IO流复制文件11种方法

1.IO流复制文件方法汇总

①字节流复制文件(FileInputStream/FileOutputStream和BufferedInputSream/BufferedOutputStream)

②字符流复制文件(InputStreamReader/OutputStreamWriter、FileReader/FileWriter、BufferedReader/BufferedWriter)

BufferedReader/BufferedWriter字符缓冲区流有三种方法，多了一种可以直接读取一行，一次写入一个字符串。其它都是两种方法。

2.代码体现

package cn.jason04;import java.io.BufferedInputStream;import java.io.BufferedOutputStream;import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.FileReader;import java.io.FileWriter;import java.io.IOException;//InputStreamReader是FileReader的父亲，FileReader是InputStreamReader的简化版import java.io.InputStreamReader;import java.io.OutputStreamWriter;//复制文件11种方法public class Test01 {public static void main(String[] args) throws IOException {// 字节流FileInputStream fis = new FileInputStream("a.txt");FileOutputStream fos = new FileOutputStream("f.txt");// 字节缓冲区流BufferedInputStream bis = new BufferedInputStream(new FileInputStream("a.txt"));BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("f.txt"));// 字符流InputStreamReader isr = new InputStreamReader(new FileInputStream("a.txt"));OutputStreamWriter osw = new OutputStreamWriter(new FileOutputStream("f.txt"));FileReader fr = new FileReader("a.txt");FileWriter fw = new FileWriter("f.txt");// 字符缓冲区流BufferedReader br = new BufferedReader(new FileReader("a.txt"));BufferedWriter bw = new BufferedWriter(new FileWriter("f.txt"));// 字节流方法copyFiles1(fis, fos);copyFiles2(fis, fos);copyFiles3(bis, bos);copyFiles4(bis, bos);// 字符流读取方法copyFiles5(isr, osw);copyFiles6(isr, osw);copyFiles7(fr, fw);copyFiles8(fr, fw);// 高效方法copyFiles9(br, bw);copyFiles10(br, bw);// 特效方法copyFiles11(br, bw);}// 字节读取方法private static void copyFiles1(FileInputStream fis, FileOutputStream fos) throws IOException {// 一次读取一个字节int bys = 0;while ((bys = fis.read()) != -1) {fos.write(bys);}// 关闭流fos.close();fis.close();}private static void copyFiles2(FileInputStream fis, FileOutputStream fos) throws IOException {// 一次读取一个字节数组byte[] bys = new byte[1024];int len = 0;// 读一个字节数组while ((len = fis.read(bys)) != -1) {fos.write(bys, 0, len);}// 关闭流fos.close();fis.close();}private static void copyFiles3(BufferedInputStream bis, BufferedOutputStream bos) throws IOException {// 一次读取一个字节int bys = 0;while ((bys = bis.read()) != -1) {bos.write(bys);}}private static void copyFiles4(BufferedInputStream bis, BufferedOutputStream bos) throws IOException {// 一次读取一个字节数组byte[] bys = new byte[1024];int len = 0;while ((len = bis.read(bys)) != -1) {bos.write(bys, 0, len);bos.flush();}// 关闭流bos.close();bis.close();}// 字符读取方法// 普通方法// 方式1public static void copyFiles5(InputStreamReader isr, OutputStreamWriter osw) throws IOException {// 一次读取一个字符// InputStreamReader是FileReader的父类int ch = 0;while ((ch = isr.read()) != -1) {osw.write(ch);osw.flush();}isr.close();osw.close();}// 方式2public static void copyFiles6(InputStreamReader isr, OutputStreamWriter osw) throws IOException {// 一次读取一个字符数组char[] ch = new char[1024];int len = 0;while ((len = isr.read(ch)) != -1) {osw.write(ch, 0, len);osw.flush();}isr.close();osw.close();}// 方法3public static void copyFiles7(FileReader fr, FileWriter fw) throws IOException {// 普通方法一次读写一个字符int ch = 0;while ((ch = fr.read()) != -1) {fw.write(ch);fw.flush();}fw.close();fr.close();}// 方法4public static void copyFiles8(FileReader fr, FileWriter fw) throws IOException {// 普通方法一次读取一个字符数组char[] chs = new char[1024];int len = 0;while ((len = fr.read(chs)) != -1) {fw.write(chs, 0, len);fw.flush();}fw.close();fr.close();}// 高效方法// 方法5public static void copyFiles9(BufferedReader br, BufferedWriter bw) throws IOException {// 高效一次读取一个字符int ch = 0;while ((ch = br.read()) != -1) {bw.write(ch);bw.flush();}br.close();bw.close();}// 方法6public static void copyFiles10(BufferedReader br, BufferedWriter bw) throws IOException {// 高效一次读取一个字符数组char[] chs = new char[1024];int len = 0;while ((len = br.read(chs)) != -1) {bw.write(chs, 0, len);bw.flush();}br.close();bw.close();}// 特效方法// 方法7public static void copyFiles11(BufferedReader br, BufferedWriter bw) throws IOException {// 特效方式String string = null;// 一次读写一行while ((string = br.readLine()) != null) {bw.write(string);bw.newLine();bw.flush();}// 关闭输入输出流br.close();bw.close();}}

3.归纳总结

1.IO流之间关系要明确,那些流有特殊用法要明确，基本流一定要掌握。

2.读文件的时候，文件目录一定要存在，否则会抛出异常，文件目录不存在。

3.写文件的时候，会自动创建文件。