行：Work=Work+All

4、ocation;Finishi=true; 轉(zhuǎn)向步驟（2）。（4）如果所有進(jìn)程的Finishi=true,則表示系統(tǒng)處于安全狀態(tài)；否則，系統(tǒng)處于不安全狀態(tài)。4、流程圖：系統(tǒng)主要過(guò)程流程圖：銀行家算法流程圖：安全性算法流程圖：5、實(shí)現(xiàn)過(guò)程：一、開(kāi)發(fā)環(huán)境編程語(yǔ)言：java開(kāi)發(fā)環(huán)境：windows & eclipse二、開(kāi)發(fā)過(guò)程：1、display（）用于初始化資源矩陣和初始化進(jìn)程，available、allocation、need、resource、process。2、print（int）用于打印T時(shí)刻的資源矩陣。3、cal（）用于進(jìn)行安全性算法。4、changeStatu（）通過(guò)requ

5、est向量改變資源使用情況并進(jìn)行安全性檢測(cè)。5、main（）用于初始化程序。三 、 關(guān)鍵代碼 1.銀行家算法while(flag)int req=new int5;System.out.print("請(qǐng)輸入您要請(qǐng)求資源的 編號(hào)：");int choose=scan.nextInt();System.out.print("請(qǐng)輸入該進(jìn)程的請(qǐng)求向量：");for (int i = 0; i < resource; i+) reqi=scan.nextInt();/將請(qǐng)求向量存入數(shù)組boolean flag1 = (req0<=needchoose0

6、&&req1<=needchoose1&&req2<=needchoose2&&req3<=needchoose3&&req4<=needchoose4);boolean flag2 = (req0<=available0&&req1<=available1&&req2<=available2&&req3<=available3&&req4<=available4); System.out.println(flag

7、1); System.out.println(flag2);if(flag1)if(flag2)/判斷請(qǐng)求向量是否小于可用資源數(shù) for (int i = 0; i < resource; i+) availablei=availablei-reqi; /改變可用資源數(shù) allocationchoosei=allocationchoosei+reqi; needchoosei=needchoosei-reqi; /改變所需資源數(shù)3int work=new int5;/資源種類數(shù)量大小的數(shù)組 boolean finish1=new booleanprocess; /設(shè)置finish標(biāo)志數(shù)組

8、 for (int i = 0; i < process; i+) finish1i=false;int array1=new intprocess;int num1=1;int count11=0; while(num1<process)for (int i = 0; i < process; i+) if(finish1i=false)if(needi0<=work0&&needi1<=work1&&needi2<=work0&&needi3<= work3&&needi4<=w

9、ork4)for (int j2 = 0; j2 < resource; j2+) availablej2=availablej2+allocationij2; availablej2 = workj2; finish1i=true; array1count11=i; count11+;num1+; /安全性算法3int count2=0;for (int i = 0; i < array1.length; i+) if(finish1i=true)count2+; /判斷有多少個(gè)進(jìn)程已經(jīng)成功得到所需進(jìn)程并結(jié)束if(count2=process)System.out.println

10、("存在一個(gè)安全序列：");for (int i = 0; i < array1.length; i+) System.out.print("P"+array1i+""); /判斷整個(gè)進(jìn)程序列書否全部完成 并打印輸出安全序列elseSystem.out.println("系統(tǒng)處于不安全狀態(tài)！");System.out.println();elseSystem.out.println("資源不夠清等待！");/if結(jié)束elseSystem.out.println("請(qǐng)求資源已超過(guò)所

11、需資源！");/while結(jié)束/end of method changeStatupublic static void main(String args) throws IOException work w = new work(); int count2 = 1; w.display(); w.print(count2+); w.cal(); w.changeStatu(); /end of method main2.安全性算法boolean finish = new booleanprocess;for (int i = 0; i < process; i+) finish

12、i=false;/初始化數(shù)組finishint array = new intprocess;/定義一個(gè)數(shù)組保存安全序列int num=1;int count1=1; while(num<process)for (int i = 0; i < process; i+) if(finishi=false)if(needi0<=available0&&needi1<=available1&&needi2<=available0&&needi3<=available3&&needi4<=avai

13、lable4)for (int j2 = 0; j2 < resource; j2+) availablej2=availablej2+allocationij2;finishi=true;arraycount1-1=i;count1+;num+; /安全性算法3、實(shí)驗(yàn)結(jié)果6、程序清單package banker;import java.io.IOException;import java.util.Scanner;public class work public int resource; int process; int available; int max; int allocat

14、ion; int need;/定義基本的數(shù)據(jù) boolean flag1; boolean flag2; Scanner scan = new Scanner(System.in);public void display()System.out.println("tt"+"操作系統(tǒng)課程設(shè)計(jì)-銀行家算法");System.out.print("請(qǐng)輸入進(jìn)程數(shù)：");process = scan.nextInt();System.out.print("請(qǐng)輸入資源種類數(shù)：");resource = scan.nextInt

15、();System.out.print("請(qǐng)輸入可用資源數(shù)：");available = new int5;for(int i = 0;i<resource;i+)availablei = scan.nextInt();System.out.println("請(qǐng)輸入資源分配矩陣");allocation = new int 55;for(int i = 0;i<process;i+)System.out.print("請(qǐng)輸入"+ i + "號(hào)進(jìn)程已分配資源數(shù)：");for(int j =0;j<r

16、esource;j+)allocationij = scan.nextInt();/end of resource /end of processneed = new int55;for(int i = 0;i<process;i+)System.out.print("請(qǐng)輸入"+ i + "號(hào)進(jìn)程還需要資源數(shù)：");for(int j =0;j<resource;j+)needij = scan.nextInt();/end of resource /end of processmax = new int55;for(int i = 0;i&

17、lt;process;i+)System.out.print("請(qǐng)輸入"+ i + "號(hào)進(jìn)程最大需求資源數(shù)：");for(int j = 0;j<resource;j+)maxij = scan.nextInt(); / end of resource/ end of for process /end of method displaypublic void print(int g)System.out.println();/* * 打印資源分配表 * */System.out.println("T"+g+"時(shí)刻的資源

18、分配矩陣");System.out.println("進(jìn)程tmaxttallocationtneedttavailable");System.out.print("P0 ");for (int i = 0; i <resource; i+) System.out.print(max0i+" ");System.out.print(" ");for (int i = 0; i <resource; i+) System.out.print(allocation0i+" ");

19、System.out.print(" ");for (int i = 0; i <resource; i+) System.out.print(need0i+" ");System.out.print(" ");for (int i = 0; i <resource; i+) System.out.print(availablei+" ");System.out.println();for (int i = 1; i < process; i+) System.out.print("P&

20、quot;+i+" ");for (int j = 0; j < resource; j+) System.out.print(maxij+" ");System.out.print(" ");for (int j = 0; j < resource; j+) System.out.print(allocationij+" ");System.out.print(" ");for (int j = 0; j < resource; j+) System.out.print(ne

21、edij+" ");System.out.println(); /此段程序輸出已輸入數(shù)據(jù)s /end of method printpublic void cal()/* * 檢查安全序列 * */boolean finish = new booleanprocess;for (int i = 0; i < process; i+) finishi=false;/初始化數(shù)組finishint array = new intprocess;/定義一個(gè)數(shù)組保存安全序列int num=1;int count1=1; while(num<process)for (int

22、 i = 0; i < process; i+) if(finishi=false)if(needi0<=available0&&needi1<=available1&&needi2<=available0&&needi3<=available3&&needi4<=available4)for (int j2 = 0; j2 < resource; j2+) availablej2=availablej2+allocationij2;finishi=true;arraycount1-1=i

23、;count1+;num+; /安全性算法int count=0;for (int i = 0; i < array.length; i+) if(finishi=true)count+;/檢查已完成的進(jìn)程數(shù)目if(count=process)System.out.println("存在一個(gè)安全序列：");for (int i = 0; i < array.length; i+) System.out.print("P"+arrayi+"");/輸出安全序列elseSystem.out.println("系統(tǒng)處于

24、不安全狀態(tài)！");System.out.println();/end of calpublic void prinSecurityList()/end of method prinSecurityListpublic void changeStatu()boolean flag=true;while(flag)int req=new int5;System.out.print("請(qǐng)輸入您要請(qǐng)求資源的 編號(hào)：");int choose=scan.nextInt();System.out.print("請(qǐng)輸入該進(jìn)程的請(qǐng)求向量：");for (int

25、 i = 0; i < resource; i+) reqi=scan.nextInt();/將請(qǐng)求向量存入數(shù)組boolean flag1 = (req0<=needchoose0&&req1<=needchoose1&&req2<=needchoose2&&req3<=needchoose3&&req4<=needchoose4);boolean flag2 = (req0<=available0&&req1<=available1&&req2<

26、;=available2&&req3<=available3&&req4<=available4); System.out.println(flag1); System.out.println(flag2);if(flag1)if(flag2)/判斷請(qǐng)求向量是否小于可用資源數(shù) for (int i = 0; i < resource; i+) availablei=availablei-reqi; /改變可用資源數(shù) 分配資源allocationchoosei=allocationchoosei+reqi; /由于已分配資源 needchoose

27、i=needchoosei-reqi; /改變所需資源數(shù)3int work=new int5;/資源種類數(shù)量大小的數(shù)組 用來(lái)構(gòu)建available的數(shù)boolean finish1=new booleanprocess; /設(shè)置finish標(biāo)志數(shù)組 for (int i = 0; i < process; i+) finish1i=false;int array1=new intprocess;int num1=1;int count11=0; while(num1<process)for (int i = 0; i < process; i+) if(finish1i=false)if(needi0<=work0&&needi1<=work1&&needi2<=work0&&needi3<=work3&&needi4<=work4)for (int j2 = 0; j2 < resource; j2+) availablej2=