内部文件存储

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.hanqi.testapp3.MainActivity"
    android:orientation="vertical">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        android:id="@+id/tv_1"/>

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="输入..."
        android:id="@+id/et_1"/>

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="写内部文件"
        android:onClick="bt2_OnClick"/>

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="读内部文件"
        android:onClick="bt3_OnClick"/>
</LinearLayout>

package com.hanqi.testapp3;

import android.content.SharedPreferences;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.PrintStream;

public class MainActivity extends AppCompatActivity {

    EditText et_1;
    TextView tv_1;

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

        et_1 = (EditText)findViewById(R.id.et_1);
        tv_1 = (TextView)findViewById(R.id.tv_1);

    }

//写内部文件
    public void bt2_OnClick(View v)
    {
        //从内存里写入文件

        //1、得到内部的存储目录
        try {

        File file = getFilesDir();

        String path = file.getAbsolutePath();

        Toast.makeText(MainActivity.this, "path = " + path, Toast.LENGTH_SHORT).show();

        //2、用输出流写入文件
        FileOutputStream fos = openFileOutput("text.txt",MODE_APPEND);

        //3、写入文件内容
            PrintStream ps = new PrintStream(fos);

            String str = et_1.getText().toString();

            ps.println(str);
            //ps.println("自动换行");
            ps.close();
            fos.close();

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

    }


    //读
    public void bt3_OnClick (View v)
    {
        try {
            //输入流
            FileInputStream fis = openFileInput("text.txt");

            //1、定义byte[]
            byte[] b = new byte[1024];
            int i = 0; //读到的数据长度

            String str1 = "";

            //2、循环读
            while ((i = fis.read(b)) > 0)
            {
                String str = new String(b, 0, i);

                str1 += str;
            }

            fis.close();

            tv_1.setText(str1);
        }
        catch (Exception ex)
        {

        }
    }

}