AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.cameraalbumtest">
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<provider
android:name="android.support.v4.content.FileProvider"
android:authorities="com.example.cameraalbumtest.fileprovider"
android:exported="false"
android:grantUriPermissions="true"
>
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="@xml/file_paths"
/>
</provider>
</application>
</manifest>res/xml/file_paths.xml
<?xml version="1.0" encoding="utf-8"?>
<paths>
<root-path name="my_images" path=""/>
</paths>activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<Button
android:id="@+id/take_photo"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Take Photo"/>
<Button
android:id="@+id/choose_from_album"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Choose From Album"/>
<ImageView
android:id="@+id/picture"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"/>
</LinearLayout>
MainActivity.class
public class MainActivity extends AppCompatActivity {
public static final int TAKE_PHOTO = 1;
public static final int CHOOSE_PHOTO = 2;
private ImageView picture;
private Uri imageUri;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final Button takePhoto = (Button) findViewById(R.id.take_photo);
picture = (ImageView) findViewById(R.id.picture);
Button chooseFromAlbum = (Button) findViewById(R.id.choose_from_album);
takePhoto.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//創建File對象,用於存儲拍照後的照片
//安卓6.0 讀寫sd被稱爲危險權限 所以存到緩存目錄 而getExternalCacheDir 就可以得到這個緩存目錄
File fileDir = getExternalCacheDir();
File imageDir = new File(fileDir,"images");
if(!imageDir.exists()){
imageDir.mkdirs();
}
File imageFile = new File(imageDir,"picture.jpg");
try{
//判斷文件是否存在
if(imageFile.exists()){
//文件存在就刪除
imageFile.delete();
}
//創建圖片
imageFile.createNewFile();
}catch (Exception e){
e.printStackTrace();
}
if(Build.VERSION.SDK_INT >= 24){
//如果設備版本大於7.0
imageUri = FileProvider.getUriForFile(MainActivity.this,
"com.example.cameraalbumtest.fileprovider",imageFile);
} else {
imageUri = Uri.fromFile(imageFile);
}
//IMAGE_CAPTURE:圖片捕獲
//MediaStore:媒體商店
//EXTRA_OUTPUT:額外輸出
Intent intent = new Intent("android.media.action.IMAGE_CAPTURE");
intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);
startActivityForResult(intent,TAKE_PHOTO);
}
});
chooseFromAlbum.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if(ContextCompat.checkSelfPermission(MainActivity.this,
Manifest.permission.WRITE_EXTERNAL_STORAGE)!= PackageManager.PERMISSION_GRANTED){
ActivityCompat.requestPermissions(MainActivity.this,
new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
} else {
openAlbum();
}
}
});
}
@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
//requestCode 發出去的請求碼 resultCode 返回的參數
switch (requestCode){
case 1:
if(grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED){
openAlbum();
} else {
Toast.makeText(this,"You denied the permission",Toast.LENGTH_SHORT).show();
}
break;
default:
break;
}
}
private void openAlbum(){
Intent intent = new Intent("android.intent.action.GET_CONTENT");
intent.setType("image/*");
startActivityForResult(intent,CHOOSE_PHOTO);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
switch (requestCode){
case TAKE_PHOTO:
if(resultCode == RESULT_OK){
try{
//將拍攝的照片顯示出來
Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(imageUri));
picture.setImageBitmap(bitmap);
} catch (Exception e){
e.printStackTrace();
}
}
break;
case CHOOSE_PHOTO:
if(resultCode == RESULT_OK){
if(Build.VERSION.SDK_INT >= 19){
//4.4 及以上系統使用這個方法處理圖片
handleImageOnKitKat(data);
}else{
//4.4 及以下系統使用這個方法處理圖片
handleImageBeforeKitKat(data);
}
}
break;
default:
break;
}
}
private void handleImageOnKitKat(Intent data){
String imagePath = null;
Uri uri = data.getData();
//data是從相冊返回的數據
//android 7.1.1
//uri == content://com.android.providers.media.documents/document/image%3A75
//uri.getAuthority() == com.android.providers.media.documents
//uri.getPath() == /document/image:75
//DocumentsContract.getDocumentId(uri) == image:75
//MediaStore.Images.Media.EXTERNAL_CONTENT_URI == content://media/external/images/media
//真實路徑 path == /storage/emulated/0/Download/picture.jpg
//android4.4
//uri == content://com.android.providers.media.documents/document/image%3A28
//uri.getAuthority() == com.android.providers.media.documents
//uri.getPath() == /document/image:28
//DocumentsContract.getDocumentId(uri) == image:28
//MediaStore.Images.Media.EXTERNAL_CONTENT_URI == content://media/external/images/media
//真實路徑 path == /storage/sdcard/images/picture.jpg
//相冊存了圖片的id，並沒有存實際路徑。
//Authority就是相冊數據庫的標識符，這裏有兩個數據庫，他們的標識符分別爲
//com.android.providers.media.documents
//com.android.providers.downloads.documents
//當點擊一張照片它會返回document封裝了的uri，然後進行解析出資源id，
//然後根據id在MediaStore數據庫中獲取真實URL路徑
//判斷該Uri是否是document封裝過的
if(DocumentsContract.isDocumentUri(this,uri)){
//如果是document類型的Uri,則通過document id 處理
String docId = DocumentsContract.getDocumentId(uri);
if("com.android.providers.media.documents".equals(uri.getAuthority())){
String id = docId.split(":")[1];
String selection = MediaStore.Images.Media._ID + "=" +id;
imagePath = getImagePath(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, selection);
}else if("com.android.providers.downloads.documents".equals(uri.getAuthority())){
//這個方法負責把id和contentUri連接成一個新的Uri
Uri contentUri = ContentUris.withAppendedId(Uri.parse("content://downloads/public_downloads"),
Long.valueOf(docId));
imagePath = getImagePath(contentUri, null);
}
}else if ("content".equalsIgnoreCase(uri.getScheme())){
//如果是content類型的Uri,則使用普通方式處理
imagePath =getImagePath(uri,null);
}else if("file".equalsIgnoreCase(uri.getScheme())){
//如果是file類型的Uri,直接獲取圖片路徑即可
imagePath = uri.getPath();
}
displayImage(imagePath);
}
private void handleImageBeforeKitKat(Intent data) {
Uri uri = data.getData();
String imagePath = getImagePath(uri, null);
displayImage(imagePath);
}
private String getImagePath(Uri uri, String selection){
String path = null;
//通過Uri和selection來獲取真實路徑
//Android系統提供了MediaScanner，MediaProvider，MediaStore等接口，並且提供了一套數據庫
//表格，通過Content Provider的方式提供給用戶。當手機開機或者有SD卡插拔等事件發生時，系統
//將會自動掃描SD卡和手機內存上的媒體文件，如audio，video，圖片等，將相應的信息放到定義好
//的數據庫表格中。在這個程序中，我們不需要關心如何去掃描手機中的文件，只要瞭解如何查詢和使
//用這些信息就可以了。MediaStore中定義了一系列的數據表格，通過ContentResolver提供的查詢
//接口，我們可以得到各種需要的信息。
//EXTERNAL_CONTENT_URI 爲查詢外置內存卡的，INTERNAL_CONTENT_URI爲內置內存卡。
//MediaStore.Audio獲取音頻信息的類
//MediaStore.Images獲取圖片信息
//MediaStore.Video獲取視頻信息
Cursor cursor = getContentResolver().query(uri,null,selection,null,null);
if(cursor != null){
if(cursor.moveToNext()){
path = cursor.getString(cursor.getColumnIndex(MediaStore.Images.Media.DATA));
}
cursor.close();
}
return path;
}
private void displayImage(String imagePath){
if(imagePath != null){
Bitmap bitmap = BitmapFactory.decodeFile(imagePath);
picture.setImageBitmap(bitmap);
} else {
Toast.makeText(this,"failed to get image",Toast.LENGTH_SHORT);
}
}
}
拍照
打開相冊
