Dapper?是一個輕量級ORM框架，在項目中如果對性能比較看中，Dapper是一個不錯的選擇。接下來我們就來看看如何在項目中使用Dapper.

1.安裝Dapper

　　這里直接使用Nuget安裝。

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?安裝完成之后，發現Nuget下已經有了Dapper。

2.創建DapperHelper

　　接下來創建一個DapperHelper幫助類，來進行讀取數據庫連接字符串，打開數據庫等操作。

代碼：

public class DapperHelper{/// 數據庫連接名private static string _connection = string.Empty;/// 獲取連接名 private static string Connection{get { return _connection; }//set { _connection = value; } }/// 返回連接實例 private static IDbConnection dbConnection = null;/// 靜態變量保存類的實例 private static DapperHelper uniqueInstance;/// 定義一個標識確保線程同步 private static readonly object locker = new object();/// <summary>/// 私有構造方法，使外界不能創建該類的實例，以便實現單例模式/// </summary>private DapperHelper(){// 這里為了方便演示直接寫的字符串，實例項目中可以將連接字符串放在配置文件中，再進行讀取。_connection = @"server=.;uid=sa;pwd=sasasa;database=Dapper";}/// <summary>/// 獲取實例，這里為單例模式，保證只存在一個實例/// </summary>/// <returns></returns>public static DapperHelper GetInstance(){// 雙重鎖定實現單例模式，在外層加個判空條件主要是為了減少加鎖、釋放鎖的不必要的損耗if (uniqueInstance == null){lock (locker){if (uniqueInstance == null){uniqueInstance = new DapperHelper();}}}return uniqueInstance;}/// <summary>/// 創建數據庫連接對象并打開鏈接/// </summary>/// <returns></returns>public static IDbConnection OpenCurrentDbConnection(){if (dbConnection == null){dbConnection = new SqlConnection(Connection);}//判斷連接狀態if (dbConnection.State == ConnectionState.Closed){dbConnection.Open();}return dbConnection;}}

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　3.創建上下文 DbContext?作用是調用Dapper中操作數據庫的方法，里面是我自己封的一些常用方法，當然了這一步可以略去，直接調用也行，這里只是提供一種思路。

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public static class DbContext{// 獲取開啟數據庫的連接private static IDbConnection Db{get{//創建單一實例 DapperHelper.GetInstance();return DapperHelper.OpenCurrentDbConnection();}}/// <summary>/// 查出一條記錄的實體/// </summary>/// <typeparam name="T"></typeparam>/// <param name="sql"></param>/// <returns></returns>public static T QueryFirstOrDefault<T>(string sql, object param = null){return Db.QueryFirstOrDefault<T>(sql, param);}public static Task<T> QueryFirstOrDefaultAsync<T>(string sql, object param = null){return Db.QueryFirstOrDefaultAsync<T>(sql, param);}/// <summary>/// 查出多條記錄的實體泛型集合/// </summary>/// <typeparam name="T">泛型T</typeparam>/// <returns></returns>public static IEnumerable<T> Query<T>(string sql, object param = null, IDbTransaction transaction = null, bool buffered = true, int? commandTimeout = null, CommandType? commandType = null){return Db.Query<T>(sql, param, transaction, buffered, commandTimeout, commandType);}public static Task<IEnumerable<T>> QueryAsync<T>(string sql, object param = null, IDbTransaction transaction = null, int? commandTimeout = null, CommandType? commandType = null){return Db.QueryAsync<T>(sql, param, transaction, commandTimeout, commandType);}public static int Execute(string sql, object param = null, IDbTransaction transaction = null, int? commandTimeout = null, CommandType? commandType = null){return Db.Execute(sql, param, transaction, commandTimeout, commandType);}public static Task<int> ExecuteAsync(string sql, object param = null, IDbTransaction transaction = null, int? commandTimeout = null, CommandType? commandType = null){return Db.ExecuteAsync(sql, param, transaction, commandTimeout, commandType);}public static T ExecuteScalar<T>(string sql, object param = null, IDbTransaction transaction = null, int? commandTimeout = null, CommandType? commandType = null){return Db.ExecuteScalar<T>(sql, param, transaction, commandTimeout, commandType);}public static Task<T> ExecuteScalarAsync<T>(string sql, object param = null, IDbTransaction transaction = null, int? commandTimeout = null, CommandType? commandType = null){return Db.ExecuteScalarAsync<T>(sql, param, transaction, commandTimeout, commandType);}/// <summary>/// 同時查詢多張表數據（高級查詢）/// "select *from K_City;select *from K_Area";/// </summary>/// <param name="sql"></param>/// <returns></returns>public static SqlMapper.GridReader QueryMultiple(string sql, object param = null, IDbTransaction transaction = null, int? commandTimeout = null, CommandType? commandType = null){return Db.QueryMultiple(sql, param, transaction, commandTimeout, commandType);}public static Task<SqlMapper.GridReader> QueryMultipleAsync(string sql, object param = null, IDbTransaction transaction = null, int? commandTimeout = null, CommandType? commandType = null){return Db.QueryMultipleAsync(sql, param, transaction, commandTimeout, commandType);}}

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接下來就可以調用了，DbContext.Action()

嗯。。。就寫到這里吧，以后再接著寫。

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轉載于:https://www.cnblogs.com/jixiaosa/p/10261778.html

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