IO字节流和缓冲流

IO字节流的读取和写入

读取

1 import java.io.FileInputStream; 2 import java.io.FileNotFoundException; 3 import java.io.IOException; 4  5 public class Test { 6     public static void main(String[] args) { 7         try (FileInputStream fis = new FileInputStream("java.txt") 8         ) { 9             byte[] bytes = new byte[40];10             int temp;11             while ((temp = fis.read(bytes)) != -1) {12                 System.out.println(new String(bytes, 0, temp));13             }14         } catch (FileNotFoundException e) {15             e.printStackTrace();16         } catch (IOException e) {17             e.printStackTrace();18         }19     }20 }

写入

1 import java.io.*; 2  3 public class Test { 4     public static void main(String[] args) { 5         try (FileOutputStream fos = new FileOutputStream("file" + File.separator + "1024.txt", true) //写入时不清除原有数据 6         ) { 7             fos.write("Hello".getBytes()); 8             fos.write("\n".getBytes());  //换行 9             fos.write("Wrold!".getBytes());10             fos.flush(); //刷新11         } catch (FileNotFoundException e) {12             e.printStackTrace();13         } catch (IOException e) {14             e.printStackTrace();15         }16     }17 }

IO字节流的文件拷贝

 

1 import java.io.*; 2  3 public class Test { 4     public static void main(String[] args) { 5         try ( 6                 FileOutputStream fos = new FileOutputStream("file" + File.separator + "new.txt"); 7                 FileInputStream fis = new FileInputStream("java.txt") 8         ) { 9             int temp;10             byte[] bytes = new byte[50];11             while ((temp = fis.read(bytes)) != -1) {12                 fos.write(bytes);13             }14         } catch (FileNotFoundException e) {15             e.printStackTrace();16         } catch (IOException e) {17             e.printStackTrace();18         }19     }20 }

IO缓冲流的读取和写入

1 import java.io.*; 2  3 /** 4  * IO缓冲字节流的读取 5  */ 6 public class Test { 7     public static void main(String[] args) { 8         try (BufferedInputStream bis = new BufferedInputStream(new FileInputStream("java.txt")); 9              BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("file" + File.separator + "new.txt"));10         ) {11             int temp;12             while ((temp = bis.read()) != -1) {13                 bos.write(temp);14             }15         } catch (FileNotFoundException e) {16             e.printStackTrace();17         } catch (IOException e) {18             e.printStackTrace();19         }20     }21 }

 

 IO字符流和缓冲流

IO字符流的文件拷贝

1 import java.io.*; 2  3 /** 4  * IO字符流的文件拷贝 5  */ 6 public class Test { 7     public static void main(String[] args) { 8         try (FileReader fr = new FileReader("java.txt"); 9              FileWriter fw = new FileWriter("file" + File.separator + "new.txt")10         ) {11             int temp;12             while ((temp = fr.read()) != -1) {13                 fw.write(temp);14             }15         } catch (FileNotFoundException e) {16             e.printStackTrace();17         } catch (IOException e) {18             e.printStackTrace();19         }20     }21 }

IO缓冲字符流的文件拷贝

1 import java.io.*; 2  3 /** 4  * IO缓冲字符流的文件拷贝 5  */ 6 public class Test { 7     public static void main(String[] args) { 8         try ( 9                 BufferedReader br = new BufferedReader(new FileReader("java.txt"));10                 BufferedWriter bw = new BufferedWriter(new FileWriter("file" + File.separator + "new.txt"))11         ) {12                 String msg;13                 while ((msg = br.readLine()) != null) {14                     bw.write(msg);15                     bw.newLine();  //换行16                     bw.flush();  //刷新17                 }18 19         } catch (FileNotFoundException e) {20             e.printStackTrace();21         } catch (IOException e) {22             e.printStackTrace();23         }24     }25 }

练习：图片简单的加密和解密

加密

1 import java.io.*; 2  3 /** 4  * 图片的简单加密 5  * 通过异或的方式 6  */ 7 public class Test { 8     public static void main(String[] args) { 9         try (10                 BufferedInputStream bis = new BufferedInputStream(new FileInputStream("file" + File.separator + "123.jpg"));11                 BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("file" + File.separator + "new123.jpg"))12         ) {13             int temp;14             while ((temp = bis.read()) != -1) {15                 bos.write(temp ^ 88);16             }17         } catch (FileNotFoundException e) {18             e.printStackTrace();19         } catch (IOException e) {20             e.printStackTrace();21         }22     }23 }

解密

1 import java.io.*; 2  3 /** 4  * 图片的简单解密 5  * 通过异或的方式 6  */ 7 public class Test { 8     public static void main(String[] args) { 9         try (10                 BufferedInputStream bis = new BufferedInputStream(new FileInputStream("file" + File.separator + "code.jpg"));11                 BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("file" + File.separator + "decode.jpg"))12         ) {13             int temp;14             while ((temp = bis.read()) != -1) {15                 bos.write(temp ^ 88);16             }17         } catch (FileNotFoundException e) {18             e.printStackTrace();19         } catch (IOException e) {20             e.printStackTrace();21         }22     }23 }