java字符流

/*
 字符流
 Reader
 Writer--FileWriter

 字符流缓冲区:提高流操作效率
 BufferedReader
 BufferedWriter

 */
package pack;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.LineNumberReader;

public class Main {

    public static void sys(Object obj) {
        System.out.println(obj);
    }

    public static void main(String[] args) throws Exception{
        //method1();//FileWriter
        //method2();//FileWriter
        //method3();//FileReader
        //method4();//拷贝文件
        //method5();//BufferedWriter
        //method6();//FileReader
        //method7();//拷贝文件
        method8();//LineNumberReader加序号功能

    }

    public static void method1() throws Exception {
        FileWriter fw = new FileWriter("E:\\1.txt");
        fw.write("abc"); //将字符串写入流中
        fw.flush(); //刷新流对象中的缓冲中的数据
        fw.close(); //关资源
    }

    public static void method2() throws Exception {
        FileWriter fw = new FileWriter("E:\\1.txt",true);//不覆盖存在的文件
        fw.write("cc\r\nc"); //换行
        fw.flush();
        fw.close();
    }

    public static void method3() throws Exception {
        FileReader fr = new FileReader("E:\\1.txt");
        /*int ch = 0;
        while((ch=fr.read())!=-1) {
            sys((char)ch);
        }*/


        /*char[] buf = new char[9];
        int ch = fr.read(buf);//写入数组中,ch为读到的个数
        sys(new String(buf));//输出数组*/


        char[] buf = new char[3];
        int num = 0;
        while((num=fr.read(buf))!=-1) //个数不是-1
            sys(new String(buf,0,num));//从0到num

        fr.close();     
    }

    /*拷贝文件*/
    public static void method4() throws Exception {
        /*FileReader fr = new FileReader("E:\\1.txt");
        FileWriter fw = new FileWriter("E:\\2.txt");
        int ch = 0;
        while((ch=fr.read())!=-1)
            fw.write(ch);
        fr.close();
        fw.close();*/



        FileReader fr = new FileReader("E:\\1.txt");
        FileWriter fw = new FileWriter("E:\\2.txt");
        char[] buf = new char[1024];
        int len = 0;
        while((len=fr.read(buf))!=-1)
            fw.write(buf,0,len);
        fw.close();
        fr.close();
    }


    public static void method5() throws Exception {
        /*缓冲区是为了提高效率，得先有流*/
        FileWriter fw = new FileWriter("E:\\1.txt");
        BufferedWriter bufw = new BufferedWriter(fw);
        bufw.write("kk");
        bufw.newLine();  //写入换行符
        bufw.write("gg");
        bufw.flush();
        bufw.close();//关闭缓冲区就是关闭缓冲区作用的流对象
    }


    public static void method6() throws Exception {
        FileReader fr = new FileReader("E:\\1.txt");
        BufferedReader bufr = new BufferedReader(fr);
        String line = null;
        while((line=bufr.readLine())!=null)//返回空表示读到末尾
            sys(line);
        bufr.close();

    }

    /*拷贝文件*/
    public static void method7() throws Exception {
        BufferedReader bufr = new BufferedReader(new FileReader("E:\\1.txt"));
        BufferedWriter bufw = new BufferedWriter(new FileWriter("E:\\2.txt"));
        String line = null;
        while((line=bufr.readLine())!=null)
            bufw.write(line);
        bufr.close();
        bufw.close();
    }

    public static void method8() throws Exception {
        FileReader fr = new FileReader("E:\\1.txt");
        LineNumberReader lnr = new LineNumberReader(fr);
        String line = null;
        while((line=lnr.readLine())!=null)
            sys(lnr.getLineNumber()+":"+line);
        lnr.close();
    }

}