以下是我对EF DB FIRST 生成的ObjectContext类进行封装，代码如下，供参考学习：
1 using System; 2 using System.Collections.Generic; 3 using System.Linq; 4 using System.Text; 5 using System.Data.Objects.DataClasses; 6 using ZBService.Model; 7 using System.Linq.Expressions; 8 9 namespace ZBService 10 { 11 public abstract class ServiceBase<T> where T:EntityObject 12 { 13 protected mZhaoBiaoEntities zbEntities = new mZhaoBiaoEntities(); 14 15 /// <summary> 16 /// 判断是否存在 17 /// </summary> 18 /// <param name="whereExpr"></param> 19 /// <returns></returns> 20 public bool Exist(Expression<Func<T,bool>> whereExpr) 21 { 22 return (this.Count(whereExpr) > 0); 23 } 24 25 /// <summary> 26 /// 获取记录数 27 /// </summary> 28 /// <param name="whereExpr"></param> 29 /// <returns></returns> 30 public int Count(Expression<Func<T, bool>> whereExpr) 31 { 32 return zbEntities.CreateObjectSet<T>().Where(whereExpr).Count(); 33 } 34 35 /// <summary> 36 /// 查找实体对象 37 /// </summary> 38 /// <param name="whereExpr"></param> 39 /// <returns></returns> 40 public T Find(Expression<Func<T, bool>> whereExpr) 41 { 42 return zbEntities.CreateObjectSet<T>().Where(whereExpr).FirstOrDefault(); 43 } 44 45 /// <summary> 46 /// 查找实体对象列表 47 /// </summary> 48 /// <param name="whereExpr"></param> 49 /// <returns></returns> 50 public IEnumerable<T> FindList<TKey>(Expression<Func<T, bool>> whereExpr, Expression<Func<T, TKey>> orderbyExpr, int orderDirection) 51 { 52 return this.FindList<T, TKey>(whereExpr,t=>t,orderbyExpr,orderDirection); 53 } 54 55 /// <summary> 56 /// 查找实体对象列表 57 /// </summary> 58 /// <typeparam name="TResult"></typeparam> 59 /// <typeparam name="TKey"></typeparam> 60 /// <param name="whereExpr"></param> 61 /// <param name="selectExpr"></param> 62 /// <param name="orderbyExpr"></param> 63 /// <param name="orderDirection"></param> 64 /// <param name="returnCount"></param> 65 /// <returns></returns> 66 public IEnumerable<TResult> FindList<TResult,TKey>(Expression<Func<T, bool>> whereExpr, Expression<Func<T, TResult>> selectExpr,Expression<Func<TResult,TKey>> orderbyExpr,int orderDirection,int returnCount=-1) 67 { 68 var result = zbEntities.CreateObjectSet<T>().Where(whereExpr).Select(selectExpr); 69 if (result != null && result.Count() > 0) 70 { 71 if (returnCount > 0) 72 { 73 if (orderDirection > 0) 74 { 75 result = result.OrderByDescending(orderbyExpr).Take(returnCount); 76 } 77 else 78 { 79 result = result.OrderBy(orderbyExpr).Take(returnCount); 80 } 81 } 82 return result.ToList(); 83 } 84 return null; 85 } 86 87 /// <summary> 88 /// 分页查找实体对象列表 89 /// </summary> 90 /// <typeparam name="TResult"></typeparam> 91 /// <typeparam name="TKey"></typeparam> 92 /// <param name="whereExpr"></param> 93 /// <param name="selectExpr"></param> 94 /// <param name="orderbyExpr"></param> 95 /// <param name="orderDirection"></param> 96 /// <param name="pageSize"></param> 97 /// <param name="pageNo"></param> 98 /// <param name="recordCount"></param> 99 /// <returns></returns> 100 public IEnumerable<TResult> FindListByPage<TResult,TKey>(Expression<Func<T, bool>> whereExpr, Expression<Func<T, TResult>> selectExpr,Expression<Func<TResult,TKey>> orderbyExpr,int orderDirection,int pageSize,int pageNo,out int recordCount) 101 { 102 var result = zbEntities.CreateObjectSet<T>().Where(whereExpr).Select(selectExpr); 103 recordCount = result.Count(); 104 105 if(pageNo>recordCount) pageNo=recordCount; 106 if(pageNo<=0) pageNo=1; 107 108 if (recordCount > 0) 109 { 110 if (recordCount > pageSize) 111 { 112 if (orderDirection > 0) 113 { 114 return result.OrderByDescending(orderbyExpr).Skip((pageNo - 1) * pageSize).Take(pageSize).ToList(); 115 } 116 else 117 { 118 return result.OrderBy(orderbyExpr).Skip((pageNo - 1) * pageSize).Take(pageSize).ToList(); 119 } 120 } 121 else 122 { 123 if (orderDirection > 0) 124 { 125 return result.OrderByDescending(orderbyExpr).ToList(); 126 } 127 else 128 { 129 return result.OrderBy(orderbyExpr).ToList(); 130 } 131 } 132 133 } 134 return null; 135 } 136 137 138 139 140 /// <summary> 141 /// 增加实体 142 /// </summary> 143 /// <param name="entity"></param> 144 public virtual void Add(T entity) 145 { 146 this.ValidateEntity(entity,ValidateMode.Add); 147 zbEntities.CreateObjectSet<T>().AddObject(entity); 148 } 149 150 151 /// <summary> 152 /// 增加实体列表 153 /// </summary> 154 /// <param name="entities"></param> 155 public virtual void AddList(IEnumerable<T> entities) 156 { 157 var objSet = zbEntities.CreateObjectSet<T>(); 158 foreach (T entity in entities) 159 { 160 this.ValidateEntity(entity, ValidateMode.Add); 161 objSet.AddObject(entity); 162 } 163 } 164 165 /// <summary> 166 /// 更新已分离实体,若未分离则不需要执行该方法 167 /// </summary> 168 /// <param name="entity"></param> 169 public virtual void Update(T entity) 170 { 171 this.ValidateEntity(entity, ValidateMode.Update); 172 zbEntities.CreateObjectSet<T>().ApplyCurrentValues(entity); 173 } 174 175 /// <summary> 176 /// 删除实体 177 /// </summary> 178 /// <param name="entity"></param> 179 public virtual void Delete(T entity) 180 { 181 this.ValidateEntity(entity, ValidateMode.Delete); 182 zbEntities.CreateObjectSet<T>().DeleteObject(entity); 183 } 184 185 /// <summary> 186 /// 删除实体 187 /// </summary> 188 /// <param name="whereExpr"></param> 189 public virtual void Delete(Expression<Func<T, bool>> whereExpr) 190 { 191 var objSet = zbEntities.CreateObjectSet<T>(); 192 T entity = objSet.Where(whereExpr).Single(); 193 //this.ValidateEntity(entity, ValidateMode.Delete); 194 objSet.DeleteObject(entity); 195 } 196 197 /// <summary> 198 /// 删除实体列表 199 /// </summary> 200 /// <param name="entities"></param> 201 public virtual void DeleteList(IEnumerable<T> entities) 202 { 203 var objSet = zbEntities.CreateObjectSet<T>(); 204 foreach (T entity in entities) 205 { 206 //this.ValidateEntity(entity, ValidateMode.Delete); 207 objSet.DeleteObject(entity); 208 } 209 } 210 211 212 /// <summary> 213 /// 提交保存所有变更操作 214 /// </summary> 215 public void SubmitSave() 216 { 217 zbEntities.SaveChanges(); 218 } 219 220 221 /// <summary> 222 /// 验证 223 /// </summary> 224 /// <param name="entity"></param> 225 /// <returns></returns> 226 protected virtual void ValidateEntity(T entity,ValidateMode mode=ValidateMode.Add) 227 { 228 229 } 230 231 /// <summary> 232 /// 验证模式 233 /// </summary> 234 protected enum ValidateMode 235 { 236 Add=0, 237 Update=1, 238 Delete=-1 239 } 240 241 } 242 }
之所以声明为abstract,要求子类必需继承后才能正常使用，这里面有一个ValidateEntity方法，主用于子类在RUD前，验证实体对象数据完整性，可重写也可不重写！
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本文转自 梦在旅途 博客园博客，原文链接：http://www.cnblogs.com/zuowj/p/4259515.html ，如需转载请自行联系原作者
