21-IO流-09-IO流(字符流-练习-复制文本文件_2)

import java.io.FileReader;import java.io.FileWriter;import java.io.IOException;//不一个一个读取，直接按照数组读取，这里用异常处理方式写代码，不再抛出public class IOPracticeDemo2 {private static final int BUFFER_SIZE = 1024;public static void main(String[] args) {FileReader fr = null;FileWriter fw = null;try {fr = new FileReader("demo.txt");fw = new FileWriter("copydemo.txt");// 创建一个临时容器，用于缓存读取到的字符char[] buf = new char[BUFFER_SIZE];// 定义一个变量记录读取到的字符数量（其实就是往数组里存储的字符个数）int len = 0;while ((len = fr.read(buf)) != -1) {fw.write(buf, 0, len);// 数据读取出来后存入容器buf中，这里指定0和len目的是读多少存多少//效率高，循环一次，读一大片，写一大片}} catch (Exception e) {throw new RuntimeException("读写失败");} finally {if (fr != null)try {fr.close();} catch (IOException e) {throw new RuntimeException("fr关闭失败");}if (fw != null)try {fw.close();} catch (IOException e) {throw new RuntimeException("fw关闭失败");}}}//该程序已经成功完成复制动作}