Java字符流操作

1)认识文本和文本文件
 java的文本(char)是16位无符号整数，是字符的unicode编码（双字节编码)
 文件是byte byte byte ...的数据序列
文本文件是文本(char)序列按照某种编码方案(utf-8,utf-16be,gbk)序列化为byte的存储结果
2)字符流(Reader Writer)---->操作的是文本文件
字符的处理，一次处理一个字符
字符的底层仍然是基本的字节序列
字符流的基本实现
   InputStreamReader   完成byte流解析为char流,按照编码解析

   OutputStreamWriter  提供char流到byte流，按照编码处理  

例子:

public static void main(String[] args)throws IOException {FileInputStream in = new FileInputStream("e:\\javaio\\imoocutf8.txt");InputStreamReader isr = new InputStreamReader(in,"utf-8");//默认项目的编码,操作的时候，要写文件本身的编码格式FileOutputStream out = new FileOutputStream("e:\\javaio\\imoocutf81.txt");OutputStreamWriter osw = new OutputStreamWriter(out,"utf-8");//第一种方法/*int c ;while((c = isr.read())!=-1){System.out.print((char)c);}*///第二种方法char[] buffer = new char[8*1024];int c;/*批量读取，放入buffer这个字符数组，从第0个位置开始放置，最多放buffer.length个  返回的是读到的字符的个数*/while(( c = isr.read(buffer,0,buffer.length))!=-1){String s = new String(buffer,0,c);System.out.print(s);osw.write(buffer,0,c);osw.flush();}isr.close();osw.close();}

FileReader/FileWriter

public static void main(String[] args) throws IOException{FileReader fr = new FileReader("e:\\javaio\\imooc.txt");FileWriter fw = new FileWriter("e:\\javaio\\imooc2.txt");//FileWriter fw = new FileWriter("e:\\javaio\\imooc2.txt",true);char[] buffer = new char[2056];int c ;while((c = fr.read(buffer,0,buffer.length))!=-1){fw.write(buffer,0,c);fw.flush();}fr.close();fw.close();}

 字符流的过滤器
  BufferedReader   ---->readLine 一次读一行

  BufferedWriter/PrintWriter   ---->写一行    

public static void main(String[] args) throws IOException{ //对文件进行读写操作 BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream("e:\\javaio\\imooc.txt")));/*BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("e:\\javaio\\imooc3.txt")));*/PrintWriter pw = new PrintWriter("e:\\javaio\\imooc4.txt");//PrintWriter pw1 = new PrintWriter(outputStream,boolean autoFlush);String line ;while((line = br.readLine())!=null){System.out.println(line);//一次读一行，并不能识别换行/*bw.write(line);//单独写出换行操作bw.newLine();//换行操作bw.flush();*/pw.println(line);pw.flush();}br.close();//bw.close();pw.close();}