字节流和字符流

读文件：

    public void readFile(){
        File f=new File("d:\\data.txt");
        try {
            InputStream in=new FileInputStream(f);
            int len=(int) f.length();
            byte[] b=new byte[len];
            in.read(b);
            in.close();
            String str=new String(b);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

写文件：

    public void writeFile(){
        File f=new File("d:\\data.txt");
        try {
            OutputStream out=new FileOutputStream(f);
            String str="hello ppa";
            byte[] b=str.getBytes();
            out.write(b);
            out.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

字节流：
OutputStream,FileOutputStream
InputStream,FileInputStream

字符流：
Writer,FileWriter
Reader,FileReader

转换流：
InputStreamReader:是Reader子类，将字节流转换为字符流读出。

    public void readerFile() throws IOException{
        File f=new File("d:\\data.txt");
        Reader in=new InputStreamReader(new FileInputStream(f));
        char c[]=new char[1024];
        int len=in.read(c);
        in.close();
        String str=new String(c,0,len);
    }

OutputStreamWriter:是Writer子类，将字符流转换为字节流写入；

    public void writerFile() throws IOException{
        File f=new File("d:\\data.txt");
        Writer out=new OutputStreamWriter(new FileOutputStream(f));
        out.write("hello ppa");
        out.close();
    }

字符缓冲类：BufferedReader

    public void bufferReader(){
        BufferedReader buf=null;
        buf=new BufferedReader(new InputStreamReader(System.in));
        String str=null;
        try {
            str=buf.readLine();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }