我们经常会用到linq 来查询 一个数组中和另一个数组中相同的项， 这个时候就会用到IEqualityComparer接口。
public class StudyInfoModel
{
public string InstanceUID = "";
}
public class StudyCompare : IEqualityComparer<StudyInfoModel>
{
// StudyInfoModel are equal if their UID equal.
public bool Equals(StudyInfoModel x, StudyInfoModel y)
{
//Check whether the compared objects reference the same data.
if (Object.ReferenceEquals(x, y)) return true;
//Check whether any of the compared objects is null.
if (Object.ReferenceEquals(x, null) || Object.ReferenceEquals(y, null))
return false;
//Check whether the Study' properties are equal.
return x.InstanceUID == y.InstanceUID;
}
// If Equals() returns true for a pair of objects
// then GetHashCode() must return the same value for these objects.
public int GetHashCode(StudyInfoModel study)
{
//Check whether the object is null
if (Object.ReferenceEquals(study, null)) return 0;
//Get hash code for the Name field if it is not null.
int hashStudyName = study.InstanceUID == null ? 0 : study.InstanceUID.GetHashCode();
return hashStudyName;
}
}
以上实现了关于StudyInfoModel的IEqualityCompare接口， 其中条件为InstanceUID相同。
具体使用：
List<StudyInfoModel> StudyData = new List<StudyInfoModel>();
List<StudyInfoModel> StudyList = new List<StudyInfoModel>();
.......
//取得StudyData数组中InstanceUID在StudyLIst存在的所有项
var needModifyStudy = StudyData.Intersect(StudyList, new StudyCompare()).ToList();
比如StudyData中是InstanceUID分别为1,2,3,4,5,6的数据， StudyList中是InstanceUID分别为2,4,6,8,10的数据，
则查询结果为StudyData中2,4,6的项。