Android【FileInputStream、FileOutputStream---本地文件I/O操作-读写操作模板（btnWrite方法、btnRead方法）】

运行截图

• 

activity_main.xml（约束布局）

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="76dp"
        android:onClick="btnRead"
        android:text="btnRead"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.498"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="68dp"
        android:onClick="btnWrite"
        android:text="btnWrite"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.498"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/button" />
</androidx.constraintlayout.widget.ConstraintLayout>

MainActivity.java

package cn.lwx.readwritetemplate;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void btnRead(View view) {
        FileInputStream fileInputStream = null;
        try {
            // 1.打开文件
            fileInputStream = openFileInput("aaa.txt");
            // 2.读操作 字节流（byte 10001） ----->  字符流（编码）ASCLL 流操作
            // Stream 字节流，reader write字符流
            BufferedReader reader = new BufferedReader(new InputStreamReader(fileInputStream));
            String line = null;
            StringBuilder builder = new StringBuilder();
            while ((line = reader.readLine()) != null) {
                builder.append(line);
            }
            System.out.println(builder.toString());
            // String str = new String();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            // 3.关闭文件
            if (fileInputStream != null) {
                try {
                    fileInputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    public void btnWrite(View view) {
        FileOutputStream fileOutputStream = null;
        try {
            // 1.打开文件
            fileOutputStream = openFileOutput("aaa.txt", MODE_PRIVATE);
            // 2.写操作
            fileOutputStream.write("卫星同学，好帅啊~ 我也要嫁给他~~~".getBytes());
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (fileOutputStream != null) {
                try {
                    fileOutputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

}

谢谢观看，点赞再走~~~   求求了~~~