Android外部SD卡的读取

  1 package com.kevin.writeorreadfile1_1;
  2
  3 import android.app.Activity;
  4 import android.bluetooth.le.ScanFilter;
  5 import android.graphics.Bitmap;
  6 import android.graphics.BitmapFactory;
  7 import android.media.MediaScannerConnection;
  8 import android.os.Bundle;
  9 import android.os.Environment;
 10 import android.util.Log;
 11 import android.view.View;
 12 import android.widget.Button;
 13 import android.widget.ImageView;
 14 import android.widget.Toast;
 15
 16 import java.io.BufferedInputStream;
 17 import java.io.BufferedOutputStream;
 18 import java.io.File;
 19 import java.io.FileNotFoundException;
 20 import java.io.FileOutputStream;
 21 import java.io.IOException;
 22 import java.io.InputStream;
 23 import java.io.OutputStream;
 24 import java.util.Scanner;
 25
 26 /**
 27  * 保存并读取数据
 28  * 1.确保外部SD卡可用Environment.getExternalStorageState()；
 29  * 2.获取SD卡的根路径
 30  * 3.写入权限
 31  * <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
 32  * <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"></uses-permission>
 33  * 4.读取
 34  */
 35 public class MainActivity extends Activity implements View.OnClickListener {
 36     private boolean state = true;
 37     private  File file;
 38     private ImageView img;
 39     private Button keepBtn,readBtn;
 40     @Override
 41     protected void onCreate(Bundle savedInstanceState) {
 42         super.onCreate(savedInstanceState);
 43         setContentView(R.layout.activity_main);
 44         //初始化控件
 45         keepBtn = (Button) findViewById(R.id.btn_keep_file);
 46         readBtn = (Button) findViewById(R.id.btn_read_file);
 47         img = (ImageView) findViewById(R.id.out_img);
 48
 49         //点击事件
 50         keepBtn.setOnClickListener(this);
 51         readBtn.setOnClickListener(this);
 52
 53         //确保SD卡可用
 54         String storageState = Environment.getExternalStorageState();//获取SD卡的状态
 55         if(storageState.equals(Environment.MEDIA_MOUNTED)){
 56             Log.i("TAG","当前SD卡可用");
 57         }else {
 58             state = false;
 59         }
 60     }
 61
 62     @Override
 63     public void onClick(View view) {
 64             switch (view.getId()){
 65                 case R.id.btn_keep_file://点击保存
 66                     if(state){
 67                         saveImg();
 68                     }
 69                     break;
 70                 case R.id.btn_read_file://点击读取
 71                     if(state){
 72                         showImg();
 73                     }
 74                     break;
 75             }
 76     }
 77     //
 78     public void saveImg(){
 79         BufferedInputStream is = null;
 80         BufferedOutputStream os = null;
 81         try {
 82             File storageDirectory = Environment.getExternalStorageDirectory();
 83             file = new File(storageDirectory,"YangKai.jpg");
 84             //读取项目中的图片
 85             InputStream inputStream = getResources().openRawResource(R.drawable.yangkai_photo);
 86             OutputStream outputStream = new FileOutputStream(file);
 87             //缓存机制
 88             is = new BufferedInputStream(inputStream);
 89             os = new BufferedOutputStream(outputStream);
 90             //读写操作
 91             int length = 0 ;
 92             byte[] bytes = new byte[1024];
 93             while ((length = is.read(bytes)) != -1){
 94                 os.write(bytes,0,length);
 95                 os.flush();//刷新操作
 96             }
 97             Toast.makeText(this,"图片已保存",Toast.LENGTH_SHORT).show();
 98             ScanFile(file.getPath());
 99         } catch (FileNotFoundException e) {
100             e.printStackTrace();
101         } catch (IOException e) {
102             e.printStackTrace();
103         }finally {
104             if ( is != null){
105                 try {
106                     is.close();
107                 } catch (IOException e) {
108                     e.printStackTrace();
109                 }
110             }
111             if (os != null){
112                 try {
113                     os.close();
114                 } catch (IOException e) {
115                     e.printStackTrace();
116                 }
117             }
118         }
119     }
120
121     //扫描进入图片
122     private void ScanFile(String path) {
123
124         MediaScannerConnection.scanFile(this,new String[]{path},null,null);
125     }
126
127     //显示图片
128     public void showImg(){
129         //从文件中读取出来
130         Bitmap bitmap = BitmapFactory.decodeFile(file.getPath());
131         img.setImageBitmap(bitmap);
132     }
133 }