存储器的分配与回收算法实现用java代码实现，源代码

以下是一些常见的内存分配和回收算法的Java代码实现：

1. 首次适应算法（First Fit）

public class FirstFitAllocation {
    private int memorySize;
    private int[] memory;
    private boolean[] isAllocated;

    public FirstFitAllocation(int memorySize) {
        this.memorySize = memorySize;
        memory = new int[memorySize];
        isAllocated = new boolean[memorySize];
    }

    public int allocate(int size) {
        for (int i = 0; i < memorySize; i++) {
            if (!isAllocated[i] && i + size <= memorySize) {
                boolean canAllocate = true;
                for (int j = 0; j < size; j++) {
                    if (isAllocated[i + j]) {
                        canAllocate = false;
                        break;
                    }
                }
                if (canAllocate) {
                    for (int j = 0; j < size; j++) {
                        memory[i + j] = i;
                        isAllocated[i + j] = true;
                    }
                    return i;
                }
            }
        }
        return -1;
    }

    public void deallocate(int start, int size) {
        for (int i = start; i < start + size; i++) {
            memory[i] = 0;
            isAllocated[i] = false;
        }
    }
}

2. 循环首次适应算法（Next Fit）

public class NextFitAllocation {
    private int memorySize;
    private int[] memory;
    private boolean[] isAllocated;
    private int lastAllocatedIndex;

    public NextFitAllocation(int memorySize) {
        this.memorySize = memorySize;
        memory = new int[memorySize];
        isAllocated = new boolean[memorySize];
        lastAllocatedIndex = 0;
    }

    public int allocate(int size) {
        for (int i = lastAllocatedIndex; i < memorySize; i++) {
            if (!isAllocated[i] && i + size <= memorySize) {
                boolean canAllocate = true;
                for (int j = 0; j < size; j++) {
                    if (isAllocated[i + j]) {
                        canAllocate = false;
                        break;
                    }
                }
                if (canAllocate) {
                    for (int j = 0; j < size; j++) {
                        memory[i + j] = i;
                        isAllocated[i + j] = true;
                    }
                    lastAllocatedIndex = i;
                    return i;
                }
            }
        }
        for (int i = 0; i < lastAllocatedIndex; i++) {
            if (!isAllocated[i] && i + size <= memorySize) {
                boolean canAllocate = true;
                for (int j = 0; j < size; j++) {
                    if (isAllocated[i + j]) {
                        canAllocate = false;
                        break;
                    }
                }
                if (canAllocate) {
                    for (int j = 0; j < size; j++) {
                        memory[i + j] = i;
                        isAllocated[i + j] = true;
                    }
                    lastAllocatedIndex = i;
                    return i;
                }
            }
        }
        return -1;
    }

    public void deallocate(int start, int size) {
        for (int i = start; i < start + size; i++) {
            memory[i] = 0;
            isAllocated[i] = false;
        }
    }
}

3. 最佳适应算法（Best Fit）

public class BestFitAllocation {
    private int memorySize;
    private int[] memory;
    private boolean[] isAllocated;

    public BestFitAllocation(int memorySize) {
        this.memorySize = memorySize;
        memory = new int[memorySize];
        isAllocated = new boolean[memorySize];
    }

    public int allocate(int size) {
        int bestFitStart = -1;
        int bestFitSize = memorySize + 1;
        for (int i = 0; i < memorySize; i++) {
            if (!isAllocated[i] && i + size <= memorySize) {
                boolean canAllocate = true;
                int currentBlockSize = 0;
                for (int j = 0; j < size; j++) {
                    if (isAllocated[i + j]) {
                        canAllocate = false;
                        break;
                    }
                    currentBlockSize++;
                }
                if (canAllocate && currentBlockSize < bestFitSize) {
                    bestFitStart = i;
                    bestFitSize = currentBlockSize;
                }
            }
        }
        if (bestFitStart >= 0) {
            for (int j = 0; j < size; j++) {
                memory[bestFitStart + j] = bestFitStart;
                isAllocated[bestFitStart + j] = true;
            }
        }
        return bestFitStart;
    }

    public void deallocate(int start, int size) {
        for (int i = start; i < start + size; i++) {
            memory[i] = 0;
            isAllocated[i] = false;
        }
    }
}

4. 最坏适应算法（Worst Fit）

public class WorstFitAllocation {
    private int memorySize;
    private int[] memory;
    private boolean[] isAllocated;

    public WorstFitAllocation(int memorySize) {
        this.memorySize = memorySize;
        memory = new int[memorySize];
        isAllocated = new boolean[memorySize];
    }

    public int allocate(int size) {
        int worstFitStart = -1;
        int worstFitSize = 0;
        for (int i = 0; i < memorySize; i++) {
            if (!isAllocated[i] && i + size <= memorySize) {
                boolean canAllocate = true;
                int currentBlockSize = 0;
                for (int j = 0; j < size; j++) {
                    if (isAllocated[i + j]) {
                        canAllocate = false;
                        break;
                    }
                    currentBlockSize++;
                }
                if (canAllocate && currentBlockSize > worstFitSize) {
                    worstFitStart = i;
                    worstFitSize = currentBlockSize;
                }
            }
        }
        if (worstFitStart >= 0) {
            for (int j = 0; j < size; j++) {
                memory[worstFitStart + j] = worstFitStart;
                isAllocated[worstFitStart + j] = true;
            }
        }
        return worstFitStart;
    }

    public void deallocate(int start, int size) {
        for (int i = start; i < start + size; i++) {
            memory[i] = 0;
            isAllocated[i] = false;
        }
    }
}