<?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.example.dell.shujucunchu.SDkacunchu"

    android:orientation="vertical">

    <EditText

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:id="@+id/et_5"/>

    <EditText

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:id="@+id/et_6"/>

    <LinearLayout

    android:layout_width="match_parent"

    android:layout_height="wrap_content">

    <Button

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_weight="1"

        android:text="读包的目录"

        android:onClick="baocun3"/>

    <Button

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_weight="1"

        android:text="读自定义目录"

        android:onClick="baocun4"/>

</LinearLayout>

    <LinearLayout

        android:layout_width="match_parent"

        android:layout_height="wrap_content">

        <Button

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:layout_weight="1"

            android:text="存包目录"

            android:onClick="baocun5"/>

        <Button

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:layout_weight="1"

            android:text="存自定义目录"

            android:onClick="baocun6"/>

    </LinearLayout>

    <LinearLayout

        android:layout_width="match_parent"

        android:layout_height="wrap_content">

        <Button

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:layout_weight="1"

            android:text="保存到带包名的目录"

            android:onClick="baocun7"/>

        <Button

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:layout_weight="1"

            android:text="从带包名目录读取"

            android:onClick="baocun8"/>

    </LinearLayout>

    <LinearLayout

        android:layout_width="match_parent"

        android:layout_height="wrap_content">

        <Button

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:layout_weight="1"

            android:text="保存到自定义的目录"

            android:onClick="baocun9"/>

        <Button

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:layout_weight="1"

            android:text="从自定义目录读取"

            android:onClick="baocun10"/>

    </LinearLayout>

</LinearLayout>

package com.hanqi.test5;

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.Toast;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

public class DataActivity2 extends AppCompatActivity {

    EditText et_5 ;

    EditText et_6 ;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_data2);

    }

    public void baocun5(View view)

    {

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

        {

            //1、获取要存储的内容

            et_5 = (EditText)findViewById(R.id.et_5);

            String content = et_5.getText().toString();

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

//

//            Toast.makeText(SDkacunchu.this, "sdpath="+sdpath, Toast.LENGTH_SHORT).show();

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

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

            Toast.makeText(DataActivity2.this, "sdpath =" + sdpath, Toast.LENGTH_SHORT).show();

            //构造输出流

            sdpath += "/sd";

            try {

                FileOutputStream fos = new FileOutputStream(sdpath);

                //传统模式  字节数组方式

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

                fos.close();

            } catch (Exception e) {

                e.printStackTrace();

            }

        }

        else

        {

            Toast.makeText(DataActivity2.this, "未发现sd卡", Toast.LENGTH_SHORT).show();

        }

    }

    public void baocun3(View view)

    {

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

        {

            //1、获取要存储的内容

            et_6 = (EditText)findViewById(R.id.et_6);

            //String content = et_6.getText().toString();

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

//

//            Toast.makeText(SDkacunchu.this, "sdpath="+sdpath, Toast.LENGTH_SHORT).show();

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

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

            //Toast.makeText(SDkacunchu.this, "sdpath =" + sdpath, Toast.LENGTH_SHORT).show();

            //构造输出流

            sdpath += "/sd";

            try {

                FileInputStream fis = new FileInputStream(sdpath);

                //传统模式  字节数组方式

                byte[]  b = new byte[1024];

                int i =0;

                StringBuilder str = new StringBuilder();

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

                    et_6.setText(str.append(new String(b, 0, i)));

                }

                fis.close();

            } catch (Exception e) {

                e.printStackTrace();

            }

        }

        else

        {

            Toast.makeText(DataActivity2.this, "未发现sd卡", Toast.LENGTH_SHORT).show();

        }

    }

    public void baocun6(View view)

    {

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

        {

            //1、获取要存储的内容

            et_5 = (EditText)findViewById(R.id.et_5);

            String content = et_5.getText().toString();

            //获取外部存储根目录

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

            //在sd卡根目录下再创建子目录

            sdpath += "/hanqi";

            File file = new File(sdpath);

            //如果不存在

            if (!file.exists())

            {

                //创建目录

                file.mkdir();

                //创建文件

                //file.createNewFile();

            }

            Toast.makeText(DataActivity2.this, "sdpath="+sdpath, Toast.LENGTH_SHORT).show();

            //构造输出流

            sdpath += "/test.txt";

            try {

                FileOutputStream fos = new FileOutputStream(sdpath);

                //传统模式  字节数组方式

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

                fos.close();

            } catch (Exception e) {

                e.printStackTrace();

            }

        }

        else

        {

            Toast.makeText(DataActivity2.this, "未发现sd卡", Toast.LENGTH_SHORT).show();

        }

    }

    public void baocun4(View view)

    {

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

        {

            //1、获取要存储的内容

            et_6 = (EditText)findViewById(R.id.et_6);

            //String content = et_6.getText().toString();

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

            Toast.makeText(DataActivity2.this, "sdpath="+sdpath, Toast.LENGTH_SHORT).show();

            //构造输出流

            sdpath += "/hanqi/test.txt";

            try {

                FileInputStream fis = new FileInputStream(sdpath);

                //传统模式  字节数组方式

                byte[]  b = new byte[1024];

                int i =0;

                StringBuilder str = new StringBuilder();

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

                    et_6.setText(str.append(new String(b, 0, i)));

                }

                fis.close();

            } catch (Exception e) {

                e.printStackTrace();

            }

        }

        else

        {

            Toast.makeText(DataActivity2.this, "未发现sd卡", Toast.LENGTH_SHORT).show();

        }

    }

}