<?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.application3.DataActivity1"

    android:orientation="vertical">

    <EditText

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:id="@+id/et_1"

        android:hint="Key"/>

    <EditText

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:id="@+id/et_2"

        android:hint="Value"/>

    <LinearLayout

        android:layout_width="match_parent"

        android:layout_height="wrap_content">

        <Button

            android:layout_width="0dp"

            android:layout_height="wrap_content"

            android:text="保存"

            android:layout_weight="1"

            android:onClick="bt1_onClick"/>

        <Button

            android:layout_width="0dp"

            android:layout_height="wrap_content"

            android:text="读取"

            android:layout_weight="1"

            android:onClick="bt2_onClick"/>

    </LinearLayout>

    <EditText

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:id="@+id/et_3"

        android:hint="要保存的内容"/>

    <EditText

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:id="@+id/et_4"

        android:hint="从文件中读取的内容"/>

    <LinearLayout

        android:layout_width="match_parent"

        android:layout_height="wrap_content">

        <Button

            android:layout_width="0dp"

            android:layout_height="wrap_content"

            android:text="保存"

            android:layout_weight="1"

            android:onClick="bt3_onClick"/>

        <Button

            android:layout_width="0dp"

            android:layout_height="wrap_content"

            android:text="读取"

            android:layout_weight="1"

            android:onClick="bt4_onClick"/>

    </LinearLayout>

    <LinearLayout

        android:layout_width="match_parent"

        android:layout_height="wrap_content">

        <Button

            android:layout_width="0dp"

            android:layout_height="wrap_content"

            android:text="保存文件"

            android:layout_weight="1"

            android:onClick="bt5_onClick"/>

        <Button

            android:layout_width="0dp"

            android:layout_height="wrap_content"

            android:text="读取文件"

            android:layout_weight="1"

            android:onClick="bt6_onClick"/>

    </LinearLayout>

    <ImageView

        android:layout_width="80dp"

        android:layout_height="80dp"

        android:src="@drawable/da1"

        android:id="@+id/iv_4"

        android:visibility="gone"/>

    <LinearLayout

        android:layout_width="match_parent"

        android:layout_height="wrap_content">

    <Button

        android:layout_width="0dp"

        android:layout_height="wrap_content"

        android:text="保存到带包名的目录"

        android:layout_weight="1"

        android:onClick="bt7_onClick"/>

    <Button

        android:layout_width="0dp"

        android:layout_height="wrap_content"

        android:text="从带包名目录读取"

        android:layout_weight="1"

        android:onClick="bt8_onClick"/>

    </LinearLayout>

    <LinearLayout

        android:layout_width="match_parent"

        android:layout_height="wrap_content">

    <Button

        android:layout_width="0dp"

        android:layout_height="wrap_content"

        android:text="保存到自定义目录"

        android:layout_weight="1"

        android:onClick="bt9_onClick"/>

    <Button

        android:layout_width="0dp"

        android:layout_height="wrap_content"

        android:text="从自定义目录读取"

        android:layout_weight="1"

        android:onClick="bt10_onClick"/>

    </LinearLayout>

</LinearLayout>

package com.hanqi.application3;

import android.content.SharedPreferences;

import android.content.res.AssetManager;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

import android.os.Bundle;

import android.os.Environment;

import android.support.v7.app.AppCompatActivity;

import android.view.View;

import android.widget.EditText;

import android.widget.ImageView;

import android.widget.Toast;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.InputStream;

import java.io.PrintStream;

public class DataActivity1 extends AppCompatActivity {

    EditText et1;

    EditText et2;

    EditText et3;

    EditText et4;

    ImageView iv4;

    SharedPreferences sp;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_data1);

        et1=(EditText)findViewById(R.id.et_1);

        et2=(EditText)findViewById(R.id.et_2);

        et3=(EditText)findViewById(R.id.et_3);

        et4=(EditText)findViewById(R.id.et_4);

        iv4= (ImageView)findViewById(R.id.iv_4);

        //1.获取sp的实例，制定了文件名和操作模式   MODE_PRIVATE私有

        sp = getSharedPreferences("mydata",MODE_PRIVATE);

    }

    //操作assets内的文件

    public void bt5_onClick(View v)

    {

        //1.获取AssetManager

        AssetManager am = getAssets();

         try{

             //2.打开文件,获取输入流

             InputStream is = am.open("denglu.jpg");

             //3.获取输出流

             FileOutputStream fos2 = openFileOutput("denglu2.jpg",MODE_PRIVATE);

             //4.边度编写

             byte[] bb2 = new byte[1024];

             int ii2 = 0;

             while ((ii2 = is.read(bb2))>0)

             {

                 fos2.write(bb2,0,ii2);

             }

             fos2.close();

             is.close();

             Toast.makeText(DataActivity1.this, "保存成功", Toast.LENGTH_SHORT).show();

         }

         catch (Exception e)

         {

             e.printStackTrace();

             Toast.makeText(DataActivity1.this, "保存失败", Toast.LENGTH_SHORT).show();

         }

    }

    //从手机内部存储读图片文件

    public void bt6_onClick(View v)

    {

        //改变ImageView的图片来源，指向手机存储空间

        //1.获取文件存储的绝对路径

        String filepath = getFilesDir().getAbsolutePath();

        //2.组合完整路径

        filepath += "/denglu2.jpg";

        //3.生成位图实例

        Bitmap bm2 = BitmapFactory.decodeFile(filepath);

        //4.改变ImageView的图片来源

        iv4.setImageBitmap(bm2);

    }

    //文件名

    final String FILENAME = "test.txt";

    public void bt3_onClick(View v)

    {

        //1.获取要存储的内容

        String content = et3.getText().toString();

        //2.获取输出流

        try {

            FileOutputStream fos1 = openFileOutput(FILENAME, MODE_APPEND);

            //3.构造一个打印输出流

            PrintStream pm1 = new PrintStream(fos1);

            //4.写入内容

            pm1.println(content);

            pm1.close();

            fos1.close();

            Toast.makeText(DataActivity1.this, "保存成功", Toast.LENGTH_SHORT).show();

        } catch (Exception e) {

            e.printStackTrace();

            Toast.makeText(DataActivity1.this, "保存失败", Toast.LENGTH_SHORT).show();

        }

    }

    public void bt4_onClick(View v)

    {

        try {

        //1.获取输入流

            FileInputStream fis1 = openFileInput(FILENAME);

            //2.定义读取的数组

            byte[] bt11 = new byte[1024];

            //3.读出数据的长度

            int ii = 0;

            StringBuilder  bb1 = new StringBuilder ();

            while ((ii = fis1.read(bt11))>0)

            {

                bb1.append(new String(bt11,0, ii));

            }

            fis1.close();

            //设置显示读出的内容

            et4.setText(bb1);

            Toast.makeText(DataActivity1.this, "显示成功", Toast.LENGTH_SHORT).show();

        }

        catch (Exception e)

        {

            e.printStackTrace();

            Toast.makeText(DataActivity1.this, "保存失败", Toast.LENGTH_SHORT).show();

        }

    }

    //保存

    public void bt1_onClick(View v)

    {

        //1.获取Key和Value

        String key = et1.getText().toString();

        String value = et2.getText().toString();

        if (key.length() ==0||value.length() == 0)

        {

            Toast.makeText(DataActivity1.this, "key或value不能为空", Toast.LENGTH_SHORT).show();

        }

        else {

        //2.取得Editor        edit编辑器

        SharedPreferences.Editor editor = sp.edit();

        //3.放入键值对

        editor.putString(key,value);

        //4.提交保存

        boolean b = editor.commit();

        if (b)

        {

            Toast.makeText(DataActivity1.this, "保存成功", Toast.LENGTH_SHORT).show();

        }

        else

        {

            Toast.makeText(DataActivity1.this, "保存失败", Toast.LENGTH_SHORT).show();

        }

        }

    }

    //读取

    public void bt2_onClick(View v)

    {

        //1.获取要读的key

        String key = et1.getText().toString();

        //2.读并设置文本框

        et2.setText(sp.getString(key,"没有发现key"));

    }

    //向外部存储空间存储文件  保存到带包名的目录

    public void bt7_onClick(View v)

    {

        if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {

            //1.获取要存储的内容

            String content = et3.getText().toString();

            //2.获取外部带包名的目录

            //String sdPath = Environment.getExternalStorageDirectory().getAbsolutePath();

            //Toast.makeText(DataActivity1.this, "sdPath= "+sdPath, Toast.LENGTH_SHORT).show();

            //参数  代表不同文件类型的子目录，如果没有，就传null

            String sdPath = getExternalFilesDir(null).getAbsolutePath();

            Toast.makeText(DataActivity1.this, "sdPath = "+sdPath, Toast.LENGTH_SHORT).show();

            //3.构造输出流

            sdPath += "/" +FILENAME;

            try {

                FileOutputStream fos3 = new FileOutputStream(sdPath);

                //传统方式  字节数组方式

                fos3.write(content.getBytes("utf-8"));

                fos3.close();

                Toast.makeText(DataActivity1.this, "保存成功", Toast.LENGTH_SHORT).show();

            }

            catch (Exception e)

            {

                e.printStackTrace();

                Toast.makeText(DataActivity1.this, "保存失败", Toast.LENGTH_SHORT).show();

            }

        }

        else

        {

            Toast.makeText(DataActivity1.this, "SD卡没有挂载", Toast.LENGTH_SHORT).show();

        }

    }

    //从外部存储空间读取文件   带包名的目录

    public void bt8_onClick(View v) {

        if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {

            //1.获取要存储的内容

            //String content = et3.getText().toString();

            //2.获取外部带包名的目录

            //String sdPath = Environment.getExternalStorageDirectory().getAbsolutePath();

            //Toast.makeText(DataActivity1.this, "sdPath= "+sdPath, Toast.LENGTH_SHORT).show();

            //参数  代表不同文件类型的子目录，如果没有，就传null

            String sdPath = getExternalFilesDir(null).getAbsolutePath();

            //Toast.makeText(DataActivity1.this, "sdPath = "+sdPath, Toast.LENGTH_SHORT).show();

            //3.构造输入流

            sdPath += "/" + FILENAME;

            try {

                FileInputStream fis3 = new FileInputStream(sdPath);

                byte[] b = new byte[1024];

                int i = 0;

                StringBuilder sb1 = new StringBuilder();

                while ((i = fis3.read(b)) > 0) {

                    sb1.append(new String(b, 0, i));

                }

                et4.setText(sb1);

                Toast.makeText(DataActivity1.this, "读取成功", Toast.LENGTH_SHORT).show();

            } catch (Exception e) {

                e.printStackTrace();

                Toast.makeText(DataActivity1.this, "读取失败", Toast.LENGTH_SHORT).show();

            }

        } else {

            Toast.makeText(DataActivity1.this, "SD卡没有挂载", Toast.LENGTH_SHORT).show();

        }

    }

    //向外部存储空间存储文件   保存到自定义的目录

    public void bt9_onClick(View v)

    {

        if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {

            //1.获取要存储的内容

            String content = et3.getText().toString();

            //2.获取外部存储的根目录

            String sdPath = Environment.getExternalStorageDirectory().getAbsolutePath();

            //在sd卡的根目录下，创建子目录

            sdPath += "/hanqi";

            //实例化File  指向一个目录

            File file = new File(sdPath);

            //如果不存在

            if(!file.exists())

            {

                //创建目录

                file.mkdirs();

            }

            Toast.makeText(DataActivity1.this, "sdPath= "+sdPath, Toast.LENGTH_SHORT).show();

            //3.构造输出流

            sdPath += "/" +FILENAME;

            try {

                FileOutputStream fos3 = new FileOutputStream(sdPath);

                //传统方式  字节数组方式

                fos3.write(content.getBytes("utf-8"));

                fos3.close();

                Toast.makeText(DataActivity1.this, "保存成功", Toast.LENGTH_SHORT).show();

            }

            catch (Exception e)

            {

                e.printStackTrace();

                Toast.makeText(DataActivity1.this, "保存失败", Toast.LENGTH_SHORT).show();

            }

        }

        else

        {

            Toast.makeText(DataActivity1.this, "SD卡没有挂载", Toast.LENGTH_SHORT).show();

        }

    }

    //从外部存储空间读取文件   带包名的目录

    public void bt10_onClick(View v) {

        if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {

            //1.获取要存储的内容

            //String content = et3.getText().toString();

            //2.获取外部带包名的目录

            String sdPath = Environment.getExternalStorageDirectory().getAbsolutePath();

            //Toast.makeText(DataActivity1.this, "sdPath= "+sdPath, Toast.LENGTH_SHORT).show();

            //参数  代表不同文件类型的子目录，如果没有，就传null

            //String sdPath = getExternalFilesDir(null).getAbsolutePath();

            //Toast.makeText(DataActivity1.this, "sdPath = "+sdPath, Toast.LENGTH_SHORT).show();

            //3.构造输入流

            sdPath += "/hanqi"+"/" + FILENAME;

            try {

                FileInputStream fis3 = new FileInputStream(sdPath);

                byte[] b = new byte[1024];

                int i = 0;

                StringBuilder sb1 = new StringBuilder();

                while ((i = fis3.read(b)) > 0) {

                    sb1.append(new String(b, 0, i));

                }

                et4.setText(sb1);

                Toast.makeText(DataActivity1.this, "读取成功", Toast.LENGTH_SHORT).show();

            } catch (Exception e) {

                e.printStackTrace();

                Toast.makeText(DataActivity1.this, "读取失败", Toast.LENGTH_SHORT).show();

            }

        } else {

            Toast.makeText(DataActivity1.this, "SD卡没有挂载", Toast.LENGTH_SHORT).show();

        }

    }

}

<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>

    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

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