实验题目三：模拟动态分区首次适应分配和回收算法

import java.util.LinkedList; public class memory { private int size;//内存大小 private static final int MIN_SIZE =3;//最小剩余分区大小 private LinkedList<Partition> mpartition;//内存分区 private int location;//上次分配的空闲区位置 class Partition{//分区节点类 private int size;//分区大小 private int head;//分区始址 private boolean Free;//空闲状态 public Partition(int head, int size) { this.head = head; this.size = size; this.Free = true; } } public memory(int size) { this.size = size; this.location = 0; this.mpartition = new LinkedList<>(); mpartition.add(new Partition(0, size)); } //首次适应算法 //size 指定需要分配的大小 void FristFit(int size){ //遍历分区链表 for (location = 0; location < mpartition.size(); location++){//每次从链首开始查找 Partition temp =mpartition.get(location); if (temp.Free && (temp.size > size)){//找到可用空闲分区且大小足够 Distribute(size, location, temp); return; } } //遍历结束后未找到可用分区, 则内存分配失败 System.out.println("无可用内存空间!"); } //执行分配函数,size 申请大小,location 当前可用分区位置,temp 可用空闲区 private void Distribute(int size, int location, Partition temp) { //如果分割后分区剩余大小过小（MIN_SIZE）则将分区全部分配，否则分割为两个分区 if (temp.size - size <= MIN_SIZE){ temp.Free = false; } else { Partition split = new Partition(temp.head + size, temp.size - size); mpartition.add(location + 1, split); temp.size = size; temp.Free = false; } System.out.println("成功分配 " + size + "KB 的内存!"); } //内存回收,id 指定要回收的分区号 public void collection(int id){ if (id >= mpartition.size()){ System.out.println("没有此分区号!"); return; } Partition temp = mpartition.get(id); int size = temp.size; if (temp.Free) { System.out.println("分区未被分配, 无需回收"); return; } //如果回收分区不是尾分区且后一个分区为空闲, 则与后一个分区合并（上不邻下邻或者上下都邻） if (id < mpartition.size() - 1 && mpartition.get(id + 1).Free){ Partition next = mpartition.get(id + 1); temp.size += next.size; mpartition.remove(next); } //如果回收分区不是首分区且前一个分区为空闲, 则与前一个分区合并（上邻下不邻或者上下都邻） if (id > 0 && mpartition.get(id - 1).Free){ Partition previous = mpartition.get(id - 1); previous.size += temp.size; mpartition.remove(id); id--; } mpartition.get(id).Free = true; System.out.println("内存回收成功!, 本次回收了 " + size + "KB 空间!"); } //展示内存分区状况 public void showmpartition(){ System.out.println("*****************************************"); System.out.println("分区编号 分区始址 分区大小 空闲状态"); for (int i = 0; i < mpartition.size(); i++){ Partition temp = mpartition.get(i); System.out.println(i + "\t\t\t" + temp.head + "\t\t " + temp.size + "\t\t" + temp.Free); } System.out.println("*****************************************"); } }