Android-内部存储-外部存储

一、存储结构

　　

 　　1. 内部存储

　　

 　　2. 外部存储

　　

 二、 内部存储

　　

 　　

 三、外部存储

 

 

 　　

 　　

　　

　　

 

 　　

 　　

 　　

 　　

 　　

 　　

 　　

 　　

 　　

 　　

 　　

 　　

 作业 习题：

 　　

 四、案例（存储数据）

 

 　　布局文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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=".ControlActivity"
    android:orientation="vertical">

    <EditText
        android:id="@+id/editText_info"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text=""
        android:layout_marginTop="50dp"/>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <Button
            android:id="@+id/button_save_internal"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="保存(内部存储)"
            android:textSize="18sp"/>

        <Button
            android:id="@+id/button_load_internal"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="读取(内部存储)"
            android:textSize="18sp"/>

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <Button
            android:id="@+id/button_save_external_root"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="保存(外存根目录）"
            android:textSize="18sp"/>

        <Button
            android:id="@+id/button_load_external_root"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="读取(外存根目录）"
            android:textSize="18sp"/>

    </LinearLayout>


    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <Button
            android:id="@+id/button_save_external_public"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="保存(外存共有目录）"
            android:textSize="18sp"/>

        <Button
            android:id="@+id/button_load_external_public"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="读取(外存共有目录）"
            android:textSize="18sp"/>

    </LinearLayout>


    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <Button
            android:id="@+id/button_save_external_private"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="保存(外存私有目录）"
            android:textSize="18sp"/>

        <Button
            android:id="@+id/button_load_external_private"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="读取(外存私有目录）"
            android:textSize="18sp"/>

    </LinearLayout>

    <Button
        android:id="@+id/button_clear_editText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="清空输入框"
        android:textSize="18sp"/>


</LinearLayout>

　　Activity

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.os.Environment;
import android.provider.ContactsContract;
import android.telephony.emergency.EmergencyNumber;
import android.text.LoginFilter;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;

public class ControlActivity extends AppCompatActivity implements View.OnClickListener {


    private final String FILE_NAME = "testData.txt";
    private final String TAG = "ControlActivity====";
    EditText infoText ;
    Button saveInternalButton;
    Button loadInternalButton;
    Button saveExternalRootButton;
    Button loadExternalRootButton;
    Button saveExternalPublicButton;
    Button loadExternalPublicButton;
    Button saveExternalprivateButton;
    Button loadExternalprivateButton;
    Button clearButton;


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


    }

    private void initComponent(){
        infoText = (EditText)findViewById(R.id.editText_info);
        saveInternalButton = (Button)findViewById(R.id.button_save_internal);
        loadInternalButton = (Button)findViewById(R.id.button_load_internal);
        saveExternalRootButton = (Button)findViewById(R.id.button_save_external_root);
        loadExternalRootButton = (Button)findViewById(R.id.button_load_external_root);
        saveExternalPublicButton = (Button)findViewById(R.id.button_save_external_public);
        loadExternalPublicButton = (Button)findViewById(R.id.button_load_external_public);
        saveExternalprivateButton = (Button)findViewById(R.id.button_save_external_private);
        loadExternalprivateButton = (Button)findViewById(R.id.button_load_external_private);
        clearButton = (Button)findViewById(R.id.button_clear_editText);

        saveInternalButton.setOnClickListener(this);
        loadInternalButton.setOnClickListener(this);
        saveExternalRootButton.setOnClickListener(this);
        loadExternalRootButton.setOnClickListener(this);
        saveExternalPublicButton.setOnClickListener(this);
        loadExternalPublicButton.setOnClickListener(this);
        saveExternalprivateButton.setOnClickListener(this);
        loadExternalprivateButton.setOnClickListener(this);
        clearButton.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
            String info = "";
        switch (view.getId()){
            case R.id.button_save_internal:
                saveToInternalStorage(infoText.getText().toString());
                Toast.makeText(this,"消息存储成功，消息是 "+infoText.getText().toString(),Toast.LENGTH_SHORT).show();
                break;
            case R.id.button_load_internal:
                info = loadFromInternalStorage();
                infoText.setText(info);
                Toast.makeText(this,"消息获取成功，消息是 "+infoText.getText().toString(),Toast.LENGTH_SHORT).show();
                break;
            case R.id.button_save_external_root:
                saveToExternalRootStorage(infoText.getText().toString());
                Toast.makeText(this,"消息存储成功，消息是 "+infoText.getText().toString(),Toast.LENGTH_SHORT).show();
                break;
            case R.id.button_load_external_root:
                info = loadFromExternalRootStorage();
                infoText.setText(info);
                Toast.makeText(this,"消息获取成功，消息是 "+infoText.getText().toString(),Toast.LENGTH_SHORT).show();
                break;
            case R.id.button_save_external_public:
                saveToExternalPublicStorage(infoText.getText().toString());
                Toast.makeText(this,"消息存储成功，消息是 "+infoText.getText().toString(),Toast.LENGTH_SHORT).show();
                break;
            case R.id.button_load_external_public:
                info = loadFromExternalPublicStorage();
                infoText.setText(info);
                Toast.makeText(this,"消息获取成功，消息是 "+infoText.getText().toString(),Toast.LENGTH_SHORT).show();
                break;
            case R.id.button_save_external_private:
                saveToExternalPrivateStorage(infoText.getText().toString());
                Toast.makeText(this,"消息存储成功，消息是 "+infoText.getText().toString(),Toast.LENGTH_SHORT).show();
                break;
            case R.id.button_load_external_private:
                info = loadFromExternalPrivateStorage();
                infoText.setText(info);
                Toast.makeText(this,"消息获取成功，消息是 "+infoText.getText().toString(),Toast.LENGTH_SHORT).show();
                break;
            case R.id.button_clear_editText:
                infoText.setText("");
                break;
        }

    }

    /**
     * 将 info 存入路径为 filePath 的文件中
     * @param file
     * @param info
     */
    private void saveToAnyFile(File file, String info) throws IOException {
        FileOutputStream out = null;

        if (!file.exists()) {
            file.createNewFile();
        }
        // 获得文件输出流
        out = new FileOutputStream(file.getAbsoluteFile());
        out.write(info.getBytes());
        try {
            if (out != null)
                out.close();
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    private String loadFromAnyFile(File file) throws IOException {
        StringBuffer res = new StringBuffer();// 存放数据
        // 打开文件输入流
        FileInputStream in = new FileInputStream(file.getAbsoluteFile());
        // 准备装载数据的容器
        byte[] buffer = new byte[1024];
        int len = in.read(buffer);
        // 不断读取文件内容
        while(len >0){
            res.append(new String(buffer,0,len));
            len = in.read(buffer);
        }
        // 关闭输入流
        in.close();
        return res.toString();
    }

    /**
     * 将数据存储到文件中（内部存储）（方法一）
     * @param info
     */
    private void saveToInternalStorage(String info){
        File filesDir = getFilesDir();
        String filesPath = filesDir.getAbsolutePath();
        File txtFile;
        try {

            txtFile = new File(filesPath,FILE_NAME);
            saveToAnyFile(txtFile,info);
            Log.d(TAG,"写入内部存储目录的文件路径："+txtFile.getAbsoluteFile());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private String loadFromInternalStorage() {
        String res = "";

        try {
            File filesDir = getFilesDir();
            File  txtFile = new File(filesDir.getAbsolutePath(),FILE_NAME);
           res =  loadFromAnyFile(txtFile);
            Log.d(TAG,"读取内部存储目录的文件路径："+txtFile.getAbsoluteFile());
        } catch (IOException e) {
            e.printStackTrace();
        }
        return res;
    }

    /**
     * 写入外部根目录
     * @param info
     */
    private void saveToExternalRootStorage(String info){
        try {
            // 检查外围设备是否存在
            String enviroment = Environment.getExternalStorageState();
            Log.d(TAG," Environment.getExternalStorageState():"+enviroment);
            if(Environment.MEDIA_MOUNTED.equals(enviroment)) {
                // 外部设备可以进行读写操作
                // 得到外部设备的根目录
                File filesDir = Environment.getExternalStorageDirectory();
                File txtFile = new File(filesDir,FILE_NAME);
                Log.d(TAG,"写入外部根目录的文件路径："+txtFile.getAbsoluteFile());
                saveToAnyFile(txtFile, info);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private String loadFromExternalRootStorage(){
        String res = "";
        try {
            // 检查外围设备是否存在
            String enviroment = Environment.getExternalStorageState();
            Log.d(TAG," Environment.getExternalStorageState():"+enviroment);
            if(Environment.MEDIA_MOUNTED.equals(enviroment)) {
                // 外部设备可以进行读写操作
                // 得到外部设备的根目录
                File filesDir = Environment.getExternalStorageDirectory();
                File txtFile = new File(filesDir,FILE_NAME);
                Log.d(TAG,"读取外部根目录的文件路径："+txtFile.getAbsoluteFile());
                res = loadFromAnyFile(txtFile);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return res;
    }

    /**
     * 写入外部存储共有目录
     * @param info
     */
    private void saveToExternalPublicStorage(String info){
        try {
            // 检查外围设备是否存在
            String enviroment = Environment.getExternalStorageState();
            Log.d(TAG," Environment.getExternalStorageState():"+enviroment);
            if(Environment.MEDIA_MOUNTED.equals(enviroment)) {
                // 外部设备可以进行读写操作
                // 得到外部设备的根目录
                File filesDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_MUSIC);
                File txtFile = new File(filesDir,FILE_NAME);
                Log.d(TAG,"写入外部存储共有目录的文件路径："+txtFile.getAbsoluteFile());
                saveToAnyFile(txtFile, info);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private String loadFromExternalPublicStorage(){
        String res = "";
        try {
            // 检查外围设备是否存在
            String enviroment = Environment.getExternalStorageState();
            Log.d(TAG," Environment.getExternalStorageState():"+enviroment);
            if(Environment.MEDIA_MOUNTED.equals(enviroment)) {
                // 外部设备可以进行读写操作
                // 得到外部设备的根目录
                File filesDir = Environment.getExternalStoragePublicDirectory("mydata");
                File txtFile = new File(filesDir,FILE_NAME);
                Log.d(TAG,"读取外部存储共有目录的文件路径："+txtFile.getAbsoluteFile());
                res = loadFromAnyFile(txtFile);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return res;
    }

    /**
     * 写入外部存储私有目录
     * @param info
     */
    private void saveToExternalPrivateStorage(String info){

        try {
            File filesDir = getExternalFilesDir("mydata");
            File txtFile  = new File(filesDir.getAbsolutePath(),FILE_NAME);
            saveToAnyFile(txtFile,info);
            Log.d(TAG,"写入外部存储私有目录的文件路径："+txtFile.getAbsoluteFile());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private String loadFromExternalPrivateStorage(){
        String res = "";
        try {
            File filesDir = getExternalFilesDir("mydata");
            File txtFile  = new File(filesDir.getAbsolutePath(),FILE_NAME);
            res = loadFromAnyFile(txtFile);
            Log.d(TAG,"读取外部存储私有目录的文件路径："+txtFile.getAbsoluteFile());
        } catch (IOException e) {
            e.printStackTrace();
        }
        return res;
    }

}