IO流

IO流概述

操作硬盘或者是网络,等待的文件

流的分类

按照流向分

       输出流-----java写文件

       输入流-----java读取文件

按照操作文件来分

       字符流,操作文本文件(只要用记事本打开的),字符流中内置了编码表,查表

       字符输入流(读取文件)

              抽象基类 Reader

       字符输入流(写入文件)

              抽象基类 OutputStream

字符输出流(写文本文件)

writer

    fileWriter

              建立对象的时候FileWriter(String fileName)字符串格式文件名

              调用write方法,写数据

              将内存中的数据,刷新到目的地(硬盘文件),调用flush

              close关闭资源

import java.io.FileWriter;import java.io.IOException;public class FileWriterDemo {public static void main(String[] args) throws IOException {FileWriter fw = new FileWriter("D:\\Demo.txt");/* * 1.在堆内存新建了一个对象 new FileWriter * 2.抛出异常 * 3.在硬盘上创建了一个文件,如果有这个文件,直接覆盖 * 4.JVM调用windows中的资源,才创建的文件 */fw.write("我是一个大好人");fw.flush();fw.close();}}

字符输出流(读文本文件)

       Reader

        FileReader

                     建立对象的时候FileReader(String fileName)字符串格式文件名

                     调用read方法,读数据,单个字符,返回int,read方法,一个一个往下读,读到结尾返回-1

                     read(字符数组)read方法读取字符的时候,将读取的字符存储在了数组中

                     返回值,表示的是,数组中存储字符的有效个数

import java.io.*;public class FileReaderDemo {public static void main(String[] args) {}public static void method_2(){FileReader fr = null;try {fr = new FileReader("D:\\hahaha.txt");int len = 0;char[] ch = new char[1024];while((len=fr.read(ch))!=-1){System.out.println(new String(ch,0,len));}} catch (IOException e) {// TODO: handle exceptione.printStackTrace();}finally{try {if(fr!=null)fr.close();} catch (IOException e2) {// TODO: handle exceptione2.printStackTrace();}}}public static void method_1(){FileReader fr = null;try {fr = new FileReader("D:\\hahaha.txt");int len = 0;while((len=fr.read())!=-1){System.out.print((char)len);}} catch (IOException e) {// TODO: handle exceptione.printStackTrace();}finally{try {if(fr!=null)fr.close();} catch (IOException e2) {// TODO: handle exceptione2.printStackTrace();}}}}

通过字符流,复制文本文件

       FileReader读取文件

       FileWriter 写入文件

拷贝文件1

import java.io.*;public class CopyText1 {public static void main(String[] args) {FileReader fr = null;FileWriter fw = null;try {fr = new FileReader("D:\\haha.txt");fw = new FileWriter("D:\\hehe.txt");int len = 0;while((len = fr.read())!=-1){fw.write(len);fw.flush();}} catch (IOException e) {// TODO: handle exceptione.printStackTrace();throw new RuntimeException("文件拷贝异常");}finally{try {if(fw!=null)fw.close();} catch (IOException e2) {// TODO: handle exceptione2.printStackTrace();System.out.println("fw关闭文件异常");}try {if(fr!=null)fr.close();} catch (IOException e2) {// TODO: handle exceptione2.printStackTrace();System.out.println("fr关闭文件异常");}}}}

拷贝文件2

import java.io.FileReader;import java.io.FileWriter;import java.io.IOException;public class CopyText2 {public static void main(String[] args) {FileReader fr = null;FileWriter fw = null;try {fr = new FileReader("D:\\haha.txt");fw = new FileWriter("D:\\heihei.txt");char[] ch = new char[1024];int len = 0;while((len = fr.read(ch))!=-1){//fw.write(new String(ch,0,len));fw.write(ch, 0, len) ;fw.flush();}} catch (IOException e) {// TODO: handle exceptione.printStackTrace();System.out.println("文件拷贝异常");}finally{try {if(fw!=null)fw.close();} catch (IOException e2) {// TODO: handle exceptione2.printStackTrace();System.out.println("fw关闭异常");}try {if(fr!=null)fr.close();} catch (IOException e2) {// TODO: handle exceptione2.printStackTrace();System.out.println("fr关闭异常");}}}}

在字符流中,java工程师,提供2个字符流缓冲区对象,提供文件的操作

BufferedWriter

       构造方法,传递的Writer的子类对象,FileWriter

       newLine() 写一个换行,跨平台,JVM是linux版本 \r JVM是windows \r\n

       在linux下,\r \r\n写在linux\n多一个字符

import java.io.BufferedWriter;import java.io.FileWriter;import java.io.IOException;public class BufferedWriterDemo {public static void main(String[] args) {FileWriter fw = null;BufferedWriter bw = null;try{fw = new FileWriter("D:\\xixi.txt");bw = new BufferedWriter(fw);bw.write("sadkljfa;sgljalksjgalksgjasg" +"sfdajfkla;fjkaslkjfsaldk;gjaksl");bw.newLine();bw.write("sdjkkfasdfas");}catch(IOException e){e.printStackTrace();}finally{try {if(bw!=null)bw.close();} catch (IOException e2) {// TODO: handle exception}}}}

BufferedReader

       构造方法,传递的子类对象,FileReader

       String readLine()读取文本一行

import java.io.*;public class BufferedReaderDemo {public static void main(String[] args) {FileReader fr = null;BufferedReader br = null;try {fr = new FileReader("D:\\hahaha.txt");br = new BufferedReader(fr);String s = null;while((s=br.readLine())!=null){System.out.print(s);}} catch (IOException e) {// TODO: handle exception}}}

拷贝文件3

import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.FileReader;import java.io.FileWriter;import java.io.IOException;public class CopyText3 {public static void main(String[] args) {// TODO Auto-generated method stubFileReader fr = null;FileWriter fw = null;BufferedReader br = null;BufferedWriter bw = null;try{fr = new FileReader("D:\\hahaha.txt");br = new BufferedReader(fr);fw = new FileWriter("D:\\heiheihei.txt");bw = new BufferedWriter(fw);String line = null;while((line = br.readLine())!=null){ bw.write(line); bw.newLine(); bw.flush();}}catch(IOException e){e.printStackTrace();System.out.println("文件拷贝异常");}finally{try {if(bw!=null)bw.close();} catch (IOException e2) {// TODO: handle exceptione2.printStackTrace();System.out.println("bw关闭流异常");}try {if(br!=null)br.close();} catch (IOException e2) {// TODO: handle exceptione2.printStackTrace();System.out.println("br关闭流异常");}}}}

装饰设计(装饰类)

为了解决现实中的问题,增强原有对象的功能而出现的,原来对象中的功能不用强大

增强对象中的功能,装饰模式出现,增强原有对象的功能

热水器,加热水,水管,进,出水管

装饰模式在IO中的应用,写入文件用的FileWriter,发现这个类的功能不够强大

         装饰类出现了BufferedWriter,增强原有FileWriter的功能,在原有FileWriter的基础上增加一个newLine(),但是BufferedWriter写一行的方法,底层用的还是FileWriter的方法

BufferedWriter构造方法BufferedWriter(Writer out)

 

继承原有类,覆盖方法,和采用装饰类来增强原有对象中的功能,有区别么? 区别在哪?

继承是面向对象三大特征之一,装饰设计模式,解决实际问题的

采用继承的方式,来增强对象中的功能,过于庞大,臃肿

例如:

文件写入

      |-- 文本写入类 TextWriter

         |-- extends TextWriter

 

      |-- 音频写入类 SoundWriter

         |-- extends SoundWriter

 

      |-- 可执行文件写入类 EXEWriter

         |-- extends EXEWriter

 

      |-- 镜像文件写入类 ISOWriter

         |-- extends ISOWriter

 

      |-- 数据库文件写入类 DatabaseWriter

         |-- extends DatabaseWriter

 

 

文件写入--Writer类

     |-- 文本写入类 TextWriter

     |-- 音频写入类 SoundWriter

     |-- 可执行文件写入类 EXEWriter

     |-- 镜像文件写入类 ISOWriter

     |-- 数据库文件写入类 DatabaseWriter

     |-- 装饰类(Writer out),增强它们功能

        |-- BufferedWriter(Writer out)extends Writer{

                              out.write()

}

                   文件的写入体系，简单，又清楚，方便使用，和学习

                        BufferedReader(Reader in)

自定义类实现readLine()方法

import java.io.IOException;import java.io.Reader;/* * 实现文本一行读取，返回字符串 */public class MyReadLine {private Reader r;public MyReadLine(Reader r){this.r = r ;}public String myReaderLine() throws IOException{StringBuffer sb = new StringBuffer();int len = 0;while((len=r.read())!=-1){if(len=='\r')continue;if(len=='\n')return sb.toString();elsesb.append((char)len);}if(sb.length()!=0)return sb.toString();return null;}public void myclose() throws IOException{r.close();}}import java.io.FileReader;import java.io.IOException;public class MyReadLineTest {public static void main(String[] args) {MyReadLine mrl = null;try {mrl = new MyReadLine(new FileReader("D:\\demo.txt"));String line = null;while((line=mrl.myReaderLine())!=null){System.out.println(line);}} catch (IOException e) {// TODO: handle exceptione.printStackTrace();throw new RuntimeException("文件读取失败");} finally{try {if(mrl!=null)mrl.myclose();} catch (IOException e) {// TODO: handle exceptione.printStackTrace();System.out.println("文件关闭异常");}}}}

字节流

读和写用的都是字节数组

字节输入流 InputStream

         FileInputStream

字节输出流 OutputStream

         FileOutputStream

 

字节流复制任意文件

import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.IOException;public class StreamCopyFile {public static void main(String[] args) {FileInputStream fis = null;FileOutputStream fos = null;try {fis = new FileInputStream("D:demo.txt");fos = new FileOutputStream("D:demo1.txt");int b = 0;while((b=fis.read())!=-1){fos.write(b);}} catch (IOException e) {// TODO: handle exceptione.printStackTrace();throw new RuntimeException("文件复制异常");} finally{try {if(fos!=null)fos.close();} catch (IOException e) {// TODO: handle exceptione.printStackTrace();throw new RuntimeException("文件关闭异常");}try {if(fis!=null)fis.close();} catch (IOException e) {// TODO: handle exceptione.printStackTrace();throw new RuntimeException("文件关闭异常");}}}}import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.IOException;public class StreamCopyFile1 {public static void main(String[] args) {FileInputStream fis = null;FileOutputStream fos = null;try {fis = new FileInputStream("D:\\WLAN_Azurewave_GE781_Win7_32_z800316.zip");fos = new FileOutputStream("D:\\haha.zip");byte[] b = new byte[1024];int len = 0;while((len=fis.read(b))!=-1){fos.write(b);}} catch (IOException e) {// TODO: handle exceptione.printStackTrace();throw new RuntimeException("文件复制异常");} finally{try {if(fos!=null)fos.close();} catch (IOException e2) {// TODO: handle exceptione2.printStackTrace();throw new RuntimeException("文件关闭异常");}try {if(fis!=null)fis.close();} catch (IOException e2) {// TODO: handle exceptione2.printStackTrace();throw new RuntimeException("文件关闭异常");}}}}import java.io.*;public class StreamCopyFile2 {public static void main(String[] args) {FileInputStream fis = null;FileOutputStream fos = null;BufferedInputStream bis = null;BufferedOutputStream bos = null;try {fis = new FileInputStream("D:\\WLAN_Azurewave_GE781_Win7_32_z800316.zip");fos = new FileOutputStream("D:\\haha.zip");bis = new BufferedInputStream(fis);bos = new BufferedOutputStream(fos);byte[] b = new byte[bis.available()];int len = 0;while((len=bis.read(b))!=-1){bos.write(b, 0, len);}} catch (IOException e) {// TODO: handle exceptione.printStackTrace();throw new RuntimeException("复制文件失败");} finally{try {if(bos!=null)bos.close();} catch (IOException e2) {// TODO: handle exceptione2.printStackTrace();throw new RuntimeException("关闭文件失败");}try {if(bis!=null)bis.close();} catch (IOException e2) {// TODO: handle exceptione2.printStackTrace();throw new RuntimeException("关闭文件失败");}}}}

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