ziplist.java

国内很牛的软件公司花费两年半开发的用EJB3开发的代码,采用STRUTS和EJB3,目前系统进行第二版.所以拿出来共享

package com.ufmobile.common.transport;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.ArrayList;
import java.util.Collection;
import java.util.ConcurrentModificationException;

import java.util.zip.ZipInputStream;
import java.util.zip.ZipOutputStream;

/**
 * <p>
 *  对要传输的对象进行内存压缩
 * <p>
 * 创建日期：Jan 4, 2007
 * 
 * @author msf
 * @since v3.0
 */
public class ZipList<T> extends ArrayList<T> {
	
	
	private int zipLever;	

	public ZipList() {
		super();
		
	}

	
	public ZipList(int initialCapacity, int zipLever) {
		super(initialCapacity);		
		this.zipLever = zipLever;
	}


	public ZipList(Collection<? extends T> c) {
		super(c);
		
	}

	public ZipList(int initialCapacity) {
		super(initialCapacity);
		
	}

	private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {
		int expectedModCount = modCount;
		// Write out element count, and any hidden stuff
		s.defaultWriteObject();
		// Write out array length
		s.writeInt(size());
		s.write(zipLever);
		
		byte[] data=writeCompressObject();
		s.writeInt(data.length);
		s.writeObject(writeCompressObject());

		if (modCount != expectedModCount) {
			throw new ConcurrentModificationException();
		}
	}

	/**
	 * Reconstitute the <tt>ArrayList</tt> instance from a stream (that is,
	 * deserialize it).
	 */
	private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException {
		// Read in size, and any hidden stuff
		s.defaultReadObject();
		// Read in array length and allocate array
		int arrayLength = s.readInt();
		zipLever=s.readInt();
		int lenth=s.readInt();
		byte[] data=new byte[lenth];
		s.read(data) ;
		readCompressObject(data,arrayLength);

	}

	private  byte[] writeCompressObject() {
		byte[] data_ = null;
		try {
			// 建立字节数组输出流
			ByteArrayOutputStream byteout= new ByteArrayOutputStream();
			// 建立gzip压缩输出流
			ZipOutputStream zout = new ZipOutputStream(byteout);
			zout.setLevel(zipLever);
			// 建立对象序列化输出流
			ObjectOutputStream out = new ObjectOutputStream(zout);
			for (int i = 0; i < size(); i++)
				out.writeObject(get(i));			
			out.flush();
			out.close();
			zout.close();
			// 返回压缩字节流
			data_ = byteout.toByteArray();
			byteout.close();
		} catch (IOException e) {
			System.out.println(e);
		}
		return (data_);
	}

	private void readCompressObject(byte[] data_,int arrayLength) {
		
		try {
			// 建立字节数组输入流
			ByteArrayInputStream bytein = new ByteArrayInputStream(data_);
			// 建立gzip解压输入流
			ZipInputStream gzin = new ZipInputStream(bytein);
			
			// 建立对象序列化输入流
			ObjectInputStream in = new ObjectInputStream(gzin);
			// 按制定类型还原对象
			for(int i=0;i<arrayLength;i++){
			T object_ = (T) in.readObject();
			}
			bytein.close();
			gzin.close();
			in.close();
		} catch (ClassNotFoundException e) {
			System.out.println(e);
		} catch (IOException e) {
			System.out.println(e);
		}
		
	}

	public int getZipLever() {
		return zipLever;
	}

	public void setZipLever(int zipLever) {
		this.zipLever = zipLever;
	}

}