JAVA IO流

字节流读取文件内容FileInputStream

//把流定义在try()里,try,catch或者finally结束的时候，会自动关闭 try (FileInputStream fis = new FileInputStream(f)) { byte[] all = new byte[(int) f.length()]; fis.read(all); for (byte b : all) { System.out.println(b); } } catch (IOException e) { e.printStackTrace(); }

字节流向文件写入数据FileOutputStream

try { File f = new File("d:/lol2.txt"); byte data[] = { 88, 89 }; FileOutputStream fos = new FileOutputStream(f); fos.write(data)； } catch (IOException e) { e.printStackTrace(); }finally { // 在finally 里关闭流 if (null != fos) try { fos.close(); } catch (IOException e) { e.printStackTrace(); } }

字符流读取文件FileReader

try (FileReader fr = new FileReader(f)) { char[] all = new char[(int) f.length()]; fr.read(all); for (char b : all) { System.out.println(b); } } catch (IOException e) { e.printStackTrace(); }

字符流写入文件FileWriter

try (FileWriter fr = new FileWriter(f)) { String data="abcdefg1234567890"; char[] cs = data.toCharArray(); fr.write(cs); } catch (IOException e) { e.printStackTrace(); }

缓存字符流可以一次读取一行数据BufferedReader

try ( FileReader fr = new FileReader(f); BufferedReader br = new BufferedReader(fr); ) { while (true) { // 一次读一行 String line = br.readLine(); if (null == line) break; System.out.println(line); } } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); }

PrintWriter 缓存字符流可以一次写出一行数据

try ( // 创建文件字符流 FileWriter fw = new FileWriter(f); // 缓存流必须建立在一个存在的流的基础上 PrintWriter pw = new PrintWriter(fw); ) { pw.println("garen kill teemo"); pw.println("teemo revive after 1 minutes"); pw.println("teemo try to garen, but killed again"); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); }

立即把数据写入到硬盘，而不是等缓存满了才写出去。 这时候就需要用到flush

对象流 写入ObjectOutputStream 读取ObjectInputStream

直接把一个对象以流的形式传输给其他的介质

把一个对象序列化有一个前提是：这个对象的类，必须实现了Serializable接口 import java.io.Serializable; public class Hero implements Serializable { //表示这个类当前的版本，如果有了变化，比如新设计了属性，就应该修改这个版本号 private static final long serialVersionUID = 1L; public String name; public float hp; } try( //写入 FileOutputStream fos = new FileOutputStream(f); ObjectOutputStream oos =new ObjectOutputStream(fos); //读取 FileInputStream fis = new FileInputStream(f); ObjectInputStream ois =new ObjectInputStream(fis); ) { oos.writeObject(h); Hero h2 = (Hero) ois.readObject(); System.out.println(h2.name); System.out.println(h2.hp); } catch (IOException e) { e.printStackTrace(); } catch (ClassNotFoundException e) { e.printStackTrace(); }

Scanner读取字符串

Scanner s = new Scanner(System.in); while(true){ String line = s.nextLine(); System.out.println(line); }