自定义Lamda表达式作为筛选条件

var ints = new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9 };

// var r = ints.Where(i => (i > 5 && i <= 7) || (i == 3)); // 要a实μ现?的?表í达?式?

// 创′建¨参?数y i

var parameter = Expression.Parameter(typeof(int), "i");

// 创′建¨表í达?式? i > 5

var con1 = Expression.Constant(5);

var bin1 = Expression.GreaterThan(parameter, con1);

// 创′建¨表í达?式? i < 7

var con2 = Expression.Constant(7);

var bin2 = Expression.LessThanOrEqual(parameter, con2);

// 创′建¨表í达?式? i == 3

var con3 = Expression.Constant(3);

var bin3 = Expression.Equal(parameter, con3);

// 组é合? i > 5 && i <= 7

var body = Expression.And(bin1, bin2);

// 组é合? ( i > 5 && i <= 7) OR (i == 3)

body = Expression.Or(body, bin3);

var lambda = Expression.Lambda<Func<int, bool>>(body, parameter);

var _r = ints.Where(lambda.Compile());
FROM:http://www.rainsts.net/article.asp?id=535