getbackusedmemory.java

java内存分配演示程序

package com.ysu.cwy;

import java.util.List;

public class GetBackUsedMemory {
	private List<MemoryBlock> memoryFreeBlockList=null;        //空闲链
	private List<MemoryBlock> memoryBlockInUseList=null;       //使用链
	private MemoryInit memoryInit=null;                        //内存初始化对象
	
	//构造函数
	public GetBackUsedMemory(List<MemoryBlock> memoryFreeBlockList,
			List<MemoryBlock> memoryBlockInUseList, MemoryInit memoryInit) {
		super();
		this.memoryFreeBlockList = memoryFreeBlockList;
		this.memoryBlockInUseList = memoryBlockInUseList;
		this.memoryInit = memoryInit;
	}
	
	/**
	 * @function 回收内存
	 * @param process  需要回收的进程信息
	 */
	public synchronized void getBackUsedBlock(Process process){
		long processId=process.getProcessID();
		MemoryBlock needGetBackMemoryBlock=null;
		MemoryBlock lastMemoryBlock=null;
		MemoryBlock nextMemoryBlock=null;
		for(int i=0;i<memoryBlockInUseList.size();i++){
			needGetBackMemoryBlock=memoryBlockInUseList.get(i);
			if(needGetBackMemoryBlock.getProcessId()==processId){
				memoryBlockInUseList.remove(i);
				break;
			}
		}
		
		if(needGetBackMemoryBlock.getBlockStartPlace()==0){
			nextMemoryBlock=memoryFreeBlockList.get(0);
			if(needGetBackMemoryBlock.getBlockEndPlace()==(nextMemoryBlock.getBlockStartPlace()-1)){
				nextMemoryBlock.setBlockStartPlace(0);
				nextMemoryBlock.setBlockSize(nextMemoryBlock.getBlockSize()+needGetBackMemoryBlock.getBlockSize());
				memoryFreeBlockList.remove(0);
				memoryFreeBlockList.add(0, nextMemoryBlock);
				return;
			}else{
				needGetBackMemoryBlock.setBlockStatus(false);
				needGetBackMemoryBlock.setProcessId(-1);
				needGetBackMemoryBlock.setFullBlock(false);
				memoryFreeBlockList.add(0, needGetBackMemoryBlock);
				return;
			}
		}else if(needGetBackMemoryBlock.getBlockEndPlace()==memoryInit.getMaxMemoryAddress()){
			int memoryFreeBlockListSize=memoryFreeBlockList.size()-1;
			lastMemoryBlock=memoryFreeBlockList.get(memoryFreeBlockListSize);
			if((needGetBackMemoryBlock.getBlockStartPlace()-1)==lastMemoryBlock.getBlockEndPlace()){
				lastMemoryBlock.setBlockEndPlace(memoryInit.getMaxMemoryAddress());
				lastMemoryBlock.setBlockSize(lastMemoryBlock.getBlockSize()+needGetBackMemoryBlock.getBlockSize());
				memoryFreeBlockList.remove(memoryFreeBlockListSize);
				memoryFreeBlockList.add(memoryFreeBlockListSize, lastMemoryBlock);
				return;
			}else{
				needGetBackMemoryBlock.setBlockStatus(false);
				needGetBackMemoryBlock.setProcessId(-1);
				needGetBackMemoryBlock.setFullBlock(false);
				memoryFreeBlockList.add(needGetBackMemoryBlock);
				return;
			}
		}else{
			int p=0;
			int memoryBlockSize=0;
			nextMemoryBlock=memoryFreeBlockList.get(p);
			while(needGetBackMemoryBlock.getBlockStartPlace()>nextMemoryBlock.getBlockEndPlace()){
				p++;
				nextMemoryBlock=memoryFreeBlockList.get(p);
			}
			lastMemoryBlock=memoryFreeBlockList.get(p-1);
			if(((needGetBackMemoryBlock.getBlockStartPlace()-1)==lastMemoryBlock.getBlockEndPlace())
				&&(needGetBackMemoryBlock.getBlockEndPlace()==(nextMemoryBlock.getBlockStartPlace()-1))){
				if(lastMemoryBlock.getBlockSize()>=nextMemoryBlock.getBlockSize()){
					memoryBlockSize=nextMemoryBlock.getBlockSize();
					nextMemoryBlock.setBlockStartPlace(needGetBackMemoryBlock.getBlockStartPlace());
					nextMemoryBlock.setBlockSize(memoryBlockSize+needGetBackMemoryBlock.getBlockSize());
					memoryFreeBlockList.remove(p);
					memoryFreeBlockList.add(p, nextMemoryBlock);
					return ;
				}else{
					memoryBlockSize=lastMemoryBlock.getBlockSize();
					lastMemoryBlock.setBlockEndPlace(needGetBackMemoryBlock.getBlockEndPlace());
					lastMemoryBlock.setBlockSize(memoryBlockSize+needGetBackMemoryBlock.getBlockSize());
					memoryFreeBlockList.remove(p-1);
					memoryFreeBlockList.add(p-1, lastMemoryBlock);
				}
				}else if(((needGetBackMemoryBlock.getBlockStartPlace()-1)!=lastMemoryBlock.getBlockEndPlace())
						&&(needGetBackMemoryBlock.getBlockEndPlace()!=(nextMemoryBlock.getBlockStartPlace()-1))){
					needGetBackMemoryBlock.setFullBlock(false);
					needGetBackMemoryBlock.setProcessId(-1);
					needGetBackMemoryBlock.setBlockStatus(false);
					memoryFreeBlockList.add(p, needGetBackMemoryBlock);
					return ;
				}else if(((needGetBackMemoryBlock.getBlockStartPlace()-1)==lastMemoryBlock.getBlockEndPlace())
						&&(needGetBackMemoryBlock.getBlockEndPlace()!=(nextMemoryBlock.getBlockStartPlace()-1))){
					memoryBlockSize=lastMemoryBlock.getBlockSize();
					lastMemoryBlock.setBlockEndPlace(needGetBackMemoryBlock.getBlockEndPlace());
					lastMemoryBlock.setBlockSize(needGetBackMemoryBlock.getBlockSize()+memoryBlockSize);
					memoryFreeBlockList.remove(p-1);
					memoryFreeBlockList.add(p-1, lastMemoryBlock);
					return ;
				}else{
					memoryBlockSize=nextMemoryBlock.getBlockSize();
					nextMemoryBlock.setBlockStartPlace(needGetBackMemoryBlock.getBlockStartPlace());
					nextMemoryBlock.setBlockSize(memoryBlockSize+needGetBackMemoryBlock.getBlockSize());
					memoryFreeBlockList.remove(p);
					memoryFreeBlockList.add(p, nextMemoryBlock);
					return ;
				}
			}
		}//end method getBackUsedBlock
}