IO字符流

1. 字符流

java IO提供了两类流，按读写信息的内容分为

• 字节流: InputStream,OutputStream. 读写的内容以字节为单位。
• 字符流: Reader,Writer。 读写的内容以字符为单位。
• 转换流：是一组高级流，能够将字节流转换成字符流。

输出字符转入文件

public class OWSDemo {
    public static void main(String[] args) throws IOException {
        FileOutputStream fos = new FileOutputStream("osw.txt");

        OutputStreamWriter osw = new OutputStreamWriter(fos,"utf-8");
        String s = "not found anything";

        
        osw.write(s);
        osw.close();
    }
}

显示文件内内容

public class ISRDemo {
    public static void main(String[] args) throws IOException {
        FileInputStream fis = new FileInputStream("osw.txt");

        InputStreamReader isr = new InputStreamReader(fis,"utf-8");

        int d;

        while ((d=isr.read())!=-1){
            System.out.print((char) d);
        }
        System.out.println("over");
        isr.close();

    }
}

2. 缓冲字符流
   

• 缓冲字符流
  java.io.BufferedWriter
  java.io.BufferedReader
  使用缓冲对文件的内容进行块读写，提高读写效率

• java.io.PrintWriter
  是BufferedWrite基础上的又一次加工
  具有自动刷新换行的功能

public class PwDemo {
    public static void main(String[] args) throws FileNotFoundException, UnsupportedEncodingException {
        PrintWriter pw = new PrintWriter("pwd.txt","utf-8");

        pw.println("像我这样优秀的人");
        pw.write("is a hero");
        System.out.println("over");

        pw.close();
    }
}

高级流由低级流转换，下面是转换过程

FileOutputStream fos = new FileOutputStream("pw.txt");
OutputStreamWriter osw = new OutputStreamWriter(fos,"utf-8");
BufferedWriter bw = new BufferedWriter(osw);
PrintWriter pw = new PrintWriter(bw);

pw.println("解决");
pw.close();