• 运行结果如下：

2017-04-13_16-20-51.gif

第一步：搭建界面布局

<?xml version="1.0" encoding="utf-8"?>
<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="拍照上传"/>

    <Button
        android:id="@+id/choose_from_album"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="从相册中选择照片"/>

    <ImageView
        android:id="@+id/picture"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        />
</LinearLayout>

第二步：在Activity中实现功能

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.layout_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 v) {
                //创建file对象，用于储存拍照后的图片，getExternalCacheDir() : 将照片存放在手机的关联缓存目录下
                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) {
                    //如果系统版本大于7.0，调用FileProvider的getUriForFile()方法将File对象转换成一个封装过的Uri对象
                    //getUriForFile()参数说明
                    //第一个参数：Context对象
                    //第二个参数：任意唯一的字符串
                    //第三个参数：创建的File对象
                    imageUri = FileProvider.getUriForFile(MainActivity.this, "com.example.cameraalbumtest.fileprovider", outputImage);
                } else {
                    //否则，调用Uri的fromFile()方法将File对象转换成Uri对象
                    imageUri = Uri.fromFile(outputImage);
                }
                //启动相机程序
                Intent intent = new Intent("android.media.action.IMAGE_CAPTURE");
                //设定图片的输出地址
                intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);
                //使用startActivityForResult()启动Intent时，Intent结束后会有结果返回到onActivityResult()方法中。
                startActivityForResult(intent, TAKE_PHOTO);
            }
        });

        //从相册中选择照片逻辑
        final Button chooseFromAlbum = (Button) findViewById(R.id.choose_from_album);
        chooseFromAlbum.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //如果未授权
                if (ContextCompat.checkSelfPermission(MainActivity.this, WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
                    //发起授权询问
                    ActivityCompat.requestPermissions(MainActivity.this, new String[]{ WRITE_EXTERNAL_STORAGE }, 1);
                } else {
                    //如果已授权，直接打开相册
                    openAlbum();
                }
            }
        });
    }
    ///打开相册的方法
    private void openAlbum() {
        Intent intent = new Intent("android.intent.action.GET_CONTENT");
        intent.setType("image/*");
        startActivityForResult(intent, CHOOSE_PHOTO);
    }
    ///用户选择完授权询问后调用
    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        switch (requestCode) {
            case 1:
                if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    //如果用户选择授权，打开相册
                    openAlbum();
                } else {
                    //如果用户拒绝，弹出提示框
                    Toast.makeText(this, "获取相册失败，你拒绝了授权请求", Toast.LENGTH_SHORT).show();
                }
                break;
            default:
                break;
        }
    }

    //Activity跳转之后再返回时调用
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        switch (requestCode) {
            case TAKE_PHOTO:
                if (resultCode == RESULT_OK) {
                    //如果拍照成功
                    try {
                        //将拍摄的照片显示出来
                        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及以下系统使用这个方法处理图片
                        handleImageBeforeKitkat(data);
                    }
                }
           default:
                break;
        }
    }

    @TargetApi(19)
    private void handleImageOnKitKat(Intent data) {
        String imagePath = null;
        Uri uri = data.getData();
        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.provides.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，直接获取图片的路径即可
            imagePath = uri.getPath();
        }
        //根据图片路径显示图片
        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;
    }
    //设置图片
    private void displayImage(String imagePath) {
        if (imagePath != null) {
            Bitmap bitmap = BitmapFactory.decodeFile(imagePath);
            picture.setImageBitmap(bitmap);
        } else {
            Toast.makeText(this,"获取图片失败",Toast.LENGTH_SHORT).show();
        }
    }
}

第三步：在Manifest添加权限声明

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
          package="com.example.anwser_mac.cameraalbumtest">

    <!--声明读取sdcard的权限-->
    <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">
        <!--注册内容提供器-->
        <provider
            android:authorities="com.example.cameraalbumtest.fileprovider"
            android:name="android.support.v4.content.FileProvider"
            android:exported="false"
            android:grantUriPermissions="true">
            <meta-data
                android:name="android.support.FILE_PROVIDER_PATHS"
                android:resource="@xml/file_paths"/>
        </provider>
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
    </application>

</manifest>