调用摄像头和相册

1.调用摄像头拍照

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    >

    <Button
        android:id="@+id/take_photo"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Take photo" />
    <ImageView 
        android:id="@+id/picture"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        />

</LinearLayout>

public class MainActivity extends Activity {

    public static final int TAKE_PHOTO = 1;
    
    public static final int GROP_PHOTO = 2;
    
    private Button takePhoto;
     
    private ImageView picture;
    
    private Uri imagrUri;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        takePhoto = (Button) findViewById(R.id.take_photo);
        picture = (ImageView) findViewById(R.id.picture);
        takePhoto.setOnClickListener(new OnClickListener() {
            
            @Override
            public void onClick(View v) {
                //创建File对象，用于存储拍照后的照片
                File outputImage = new File(Environment.getExternalStorageDirectory(),"tempImage.jpg");
                try{
                    if(outputImage.exists()){
                        outputImage.delete();
                    }
                    outputImage.createNewFile();
                }catch(IOException e){
                    e.printStackTrace();
                }
                imagrUri=Uri.fromFile(outputImage);
                Intent intent=new Intent("android.media.action.IMAGE_CAPTURE");
                intent.putExtra(MediaStore.EXTRA_OUTPUT, imagrUri);
                startActivityForResult(intent, TAKE_PHOTO);
                //启动照相机
            }
        });
    }


    @Override
    public void onActivityResult(int requestCode,int resultCode,Intent data) {
        switch(requestCode){
        case TAKE_PHOTO:
            if(resultCode==RESULT_OK){
                Intent intent = new Intent("com.android.camera.action.CROP");
                intent.setDataAndType(imagrUri, "image/**");
                intent.putExtra("scale", true);
                intent.putExtra(MediaStore.EXTRA_OUTPUT, imagrUri);
                startActivityForResult(intent, GROP_PHOTO);
                //启动剪裁程序
            }
            break;
        case GROP_PHOTO:
            if(resultCode == RESULT_OK){
                try{
                    Bitmap bitmap=BitmapFactory.decodeStream(
                            getContentResolver().openInputStream(imagrUri));
                    picture.setImageBitmap(bitmap);
                    //将剪裁后的照片显示出来
                }catch(FileNotFoundException e){
                    e.printStackTrace();
                }
            }
            break;
            default:
                break;
        }
    }
    
}

 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

声明权限，向SD卡中写数据操作的声明。

MainActivity要做的第一件事是分别获得Button和ImageView的实例，并给Button注册商点击事件，然后再Button的点击事件里开始处理调用摄像头的逻辑。

首先，创建一个File对象，用于存储摄像头拍下的图片，这里把图片名字命名为tempImage.jpg，并把它存放在手机SD卡的根目录，调用Enviroment的getExternalStorageDirectory()方法获得的就是SD卡的根目录；然后调用Uri的fromFile()将File对象转换成Uri对象，这个Uri对象标志着output_image.jpg这张图片的唯一地址。

调用BitmapFactory的decodeStream()方法将图片解析成Bitmap对象，然后把他设置到ImageView中显示出来

2.从相册中选择照片

choose.setOnClickListener(new OnClickListener() {
            
            @Override
            public void onClick(View v) {
                File outputImage=new File(Environment.getExternalStorageDirectory(),"output_image.jpg");
                try{
                    if(outputImage.exists()){
                        outputImage.delete();
                    }
                    outputImage.createNewFile();
                }catch(IOException e){
                    e.printStackTrace();
                }                
            
            imageUri = Uri.fromFile(outputImage);
            Intent intent=new Intent("android.intent.action.GET_CONTENT");
            intent.setType("image/*");
            intent.putExtra("crop",true);
            intent.putExtra("scale",true);
            intent.putExtra(MediaStore.EXTRA_OUTPUT,imageUri);
            startActivityForResult(intent,CROP_PHOTO);
            }
        });