Linq 简易处理

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

    public static class SingletonProvider<T> where T : new()
    {
        private static T m_instance;
        private static readonly object sync = new object();
        #region 无够构造函数的泛型单列
        /// <summary>
        /// 无够构造函数的泛型单列
        /// </summary>
        public static T Instance
        {
            get
            {
                if (m_instance == null)
                {
                    lock (sync)
                    {
                        if (m_instance == null)
                        {
                            try
                            {
                                m_instance = new T();
                            }
                            catch
                            {
                            }
                        }
                    }
                }
                return m_instance;
            }
        }
        #endregion
        #region 带构造函数的泛型单列模式
        /// <summary>
        /// 带构造函数的泛型单列模式
        /// </summary> 
        public static T InstanceForParameter(params object[] objarr)
        {

            if (m_instance == null)
            {
                lock (sync)
                {
                    if (m_instance == null)
                    {
                        var t = typeof(T);
                        var tp = new Type[objarr.Length];
                        for (int i = 0; i < objarr.Length; i++)
                        {
                            tp[i] = objarr[i].GetType();
                        }
                        try
                        {
                            System.Reflection.ConstructorInfo ci = t.GetConstructor(tp);
                            m_instance = (T)ci.Invoke(objarr);
                        }
                        catch
                        {
                        }

                    }
                }
            }
            return m_instance;
        } 
        #endregion
    }

1.先放个单例，减少开销

 2.LinqReflectionHelp，这类辅助LINQ

 

 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Reflection;
using System.Text;
using System.Linq.Expressions;

namespace MvcApplication1.Models
{
    public static class LinqReflectionHelp
    {
        public static void ExecMethodMForMainObject<T>(T MainObject, string methodName, params object[] paramesForMethod)
        {
            Type t = MainObject.GetType();
            MethodInfo[] methods = t.GetMethods();
            MethodInfo method = findAMethodInT(methodName, methods);
            if (method != null)
            {
                try
                {
                    method.Invoke(MainObject, paramesForMethod);
                }
                catch
                {
                    throw new Exception();
                }
            }
        }
        private static MethodInfo findAMethodInT(string MethodName, MethodInfo[] methods)
        {
            foreach (MethodInfo item in methods)
            {
                if (item.Name.Equals(MethodName))
                {
                    return item;
                }
            }
            return null;
        }
        public static System.Data.Linq.Table<TableName> SelTableListLinqDB<LinqDBContextType, TableName>(LinqDBContextType reflectionEntity) where TableName : class
        {
            object PropertiesValue = null;
            Type t = typeof(LinqDBContextType);
            foreach (var item in t.GetProperties())
            {
                if (item.PropertyType == typeof(System.Data.Linq.Table<TableName>))
                {
                    PropertiesValue = item.GetValue(reflectionEntity, null);
                    return (System.Data.Linq.Table<TableName>)PropertiesValue;
                }
            }
            return default(System.Data.Linq.Table<TableName>);
        }
        public static T2 FindModel<PropertiesList, T2>(PropertiesList reflectionEntity, int id) where T2 : class
        {
            object PropertiesValue = null;
            Type t = typeof(PropertiesList);
            foreach (var item in t.GetProperties())
            {
                if (item.PropertyType == typeof(T2))
                {
                    PropertiesValue = item.GetValue(reflectionEntity, null);
                    return (T2)PropertiesValue;
                }
            }
            return default(T2); ;
        }
        
    }
}

 

 

3.LINQ数据库处理

 

 

  public static class LinqDBHelper<LinqContextDB>
        where LinqContextDB : new()
    {
        public static LinqContextDB LinqDBContextEntity
        {
            get
            {
                return SingletonProvider<LinqContextDB>.Instance;
            }
        }
        public static LinqContextDB LinqDBContextEntityForParameter(params object[] objarr)
        {

            return SingletonProvider<LinqContextDB>.InstanceForParameter(objarr);
        }
        public static System.Data.Linq.Table<TableName> getTableList<TableName>()
            where TableName : class
        {
            return LinqReflectionHelp.SelTableListLinqDB<LinqContextDB, TableName>(LinqDBContextEntity);

        }
        public static void Save()
        {
            LinqReflectionHelp.ExecMethodMForMainObject(LinqDBContextEntity, "SubmitChanges", null);
        }

        public static void Add<TableName>(TableName T2Model) where TableName : class
        {
            LinqReflectionHelp.ExecMethodMForMainObject(LinqDBContextEntity, "InsertOnSubmit", T2Model);
        }
        public static void Delete<TableName>(TableName T2Model) where TableName : class
        {
            LinqReflectionHelp.ExecMethodMForMainObject(LinqDBContextEntity, "DeleteOnSubmit", T2Model);
        }
        public static IQueryable<LinqTableObjct> FindSomeTableListFromLinqTableObjct<LinqTableObjct>
         (IQueryable<LinqTableObjct> linqTableObjct, Expression<Func<LinqTableObjct, bool>> expression)
         where LinqTableObjct : class,new()
        {
            try
            {
                IQueryable<LinqTableObjct> TableEntity = linqTableObjct.Where<LinqTableObjct>(expression);
                return TableEntity;
            }
            catch
            {
            }
            return default(System.Data.Linq.Table<LinqTableObjct>);
        }
        public static TableName FindModel<TableName>(System.Data.Linq.Table<TableName> tableList, Expression<Func<TableName, bool>> expression)
                   where TableName : class,new()
        {
            try
            {
                TableName TableEntity = tableList.Single<TableName>(expression);
                return TableEntity;
            }
            catch
            {
            }
            return default(TableName);
        }

    }

 

 

 

 

 

 

调用方法

 

 

 public static class DepartmentRepository
    {

        public static System.Data.Linq.Table<Department> AllDepartments
        {
            get
            {
                 return LinqDBHelper<SchoolDBDataContext>.getProperties<System.Data.Linq.Table<Department>>();

            }
        } 
        public static SchoolDBDataContext schoolContext
        {
            get
            {
                return LinqDBHelper<SchoolDBDataContext>.LinqDBContextEntity;
            }
        } 


        public static IQueryable<Department> FindSomeDepartment(OrderDirection OrderBy)
        {
            Expression<Func<Department, bool>> expression = PredicateExtensions.True<Department>();
            expression.And(d => (d.Budget > 1 && d.Administrator > 1));
            IQueryable<Department> DepartLinqList = LinqDBHelper<SchoolDBDataContext>.FindSomeTableListFromLinqTableObjct<Department>(AllDepartments, expression);
            if (OrderBy == OrderDirection.ASC)
            {
                return DepartLinqList.OrderBy(d => d.Budget);
            }
            return DepartLinqList.OrderByDescending(d => d.Budget);
        }


        public static Department GetDepartment(int departmentID)
        {
            Expression<Func<Department, bool>> expr = d => d.DepartmentID == departmentID;
            return LinqDBHelper<SchoolDBDataContext>.FindModel<Department>(AllDepartments, expr);
        }

      
        public static void Add(Department department)
        {
        //    LinqDBHelper<SchoolDBDataContext>.Add(department);
            object[] ParameterList = { department };

//两种调用方法随意
            LinqReflectionHelp.ExecMethodMForMainObject(LinqDBHelper<SchoolDBDataContext>.LinqDBContextEntity.Department, "InsertOnSubmit", ParameterList);
        }
        public static void Delete(Department department)
        {
            LinqDBHelper<SchoolDBDataContext>.Delete(department);
        }
 

    }

    public enum OrderDirection
    {
        ASC, DESC
    }

 

 还少放了一个东西 补上

 

网上好多下的 ，

PredicateExtensions,处理EXPRESSION表达式的一个老外写的，这里就不浪费空间了。。。