Java中DataInputStream和DataOutputStream的使用方法

DataOutputStream out = new DataOutputStream(相接的流)

writeInt(int i)

writeDouble(double d)

writeUTF()

DataInputStream dis = new DataInputStream(InputStream in);

readInt()

readDouble()

readUTF()

public class Main {
    public static void main(String[] args) throws Exception {
        DataOutputStream out = new DataOutputStream(new FileOutputStream("d:/abc/f5"));
        out.writeInt(20211011);
        out.writeUTF("晴，18度");
        out.writeInt(20211012);
        out.writeUTF("晴，19度");
        out.writeInt(20211013);
        out.writeUTF("多云，17度");
        out.close();
    }
}

public class Main {
    public static void main(String[] args) throws Exception {
        DataInputStream in = new DataInputStream(new FileInputStream("d:/abc/f5"));
        try {
            while (true) {
                int date = in.readInt();
                String s = in.readUTF();
                System.out.println(date);
                System.out.println(s);
            }
        } catch (EOFException e) {
            //正确读取结束，不需要处理
        }
        in.close();
    }
}

<LinearLayout xmlns:Android="Http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="20dp">
    <EditText
        android:id="@+id/et1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="学号" />
    <EditText
        android:id="@+id/et2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="姓名" />
    <EditText
        android:id="@+id/et3"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="性别" />

    <EditText
        android:id="@+id/et4"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="年龄" />

    <Button
        android:id="@+id/btn1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="保存" />
    <Button
        android:id="@+id/btn2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="读取" />
    <TextView
        android:id="@+id/tv"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp" />
</LinearLayout>

public class IoActivity extends AppCompatActivity {
    private EditText et1;
    private EditText et2;
    private EditText et3;
    private EditText et4;
    private Button btn1;
    private Button btn2;
    private TextView tv;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_io);
        setViews();
        setListeners();
    }
    private void setViews() {
        et1 = findViewById(R.id.et1);
        et2 = findViewById(R.id.et2);
        et3 = findViewById(R.id.et3);
        et4 = findViewById(R.id.et4);
        btn1 = findViewById(R.id.btn1);
        btn2 = findViewById(R.id.btn2);
        tv = findViewById(R.id.tv);
    }
    private void setListeners() {
        btn1.setOnClickListener(view -> baocun());
        btn2.setOnClickListener(view -> duqu());
    }
    private void baocun() {
        //IO操作有IO异常，所以进行try...catch...
        
        try {
            int id = Integer.parseInt(et1.getText().toString());
            String name = et2.getText().toString();
            String gender = et3.getText().toString();
            int age = Integer.parseInt(et4.getText().toString());

            DataOutputStream out = new DataOutputStream(
                    new FileOutputStream(getExternalFilesDir(null) + "/stu.txt", true)
            );
            out.writeInt(id);
            out.writeUTF(name);
            out.writeChar(gender.charAt(0));
            out.writeInt(age);
            out.close();

            Toast.makeText(this, "保存成功", Toast.LENGTH_SHORT).show();
        } catch (Exception e) {
            Toast.makeText(this, "保存失败", Toast.LENGTH_SHORT).show();
            e.printStackTrace();
        }
    }

    private void duqu() {
        //IO操作有IO异常，所以进行try...catch...
        try {
            DataInputStream in = new DataInputStream(
                    new FileInputStream(getExternalFilesDir(null) + "/stu.txt")
            );

            try {
                tv.setText("");
                while (true) {
                    int id = in.readInt();
                    String name = in.readUTF();
                    char gender = in.readChar();
                    int age = in.readInt();
                    tv.append("id:" + id + "\n" + "name:" + name + "\n" + "gender:" + gender + "\n" + "age:" + age + "\n");
                }
            } catch (EOFException e) {

            }
            in.close();
            Toast.makeText(this, "读取成功", Toast.LENGTH_SHORT).show();
        } catch (Exception e) {
            Toast.makeText(this, "读取失败", Toast.LENGTH_SHORT).show();
            e.printStackTrace();
        }
    }
}