IO流文件读取，写入；复制操作

IO流文件读取

1. 一次性读一个字节

           package com.IO;
           import java.io.*;
           import static java.io.File.separator;
           public class FileIO {
               public static void main(String[] args) {
                   //对这个文件创建对象，导入数据包
                   File file = new File("d:"+ separator +"IDEA/Test.txt");
                   try {
                       //创建数据流FileReader，写入文件对象
                       FileReader reader = new FileReader(file);
                       int i =0 ;
                       //如果未读到-1；则一直读
                       while ((i=reader.read())!=-1){
                           //将读取的值转成char
                           System.out.println((char) i);
                       }
                   } catch (FileNotFoundException e) {
                       e.printStackTrace();
                   } catch (IOException e) {
                       e.printStackTrace();
                   }
    
               }
           }
    

2. 一次性读五个字节；通过创建存储空间；做缓存流

          package com.IO;
          import java.io.*;
          import static java.io.File.separator;
          public class FileIO {
              public static void main(String[] args) {
                  //对这个文件创建对象，导入数据包
                  File file = new File("d:"+ separator +"IDEA/Test.txt");
                  try {
                      //创建数据流FileReader，写入文件对象
                      FileReader reader = new FileReader(file);
                      int i =0 ;
                      //如果未读到-1；则一直读
                      while ((i=reader.read())!=-1){
                          //将读取的值转成char
                          System.out.println((char) i);
                      }
                      //一定一定要关闭数据流
                      reader.close();
                  } catch (FileNotFoundException e) {
                      e.printStackTrace();
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
  
              }
          }
  

3. 写入字符流

           package com.IO;
           import java.io.File;
           import java.io.FileWriter;
           import java.io.IOException;
           import static java.io.File.separator;
           public class DemoRead {
               public static void main(String[] args) {
                   File file = new File("d:"+ separator +"IDEA/Demo.txt");
                   try {
                       //创建写入对象，传入写入目录
                       FileWriter fileWriter = new FileWriter(file);
    
                       String s = "你好，再见";
                       //将字符传封装成对象，传入容器中
                       //通过char做写入缓存000
                       char[] chars = s.toCharArray();
                       //将包装好的chars对象传入到写的方法中
                       fileWriter.write(chars);
                       //一定要关闭写入IO流；否则写入不成功
                       fileWriter.close();
    
                   } catch (IOException e) {
                       e.printStackTrace();
                   }
                   /*try {
                       FileReader fileRead = new FileReader(file);
                       char []ch =new char[5];
                       try {
                           int i = fileRead.read(ch);
                           while (i!=-1){
                               String s = new String(ch,0,i);
                               System.out.println(s);
                               i = fileRead.read(ch);
                           }
                           fileRead.close();
    
                       } catch (IOException e) {
                           e.printStackTrace();
                       }
                   } catch (FileNotFoundException e) {
                       e.printStackTrace();
                   }*/
    
               }
           }
    

   4. 复制文本操作

           package com.IO;
           import java.io.*;
           public class Copy {
               public static void main(String[] args) {
                   File file = new File("D://IDEA/Copy.txt");//这是复制的目标文件夹；如无此路径。则会自动创建
                   File file1 = new File("D://IDEA/Demo.txt");
                   //读取部分
                   try {
                       FileReader fileReader =new FileReader(file1);
                       char []chars1 = new char[5];
                       try {
                           int i = fileReader.read(chars1);
                           FileWriter fileWriter = new FileWriter(file);
    
                           while (i!=-1){
                               String s1 =new String(chars1,0,i);
                               System.out.println(s1);
                               //将读出来的东西S1写到另一个文件夹中  
                               i = fileReader.read();
                               String s =s1;
                               char []chars = s.toCharArray();
                               fileWriter.write(chars);
                           }
                           fileWriter.close();
                           fileReader.close();
                       } catch (IOException e) {
                           e.printStackTrace();
                       }
                   } catch (FileNotFoundException e) {
                       e.printStackTrace();
                   }
    
                  /*这里的原本的写入操作 
                  try {
                       FileWriter fileWriter = new FileWriter(file);
                       String s =i;
                       char []chars = s.toCharArray();
                       fileWriter.write(chars);
                       fileWriter.close();
    
    
    
                   } catch (IOException e) {
                       e.printStackTrace();
                   }*/
               }
    
           }