Android——数据存储（四种方式之二）读写SD卡

Android——数据存储（四种方式）

1.SharedPrefereces 只能保存一些简单的数轻量级.XML  存储文件名，

数据保存在data/data/basepackage/shared_prefs/myopt.xml中  

 实例-收藏-记住密码自动登录

//一种轻量级的数据存储方式//通过KEY

存入数据——putxxxx（key，value）

取出数据——getxxxx（key  default）

2.读写SD卡  SD的根目录  适用于数据流读写

实现步骤：加入读写SD卡权限

判断SD卡是否存在

读写文件

3.SQLite  轻量级 .dp文件多用于手机里

4.Content prowvider内容提供者

网路存储 在网络后台存储

1保存文件内存储

package com.example.jreduch08;

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

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;

public class InnerIoActivity extends AppCompatActivity {
private EditText content;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_inner_io);
        Button  save= (Button) findViewById(R.id.save);
        Button  read= (Button) findViewById(R.id.read);
        Button  delete= (Button) findViewById(R.id.delete);

        final TextView show= (TextView) findViewById(R.id.show);
     content= (EditText) findViewById(R.id.content);
               save.setOnClickListener(new View.OnClickListener() {
                   @Override
                   public void onClick(View view) {
                      saveFile();
                   }
               });
        read.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                show.setText( readFile());
            }
        });
        delete.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                removeFile();
            }
        });
    }

    //保存文件内存储
    public  void saveFile(){
        FileOutputStream  fos=null;
        /*MODE_APPEND 追加 MODE_PRIVATE  覆盖
        //OpenFileoutput返回一个 输出字节流
        //指向的路径为data/data/包名/file/
        //参数1.文件名称（如果不存在则自动创建）
         参数2.模式MODE_APPEND 文件内容追加
                    MODE_PRIVATE  文件内容被覆盖
        */
        try {
            fos= openFileOutput("text.txt",MODE_APPEND);

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

            try {
                fos.write(str.getBytes());
                Toast.makeText(InnerIoActivity.this,"保存成功",Toast.LENGTH_SHORT).show();
            } catch (IOException e) {
                e.printStackTrace();
            }

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }finally {
            if (fos!=null){
                try {
                    fos.flush();
                    fos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }

            }
        }
    }
    //从内存读文件
    public String readFile(){
        StringBuilder  sbd=new StringBuilder();
        BufferedReader  reader=null;

        FileInputStream fis=null;
        try {
            fis=openFileInput("text.txt");
            reader=new BufferedReader(new InputStreamReader(fis));
            try {
                sbd.append(getFilesDir().getCanonicalPath());
            } catch (IOException e) {
                e.printStackTrace();
            }
            String row="";


            try {
                while ((row=reader.readLine())!=null){
                   sbd.append(row);

                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        } catch (FileNotFoundException e) {
            Toast.makeText(getBaseContext(),"文件不存在",Toast.LENGTH_SHORT).show();
            e.printStackTrace();
        }finally {
            if (reader!=null){
                try {
                    reader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }



        return  sbd.toString();
    }
   //删除文件
    public  void removeFile(){
        String[]  files=fileList();
         for (String str:files){
            // Log.d("=====",str);

             if (str.equals("text.txt")){
           deleteFile("text.txt");}

         }

    }
}

 2保存文件到SD卡

从SD卡读取文件

package com.example.jreduch08;

import android.os.Bundle;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;

public class SaveToSdCarActivity extends AppCompatActivity {
 private Button save,read,delete;
    private EditText content;
    private TextView show;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_inner_io);
      save= (Button) findViewById(R.id.save);
         read= (Button) findViewById(R.id.read);
      delete= (Button) findViewById(R.id.delete);
        content= (EditText) findViewById(R.id.content);
       show= (TextView) findViewById(R.id.show);
        save.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
               saveFile();
            }
        });
        read.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                show.setText(readFile());
            }
        });
        delete.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                removeFile();
            }
        });
    }
    //保存文件到SD卡
    public  void saveFile(){
        FileOutputStream fos=null;


        //获取SD卡状态
       String state= Environment.getExternalStorageState();
        //判断SD卡是否就绪
        if(!state.equals(Environment.MEDIA_MOUNTED)){
            Toast.makeText(this,"请检查SD卡",Toast.LENGTH_SHORT).show();
            return;
        }
        //取得SD卡根目录
       File file= Environment.getExternalStorageDirectory();

        try {
            Log.d("=====SD卡根目录：",file.getCanonicalPath().toString());
//            File myFile=new File(file.getCanonicalPath()+"/sd.txt");
//            fos=new FileOutputStream(myFile);
            //输出流的构造参数1可以是 File对象  也可以是文件路径
            //输出流的构造参数2：默认为False=>覆盖内容；ture=》追加内容
            //追加  ，ture
            fos=new FileOutputStream(file.getCanonicalPath()+"/sd.txt",true);
            String  str=content.getText().toString();
            fos.write(str.getBytes());
            Toast.makeText(this,"保存成功",Toast.LENGTH_SHORT).show();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            if (fos!=null){
                try {
                    fos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    //从SD卡读取文件
    public String  readFile(){

        BufferedReader  reader=null;

        FileInputStream fis=null;
        StringBuilder sbd=new StringBuilder();

        String statu=Environment.getExternalStorageState();
        if (!statu.equals(Environment.MEDIA_MOUNTED)){

           Toast.makeText(this,"SD卡未就绪",Toast.LENGTH_SHORT).show();
            return  "";
        }
        File root=Environment.getExternalStorageDirectory();
        try {
            fis=new FileInputStream(root+"/sd.txt");
            reader= new BufferedReader(new InputStreamReader(fis));
            String row="";
            try {
                while ((row=reader.readLine())!=null){

                    sbd.append(row);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }

        } catch (FileNotFoundException e) {
            Toast.makeText(this,"文件不存在",Toast.LENGTH_SHORT).show();

            e.printStackTrace();
        }finally {
            if (reader!=null){
                try {
                    reader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return  sbd.toString();
    }

    //删除SD卡文件
    public void removeFile(){
        String statu=Environment.getExternalStorageState();

        if (!statu.equals(Environment.MEDIA_MOUNTED)){
            Toast.makeText(this,"SD卡未就绪",Toast.LENGTH_SHORT).show();
            return;
        }
        File root=Environment.getExternalStorageDirectory();
       // File sd=new File(root,"sd.txt");
        File sd=new File(root+"/sd.txt");
         if(sd.exists()){

            sd.delete();
             Toast.makeText(this,"文件删除成功",Toast.LENGTH_SHORT).show();
        }else{

             Toast.makeText(this,"文件不存在",Toast.LENGTH_SHORT).show();
         }

    }
}

3读取assets目录   读取raw文件夹

package com.example.jreduch08;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

public class ReadRawAssetsActivity extends AppCompatActivity {
private Button raw,assets;
  private TextView show;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_read_raw_assets);
        raw=(Button)findViewById(R.id.raw);
        assets= (Button) findViewById(R.id.assets);
        show= (TextView) findViewById(R.id.show);

        raw.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
               show.setText(readRaw());
            }
        });
   assets.setOnClickListener(new View.OnClickListener() {
       @Override
       public void onClick(View view) {
           show.setText(readAssets());
       }
   });

    }
 //读取assets目录
public  String readAssets(){
    StringBuilder sbd=new StringBuilder();
    BufferedReader reader=null;
    InputStream is=null;
    try {
        is=getResources().getAssets().open("cityinfo");
        reader=new BufferedReader(new InputStreamReader(is));
        String row="";
        while ((row=reader.readLine())!=null){
            sbd.append(row);
            sbd.append("\n");


        }


    } catch (IOException e) {
        e.printStackTrace();
    }finally {
        if (reader!=null){
            try {
                reader.close();
            } catch (IOException e) {
                e.printStackTrace();
            }

        }
    }

    return  sbd.toString();
}



    //读取raw文件夹
    public String readRaw(){
        StringBuilder sbd=new StringBuilder();
        BufferedReader reader=null;
        InputStream is=null;
        is=getResources().openRawResource(R.raw.settings);
        reader=new BufferedReader(new InputStreamReader(is));
        String row="";
        try {
            while ((row=reader.readLine())!=null){
                sbd.append(row);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            if (reader!=null){
                try {
                    reader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }

            }
        }
return sbd.toString();

    }
}

4

将图片保存到SD卡

从SD卡读取图片

从网络获取图片

从网络获取图片直接保存

package com.example.jreduch08;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.drawable.BitmapDrawable;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ImageView;
import android.widget.Toast;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

public class ViewPagerSdActivity extends AppCompatActivity {
private ImageView  img1,img2;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_view_pager_sd);

        img1= (ImageView) findViewById(R.id.img1);
        img2= (ImageView) findViewById(R.id.img2);




    }
    //从网络获取图片直接保存
    public void SaveHttp(View view){

        new SaveHttpImg().execute("http://p2.so.qhmsg.com/t0165453974dc3b9af7.jpg");
    }
//从网络获取图片
    public void GetUrlImg(View view){
new GetImg().execute("http://p1.so.qhmsg.com/dm/365_365_/t01df531d143d2554d7.jpg");
    }

    //保存网络图片
    public  void SaveUrlImg(View view){
        new Get2Img().execute("http://p1.so.qhmsg.com/dm/365_365_/t01df531d143d2554d7.jpg");


    }

   //从SD卡读取图片
    public void rawImg(View view){
        String  path=Environment.getExternalStorageDirectory()+"/1.png";

        //方法一  根据URI加载数据图片
//        img2.setImageURI(Uri.parse(path));
//    方法二：通过BitmapFactory的静态方法decodeFile（）
      //  参数图片路径
      Bitmap bitmap= BitmapFactory.decodeFile(path);
   img2.setImageBitmap(bitmap);
        /*方法三：通过BitmapFactory的静态方法 decodeStream（）
       // 参数为  输入流InputStream
        try {
            BitmapFactory.decodeStream(new FileInputStream(path));
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    */



    }



    //将图片保存到SD卡
    //布局监听
    public  void saveImg(View view){
        //获取ImageView中的图片
        BitmapDrawable bitmapDrawable=(BitmapDrawable)
                img1.getDrawable();
        Bitmap bitmap=bitmapDrawable.getBitmap();

        String statu= Environment.getExternalStorageState();

        if (!statu.equals(Environment.MEDIA_MOUNTED)){
            Toast.makeText(this,"SD卡未就绪",Toast.LENGTH_SHORT).show();
            return;
        }


       /*
        通过 Bitmap(位图）压缩的方法（compress）保存图片到SD卡
        参数1：图片格式（PNG,JPEG WEBP）
        参数2：图片质量（0-100）
        参数3：输出流
         */
        File root=Environment.getExternalStorageDirectory();
        FileOutputStream  fos=null;
        try {
           fos=new FileOutputStream(root+"/1.png");
            bitmap.compress(Bitmap.CompressFormat.PNG,100,fos);
            Toast.makeText(this,"图片保存成功",Toast.LENGTH_SHORT).show();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }finally {
            if (fos!=null){
                try {
                    fos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }

            }
        }

    }
    //网络存储图片
    public  void save2Img(){
        //获取ImageView中的图片
        BitmapDrawable bitmapDrawable=(BitmapDrawable)
                img2.getDrawable();
        Bitmap bitmap=bitmapDrawable.getBitmap();

        String statu= Environment.getExternalStorageState();

        if (!statu.equals(Environment.MEDIA_MOUNTED)){
            Toast.makeText(this,"SD卡未就绪",Toast.LENGTH_SHORT).show();
            return;
        }


       /*
        通过 Bitmap(位图）压缩的方法（compress）保存图片到SD卡
        参数1：图片格式（PNG,JPEG WEBP）
        参数2：图片质量（0-100）
        参数3：输出流
         */
        File root=Environment.getExternalStorageDirectory();
        FileOutputStream  fos=null;
        try {
            fos=new FileOutputStream(root+"/1.png");
            bitmap.compress(Bitmap.CompressFormat.PNG,100,fos);
            Toast.makeText(this,"图片保存成功",Toast.LENGTH_SHORT).show();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }finally {
            if (fos!=null){
                try {
                    fos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }

            }
        }

    }

public  class GetImg extends AsyncTask {

    //onPreExecute在主线程中执行命令
    //进度条的初始化
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
    }

    //doInBackground在子线程中执行名命令
    @Override
    protected Bitmap doInBackground(String... strings) {
        HttpURLConnection con = null;
        InputStream is = null;
        Bitmap bitmap = null;
        try {
            URL url = new URL(strings[0]);
            con = (HttpURLConnection) url.openConnection();
            con.setConnectTimeout(5 * 1000);
            con.setReadTimeout(5 * 1000);
                /*
                *http相应200：成功
                * 404未找到
                * 500发生错误
                 */
            if (con.getResponseCode() == 200) {
                is = con.getInputStream();
                bitmap = BitmapFactory.decodeStream(is);

                return bitmap;
            }


        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (is != null) {
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                if (con != null) {
                    con.disconnect();  //断开连接
                }
            }
        }

        return null;
    }

    //onPostExecute在UI线程中执行命令  主线程
    @Override
    protected void onPostExecute(Bitmap bitmap) {
        super.onPostExecute(bitmap);
        img2.setImageBitmap(bitmap);


    }

}






    public  class Get2Img extends AsyncTask {

        //onPreExecute在主线程中执行命令
        //进度条的初始化
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
        }

        //doInBackground在子线程中执行名命令
        @Override
        protected Bitmap doInBackground(String... strings) {
            HttpURLConnection con = null;
            InputStream is = null;
            Bitmap bitmap = null;
            try {
                URL url = new URL(strings[0]);
                con = (HttpURLConnection) url.openConnection();
                con.setConnectTimeout(5 * 1000);
                con.setReadTimeout(5 * 1000);
                /*
                *http相应200：成功
                * 404未找到
                * 500发生错误
                 */
                if (con.getResponseCode() == 200) {
                    is = con.getInputStream();
                    bitmap = BitmapFactory.decodeStream(is);
                    return bitmap;
                }


            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                if (is != null) {
                    try {
                        is.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                    if (con != null) {
                        con.disconnect();  //断开连接
                    }
                }
            }

            return null;
        }

        //onPostExecute在UI线程中执行命令  主线程
        @Override
        protected void onPostExecute(Bitmap bitmap) {
            super.onPostExecute(bitmap);
            img2.setImageBitmap(bitmap);
             save2Img();

        }

    }

    public class SaveHttpImg extends AsyncTask{

        @Override
        protected String doInBackground(String... strings) {
            HttpURLConnection con = null;
            InputStream is = null;
            try {
                URL url = new URL(strings[0]);
                con = (HttpURLConnection) url.openConnection();
                con.setConnectTimeout(5*1000);
                con.setReadTimeout(5*1000);
                File root = Environment.getExternalStorageDirectory();
                FileOutputStream fos = new FileOutputStream(root+"/http.jpg");
                if(con.getResponseCode()==200){
                    is = con.getInputStream();
                    int next=0;
                    byte[] bytes = new byte[1024];
                    while ( (next = is.read(bytes))>0){
                        fos.write(bytes,0,next);
                    }
                    fos.flush();
                    fos.close();
                    return  root+"/http.jpg";
                }
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                if(is!=null){
                    try {
                        is.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
                if(con!=null){
                    con.disconnect();
                }
            }
            return "";
        }

        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
            if(!s.equals("")){
                Toast.makeText(ViewPagerSdActivity.this,"保存路径:"+s,Toast.LENGTH_SHORT).show();
            }else{
                Toast.makeText(ViewPagerSdActivity.this,"保存失败:",Toast.LENGTH_SHORT).show();
            }
        }
    }
}