autofac中的AsSelf()是什么？
我是autofac的新手，究竟是什么AsSelf以及下面两者之间有什么区别？
builder.RegisterType<SomeType>().AsSelf().As<IService>();
builder.RegisterType<SomeType>().As<IService>();
谢谢！
答案 0 :(得分：28)
通常，您希望将接口而不是实现注入到类中。
但是，假设你有：
interface IFooService { }
class FooService { }
注册builder.RegisterType<FooService>()可以注入FooService，但即使IFooService实施FooService，您也无法注入builder.RegisterType<FooService>().AsSelf()。这相当于builder.RegisterType<FooService>().As<IFooService>()。
注册IFooService可让您注入FooService，而不是.As<T> - 使用.AsSelf()＆＃34;覆盖＆＃34;默认注册＆＃34;按类型＆＃34;如上所示。
为了能够按类型和界面注入服务，您应该将builder.RegisterType<FooService>().As<IFooService>().AsSelf()添加到之前的注册：builder.RegisterType<SomeType>().AsImplementedInterfaces()。
如果您的服务实现了许多接口并且您想要全部注册它们，则可以使用/**
* This example illustrates how to add/update EXIF metadata in a JPEG file.
*
* @param jpegImageFile
* A source image file.
* @param dst
* The output file.
* @throws IOException
* @throws ImageReadException
* @throws ImageWriteException
*/
public void changeExifMetadata(final File jpegImageFile, final File dst)
throws IOException, ImageReadException, ImageWriteException {
try (FileOutputStream fos = new FileOutputStream(dst);
OutputStream os = new BufferedOutputStream(fos);) {
TiffOutputSet outputSet = null;
// note that metadata might be null if no metadata is found.
final ImageMetadata metadata = Imaging.getMetadata(jpegImageFile);
final JpegImageMetadata jpegMetadata = (JpegImageMetadata) metadata;
if (null != jpegMetadata) {
// note that exif might be null if no Exif metadata is found.
final TiffImageMetadata exif = jpegMetadata.getExif();
if (null != exif) {
// TiffImageMetadata class is immutable (read-only).
// TiffOutputSet class represents the Exif data to write.
//
// Usually, we want to update existing Exif metadata by
// changing
// the values of a few fields, or adding a field.
// In these cases, it is easiest to use getOutputSet() to
// start with a "copy" of the fields read from the image.
outputSet = exif.getOutputSet();
}
}
// if file does not contain any exif metadata, we create an empty
// set of exif metadata. Otherwise, we keep all of the other
// existing tags.
if (null == outputSet) {
outputSet = new TiffOutputSet();
}
{
// Example of how to add a field/tag to the output set.
//
// Note that you should first remove the field/tag if it already
// exists in this directory, or you may end up with duplicate
// tags. See above.
//
// Certain fields/tags are expected in certain Exif directories;
// Others can occur in more than one directory (and often have a
// different meaning in different directories).
//
// TagInfo constants often contain a description of what
// directories are associated with a given tag.
//
final TiffOutputDirectory exifDirectory = outputSet.getOrCreateExifDirectory();
// make sure to remove old value if present (this method will
// not fail if the tag does not exist).
exifDirectory.removeField(ExifTagConstants.EXIF_TAG_APERTURE_VALUE);
exifDirectory.add(ExifTagConstants.EXIF_TAG_APERTURE_VALUE,
new RationalNumber(3, 10));
}
{
// Example of how to add/update GPS info to output set.
// New York City
final double longitude = -74.0; // 74 degrees W (in Degrees East)
final double latitude = 40 + 43 / 60.0; // 40 degrees N (in Degrees
// North)
outputSet.setGPSInDegrees(longitude, latitude);
}
// printTagValue(jpegMetadata, TiffConstants.TIFF_TAG_DATE_TIME);
new ExifRewriter().updateExifMetadataLossless(jpegImageFile, os,
outputSet);
}
}
- 这允许您通过它实现的任何接口来解析您的服务。
您必须明确注册，因为Autofac不会自动执行此操作（因为在某些情况下您可能不想注册某些接口）。
中也对此进行了描述