持久化list

henry2009

简单的做了持久化list的操作，方便网络传输数据，待时日可扩展为持久化队列系统或nosql数据库。为自主开发的的nosql作准备，以此为记：
package com.test.list;import java.io.ByteArrayInputStream;import java.io.ByteArrayOutputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.ObjectInput;import java.io.ObjectInputStream;import java.io.ObjectOutput;import java.io.ObjectOutputStream;import java.io.OutputStream;import java.io.RandomAccessFile;import java.io.Serializable;import java.util.ArrayList;import java.util.List;/** * * 持久化list对象 *  * @author LiuZiHeng * @version * @date 2010-8-16 */public class ListToBytes {public byte[] int2Bytes(int val) {byte[] bval = new byte[4];bval[0] = (byte)(val >> 24);bval[1] = (byte)((val << 8) >> 24);bval[2] = (byte)((val << 16)>>24);bval[3] = (byte)((val << 24) >> 24);return bval;}public void saveList(OutputStream out, List<A> list) throws IOException {if(list == null || list.size() == 0) {return;}for(int i = 0; i < list.size(); i++) {A a = list.get(i);byte[] objb = ObjectToBytes(a);out.write(int2Bytes(objb.length));out.write(objb);}}/** * Object to byte[] *  * @param obj * @return */public byte[] ObjectToBytes(Object obj) {ObjectOutput out = null;try {ByteArrayOutputStream byteout = new ByteArrayOutputStream();out = new ObjectOutputStream(byteout);out.writeObject(obj);byte[] buf = byteout.toByteArray();return buf;} catch (IOException e) {return null;} finally {if (out != null) {try {out.close();} catch (IOException e) {}}}}/** * byte[] to long *  * @param b * @return */public Object bytesToObject(byte[] b) {if (b.length > 0) {ObjectInput in = null;try {ByteArrayInputStream byteIn = new ByteArrayInputStream(b);in = new ObjectInputStream(byteIn);Object obj = in.readObject();if(obj != null) {return obj;}} catch (IOException e) {} catch (ClassNotFoundException e) {} finally {if (in != null) {try {in.close();} catch (IOException e) {}}}return null;} else {return null;}}public List getListFromSave(String filePath) {List<Object> l2 = new ArrayList<Object>();RandomAccessFile ram =null;try {ram = new RandomAccessFile(filePath, "r");while(ram.getFilePointer() != ram.length()) {int len = ram.readInt();byte[] buf = new byte[len];ram.readFully(buf);Object tmpa = bytesToObject(buf);l2.add(tmpa);}} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();} finally {if(ram != null) {try {ram.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}return l2;}public static void main(String[] args) {ListToBytes ltb = new ListToBytes();List<A> list = new ArrayList<A>();A a = new A("a", 1);A a2 = new A("b", 2);A a3 = new A("c", 3);list.add(a);list.add(a2);list.add(a3);System.out.println("list before mod:");for(A ab : list) {System.out.println(ab.getA() + "->" + ab.getB());}FileOutputStream out = null;try {out = new FileOutputStream("./savelist/list.f");ltb.saveList(out, list);} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();} finally {try {out.flush();out.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}System.out.println("\nmod list:");list.get(0).setA("a11");for(A ab : list) {System.out.println(ab.getA() + "->" + ab.getB());}System.out.println("\nload it from save:");List l2 = ltb.getListFromSave("./savelist/list.f");for(Object a22 : l2) {System.out.println(((A)a22).getA() + "=" + ((A)a22).getB());}}}class A implements Serializable {private static final long serialVersionUID = -2278862909904751331L;private String a;private int b;public A(String a, int b) {this.a = a;this.b = b;}public void setA(String a) {this.a = a;}public String getA() {return a;}public void setB(int b) {this.b = b;}public int getB() {return b;}}