think in java interview-高级开发人员面试宝典(八)-优快云博客

面经出了7套，收到许多读者的Email，有许多人说了，这些基础知识是不是为了后面进一步的”通向架构师的道路“做准备的？

对的，你们没有猜错，就是这样的，我一直在酝酿后面的”通向架构师的道路“如何开章。

说实话，我已经在肚子里准备好的后面的”通向架构师的道路“的内容自己觉得如果一下子全拿出来的话，很多人吃不消，因为架构越来越复杂，用到的知识越来越多，而且很多都是各知识点的混合应用。

所以，先以这几套面经来铺路，我们把基础打实了，才能把大楼造的更好。因为，一个架构师首先他是一个程序员，他的基础知识必须非常的扎实，API对于架构师来说已经不太需要eclipse的code insight(即在eclipse编辑器里打一个小点点就可以得到后面的函数），尤其是一些常用的JAVA API来说，是必须熟记于心的。

下面我们继续来几天面经，顺带便复习一下JAVA和数据库的一些基础。

Java IO流的复习

大家平时J2EE写多了，JAVA的IO操作可能都已经生疏了，面试时如果来上这么几道，是不是有点”其实这个问题很简单，可是我就是想不起来“的感觉啊？

呵呵！

JAVA的IO操作太多，我这边挑腾迅，盛大和百度的几道面试题，并整理出答案来供大家参考。

InputFromConsole

这个最简单不过了，从console接受用户输入的字符，如和用户有交互的命令行。

如果你不复习的话，嘿嘿，还真答不出，来看：

[java] view plain copy print ?

packageorg.sky.io;
publicclassInputFromConsole{
/**
*@paramargs
*/
publicstaticvoidmain(String[]args)throwsException{
inta=0;
byte[]input=newbyte[1024];
System.in.read(input);
System.out.println("yourinputis:"+newString(input));
}
}

package org.sky.io;

public class InputFromConsole {

	/**
	 * @param args
	 */
	public static void main(String[] args) throws Exception {
		int a = 0;
		byte[] input = new byte[1024];
		System.in.read(input);
		System.out.println("your input is: " + new String(input));

	}

}

ListDir

[java] view plain copy print ?

packageorg.sky.io;
importjava.io.*;
publicclassListMyDir{
/**
*@paramargs
*/
publicstaticvoidmain(String[]args){
StringfileName="D:"+File.separator+"tomcat2";
Filef=newFile(fileName);
File[]fs=f.listFiles();
for(inti=0;i<fs.length;i++){
System.out.println(fs[i].getName());
}
}
}

package org.sky.io;

import java.io.*;

public class ListMyDir {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		String fileName = "D:" + File.separator + "tomcat2";
		File f = new File(fileName);
		File[] fs = f.listFiles();
		for (int i = 0; i < fs.length; i++) {
			System.out.println(fs[i].getName());
		}

	}

}

咦，上面这个程序只列出了一层目录，我们想连子目录一起List出来怎么办？

ListMyDirWithSubDir

[java] view plain copy print ?

packageorg.sky.io;
importjava.io.*;
publicclassListMyDirWithSubDir{
/**
*@paramargs
*/
publicvoidprint(Filef){
if(f!=null){
if(f.isDirectory()){
File[]fileArray=f.listFiles();
if(fileArray!=null){
for(inti=0;i<fileArray.length;i++){
print(fileArray[i]);
}
}
}else{
System.out.println(f);
}
}
}
publicstaticvoidmain(String[]args){
StringfileName="D:"+File.separator+"tomcat2";
Filef=newFile(fileName);
ListMyDirWithSubDirlistDir=newListMyDirWithSubDir();
listDir.print(f);
}
}

package org.sky.io;

import java.io.*;

public class ListMyDirWithSubDir {

	/**
	 * @param args
	 */
	public void print(File f) {
		if (f != null) {
			if (f.isDirectory()) {
				File[] fileArray = f.listFiles();
				if (fileArray != null) {
					for (int i = 0; i < fileArray.length; i++) {
						print(fileArray[i]);
					}
				}
			} else {
				System.out.println(f);
			}
		}
	}

	public static void main(String[] args) {
		String fileName = "D:" + File.separator + "tomcat2";
		File f = new File(fileName);
		ListMyDirWithSubDir listDir = new ListMyDirWithSubDir();
		listDir.print(f);

	}
}

InputStreamDemo

从外部读入一个文件

[java] view plain copy print ?

packageorg.sky.io;
importjava.io.File;
importjava.io.FileInputStream;
importjava.io.FileOutputStream;
importjava.io.InputStream;
importjava.io.OutputStream;
publicclassInputStreamDemo{
publicvoidreadFile(StringfileName){
FilesrcFile=newFile(fileName);
InputStreamin=null;
try{
in=newFileInputStream(srcFile);
byte[]b=newbyte[(int)srcFile.length()];
for(inti=0;i<b.length;i++){
b[i]=(byte)in.read();
}
System.out.println(newString(b));
}catch(Exceptione){
e.printStackTrace();
}finally{
try{
if(in!=null){
in.close();
in=null;
}
}catch(Exceptione){
}
}
}
publicstaticvoidmain(String[]args){
InputStreamDemoid=newInputStreamDemo();
Stringsrc="D:"+File.separator+"hello.txt";
id.readFile(src);
}
}

package org.sky.io;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;

public class InputStreamDemo {
	public void readFile(String fileName) {
		File srcFile = new File(fileName);
		InputStream in = null;
		try {
			in = new FileInputStream(srcFile);
			byte[] b = new byte[(int) srcFile.length()];
			for (int i = 0; i < b.length; i++) {
				b[i] = (byte) in.read();
			}
			System.out.println(new String(b));
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				if (in != null) {
					in.close();
					in = null;
				}
			} catch (Exception e) {
			}
		}
	}

	public static void main(String[] args) {
		InputStreamDemo id = new InputStreamDemo();
		String src = "D:" + File.separator + "hello.txt";
		id.readFile(src);
	}

}

OutputStreamDemo

讲完了InputStream来讲OutputStream，输出内容至外部的一个文件

[java] view plain copy print ?

packageorg.sky.io;
importjava.io.*;
publicclassOutputStreamDemo{
publicvoidwriteWithByte(){
StringfileName="D:"+File.separator+"hello.txt";
OutputStreamout=null;
Filef=newFile(fileName);
try{
out=newFileOutputStream(f,true);
Stringstr="[PublicityministryofShangHaiMunicipalcommitteeofCPC]";
byte[]b=str.getBytes();
out.write(b);
}catch(Exceptione){
e.printStackTrace();
}finally{
try{
if(out!=null){
out.close();
out=null;
}
}catch(Exceptione){
}
}
}
publicvoidwriteWithByteArray(){
StringfileName="D:"+File.separator+"hello.txt";
OutputStreamout=null;
Filef=newFile(fileName);
try{
out=newFileOutputStream(f,true);
Stringstr="[hellowithbyteyigegexie]";
byte[]b=str.getBytes();
for(inti=0;i<b.length;i++){
out.write(b[i]);
}
}catch(Exceptione){
e.printStackTrace();
}finally{
try{
if(out!=null){
out.close();
out=null;
}
}catch(Exceptione){
}
}
}
publicstaticvoidmain(String[]args){
OutputStreamDemood=newOutputStreamDemo();
od.writeWithByte();
od.writeWithByteArray();
}
}

package org.sky.io;

import java.io.*;

public class OutputStreamDemo {

	public void writeWithByte() {
		String fileName = "D:" + File.separator + "hello.txt";
		OutputStream out = null;
		File f = new File(fileName);
		try {
			out = new FileOutputStream(f, true);
			String str = "   [Publicity ministry of ShangHai Municipal committee of CPC]";
			byte[] b = str.getBytes();
			out.write(b);
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				if (out != null) {
					out.close();
					out = null;
				}
			} catch (Exception e) {
			}
		}
	}

	public void writeWithByteArray() {
		String fileName = "D:" + File.separator + "hello.txt";
		OutputStream out = null;
		File f = new File(fileName);
		try {
			out = new FileOutputStream(f, true);
			String str = "   [hello with byte yi ge ge xie]";
			byte[] b = str.getBytes();
			for (int i = 0; i < b.length; i++) {
				out.write(b[i]);
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				if (out != null) {
					out.close();
					out = null;
				}
			} catch (Exception e) {
			}
		}
	}

	public static void main(String[] args) {
		OutputStreamDemo od = new OutputStreamDemo();
		od.writeWithByte();
		od.writeWithByteArray();

	}

}

这个Demo里分别用了”writeWithByte“和 ”writeWithByteArray“两种方法，注意查看

CopyFile

我们讲完了InputStream和OutputStream，我们就可以自己实现一个File Copy的功能了，来看

[java] view plain copy print ?

packageorg.sky.io;
importjava.io.*;
publicclassCopyFile{
publicvoidcopy(Stringsrc,Stringdes){
FilesrcFile=newFile(src);
FiledesFile=newFile(des);
InputStreamin=null;
OutputStreamout=null;
try{
in=newFileInputStream(srcFile);
out=newFileOutputStream(desFile);
byte[]b=newbyte[(int)srcFile.length()];
for(inti=0;i<b.length;i++){
b[i]=(byte)in.read();
}
out.write(b);
System.out.println("copied["+srcFile.getName()+"]with"
+srcFile.length());
}catch(Exceptione){
e.printStackTrace();
}finally{
try{
if(out!=null){
out.close();
out=null;
}
}catch(Exceptione){
}
try{
if(in!=null){
in.close();
in=null;
}
}catch(Exceptione){
}
}
}
publicstaticvoidmain(String[]args){
CopyFilecp=newCopyFile();
Stringsrc="D:"+File.separator+"UltraEdit.zip";
Stringdes="D:"+File.separator+"UltraEdit_Copy.zip";
longsTime=System.currentTimeMillis();
cp.copy(src,des);
longeTime=System.currentTimeMillis();
System.out.println("Totalspend:"+(eTime-sTime));
}
}

package org.sky.io;

import java.io.*;

public class CopyFile {

	public void copy(String src, String des) {
		File srcFile = new File(src);
		File desFile = new File(des);
		InputStream in = null;
		OutputStream out = null;
		try {
			in = new FileInputStream(srcFile);
			out = new FileOutputStream(desFile);
			byte[] b = new byte[(int) srcFile.length()];
			for (int i = 0; i < b.length; i++) {
				b[i] = (byte) in.read();
			}
			out.write(b);
			System.out.println("copied [" + srcFile.getName() + "]    with    "
					+ srcFile.length());
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				if (out != null) {
					out.close();
					out = null;
				}
			} catch (Exception e) {
			}
			try {
				if (in != null) {
					in.close();
					in = null;
				}
			} catch (Exception e) {
			}
		}
	}

	public static void main(String[] args) {
		CopyFile cp = new CopyFile();
		String src = "D:" + File.separator + "UltraEdit.zip";
		String des = "D:" + File.separator + "UltraEdit_Copy.zip";
		long sTime = System.currentTimeMillis();
		cp.copy(src, des);
		long eTime = System.currentTimeMillis();
		System.out.println("Total spend: " + (eTime - sTime));
	}

}

运行后显示：

来看我们被Copy的这个文件的大小：

也不大，怎么用了7秒多？

原是我们没有使用Buffer这个东西，即缓冲，性能会相差多大呢？来看

BufferInputStreamDemo

[java] view plain copy print ?

packageorg.sky.io;
importjava.io.*;
publicclassBufferInputStreamDemo{
/**
*@paramargs
*/
publicvoidcopy(Stringsrc,Stringdes){
FilesrcFile=newFile(src);
FiledesFile=newFile(des);
BufferedInputStreambin=null;
BufferedOutputStreambout=null;
try{
bin=newBufferedInputStream(newFileInputStream(srcFile));
bout=newBufferedOutputStream(newFileOutputStream(desFile));
byte[]b=newbyte[1024];
while(bin.read(b)!=-1){
bout.write(b);
}
bout.flush();
System.out.println("copied["+srcFile.getName()+"]with"
+srcFile.length());
}catch(Exceptione){
e.printStackTrace();
}finally{
try{
if(bout!=null){
bout.close();
bout=null;
}
}catch(Exceptione){
}
try{
if(bin!=null){
bin.close();
bin=null;
}
}catch(Exceptione){
}
}
}
publicstaticvoidmain(String[]args){
BufferInputStreamDemobd=newBufferInputStreamDemo();
Stringsrc="D:"+File.separator+"UltraEdit.zip";
Stringdes="D:"+File.separator+"UltraEdit_Copy.zip";
longsTime=System.currentTimeMillis();
bd.copy(src,des);
longeTime=System.currentTimeMillis();
System.out.println("Totalspend:"+(eTime-sTime));
}
}

package org.sky.io;

import java.io.*;

public class BufferInputStreamDemo {

	/**
	 * @param args
	 */
	public void copy(String src, String des) {
		File srcFile = new File(src);
		File desFile = new File(des);
		BufferedInputStream bin = null;
		BufferedOutputStream bout = null;
		try {
			bin = new BufferedInputStream(new FileInputStream(srcFile));
			bout = new BufferedOutputStream(new FileOutputStream(desFile));
			byte[] b = new byte[1024];
			while (bin.read(b) != -1) {
				bout.write(b);
			}
			bout.flush();
			System.out.println("copied [" + srcFile.getName() + "]    with    "
					+ srcFile.length());
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				if (bout != null) {
					bout.close();
					bout = null;
				}
			} catch (Exception e) {
			}
			try {
				if (bin != null) {
					bin.close();
					bin = null;
				}
			} catch (Exception e) {
			}
		}
	}

	public static void main(String[] args) {
		BufferInputStreamDemo bd = new BufferInputStreamDemo();
		String src = "D:" + File.separator + "UltraEdit.zip";
		String des = "D:" + File.separator + "UltraEdit_Copy.zip";
		long sTime = System.currentTimeMillis();
		bd.copy(src, des);
		long eTime = System.currentTimeMillis();
		System.out.println("Total spend: " + (eTime - sTime));

	}

}

我们Copy同样一个文件，用了多少时间呢？来看！

丫只用了14毫秒，CALL！！！

ByteArrayDemo

来看看使用ByteArray输出文件吧

[java] view plain copy print ?

packageorg.sky.io;
importjava.io.*;
publicclassByteArrayDemo{
/**
*@paramargs
*/
publicvoidtestByteArray(){
Stringstr="HOLLYJESUS";
ByteArrayInputStreaminput=null;
ByteArrayOutputStreamoutput=null;
try{
input=newByteArrayInputStream(str.getBytes());
output=newByteArrayOutputStream();
inttemp=0;
while((temp=input.read())!=-1){
charch=(char)temp;
output.write(Character.toLowerCase(ch));
}
StringoutStr=output.toString();
input.close();
output.close();
System.out.println(outStr);
}catch(Exceptione){
e.printStackTrace();
}finally{
try{
if(output!=null){
output.close();
output=null;
}
}catch(Exceptione){
}
try{
if(input!=null){
input.close();
input=null;
}
}catch(Exceptione){
}
}
}
publicstaticvoidmain(String[]args){
ByteArrayDemobd=newByteArrayDemo();
bd.testByteArray();
}
}

package org.sky.io;

import java.io.*;

public class ByteArrayDemo {

	/**
	 * @param args
	 */
	public void testByteArray() {
		String str = "HOLLYJESUS";
		ByteArrayInputStream input = null;
		ByteArrayOutputStream output = null;
		try {
			input = new ByteArrayInputStream(str.getBytes());
			output = new ByteArrayOutputStream();
			int temp = 0;
			while ((temp = input.read()) != -1) {
				char ch = (char) temp;
				output.write(Character.toLowerCase(ch));
			}
			String outStr = output.toString();
			input.close();
			output.close();
			System.out.println(outStr);
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				if (output != null) {
					output.close();
					output = null;
				}
			} catch (Exception e) {
			}
			try {
				if (input != null) {
					input.close();
					input = null;
				}
			} catch (Exception e) {
			}
		}
	}

	public static void main(String[] args) {
		ByteArrayDemo bd = new ByteArrayDemo();
		bd.testByteArray();

	}

}

RandomAccess

有种输出流叫Random，你们还记得吗？学习时记得的，工作久了，HOHO，忘了，它到底有什么特殊的地方呢？来看：

[java] view plain copy print ?

packageorg.sky.io;
importjava.io.*;
publicclassRandomAccess{
publicvoidwriteToFile(){
StringfileName="D:"+File.separator+"hello.txt";
RandomAccessFilerandomIO=null;
try{
Filef=newFile(fileName);
randomIO=newRandomAccessFile(f,"rw");
randomIO.writeBytes("asdsad");
randomIO.writeInt(12);
randomIO.writeBoolean(true);
randomIO.writeChar('A');
randomIO.writeFloat(1.21f);
randomIO.writeDouble(12.123);
}catch(Exceptione){
e.printStackTrace();
}finally{
try{
if(randomIO!=null){
randomIO.close();
randomIO=null;
}
}catch(Exceptione){
}
}
}
publicstaticvoidmain(String[]args){
RandomAccessrandomA=newRandomAccess();
randomA.writeToFile();
}
}

package org.sky.io;

import java.io.*;

public class RandomAccess {
	public void writeToFile() {
		String fileName = "D:" + File.separator + "hello.txt";
		RandomAccessFile randomIO = null;
		try {

			File f = new File(fileName);
			randomIO = new RandomAccessFile(f, "rw");
			randomIO.writeBytes("asdsad");
			randomIO.writeInt(12);
			randomIO.writeBoolean(true);
			randomIO.writeChar('A');
			randomIO.writeFloat(1.21f);
			randomIO.writeDouble(12.123);
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				if (randomIO != null) {
					randomIO.close();
					randomIO = null;
				}
			} catch (Exception e) {
			}
		}
	}

	public static void main(String[] args) {
		RandomAccess randomA = new RandomAccess();
		randomA.writeToFile();
	}
}

它输出后的文件是怎么样的呢？

PipeStream

这个流很特殊，我们在线程操作时，两个线程都在运行，这时通过发送一个指令让某个线程do something，我们在以前的jdk1.4中为了实现这样的功能，使用的就是这个PipeStream

先来看两个类，一个叫SendMessage，即发送一个指令。一个叫ReceiveMessage，用于接受指令。

SendMessage

[java] view plain copy print ?

packageorg.sky.io;
importjava.io.*;
publicclassSendMessageimplementsRunnable{
privatePipedOutputStreamout=null;
publicPipedOutputStreamgetOut(){
returnthis.out;
}
publicSendMessage(){
this.out=newPipedOutputStream();
}
publicvoidsend(){
Stringmsg="start";
try{
out.write(msg.getBytes());
}catch(Exceptione){
e.printStackTrace();
}finally{
try{
if(out!=null){
out.close();
out=null;
}
}catch(Exceptione){
}
}
}
publicvoidrun(){
try{
System.out.println("waitingforsignal...");
Thread.sleep(2000);
send();
}catch(Exceptione){
e.printStackTrace();
}
}
}

package org.sky.io;

import java.io.*;

public class SendMessage implements Runnable {
	private PipedOutputStream out = null;

	public PipedOutputStream getOut() {
		return this.out;
	}

	public SendMessage() {
		this.out = new PipedOutputStream();
	}

	public void send() {

		String msg = "start";
		try {
			out.write(msg.getBytes());
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				if (out != null) {
					out.close();
					out = null;
				}
			} catch (Exception e) {
			}
		}
	}

	public void run() {
		try {
			System.out.println("waiting for signal...");
			Thread.sleep(2000);
			send();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

ReceiveMessage

[java] view plain copy print ?

packageorg.sky.io;
importjava.io.*;
publicclassReceiveMessageimplementsRunnable{
privatePipedInputStreaminput=null;
publicPipedInputStreamgetInput(){
returnthis.input;
}
publicReceiveMessage(){
this.input=newPipedInputStream();
}
privatevoidreceive(){
byte[]b=newbyte[1000];
intlen=0;
Stringmsg="";
try{
len=input.read(b);
msg=newString(b,0,len);
if(msg.equals("start")){
System.out
.println("receivedthestartmessage,receivenowcandosomething......");
Thread.interrupted();
}
}catch(Exceptione){
e.printStackTrace();
}finally{
try{
if(input!=null){
input.close();
input=null;
}
}catch(Exceptione){
}
}
}
publicvoidrun(){
try{
receive();
}catch(Exceptione){
}
}
}

package org.sky.io;

import java.io.*;

public class ReceiveMessage implements Runnable {
	private PipedInputStream input = null;

	public PipedInputStream getInput() {
		return this.input;
	}

	public ReceiveMessage() {
		this.input = new PipedInputStream();
	}

	private void receive() {

		byte[] b = new byte[1000];
		int len = 0;
		String msg = "";
		try {
			len = input.read(b);
			msg = new String(b, 0, len);
			if (msg.equals("start")) {
				System.out
						.println("received the start message, receive now can do something......");
				Thread.interrupted();
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				if (input != null) {
					input.close();
					input = null;
				}
			} catch (Exception e) {
			}
		}
	}

	public void run() {
		try {
			receive();
		} catch (Exception e) {
		}
	}
}

如何使用这两个类呢？

TestPipeStream

[java] view plain copy print ?

packageorg.sky.io;
publicclassTestPipeStream{
/**
*@paramargs
*/
publicstaticvoidmain(String[]args){
SendMessagesend=newSendMessage();
ReceiveMessagereceive=newReceiveMessage();
try{
send.getOut().connect(receive.getInput());
Threadt1=newThread(send);
Threadt2=newThread(receive);
t1.start();
t2.start();
}catch(Exceptione){
e.printStackTrace();
}
}
}

package org.sky.io;

public class TestPipeStream {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		SendMessage send = new SendMessage();
		ReceiveMessage receive = new ReceiveMessage();
		try {
			send.getOut().connect(receive.getInput());
			Thread t1 = new Thread(send);
			Thread t2 = new Thread(receive);
			t1.start();
			t2.start();

		} catch (Exception e) {
			e.printStackTrace();
		}

	}

}

注意这边有一个send.getOut().connect(receive.getInput());

这个方法就把两个线程”connect“起来了。

Serializable的IO操作

把一个类序列化到磁盘上，怎么做？

先来看我们要序列化的一个Java Bean

Person

[java] view plain copy print ?

packageorg.sky.io;
importjava.io.Serializable;
publicclassPersonimplementsSerializable{
privateStringname="";
privateStringage="";
privateStringpersonId="";
publicStringgetName(){
returnname;
}
publicvoidsetName(Stringname){
this.name=name;
}
publicStringgetAge(){
returnage;
}
publicvoidsetAge(Stringage){
this.age=age;
}
publicStringgetPersonId(){
returnpersonId;
}
publicvoidsetPersonId(StringpersonId){
this.personId=personId;
}
publicStringgetCellPhoneNo(){
returncellPhoneNo;
}
publicvoidsetCellPhoneNo(StringcellPhoneNo){
this.cellPhoneNo=cellPhoneNo;
}
privateStringcellPhoneNo="";
}

package org.sky.io;

import java.io.Serializable;

public class Person implements Serializable {

	private String name = "";
	private String age = "";
	private String personId = "";

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getAge() {
		return age;
	}

	public void setAge(String age) {
		this.age = age;
	}

	public String getPersonId() {
		return personId;
	}

	public void setPersonId(String personId) {
		this.personId = personId;
	}

	public String getCellPhoneNo() {
		return cellPhoneNo;
	}

	public void setCellPhoneNo(String cellPhoneNo) {
		this.cellPhoneNo = cellPhoneNo;
	}

	private String cellPhoneNo = "";
}

下面来看序列化的操作

SerializablePersonToFile

[java] view plain copy print ?

packageorg.sky.io;
importjava.io.*;
importjava.util.*;
publicclassSerializablePersonToFile{
/**
*@paramargs
*/
privateList<Person>initList(){
List<Person>userList=newArrayList<Person>();
PersonloginUser=newPerson();
loginUser.setName("sam");
loginUser.setAge("30");
loginUser.setCellPhoneNo("13333333333");
loginUser.setPersonId("111111111111111111");
userList.add(loginUser);
loginUser=newPerson();
loginUser.setName("tonny");
loginUser.setAge("31");
loginUser.setCellPhoneNo("14333333333");
loginUser.setPersonId("111111111111111111");
userList.add(loginUser);
loginUser=newPerson();
loginUser.setName("jim");
loginUser.setAge("28");
loginUser.setCellPhoneNo("15333333333");
loginUser.setPersonId("111111111111111111");
userList.add(loginUser);
loginUser=newPerson();
loginUser.setName("Simon");
loginUser.setAge("30");
loginUser.setCellPhoneNo("17333333333");
loginUser.setPersonId("111111111111111111");
userList.add(loginUser);
returnuserList;
}
privatevoidserializeFromFile(){
FileInputStreamfs=null;
ObjectInputStreamois=null;
try{
fs=newFileInputStream("person.txt");
ois=newObjectInputStream(fs);
List<Person>userList=(ArrayList<Person>)ois.readObject();
for(Personp:userList){
System.out.println(p.getName()+""+p.getAge()+""
+p.getCellPhoneNo()+""+p.getCellPhoneNo());
}
}catch(Exceptionex){
ex.printStackTrace();
}finally{
try{
if(ois!=null){
ois.close();
}
}catch(Exceptione){
}
try{
if(fs!=null){
fs.close();
}
}catch(Exceptione){
}
}
}
privatevoidserializeToFile(){
List<Person>userList=newArrayList<Person>();
userList=initList();
FileOutputStreamfs=null;
ObjectOutputStreamos=null;
try{
fs=newFileOutputStream("person.txt");
os=newObjectOutputStream(fs);
os.writeObject(userList);
}catch(Exceptionex){
ex.printStackTrace();
}finally{
try{
if(os!=null){
os.close();
}
}catch(Exceptione){
}
try{
if(fs!=null){
fs.close();
}
}catch(Exceptione){
}
}
}
publicstaticvoidmain(String[]args){
SerializablePersonToFilesf=newSerializablePersonToFile();
sf.serializeToFile();
sf.serializeFromFile();
}
}

package org.sky.io;

import java.io.*;
import java.util.*;

public class SerializablePersonToFile {

	/**
	 * @param args
	 */
	private List<Person> initList() {
		List<Person> userList = new ArrayList<Person>();
		Person loginUser = new Person();
		loginUser.setName("sam");
		loginUser.setAge("30");
		loginUser.setCellPhoneNo("13333333333");
		loginUser.setPersonId("111111111111111111");
		userList.add(loginUser);
		loginUser = new Person();
		loginUser.setName("tonny");
		loginUser.setAge("31");
		loginUser.setCellPhoneNo("14333333333");
		loginUser.setPersonId("111111111111111111");
		userList.add(loginUser);
		loginUser = new Person();
		loginUser.setName("jim");
		loginUser.setAge("28");
		loginUser.setCellPhoneNo("15333333333");
		loginUser.setPersonId("111111111111111111");
		userList.add(loginUser);
		loginUser = new Person();
		loginUser.setName("Simon");
		loginUser.setAge("30");
		loginUser.setCellPhoneNo("17333333333");
		loginUser.setPersonId("111111111111111111");
		userList.add(loginUser);
		return userList;
	}

	private  void serializeFromFile() {
		FileInputStream fs = null;
		ObjectInputStream ois = null;
		try {
			fs = new FileInputStream("person.txt");
			ois = new ObjectInputStream(fs);
			List<Person> userList = (ArrayList<Person>) ois.readObject();
			for (Person p : userList) {
				System.out.println(p.getName() + "   " + p.getAge() + "   "
						+ p.getCellPhoneNo() + "   " + p.getCellPhoneNo());
			}
		} catch (Exception ex) {
			ex.printStackTrace();
		} finally {
			try {
				if (ois != null) {
					ois.close();
				}
			} catch (Exception e) {
			}
			try {
				if (fs != null) {
					fs.close();
				}
			} catch (Exception e) {
			}
		}
	}

	private void serializeToFile() {
		List<Person> userList = new ArrayList<Person>();
		userList = initList();
		FileOutputStream fs = null;
		ObjectOutputStream os = null;
		try {
			fs = new FileOutputStream("person.txt");
			os = new ObjectOutputStream(fs);
			os.writeObject(userList);
		} catch (Exception ex) {
			ex.printStackTrace();
		} finally {
			try {
				if (os != null) {
					os.close();
				}
			} catch (Exception e) {
			}
			try {
				if (fs != null) {
					fs.close();
				}
			} catch (Exception e) {
			}
		}
	}

	public static void main(String[] args) {
		SerializablePersonToFile sf = new SerializablePersonToFile();
		sf.serializeToFile();
		sf.serializeFromFile();
	}

}

这边先把Person输出到Person.txt，再从Person.txt里反序列化出这个Person的Java Bean。

先讲这么些吧！

Java的流操作还有很多，这些是经常会被面试到的，很基础，因此经常被考到。

以前听一个读IT的同学说过，这些IO操作，就算没有Eclipse编辑器的话，用文本编辑器也应该能够写出来，你写不出只能代表你的基础太弱了。

转载地址：http://blog.youkuaiyun.com/lifetragedy/article/details/10363489