我想写一个模块，在点击一个按钮，相机打开，我可以点击和捕捉图像。如果我不喜欢图像，我可以删除它，然后点击另一个图像，然后选择图像，它应该返回并在活动中显示该图像。
当前回答
更新(2020)
谷歌已经添加了一个新的ActivityResultRegistry API，“让你处理startActivityForResult() + onActivityResult()以及requestPermissions() + onRequestPermissionsResult()流，而无需覆盖你的活动或片段中的方法，通过ActivityResultContract带来了增加的类型安全性，并为测试这些流提供了钩子”。
该API是在androidx中添加的。和androidx.fragment 1.3.0-alpha02。
所以你现在可以这样做:
val takePicture = registerForActivityResult(ActivityResultContracts.TakePicture()) { success: Boolean ->
if (success) {
// The image was saved into the given Uri -> do something with it
}
}
val imageUri: Uri = ...
button.setOnClickListener {
takePicture.launch(imageUri)
}
查看文档了解如何使用新的Activity结果API: https://developer.android.com/training/basics/intents/result#kotlin
有许多内置的activityresultcontract，允许您做不同的事情，如选择联系人，请求权限，拍照或拍摄视频。您可能对ActivityResultContracts感兴趣。拍摄上图。
注意androidx.fragment 1.3.0-alpha04弃用了Fragment上的startActivityForResult() + onActivityResult()和requestPermissions() + onRequestPermissionsResult() api。因此，从现在开始ActivityResultContracts似乎是一种新的做事方式。
原答案(2015)
我花了好几个小时才把它修好。代码几乎是从developer.android.com复制粘贴而来的，只有细微的区别。
在AndroidManifest.xml上请求此权限:
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
在你的Activity中，首先定义这个:
static final int REQUEST_IMAGE_CAPTURE = 1;
private Bitmap mImageBitmap;
private String mCurrentPhotoPath;
private ImageView mImageView;
然后在onClick中触发这个Intent:
Intent cameraIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
if (cameraIntent.resolveActivity(getPackageManager()) != null) {
// Create the File where the photo should go
File photoFile = null;
try {
photoFile = createImageFile();
} catch (IOException ex) {
// Error occurred while creating the File
Log.i(TAG, "IOException");
}
// Continue only if the File was successfully created
if (photoFile != null) {
cameraIntent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(photoFile));
startActivityForResult(cameraIntent, REQUEST_IMAGE_CAPTURE);
}
}
添加以下支持方法:
private File createImageFile() throws IOException {
// Create an image file name
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
String imageFileName = "JPEG_" + timeStamp + "_";
File storageDir = Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_PICTURES);
File image = File.createTempFile(
imageFileName, // prefix
".jpg", // suffix
storageDir // directory
);
// Save a file: path for use with ACTION_VIEW intents
mCurrentPhotoPath = "file:" + image.getAbsolutePath();
return image;
}
然后接收结果:
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == REQUEST_IMAGE_CAPTURE && resultCode == RESULT_OK) {
try {
mImageBitmap = MediaStore.Images.Media.getBitmap(this.getContentResolver(), Uri.parse(mCurrentPhotoPath));
mImageView.setImageBitmap(mImageBitmap);
} catch (IOException e) {
e.printStackTrace();
}
}
}
使它工作的是MediaStore.Images.Media.getBitmap(this.getContentResolver()， Uri.parse(mCurrentPhotoPath))，这与developer.android.com的代码不同。原始代码给了我一个FileNotFoundException。
其他回答
你得好好研究一下相机。(我认为要做到你想要的，你必须保存当前的图像到你的应用程序，在那里做选择/删除，然后召回相机再试一次，而不是直接在相机内部重试。)
2021年5月，爪哇
在处理了本文旁边所述的必要权限后， 在manifest中添加:
<uses-permission
android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission
android:name="android.permission.WRITE_EXTERNAL_STORAGE"
android:maxSdkVersion="18" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature
android:name="android.hardware.camera"
android:required="true" />
....
<provider
android:name="androidx.core.content.FileProvider"
android:authorities="${applicationId}.fileprovider"
android:exported="false"
android:grantUriPermissions="true">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="@xml/provider_paths" />
</provider>
....
其中${applicationId}是应用程序的包名，例如my.app.com。
在res - > xml > provider_paths.xml
<?xml version="1.0" encoding="utf-8"?>
<paths>
<external-files-path name="my_images" path="Pictures" />
<external-path name="external_files" path="."/>
<files-path
name="files" path="." />
<external-cache-path
name="images" path="." />
</paths>
在活动:
private void onClickCaptureButton(View view) {
Intent takePictureIntent_ = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
// Ensure that there's a camera activity to handle the intent
if (takePictureIntent_.resolveActivity(getPackageManager()) != null) {
// Create the File where the photo should go
File photoFile_ = null;
try {
photoFile_ = createImageFile();
} catch (IOException ex) {
}
if(photoFile_!=null){
picturePath=photoFile_.getAbsolutePath();
}
// Continue only if the File was successfully created
if (photoFile_ != null) {
Uri photoURI_ = FileProvider.getUriForFile(this,
"my.app.com.fileprovider", photoFile_);
takePictureIntent_.putExtra(MediaStore.EXTRA_OUTPUT, photoURI_);
startActivityForResult(takePictureIntent_, REQUEST_IMAGE_CAPTURE);
}
}
}
还有三招:
...
private static String picturePath;
private static final int REQUEST_IMAGE_CAPTURE = 2;
...
private File createImageFile() throws IOException {
// Create an image file name
String timeStamp_ = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new
Date());
String imageFileName_ = "JPEG_" + timeStamp_ + "_";
File storageDir_ = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
File image_ = File.createTempFile(
imageFileName_, /* prefix */
".jpg", /* suffix */
storageDir_ /* directory */
);
// Save a file: path for use with ACTION_VIEW intents
picturePath= image_.getAbsolutePath();
return image_;
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if(requestCode == REQUEST_IMAGE_CAPTURE && resultCode == Activity.RESULT_OK
){
try {
File file_ = new File(picturePath);
Uri uri_ = FileProvider.getUriForFile(this,
"my.app.com.fileprovider", file_);
rasm.setImageURI(uri_);
} catch (/*IO*/Exception e) {
e.printStackTrace();
}
}
}
and
@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
savedInstanceState.putString("safar", picturePath);
// Always call the superclass so it can save the view hierarchy state
super.onSaveInstanceState(savedInstanceState);
}
and:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (savedInstanceState != null) {
picturePath = savedInstanceState.getString("safar");
}
....
}
下面是一个示例活动，它将启动相机应用程序，然后检索图像并显示它。
package edu.gvsu.cis.masl.camerademo;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
public class MyCameraActivity extends Activity
{
private static final int CAMERA_REQUEST = 1888;
private ImageView imageView;
private static final int MY_CAMERA_PERMISSION_CODE = 100;
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
this.imageView = (ImageView)this.findViewById(R.id.imageView1);
Button photoButton = (Button) this.findViewById(R.id.button1);
photoButton.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
if (checkSelfPermission(Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED)
{
requestPermissions(new String[]{Manifest.permission.CAMERA}, MY_CAMERA_PERMISSION_CODE);
}
else
{
Intent cameraIntent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
startActivityForResult(cameraIntent, CAMERA_REQUEST);
}
}
});
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults)
{
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if (requestCode == MY_CAMERA_PERMISSION_CODE)
{
if (grantResults[0] == PackageManager.PERMISSION_GRANTED)
{
Toast.makeText(this, "camera permission granted", Toast.LENGTH_LONG).show();
Intent cameraIntent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
startActivityForResult(cameraIntent, CAMERA_REQUEST);
}
else
{
Toast.makeText(this, "camera permission denied", Toast.LENGTH_LONG).show();
}
}
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
if (requestCode == CAMERA_REQUEST && resultCode == Activity.RESULT_OK)
{
Bitmap photo = (Bitmap) data.getExtras().get("data");
imageView.setImageBitmap(photo);
}
}
}
请注意，相机应用程序本身提供了查看/重拍图像的功能，一旦图像被接受，活动就会显示它。
下面是上面的活动使用的布局。它只是一个包含id为button1的Button和id为imageview1的ImageView的LinearLayout:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<Button android:id="@+id/button1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/photo"></Button>
<ImageView android:id="@+id/imageView1" android:layout_height="wrap_content" android:src="@drawable/icon" android:layout_width="wrap_content"></ImageView>
</LinearLayout>
最后一个细节，一定要加上:
<uses-feature android:name="android.hardware.camera"></uses-feature>
如果摄像头是你应用功能的可选选项。请确保在权限中将require设置为false。像这样
<uses-feature android:name="android.hardware.camera" android:required="false"></uses-feature>
到你的manifest.xml。
以下是完整的代码:
package com.example.cameraa;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
public class MainActivity extends Activity {
Button btnTackPic;
Uri photoPath;
ImageView ivThumbnailPhoto;
static int TAKE_PICTURE = 1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Get reference to views
btnTackPic = (Button) findViewById(R.id.bt1);
ivThumbnailPhoto = (ImageView) findViewById(R.id.imageView1);
btnTackPic.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent cameraIntent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
startActivityForResult(cameraIntent, TAKE_PICTURE);
}
});
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent intent) {
if (requestCode == TAKE_PICTURE && resultCode == RESULT_OK) {
Bitmap photo = (Bitmap)intent.getExtras().get("data");
ivThumbnailPhoto.setImageBitmap(photo);
ivThumbnailPhoto.setVisibility(View.VISIBLE);
}
}
}
记住也要为相机添加权限。
正如其他人所讨论的，使用data. getextras ().get("data")只会得到低质量的缩略图。
解决方案是通过ACTION_IMAGE_CAPTURE意图传递一个位置，告诉相机在哪里存储全质量图像。
代码是Kotlin，不需要任何权限。
val f = File("${getExternalFilesDir(null)}/imgShot")
val photoURI = FileProvider.getUriForFile(this, "${packageName}.fileprovider", f)
val intent = Intent(MediaStore.ACTION_IMAGE_CAPTURE)
.apply { putExtra(MediaStore.EXTRA_OUTPUT, photoURI) }
startActivityForResult(intent, 1234)
然后对拍摄后的结果进行处理:
override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
if (requestCode == 1234 && resultCode == Activity.RESULT_OK) {
val bitmap = BitmapFactory.decodeFile(
File("${getExternalFilesDir(null)}/imgShot").toString()
)
// use imageView.setImageBitmap(bitmap) or whatever
}
}
您还需要像这里描述的那样添加一个外部FileProvider。AndroidManifest.xml:
<manifest>
<application>
<provider
android:name="androidx.core.content.FileProvider"
android:authorities="${applicationId}.fileprovider"
android:exported="false"
android:grantUriPermissions="true">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="@xml/provide_paths" />
</provider>
</application>
</manifest>
添加一个新文件app/src/main/res/xml/provide_paths.xml:
<?xml version="1.0" encoding="utf-8"?>
<paths>
<external-path name="external_files" path="." />
</paths>
最后，你应该用你自己的逻辑替换1234来跟踪请求代码(通常是一个包含RequestCode.CAPTURE_IMAGE等成员的枚举)
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