这个代码是在温习操作系统时编写的，主要用于通过文字来模拟操作系统中的分页式存储。
该项目一共有两个类构成：
MemoryBlock 类 和 用于运行的 Run 类（主函数类）
MemoryBlock 类：
public class MemoryBlock
{
static int initsize = 2048;//一块的大小
private String name;//块的名字
private int size;//一块用了多少
private String work;//作业名
private int block;//块号
private int page;//页号
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getSize() {
return size;
}
public void setSize(int size) {
this.size = size;
}
public MemoryBlock(){}
public MemoryBlock(String name,int size,int block)
{
this.name = name;
this.size = size;
this.block = block;
}
public String getWork() {
return work;
}
public void setWork(String work) {
this.work = work;
}
public int getBlock() {
return block;
}
public void setBlock(int block) {
this.block = block;
}
public int getPage() {
return page;
}
public void setPage(int page) {
this.page = page;
}
public void show()
{
if(this.size != 0)
{
System.out.println(work + ",页号=" + page + ",块号=" + block + ",占用空间=" +size);
}
else
{
System.out.println(name);
}
}
}
Run 类（主函数类）
import java.util.*;
public class Run
{
public static void main(String[] args)
{
int flag = 0;//标记已经使用了多少块
int work = 0;//作业编号
List list = new ArrayList<MemoryBlock>();
List indexof = new ArrayList();
for(int i=0;i<32;i++)
{
list.add(new MemoryBlock("空闲块号"+i,0,i));
}
try
{
while(true)
{
System.out.println("转载自 http://www.codecrh.com/");
MemoryBlock mb = new MemoryBlock();
for(int i=0;i<list.size();i++)
{
mb = (MemoryBlock)list.get(i);
mb.show();
}
System.out.println("总块号" + (list.size()-1) + "," + "已分配" + flag + ",剩余" + (list.size()-flag) + ",每块大小" + mb.initsize);
System.out.println("页式内存管理");
System.out.println("1申请内存 2释放内存");
try
{
Scanner sc = new Scanner(System.in);
int input = sc.nextInt();
switch (input)
{
case 1:
System.out.println("请输入申请内存的大小 (按0返回上一级):");
int size = sc.nextInt();//申请内存的大小
int count = size / mb.initsize;//计算需要的块数
if(size % mb.initsize != 0)//不是整倍数
{
if(size < mb.initsize)
{
for(int i=0;i<list.size();i++)
{
mb = (MemoryBlock)list.get(i);
if(mb.getSize() == 0)
{
mb = (MemoryBlock)list.get(i);
break;
}
}
mb.setWork("作业" + work);
mb.setPage(0);
mb.setSize(size);
work++;
flag++;
}
else if((list.size()-flag)>(count+1))//剩余空间足够
{
//for(int j=flag,i=0;i<count;i++,j++)
//{
int jsq = 0;
for(int s=0;s<list.size();s++)
{
mb = (MemoryBlock)list.get(s);
if(mb.getSize() == 0 && jsq < count)
{
mb = (MemoryBlock)list.get(s);
mb.setWork("作业" + work);
mb.setPage(jsq);
mb.setSize(2048);
jsq += 1;
}
}
//}
for(int i=0;i<list.size();i++)
{
mb = (MemoryBlock)list.get(i);
if(mb.getSize() == 0)
{
mb = (MemoryBlock)list.get(i);
break;
}
}
//mb = (MemoryBlock)list.get((flag + count));
mb.setWork("作业" + work);
mb.setPage(count);
mb.setSize(size % mb.initsize);
work++;
flag = flag + count + 1;
continue;
}
else
{
System.out.println("内存不足!!!");
System.out.println("申请内存大小为" + size + ",但没有空间可分配,请重新输入");
continue;
}
}
else//是整倍数
{
if((list.size()-flag)>count)//剩余空间足够
{
//for(int i=0;i<count;i++)
//{
int jsq = 0;
for(int j = 0;j<list.size();j++)
{
mb = (MemoryBlock)list.get(j);
if(mb.getSize() == 0 && jsq < count)
{
mb = (MemoryBlock)list.get(j);
mb.setWork("作业" + work);
mb.setPage(jsq-1);
mb.setSize(2048);
jsq++;
}
}
//}
work++;
flag = flag + 1;
}
else
{
System.out.println("内存不足!!!");
System.out.println("申请内存大小为" + size + ",但没有空间可分配,请重新输入");
continue;
}
}
break;
case 2:
List list2 = new ArrayList();
System.out.println("请输入释放内存的作业名 (按x退出，按0返回上一级):");
sc.nextLine();
String name = sc.nextLine();
for(int i=0;i<list.size();i++)
{
mb = (MemoryBlock)list.get(i);
if(name.equals(mb.getWork()))
list2.add(i);
}
for(int i=0;i<list2.size();i++)
{
int j = (int)list2.get(i);
mb = (MemoryBlock)list.get(j);
mb.setWork("");
mb.setSize(0);
mb.setPage(0);
flag--;
}
break;
default:
break;
}
}
catch(Exception ex)
{
continue;
}
}
}
catch(Exception ex)
{
System.out.println("发生了意料之外的错误，程序关闭");
}
}
}
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