问题描述
|
我有一个包含大约500个String成员的类,我想通过将它们设置为String.Empty来“重置”它们。谁能告诉我如何使用反射来做到这一点,以便我可以遍历每个String成员?
谢谢
解决方法
foreach (PropertyInfo pi in MyObj.GetType().GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic ).ToArray() )
{
if (pi.PropertyType == typeof(string))
{
pi.SetValue(MyObj,string.Empty,null);
}
}
田间使用
foreach (FieldInfo fi in MyObj.GetType().GetFields(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic ).ToArray() )
{
if (fi.FieldType == typeof(string))
{
fi.SetValue(MyObj,string.Empty);
}
}
, typeof(MyClass).GetProperties()
.Where(p => p.PropertyType == typeof(string))
.ToList()
.ForEach(p => p.SetValue(myObj,null));
编辑:
如果您要处理字段而不是属性,则非常相似
typeof(MyClass).GetFields()
.Where(f => f.FieldType == typeof(string))
.ToList()
.ForEach(f => f.SetValue(myObj,string.Empty));
, 使用编译的Expression-Tree实现的相同代码:
private static Action<TObject> CreateClearStringProperties<TObject>()
{
var memberAccessExpressions = new List<System.Linq.Expressions.Expression>();
System.Linq.Expressions.ParameterExpression arg = System.Linq.Expressions.Expression.Parameter(typeof(TObject),\"x\");
foreach (var propertyInfo in typeof(TObject).GetProperties(System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.FlattenHierarchy))
{
if (propertyInfo.PropertyType == typeof(string) && propertyInfo.SetMethod != null)
{
var memberAccess = System.Linq.Expressions.Expression.MakeMemberAccess(arg,propertyInfo);
var assignment = System.Linq.Expressions.Expression.Assign(memberAccess,System.Linq.Expressions.Expression.Constant(string.Empty));
memberAccessExpressions.Add(assignment);
}
}
foreach (var fieldInfo in typeof(TObject).GetFields(System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.FlattenHierarchy))
{
if (fieldInfo.FieldType == typeof(string))
{
var memberAccess = System.Linq.Expressions.Expression.MakeMemberAccess(arg,fieldInfo);
var assignment = System.Linq.Expressions.Expression.Assign(memberAccess,System.Linq.Expressions.Expression.Constant(string.Empty));
memberAccessExpressions.Add(assignment);
}
}
if (memberAccessExpressions.Count == 0)
return new Action<TObject>((e) => { });
var allProperties = System.Linq.Enumerable.Aggregate(memberAccessExpressions,System.Linq.Expressions.Expression.Block);
return System.Linq.Expressions.Expression.Lambda<Action<TObject>>(allProperties,arg).Compile();
}
使用方法示例:
Action<MyClass> clearObject = CreateClearStringProperties<MyClass>();
MyClass obj = new MyClass();
clearObject(obj);
一些通用池逻辑需要使用该逻辑,其中放回池中的对象不应使过时的字符串对象保持活动状态。