Java 文件读写方式

1. 以FileInputStream，FileInputStream 字节流的方式进行读写文件操作

@Test
    public void test_write_file() throws IOException {
        FileInputStream inputStream = new FileInputStream("C:\\Users\\qq\\Desktop\\spa\\test.txt");
        coutputStream = new FileOutputStream("C:\\Users\\qq\\Desktop\\spa\\test1.txt");
        //定义一次读入或写入多少字节
        byte[] bytes = new byte[2];
        int n = 0;
        //循环取出数据
        while ((n = inputStream.read(bytes,0,bytes.length)) != -1){
            //转换成字符串
            String readString = new String(bytes,0,n,"GBK");
            System.out.println(readString);
            //写入相关文件
            outputStream.write(bytes,0,n);
        }
        //清除缓存
        outputStream.flush();
        //关闭流
        inputStream.close();
        outputStream.close();
    }

2. BufferedInputStream、BufferedOutputStream（缓存字节流）使用方式和字节流差不多，但是效率更高（推荐使用）

@Test
    public void test_write_file_2() throws IOException {
        BufferedInputStream in = new BufferedInputStream(new FileInputStream("C:\\Users\\qq\\Desktop\\spa\\test.txt"));
        BufferedOutputStream out =new BufferedOutputStream(new FileOutputStream("C:\\Users\\qq\\Desktop\\spa\\test1.txt"));
        byte[] bytes = new byte[3];
        int n = 0;
        while ((n = in.read(bytes,0, bytes.length)) != -1){
            String temps = new String(bytes, 0, n);
            System.out.println(temps);
            out.write(bytes, 0, n);
        }
        out.flush();
        in.close();
        out.close();
    }

3. BufferedReader、BufferedWriter(缓存流，提供readLine方法读取一行文本)

@Test
    public void test_write_file_3() throws IOException {
        BufferedReader in = new BufferedReader(new InputStreamReader(new FileInputStream("C:\\Users\\qq\\Desktop\\spa\\test.txt")));
        BufferedWriter out = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("C:\\Users\\qq\\Desktop\\spa\\test1.txt")));
        String str = null;
        while ((str = in.readLine()) != null){
            System.out.println(str);
            out.write(str);
            out.newLine();
        }
        out.flush();
        out.close();
        in.close();
    }

4. Reader、PrintWriter（PrintWriter这个很好用，在写数据的同事可以格式化）

　　　　 //读取文件(字节流)
        Reader in = new InputStreamReader(new FileInputStream("d:\\1.txt"),"GBK");
        //写入相应的文件
        PrintWriter out = new PrintWriter(new FileWriter("d:\\2.txt"));
        //读取数据
        //循环取出数据
        byte[] bytes = new byte[1024];
        int len = -1;
        while ((len = in.read()) != -1) {
            System.out.println(len);
            //写入相关文件
            out.write(len);
        }
        //清楚缓存
        out.flush();
        //关闭流
        in.close();
        out.close();