利用buffer缓冲区读写入文件字符流缓冲区和LineNumberReader

本文介绍了Java中字符流缓冲区(BufferedReader和BufferedWriter)的使用方法，并通过实例展示了如何利用这些类来读取、写入及复制文本文件。此外，还探讨了LineNumberReader类的应用，用于跟踪文件读取过程中的行号。

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package demo.io;

import java.io.*;

class 字符流缓冲区和LineNumberReader {
    public static void main(String[] args) {
//        bufferWriter();//利用buffer缓冲区写入文件
//        bufferReader();//利用buffer缓冲区读取文件
//        test();//测试：复制文本内容
        lineNumberReader();//跟踪行号的缓冲字符输入流
    }

    //跟踪行号的缓冲字符输入流
    private static void lineNumberReader() {
        LineNumberReader lnr = null;
        try {
            lnr = new LineNumberReader(new FileReader("后期设备的配置文件.properties"));
            lnr.setLineNumber(100);//修改行号为100   下次输出为101
            String line = null;
            while ((line = lnr.readLine()) != null) {
                System.out.println(lnr.getLineNumber() + ": " + line);//获取当前行号并输出此行信息
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (lnr != null)
                    lnr.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    //测试：复制文本内容
    private static void test() {
        FileReader fr = null;
        FileWriter fw = null;
        BufferedReader bufr = null;
        BufferedWriter bufw = null;
        try {
            fr = new FileReader("后期设备的配置文件.properties");
            fw = new FileWriter("I:\\bb.txt");
            bufr = new BufferedReader(fr);
            bufw = new BufferedWriter(fw);
            String line = null;
            while ((line = bufr.readLine()) != null) {
                bufw.write(line);
                bufw.newLine();
                bufw.flush();
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (bufr != null)
                    bufr.close();
                if (bufw != null)
                    bufw.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    //利用buffer缓冲区读取文件
    private static void bufferReader() {
        BufferedReader bufr = null;
        try {
            FileReader fr = new FileReader("后期设备的配置文件.properties");
            bufr = new BufferedReader(fr);
            int len = 0;
            /*while ((len = bufr.read()) != -1) {//逐一读取字符
                System.out.print((char) len);
            }*/
            /*
            char[] ch = new char[1024];
            while ((len = bufr.read(ch)) != -1) {//读取多少长度的字符，构造相应长度的字符串
                System.out.println(new String(ch, 0 , len));
            }*/
            String line = null;
            while ((line = bufr.readLine()) != null) {//一行一行读取
                System.out.println(line);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (bufr != null)
                    bufr.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    //利用buffer缓冲区写入文件
    private static void bufferWriter() {
        FileWriter fw = null;
        BufferedWriter bufw = null;
        try {
            fw = new FileWriter("后期设备的配置文件.properties", true);
            bufw = new BufferedWriter(fw);
            bufw.write("haha");
            bufw.newLine();//换行
            bufw.write("hehe");
            bufw.flush();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (bufw != null)
                    bufw.close();//等效于 fw.close()
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}
/**
 * 字符流缓冲区：
 * BufferedWriter
 * ：newLine();
 * <p>
 * BufferedReader:
 * : readLine();
 */