什么是IO流：
IO流流简单来说就是Input和Output流，IO流主要是用来处理设备之间的数据传输，Java对于数据的操作都是通过流实现，而java用于操作流的对象都在IO包中。分类：
按操作数据分为：字节流和字符流。 如：Reader和InpurStream按流向分：输入流和输出流。如：InputStream和OutputStream
IO流常用的基类：
* InputStream ， OutputStream字符流的抽象基类：
* Reader ，Writer由上面四个类派生的子类名称都是以其父类名作为子类的后缀：如：FileReader和FileInputStream
经常用的数据流操作实例：
FileInputSteram 与FileOutStream ：
public static void main(String[] args) {try {//新建一个文件File f=new File("E:/IOtest/fileInputStream.txt");//字节输出流FileOutputStream fout=new FileOutputStream(f);String str="往文件中输入数据";fout.write(str.getBytes());//字节输入流FileInputStream fis=new FileInputStream(f);//建一个水桶，用于存放读的数据byte[] b=new byte[50];int hasnum=-1;String line="";while((hasnum=fis.read(b))!=-1){line +=new String(b,0,hasnum);}System.out.println(line);} catch (FileNotFoundException e) {e.printStackTrace();}catch (IOException e) {e.printStackTrace();}}
FileReader 与FileWriter
public static void main(String[] args) {try {//新建一个文件File f=new File("E:/IOtest/fileRead.txt");//字节输出流FileWriter fout=new FileWriter(f);String str="往文件中输入数据--字符流";fout.write(str);fout.flush(); //必须执行flush或close方法，因为字符流不是直接写入磁盘的，fout.close(); //而是先写入内存中的。如果不执行flush与close方法，是不会写入文件中的。//字符输入流FileReader fr=new FileReader(f);//建一个水桶，用于成输入进来的数据char[] c=new char[50];int hasnum=-1;String line="";while((hasnum=fr.read(c))!=-1){line +=new String(c,0,hasnum);}System.out.println(line);} catch (Throwable e) {e.printStackTrace();}}
字节流缓冲区：BufferedInputSteram和BufferedOutputStream
public static void main(String[] args) {try {//新建一个文件File f = new File("E:/IOtest/bufferedfileInputStream.txt");//字节输出流FileOutputStream fout = new FileOutputStream(f);BufferedOutputStream bufferOut=new BufferedOutputStream(fout);String outStr = "往文件中输入数据-字节流-缓存";bufferOut.write(outStr.getBytes());bufferOut.flush();//缓冲字节流需要进行刷新操作，bufferOut.close();//输入流FileInputStream fis=new FileInputStream(f);BufferedInputStream buffIn=new BufferedInputStream(fis);//水桶byte[] b=new byte[100];int hasNum=-1;String inStr="";while((hasNum=buffIn.read(b))!=-1){inStr+= new String(b,0,hasNum);}System.out.println(inStr);}catch (Throwable th){th.printStackTrace();}}
字符流的缓冲区：BufferedReader和BufferedWreiter
public static void main(String[] args) {try {//新建一个文件File f = new File("E:/IOtest/bufferedfileReader.txt");//字节输出流FileWriter wOut = new FileWriter(f);BufferedWriter bufferOut=new BufferedWriter(wOut);String outStr = "往文件中输入数据-字符流-缓存";bufferOut.write(outStr);bufferOut.flush();bufferOut.close();//输入流BufferedReader buffRead=new BufferedReader(new FileReader(f));//水桶char[] c=new char[100];int hasNum=-1;String rStr="";while((hasNum=buffRead.read(c))!=-1){rStr+= new String(c,0,hasNum);}System.out.println(rStr);}catch (Throwable th){th.printStackTrace();}}
转换流：InputStreamReader 与OutputStreamWriter
public static void main(String[] args) {try {//新建一个文件File f = new File("E:/IOtest/InputSreamReader.txt");FileOutputStream fout = new FileOutputStream(f); //字节流OutputStreamWriter osr=new OutputStreamWriter(fout,"utf-8");//转换流BufferedWriter fw=new BufferedWriter(osr); //缓冲字符流String outStr = "往文件中输入数据-字节流-转换流-缓冲流";fw.write(outStr);fw.flush();fw.close();//输入流BufferedReader br=new BufferedReader(new InputStreamReader(new FileInputStream(f),"utf-8"));//水桶char[] c=new char[100];int hasNum=-1;String inStr="";while((hasNum=br.read(c))!=-1){inStr+= new String(c,0,hasNum);}System.out.println(inStr);}catch (Throwable th){th.printStackTrace();}}
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