java基本IO

一、文件和目录，File类
File f = new File("d:\\test.txt");
f.createNewFile();

二、输入流及输出流
1.单字节数据读取

1）文件字节输入流，FileInputStream,继承自InputStream

public static void main(String[] args) throws Exception { File f = new File("d:\\test.txt"); FileInputStream fis = new FileInputStream(f); char ch; for (int i = 0; i < f.length(); i++) { ch = (char) fis.read(); System.out.print(ch); } fis.close(); }

含中文乱码
2）文件字节输出流,FileOutputStream,继承自OutputStream

public static void main(String[] args)throws Exception { File f=new File("d:\\test.txt"); FileOutputStream fos=new FileOutputStream(f); String str="我来自哪里ssss"; byte[] by=str.getBytes(); for(int i=0;i<by.length;i++) { fos.write(by[i]); } fos.close(); }

3）文件字节输入与输出流

public static void main(String[] args)throws Exception{ File f=new File("d:\\test.txt"); File f1=new File("d:\\test2.txt"); FileInputStream fis=new FileInputStream(f); FileOutputStream fos=new FileOutputStream(f1); byte[] b=new byte[(int)f.length()]; fis.read(b); for(int i=0;i<f.length();i++){ fos.write(b[i]); } fis.close(); fos.close(); }

2.多字节数据读取
FilterOutputStream、DataOutputStream；FilterInputStream、DataInputStream
1）DataOutputStream，实现了DataOutput接口，继承了FilterOutputStream

public static void main(String[] args)throws Exception{ File f=new File("d:\\test.txt"); FileOutputStream fos=new FileOutputStream(f); DataOutputStream dos=new DataOutputStream(fos); try{ dos.writeUTF("我要去哪里ssss"); //dos.writeBytes("我要去哪里ddddd"); }catch(Exception e){ e.printStackTrace(); } dos.close(); }

2)DataInputStream,实现了DataInput接口，继承了FilterInputStream

public static void main(String[] args)throws Exception { File f=new File("d:\\test.txt"); FileInputStream fis=new FileInputStream(f); DataInputStream dis=new DataInputStream(fis); try{ System.out.println(dis.readUTF()); }catch(Exception e){ e.printStackTrace(); } dis.close(); }

3.字符流
InputStreamReader、BufferedReader；OutputStreamWriter、BufferedWriter
1）BufferedReader，继承自Reader类，带有缓冲机制，可以以行为单位进行数据操作

public static void main(String[] args)throws Exception{ File f=new File("d:\\","test.txt"); FileInputStream fis=new FileInputStream(f); InputStreamReader isr=new InputStreamReader(fis); BufferedReader br=new BufferedReader(isr); System.out.println(br.readLine()); }

2）BufferedWriter，继承自Writer类

public static void main(String[] args)throws Exception{ File f=new File("d:\\","test.txt"); FileOutputStream fos=new FileOutputStream(f); OutputStreamWriter osw=new OutputStreamWriter(fos); BufferedWriter bw=new BufferedWriter(osw); bw.write("这是要去哪里ssss"); bw.newLine(); bw.write("这是要去哪里ssss"); bw.newLine(); //写入一个行结束标记 bw.close(); }

另：StringBuffer中文乱码问题

public String read(String str) throws IOException{ File file=new File(str); FileInputStream fis=new FileInputStream(file); StringBuffer sb=new StringBuffer(); BufferedInputStream bis=new BufferedInputStream(fis); BufferedReader read = new BufferedReader (new InputStreamReader(bis)); int c=0; while ((c=read.read())!=-1) { sb.append((char) c); } read.close(); bis.close(); fis.close(); String verify=sb.toString(); return verify; }