JAVA |
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JAVA
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I/O即为Input（输入）/Output（输出），这里的输入指的是将存储在硬盘的文件中的数据输入到内存中，经过一系列数据处理（也有可能不需要处理，比如复制文件）。输出是将内存中的数据在硬盘中创建一个文件，输出到文件中。 在java中输入输出流可以分为两大类，字节流和字符流。为什么是有两种流呢？不同字符集对一个中文编码，字节编码不同，就会导致字节流操作中文时不方便，操作不当就会出现乱码的情况。 下面是总结的JAVA中I/O流使用的类。
1、使用FileInputStream和FileOutputstream来进行文件的复制 。 package io.stream; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; public class CopyFileTest { public static void main(String[] args) { FileInputStream fileInputStream = null; FileOutputStream fileOutputStream = null; try { fileInputStream = new FileInputStream("a.txt"); fileOutputStream = new FileOutputStream("a副本.txt"); int byte_value; while ((byte_value = fileInputStream.read()) != -1) { fileOutputStream.write(byte_value); } } catch (Exception e) { e.printStackTrace(); } finally { if (fileInputStream != null) { try { fileInputStream.close(); } catch (IOException e) { e.printStackTrace(); } } if (fileOutputStream != null) { try { fileOutputStream.close(); } catch (IOException e) { e.printStackTrace(); } } } } }2、使用BufferedInputStream和BufferedOutputStream进行复制视频文件 package io.stream; import java.io.*; public class CopyVedioByBufferedTest { public static void main(String[] args) { BufferedInputStream bufferedInputStream = null; BufferedOutputStream bufferedOutputStream = null; try { bufferedInputStream = new BufferedInputStream(new FileInputStream("C:\\demo\\a\\aaa.mp4")); bufferedOutputStream = new BufferedOutputStream(new FileOutputStream("C:\\demo\\b\\aaa.mp4")); byte[] byt = new byte[1024]; while ((bufferedInputStream.read(byt)) != -1) { bufferedOutputStream.write(byt); } } catch (Exception e) { e.printStackTrace(); } finally { if (bufferedInputStream != null) { try { bufferedInputStream.close(); } catch (IOException e) { e.printStackTrace(); } } if (bufferedOutputStream != null) { try { bufferedOutputStream.close(); } catch (IOException e) { e.printStackTrace(); } } } } }3、使用FileReader和FileWriter来实现输入用户名和密码，将其存到本地，以及查看文件中的用户名和密码。 package io.stream; import java.io.FileReader; import java.io.FileWriter; import java.io.IOException; import java.util.Scanner; public class UserRegisterByCharStream { public static void main(String[] args) { FileReader fileReader = null; FileWriter fileWriter = null; Scanner scanner = new Scanner(System.in); try { fileWriter = new FileWriter("UserInfo.txt",true); fileReader = new FileReader("UserInfo.txt"); String name = ""; String password = ""; String userinfo = ""; System.out.println("如果您是新用户，请输入【r】进行注册\r\n如果您是老用户，请输入【s】查看用户名和密码\r\n输入其他任意键结束"); while (true) { System.out.println("请输入："); String select_result = scanner.next(); if (select_result.equals("r")) { System.out.println("请输入用户名："); name = scanner.next(); System.out.println("请输入密码："); password = scanner.next(); userinfo = name + "," + password + "\r\n"; fileWriter.write(userinfo); fileWriter.flush(); } else if (select_result.equals("s")) { char[] chars = new char[1024]; int len; while ((len = fileReader.read(chars)) != -1) { String user = new String(chars,0,len); System.out.println(user); } } else { break; } } } catch (Exception e) { e.printStackTrace(); } finally { if (fileReader != null) { try { fileReader.close(); } catch (IOException e) { e.printStackTrace(); } } if (fileWriter != null) { try { fileWriter.close(); } catch (IOException e) { e.printStackTrace(); } } } } }4、使用BufferedReader和BufferedWriter实现读取文件中的数据，排序后输出。 package io.stream; import java.io.*; import java.util.Arrays; public class BufferedWriterAndBufferedReaderTest { public static void main(String[] args) { BufferedReader bufferedReader = null; BufferedWriter bufferedWriter = null; try { bufferedReader = new BufferedReader(new FileReader("array.txt")); bufferedWriter = new BufferedWriter(new FileWriter("arraySort.txt")); String line = bufferedReader.readLine(); String[] splits = line.split(","); int[] nums = new int[splits.length]; for (int i = 0; i < splits.length; i++) { nums[i] = Integer.parseInt(splits[i]); } Arrays.sort(nums); for (int i = 0; i < nums.length; i++) { bufferedWriter.write(nums[i] + " "); bufferedWriter.flush(); } } catch (Exception e) { e.printStackTrace(); } finally { if (bufferedReader != null) { try { bufferedReader.close(); } catch (IOException e) { e.printStackTrace(); } } if (bufferedWriter != null) { try { bufferedWriter.close(); } catch (IOException e) { e.printStackTrace(); } } } } } |
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