<?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"/>

     <Button

         android:layout_width="match_parent"

         android:layout_height="wrap_content"

         android:text="SP存储"

         android:onClick="bt_onClick"/>

     <Button

         android:layout_width="match_parent"

         android:layout_height="wrap_content"

         android:text="SP读取"

         android:onClick="bt1_onClick"/>

     <EditText

         android:layout_width="match_parent"

         android:layout_height="wrap_content"

         android:hint="请输入……"

         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);

     }

     public void bt_onClick(View v)        //SharedPreferences存储

     {

         //1.得到SharedPreferences对象

         SharedPreferences sharedPreferences = getSharedPreferences("abc", MODE_APPEND);

         //2.得到编辑器

         SharedPreferences.Editor editor =sharedPreferences.edit();

         //3.使用Editor添加数据

 //        editor.putString("a","abcdef");

 //        editor.putLong("long",12345);

         editor.remove("a");

         //4.提交保存

         editor.commit();

         Toast.makeText(MainActivity.this, "保存数据成功", Toast.LENGTH_SHORT).show();

     }

     //读取

     public void bt1_onClick(View v)

     {

         SharedPreferences sp = getSharedPreferences("abc",MODE_PRIVATE);

         String str = sp.getString("a", "默认值");

         Toast.makeText(MainActivity.this, "key = a"+" value = "+str, Toast.LENGTH_SHORT).show();

     }

     //写内部文件(手机内部文件存储)

     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("test.txt",MODE_APPEND);

             //3.写入文件内容

             PrintStream ps = new PrintStream(fos);

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

             ps.print(str);

 //            ps.print("测试");

 //            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();

         }

     }

     public void bt3_onClick(View v)

     {

         try {

             //输入流

             FileInputStream fis = openFileInput("test.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 e)

         {

         }

     }

 }