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 }
