对IO学习的总结

IO是用来干什么的？

主要涉及文件、网络数据流、内存缓冲等的输入和输出。

经常搞混的概念：

字节：byte 占八位 1byte=8bit

字符：charset 占两个字节 1char=2byte; http://blog.csdn.net/ocean20/article/details/6743385

文件的写入和读出，字节：

import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.util.Scanner;public class FileDemo {public static void main(String[] args) {// TODO Auto-generated method stub//创建文件File file=new File("d:"+File.separator+"test.txt");if(file.exists()){file.delete();}else {try{file.createNewFile();}catch(IOException e){e.printStackTrace();}}//输出，写入文件OutputStream out=null;try{out=new FileOutputStream(file);}catch(FileNotFoundException e){e.printStackTrace();}String info="hello";byte[] b0=info.getBytes();try{out.write(b0);}catch(IOException e){e.printStackTrace();}try{out.close();}catch(IOException e){e.printStackTrace();}Scanner sin=new Scanner(System.in);sin.nextLine();//写入，从文件里面得到内容InputStream in=null;//输入流try{in=new FileInputStream(file);//接受file里面的信息，获取字节流输入对象}catch(FileNotFoundException e){e.printStackTrace();}int len=0;//输入数组的长度，也是读取的长度byte[] b=new byte[1024];//1024b=1ktry{len=in.read(b);}catch(IOException e){e.printStackTrace();}try{in.close();}catch(IOException e){e.printStackTrace();}//将字节变成字符串然后输出System.out.println(new String(b,0,len));}}

文件读取，字符：

import java.io.*;public class FileReaders {public static void main(String[] args) {// TODO Auto-generated method stubFile file=new File("D:"+File.separator+"test.txt");FileReader read=null;//字符输入流try{read=new FileReader(file);}catch(IOException e){e.printStackTrace();}String len=null;BufferedReader bufferReader=new BufferedReader(read);try{len=bufferReader.readLine();}catch(IOException e){e.printStackTrace();}finally{try{read.close();}catch(IOException e){e.printStackTrace();}}System.out.println(len);}}

对象的序列化：

import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.IOException;import java.io.ObjectInputStream;import java.io.ObjectOutputStream;import java.io.Serializable;class Person implements Serializable{String name;int age;public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}}public class SerializePerson {public static void main(String[] args) {// TODO Auto-generated method stubSerialize();Deserialize();}public static void Deserialize(){ObjectInputStream ois=null;try{ois=new ObjectInputStream(new FileInputStream(new File("e:/person.txt")));}catch(IOException e){e.printStackTrace();}Person p=null;try{p=(Person)ois.readObject();}catch(ClassNotFoundException e){e.printStackTrace();}catch(IOException e){e.printStackTrace();}System.out.println(p.name+" "+p.age);}public static void Serialize(){Person p =new Person();p.setAge(22);p.setName("Dustin");ObjectOutputStream oo=null;try{oo=new ObjectOutputStream(new FileOutputStream(new File("e:/person.txt")));}catch(IOException e){e.printStackTrace();}try{oo.writeObject(p);}catch(IOException e){e.printStackTrace();}System.out.println("Person对象序列化成功");try{oo.close();}catch(IOException e){e.printStackTrace();}}}

内存流：

内存操作流现在在Java SE阶段是感觉不出有什么作用，但是在学习Java WEB 中的AJAX技术的时候，会结合XML解析和JavaScript、AJAX完成一些动态效果的使用

管道流：

用于线程之间的通信

import java.io.*;class Send implements Runnable{private PipedOutputStream out=null;public Send(){this.out=new PipedOutputStream();}public PipedOutputStream getPipedOutputStream(){return this.out;}@Overridepublic void run() {// TODO Auto-generated method stubString str="hello world";try{this.out.write(str.getBytes());}catch(IOException e){e.printStackTrace();}try{out.close();}catch(IOException e){e.printStackTrace();}}}class Receive implements Runnable{private PipedInputStream in=null;public Receive(){this.in=new PipedInputStream();}public PipedInputStream getPipedInputStream(){return in;}@Overridepublic void run() {// TODO Auto-generated method stubbyte b[]=new byte[1024];int len=0;//BufferedReader read=new BufferedReader(new InputStreamReader(in));//try{//System.out.println(read.readLine());//}catch(IOException e){//e.printStackTrace();//}//try{//read.close();//}//catch(IOException e){//e.printStackTrace();//}//读出数据try{len=in.read(b);}catch(IOException e){e.printStackTrace();}try{in.close();}catch(IOException e){e.printStackTrace();}System.out.println(new String(b,0,len));}}public class PipedInputDemo{public static void main(String[] args){Send send=new Send();Receive receive=new Receive();try{send.getPipedOutputStream().connect(receive.getPipedInputStream());}catch(IOException e){e.printStackTrace();}new Thread(send).start();new Thread(receive).start();}}