Java银行家算法代码
时间: 2024-08-12 19:10:26 浏览: 34
Java银行家算法是一种资源分配策略,用于解决死锁问题。它基于银行家算法的概念,通过预先分析系统的资源分配请求和进程的资源需求,避免系统进入不安全状态。以下是一个简单的Java实现银行家算法的例子:
```java
import java.util.*;
class ResourceRequest {
int[] request;
int processId;
public ResourceRequest(int[] req, int pid) {
this.request = req;
this.processId = pid;
}
}
class SystemResources {
int[] limits;
int[] allocation;
int[] available;
public SystemResources(int[] lims, int[] alloc) {
limits = lims;
allocation = alloc;
available = new int[limits.length];
for (int i = 0; i < limits.length; i++) {
available[i] = limits[i] - allocation[i];
}
}
public boolean canAllocate(ResourceRequest request) {
for (int i = 0; i < request.request.length; i++) {
if (request.request[i] > available[i]) {
return false;
}
}
boolean deadlockFree = true;
for (int i = 0; deadlockFree && i < request.request.length; i++) {
deadlockFree &= allocate(request, i);
}
return deadlockFree;
}
private boolean allocate(ResourceRequest request, int resourceIndex) {
if (available[resourceIndex] >= request.request[resourceIndex]) {
allocation[request.processId][resourceIndex]++;
available[resourceIndex]--;
return true;
} else {
return false;
}
}
public void release(ResourceRequest request) {
allocation[request.processId][request.request]--;
available[request.request]++;
}
}
public class BankerAlgorithmExample {
public static void main(String[] args) {
// 初始化资源限制和当前分配
int[] limits = {2, 3, 1}; // 假设系统有3种资源,每种资源的上限分别为2, 3, 1
int[] allocation = {0, 0, 0}; // 每个进程已分配的资源
// 创建系统资源实例
SystemResources sysRes = new SystemResources(limits, allocation);
// 测试资源请求
ResourceRequest request1 = new ResourceRequest(new int[]{1, 2, 0}, 0); // 进程1请求1, 2, 0个单位
ResourceRequest request2 = new ResourceRequest(new int[]{1, 1, 0}, 1); // 进程2请求1, 1, 0个单位
while (true) {
if (sysRes.canAllocate(request1)) {
System.out.println("Allocating to process 1: " + Arrays.toString(sysRes.allocation));
} else if (sysRes.canAllocate(request2)) {
System.out.println("Allocating to process 2: " + Arrays.toString(sysRes.allocation));
} else {
break; // 如果没有请求可以满足,说明无法分配,可能需要调整或终止某些进程的资源
}
// 使用完资源后释放
sysRes.release(request1); // 假设进程1用完资源,释放
request1 = request2; // 更新请求
request2 = new ResourceRequest(new int[]{0, 0, 0}, 2); // 进程2切换请求
}
}
}
```