前言
Java文件读写能够分为字节流和字符流，之前始终没有好好演绎以下，借此机会做一个小笔记。
目录
字节流
字节流就是一个字节一个字节的传输，最罕用的就是FileInputStream和FileOutputStream，代码如下
public static void readByFIS(String filepath) { File file = new File(filepath); try { FileInputStream fis = new FileInputStream(file); byte [] bytes = new byte[fis.available()]; while (fis.read(bytes, 0, bytes.length) != -1) { System.out.println(new String(bytes)); } fis.close(); } catch (IOException e) { e.printStackTrace(); } } public static void writeByFIS(String filepath) { File file = new File(filepath); if(!file.exists()) { try { file.createNewFile(); } catch (IOException e) { e.printStackTrace(); } } try { FileOutputStream fos = new FileOutputStream(file, true); fos.write("从此无可爱良夜，任他明月下西楼\n".getBytes()); fos.close(); } catch (IOException e) { e.printStackTrace(); } }留神在读的的时候咱们使用了available去获取一个和文件大小刚好的空间，这存在一个问题，如果文件过大可能会导致内存溢出。
应用BufferedInputStream 和BufferedOutputStream如下
public static void readByBIS(String filepath) { File file = new File(filepath); if(file.exists()) { try { BufferedInputStream bis = new BufferedInputStream(new FileInputStream(file)); byte[] bytes = new byte[bis.available()]; bis.read(bytes); System.out.println(new String(bytes)); bis.close(); } catch (IOException e) { e.printStackTrace(); } } } public static void writeByBIS(String filepath) { File file = new File(filepath); if(!file.exists()) { try { file.createNewFile(); } catch (IOException e) { e.printStackTrace(); } } try { BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(filepath)); bos.write("从此无可爱良夜，任他明月下西楼".getBytes()); bos.flush(); bos.close(); } catch (IOException e) { e.printStackTrace(); } }字符流
使用FileWriter和FileReader
public static void writeByFR(String filepath) { File file = new File(filepath); if(!file.exists()) { try { file.createNewFile(); } catch (IOException e) { e.printStackTrace(); } } try { FileWriter writer = new FileWriter(filepath, true); writer.write("从此无可爱良夜，任他明月下西楼"); writer.close(); } catch (IOException e) { e.printStackTrace(); } } public static void readByFR(String filepath) { File file = new File(filepath); if(file.exists()) { try { FileReader reader = new FileReader(file); char[] chars = new char[100]; reader.read(chars); System.out.println(chars); reader.close(); } catch (IOException e) { e.printStackTrace(); } } }使用BufferedWriter和BufferedReader
ublic static void readByBR(String filepath) { File file = new File(filepath); String line; try { BufferedReader reader = new BufferedReader(new FileReader(file)); while ((line = reader.readLine()) != null) { System.out.println(line);; } reader.close(); } catch (IOException e) { e.printStackTrace(); } } public static void writeByBR(String filepath) { File file = new File(filepath); if(!file.exists()) { try { file.createNewFile(); } catch (IOException e) { e.printStackTrace(); } } try { BufferedWriter writer = new BufferedWriter(new FileWriter(file, true)); writer.write("从此无可爱良夜，任他明月下西楼"); writer.flush(); writer.newLine(); writer.close(); } catch (IOException e) { e.printStackTrace(); } }最初
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