Io

从控制台输入输出 import java.util.Scanner; public class IoTest { public static void main(String args[]){ Scanner sc = new Scanner(System.in); int n = sc.nextInt(); System.out.println(n); String s = sc.next(); System.out.println(s); String line = sc.nextLine(); System.out.println(line);//从控制台输出 } } 字节流 FileOutputStream import java.io.File; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.OutputStream; public class IoTest { public static void main(String args[]){ File file = new File("aa.txt"); try { //FileOutputStream(File,boolean) 是否把内容追加 OutputStream out = new FileOutputStream(file); String str = "Hello World"; byte[] b=str.getBytes(); out.write(b); out.close(); } catch (FileNotFoundException e) { e.printStackTrace(); }catch (Exception e){ e.printStackTrace(); } } } FileInputStream import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.InputStream; public class IoTest { public static void main(String args[]){ try { File file = new File("E:"+File.separator+"tt.txt"); InputStream is = new FileInputStream(file); // byte[] bytes = new byte[1024]; //也可以这样 byte[] bytes = new byte[(int) file.length()]; is.read(bytes); System.out.println(new String(bytes)); //关闭流 is.close(); } catch (FileNotFoundException e) { e.printStackTrace(); }catch (Exception e){ e.printStackTrace(); } } } BufferedOutputStream import java.io.*; public class IoTest { public static void main(String args[]){ File file = new File("aa.txt"); try { OutputStream out = new FileOutputStream(file); BufferedOutputStream bos = new BufferedOutputStream(out); byte[] bytes = "土豆，土豆，呼叫土豆".getBytes(); bos.write(bytes); //刷新缓存 bos.flush(); bos.close(); out.close(); } catch (FileNotFoundException e) { e.printStackTrace(); }catch (Exception e){ e.printStackTrace(); } } } BufferedInputStream import java.io.*; public class IoTest { public static void main(String args[]){ try { File file = new File("E:"+File.separator+"tt.txt"); InputStream is = new FileInputStream(file); BufferedInputStream bis = new BufferedInputStream(is); byte[] bytes = new byte[(int) file.length()]; bis.read(bytes); System.out.println(new String(bytes)); bis.close(); is.close(); } catch (FileNotFoundException e) { e.printStackTrace(); }catch (Exception e){ e.printStackTrace(); } } } 字符流 FileWriter import java.io.File; import java.io.FileWriter; import java.io.IOException; import java.io.Writer; public class IoTest { public static void main(String args[]){ try { File file = new File("aa.txt"); Writer writer = new FileWriter(file); writer.write("土豆。。。\n"); writer.write("地瓜，对不起"); writer.close(); } catch (IOException e) { e.printStackTrace(); } } } FileReader import java.io.File; import java.io.FileReader; import java.io.IOException; import java.io.Reader; public class IoTest { public static void main(String args[]){ try { File file = new File("aa.txt"); Reader reader = new FileReader(file); char[] chars = new char[1024]; reader.read(chars); System.out.println(new String(chars)); reader.close(); } catch (IOException e) { e.printStackTrace(); } } } 转换流(字节流转字符流) OutputStreamWriter import java.io.*; public class IoTest { public static void main(String args[]){ File file = new File("aa.txt"); try { OutputStream out = new FileOutputStream(file); OutputStreamWriter osw = new OutputStreamWriter(out); osw.write("这是字节流转成了字符流"); String encoding = osw.getEncoding(); System.out.println("文件的编码："+encoding); //文件的编码：UTF8 osw.close(); out.close(); } catch (FileNotFoundException e) { e.printStackTrace(); }catch (Exception e){ e.printStackTrace(); } } } InputStreamReader import java.io.*; public class IoTest { public static void main(String args[]){ try { File file = new File("aa.txt"); InputStream is = new FileInputStream(file); InputStreamReader isr = new InputStreamReader(is,"utf-8");//指定编码 char[] chars = new char[1024]; isr.read(chars); System.out.println(chars); System.out.println("编码："+isr.getEncoding()); isr.close(); isr.close(); } catch (FileNotFoundException e) { e.printStackTrace(); }catch (Exception e){ e.printStackTrace(); } } } 字符缓冲流(高效流) BufferedWriter import java.io.*; public class IoTest { public static void main(String args[]){ File file = new File("aa.txt"); try { OutputStream out = new FileOutputStream(file); OutputStreamWriter osw = new OutputStreamWriter(out); BufferedWriter bw = new BufferedWriter(osw); bw.write("hello 这是字符缓冲流"); bw.newLine(); bw.write("下一行"); bw.close(); osw.close(); out.close(); } catch (FileNotFoundException e) { e.printStackTrace(); }catch (Exception e){ e.printStackTrace(); } } } BufferedReader import java.io.*; public class IoTest { public static void main(String args[]){ try { File file = new File("aa.txt"); InputStream is = new FileInputStream(file); InputStreamReader isr = new InputStreamReader(is,"utf-8"); BufferedReader br = new BufferedReader(isr); String str; while ((str=br.readLine())!=null){ System.out.println(str); } br.close(); isr.close(); is.close(); } catch (FileNotFoundException e) { e.printStackTrace(); }catch (Exception e){ e.printStackTrace(); } } } 字节流与字符流的区别 字节流在操作的时候本身是不会用到缓冲区（内存）的，是与文件本身直接操作的，而字符流在操作的时候是使用到缓冲区的 ...