目录
学完本篇文章可以收获如何调用手机的摄像头和打开手机相册选择图片功能。
一、调用摄像头拍照
先新建一个CameraAlbumTest项目。
修改activity_main.xml,代码如下：
<?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="打开摄像头"/>
<ImageView
android:id="@+id/picture"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"/>
</LinearLayout>下面编写调用摄像头的具体逻辑，修改MainActivity代码，如下：
public class MainActivity extends AppCompatActivity {
public static final int TAKE_PHOTO = 1;
private ImageView picture;
private Uri imageUri;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button takePhoto = (Button) findViewById(R.id.take_photo);
picture = (ImageView) findViewById(R.id.picture);
takePhoto.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
// 创建File对象，用于存储拍照后的照片
File outputImage = new File(getExternalCacheDir(),"output_image.jpg");
try {
if(outputImage.exists()){
outputImage.delete();
}
outputImage.createNewFile();
}catch (IOException e){
e.printStackTrace();
}
if(Build.VERSION.SDK_INT >= 24){
imageUri = FileProvider.getUriForFile(MainActivity.this,"com.example.cameraalbumtest.fileprovider",outputImage);
}else{
imageUri = Uri.fromFile(outputImage);
}
// 启动相机
Intent intent = new Intent("android.media.action.IMAGE_CAPTURE");
intent.putExtra(MediaStore.EXTRA_OUTPUT,imageUri);
startActivityForResult(intent,TAKE_PHOTO);
}
});
}
protected void onActivityResult(int requestCode,int resultCode,Intent data) {
super.onActivityResult(requestCode, resultCode, data);
switch (requestCode) {
case TAKE_PHOTO:
if (resultCode == RESULT_OK) {
try {
// 显示拍摄的照片
Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(imageUri));
picture.setImageBitmap(bitmap);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
break;
default:
break;
}
}
}然后在res目录下新建一个名字为xml的目录（如果有则忽略这步），右键xml目录 -> New -> File，创建一个file_paths.xml文件，修改内容，代码如下：
<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
<external-path
name="my_images" path=""/>
</paths>最后修改AndroidManifest.xml文件代码，如下：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
package="com.example.cameraalbumtest">
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<application
android:allowBackup="true"
android:dataExtractionRules="@xml/data_extraction_rules"
..........
<provider
android:authorities="com.example.cameraalbumtest.fileprovider"
android:name="androidx.core.content.FileProvider"
android:exported="false"
android:grantUriPermissions="true">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="@xml/file_paths"/>
</provider>
...................
效果如下：
二、打开相册选择照片
在以上项目的基础上进行修改。
修改activity_main.xml文件，在布局中添加一个按钮用于从相册中选择照片，如下：
...................
<Button
android:id="@+id/choose_from_album"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="选择照片"/>
...................修改MainActivity代码，如下：
public class MainActivity extends AppCompatActivity {
public static final int TAKE_PHOTO = 1;
private ImageView picture;
private Uri imageUri;
public static final int CHOOSE_PHOTO = 2;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button takePhoto = (Button) findViewById(R.id.take_photo);
Button chooseFromAlbum = (Button) findViewById(R.id.choose_from_album);
picture = (ImageView) findViewById(R.id.picture);
takePhoto.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
// 创建File对象，用于存储拍照后的照片
File outputImage = new File(getExternalCacheDir(),"output_image.jpg");
try {
if(outputImage.exists()){
outputImage.delete();
}
outputImage.createNewFile();
}catch (IOException e){
e.printStackTrace();
}
if(Build.VERSION.SDK_INT >= 24){
imageUri = FileProvider.getUriForFile(MainActivity.this,"com.example.cameraalbumtest.fileprovider",outputImage);
}else{
imageUri = Uri.fromFile(outputImage);
}
// 启动相机
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();
}
}
});
}
private void openAlbum(){
Intent intent = new Intent("android.intent.action.GET_CONTENT");
intent.setType("image/*");
startActivityForResult(intent,CHOOSE_PHOTO);//打开相册
}
public void onRequestPermissionsResult(int requestCode,String[] permissions,int[] grantResults){
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
switch (requestCode){
case 1:
if(grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED){
openAlbum();
}else{
Toast.makeText(this, "你拒绝了权限申请", Toast.LENGTH_SHORT).show();
}
break;
default:
}
}
protected void onActivityResult(int requestCode,int resultCode,Intent data) {
super.onActivityResult(requestCode, resultCode, data);
switch (requestCode) {
case TAKE_PHOTO:
if (resultCode == RESULT_OK) {
try {
// 显示拍摄的照片
Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(imageUri));
picture.setImageBitmap(bitmap);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
break;
case CHOOSE_PHOTO:
if(resultCode == RESULT_OK){
// 判断手机系统版本号
if(Build.VERSION.SDK_INT >= 19){
// 4.4及以上系统使用这个方法处理图片
handleImageOnKitKat(data);
}else{
// 4.4以下用这个方法
handleImageBeforeKitKat(data);
}
}
break;
default:
break;
}
}
@TargetApi(19)
private void handleImageOnKitKat(Intent data) {
String imagePath = null;
Uri uri = data.getData();
Log.d("TAG", "handleImageOnKitKat: uri is " + uri);
if (DocumentsContract.isDocumentUri(this, uri)) {
// 如果是document类型的Uri，则通过document id处理
String docId = DocumentsContract.getDocumentId(uri);
if("com.android.providers.media.documents".equals(uri.getAuthority())) {
String id = docId.split(":")[1]; // 解析出数字格式的id
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())) {
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类型的Uri，则使用普通方式处理
imagePath = getImagePath(uri, null);
} else if ("file".equalsIgnoreCase(uri.getScheme())) {
// 如果是file类型的Uri，直接获取图片路径即可
imagePath = uri.getPath();
}
displayImage(imagePath); // 根据图片路径显示图片
}
private void handleImageBeforeKitKat(Intent data) {
Uri uri = data.getData();
String imagePath = getImagePath(uri, null);
displayImage(imagePath);
}
@SuppressLint("Range")
private String getImagePath(Uri uri, String selection) {
String path = null;
// 通过Uri和selection来获取真实的图片路径
Cursor cursor = getContentResolver().query(uri, null, selection, null, null);
if (cursor != null) {
if (cursor.moveToFirst()) {
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).show();
}
}
}最后提醒一下，因为有些照片尺寸很大，直接加载到内存中会导致程序崩溃，需要根据需求对照片进行压缩，再加载到内存中。
