Java基础--常用IO流使用实例

读取文本文件:

private static void ioDemo1() {
    try {
        FileReader fileReader = new FileReader("C:\Users\yan\Desktop\编码规范 (2).txt");
        int aa;
        aa = fileReader.read();
        while (aa!=-1) {//转换为char类型，否则是一堆数字
            System.out.print((char)aa);
            aa = fileReader.read();
        }
        fileReader.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

复制二进制文件:

private static void ioDemo2() {
    try {
        FileInputStream fr = new FileInputStream("D:/test.xlsx");//不能使用FileReader（字符流）
        FileOutputStream fw = new FileOutputStream("D:/test1.xlsx");
        int read = fr.read();
        while (read!=-1) {
            fw.write(read);
            read=fr.read();
        }
        fw.flush();//杯子中没有饮料不代表饮料已喝完，此方法就是清空吸管中的饮料
        fw.close();
        fr.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

使用缓冲流复制二进制文件:

private static void ioDemo3() {
    try {
        BufferedInputStream bis = new BufferedInputStream(new FileInputStream("D:/test.xlsx"));
        BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("C:\Users\yan\Desktop\test.xlsx"));
        byte[] buffer = new byte[2048];
        int read = bis.read(buffer);
        while(read!=-1)
        {
            bos.write(buffer, 0, read);
            read = bis.read(buffer);
        }
        bos.flush();
        bos.close();
        bis.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

数据流传递数据:

    private static void ioDemo4() {
        try {

            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            DataOutputStream dos = new DataOutputStream(baos);
            long src = 1234454544;
            dos.writeLong(src);

            byte[] bytes = baos.toByteArray();
            ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
            DataInputStream dis = new DataInputStream(bais);
            long recieve;
            recieve = dis.readLong();

            System.out.println("recieve:" + recieve);

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

PrintStream:

参考

ObjectStream：

    private static void ioDemo5() {
        ObjectOutputStream oos = null;
        ObjectInputStream ois = null;
        Student s = new Student("悟空", 007, 95.5f);
        Student s1 = null;

        try {
            FileOutputStream fos = new FileOutputStream("C:\Users\yan\Desktop/ccc.txt");
            oos = new ObjectOutputStream(fos);
            oos.writeObject(s);

            ois = new ObjectInputStream(new FileInputStream("C:\Users\yan\Desktop/ccc.txt"));
            s1 = (Student) ois.readObject();

            System.out.println("姓名：" + s1.getName());
            System.out.println("学号：" + s1.getId());
            System.out.println("成绩：" + s1.getScore());
            fos.close();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                oos.close();
                ois.close();
                System.exit(-1);
            } catch (Exception e) {
                System.exit(-1);
            }
        }
    }
//实现Serializable的作用是可以将对象保存在文件中用于传输
class Student implements Serializable {
    private static final long serialVersionUID = -111977186014986048L;
    private String name;
    private int id;
    private transient float score;//transient意思是转瞬即逝，起的作用是反序列化

    public Student(String name, int id, float score) {
        super();
        this.name = name;
        this.id = id;
        this.score = score;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public float getScore() {
        return score;
    }

    public void setScore(float score) {
        this.score = score;
    }
}