前几天偶然看到了dapper，由于以前没有用过，只用过ef core，稍微看了一下，然后写了一些简单的可复用的封装。
Dapper的用法比较接近ADO.NET所以性能也是比较快。所以我们先来看看使用ADO.NET的时候我们怎么实现代码复用的封装。
一、ADO.NET的封装案例
利用反射对ADO.NET进行封装，看代码：
DBHelper.cs:这边用的是mysql，如果要用sqlserver将MySqlConnection换成SqlConnection即可。
这个写的比较简单，如果有复杂的sql可能就支持不了了。读取配置文件的代码需要用到两个包：
using System; using System.Collections.Generic; using System.Data; using System.Linq; using System.Reflection; using System.Text; using Microsoft.Extensions.Configuration; using Microsoft.Extensions.Configuration.Json; using MySqlConnector;
namespace DB.Model
{
public class DBHelper
{
private static IConfiguration Configuration { get; set; }
private static readonly string ConnStr = null;
private static MySqlConnection conn;
static DBHelper()
{
//ReloadOnChange = true 当appsettings.json被修改时重新加载
Configuration = new ConfigurationBuilder()
.Add(new JsonConfigurationSource { Path = "appsettings.json", ReloadOnChange = true }).Build();
ConnStr = Configuration.GetConnectionString("MySql");
}
public static void Init()
{
if (connnull)
{
conn = new MySqlConnection(ConnStr);
conn.Open();
}
else if (conn.State ConnectionState.Closed)
{
conn.Open();
}
else if(conn.State==ConnectionState.Broken)
{
conn.Close();
conn.Open();
}
}
/// <summary>
/// 查全部
/// </summary>
/// <typeparam name="T"></typeparam>
/// <returns></returns>
public static List<T> GetDataAll<T>()
{
Init();
Type type = typeof(T);
//用type.Name代替表名
string sql = $"select * from {type.Name}";
MySqlCommand cmd = new MySqlCommand(sql, conn);
List<T> Data = new List<T>();
MySqlDataReader reader= cmd.ExecuteReader();
while (reader.Read())
{
object obj = Activator.CreateInstance(type);
foreach (PropertyInfo property in type.GetProperties())
{
property.SetValue(obj,reader[property.Name]);
}
Data.Add((T)obj);
}
reader.Close();
conn.Close();
return Data;
}
/// <summary>
/// 按id查询
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="id"></param>
/// <returns></returns>
public static T GetDataById<T>(int id)
{
Init();
Type type = typeof(T);
string sql = $"select * from {type.Name} where id={id}";
MySqlCommand cmd = new MySqlCommand(sql, conn);
MySqlDataReader reader = cmd.ExecuteReader();
object obj = Activator.CreateInstance(type);
while (reader.Read())
{
foreach (PropertyInfo property in type.GetProperties())
{
property.SetValue(obj,reader[property.Name]);
}
}
reader.Close();
conn.Close();
return (T) obj;
}
/// <summary>
/// 单条添加数据
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="t"></param>
/// <returns></returns>
public static int Add<T>(T t)
{
Init();
Type type = t.GetType();
Func<PropertyInfo, object> f = (x) =>
{
if (x.GetValue(t).GetType().Equals(typeof(string)))
{
return $"'{x.GetValue(t)}'";
}
else
{
return x.GetValue(t);
}
};
string sql = $"insert into {type.Name} " +
$"({string.Join(",", type.GetProperties().Select(n => $"{n.Name}"))}) " +
$"values({string.Join(",", type.GetProperties().Select(n => $"{f(n)}"))})";
MySqlCommand cmd = new MySqlCommand(sql,conn);
int result = cmd.ExecuteNonQuery();
conn.Close();
return result;
}
}
}
二、Dapper原生封装
dapper框架是给IDBConnection写了一些扩展方法，底层还是反射实现对象的关系映射。我们使用的时候只需要会用泛型即可。
using System; using System.Collections.Generic; using System.Data; using System.Data.SqlClient; using System.IO; using System.Linq; using System.Threading.Tasks; using Dapper; using Microsoft.Extensions.Configuration; using Microsoft.Extensions.Configuration.Json;namespace Model
{
public class DapperHelper
{
static DapperHelper()
{
//ReloadOnChange = true 当appsettings.json被修改时重新加载
_dbConnection = new SqlConnection();
_dbConnection.ConnectionString = new ConfigurationBuilder()
.SetBasePath(Directory.GetCurrentDirectory())
.AddJsonFile("appsettings.json").Build().GetConnectionString("Default");
}private static readonly IDbConnection _dbConnection; #region Query public async Task<T> QueryFirstOrDefaultAsync<T>(string sql, object param = null, IDbTransaction transaction = null, int? commandTimeout = null, CommandType? commandType = null) { return await _dbConnection.QueryFirstOrDefaultAsync<T>(sql, param, transaction, commandTimeout, commandType); } public T QueryFirstOrDefault<T>(string sql, object param = null, IDbTransaction transaction = null, int? commandTimeout = null, CommandType? commandType = null) { return _dbConnection.QueryFirstOrDefault<T>(sql, param, transaction, commandTimeout, commandType); } public async Task<List<T>> QueryAsync<T>(string sql, object param = null, IDbTransaction transaction = null, int? commandTimeout = null, CommandType? commandType = null) { return (await _dbConnection.QueryAsync<T>(sql, param, transaction, commandTimeout, commandType)).ToList(); } public List<T> Query<T>(string sql, object param = null, IDbTransaction transaction = null, bool buffered = true, int? commandTimeout = null, CommandType? commandType = null) { return _dbConnection.Query<T>(sql, param, transaction, buffered, commandTimeout, commandType).ToList(); } #endregion #region Excute public Task<int> ExecuteAsync(string sql, object param = null, IDbTransaction transaction = null, int? commandTimeout = null, CommandType? commandType = null) { return _dbConnection.ExecuteAsync(sql, param, transaction, commandTimeout, commandType); } public int Execute(string sql, object param = null, IDbTransaction transaction = null, int? commandTimeout = null, CommandType? commandType = null) { return _dbConnection.Execute(sql, param, transaction, commandTimeout, commandType); } #endregion }
}
使用：
using Model; using Newtonsoft.Json; using System; using System.Collections.Generic; using System.IO; using System.Linq; using System.Threading.Tasks;namespace dapperDemo
{
class Program
{
static async Task Main(string[] args)
{
#region 原生dapper封装
DapperHelper dapper = new DapperHelper();#region 查询集合 Console.WriteLine("-----------------查询集合-------------------"); var students = await dapper.QueryAsync<Student>("select * from Student"); Console.WriteLine(JsonConvert.SerializeObject(students)); #endregion #region 单个查询 Console.WriteLine("-----------------单个查询-------------------"); string sql = "select * from student where StudentName=@StudentName"; var stu = await dapper.QueryFirstOrDefaultAsync<Student>(sql, new { StudentName = "小红帽" }); Console.WriteLine(JsonConvert.SerializeObject(stu)); #endregion #region 新增 Console.WriteLine("-----------------新增-------------------"); Student student = new Student() { Id = Guid.NewGuid(), StudentName = "小红帽", Sex = SexType.Male, CreateTime = DateTime.Now, IsDelete = false, Birthday = DateTime.Now }; string excuteSql = "insert into student(id,studentname,sex,createtime,isdelete,birthday)" + " values(@Id,@StudentName,@Sex,@CreateTime,@IsDelete,@Birthday)"; var result = await dapper.ExecuteAsync(excuteSql, student); Console.WriteLine(result); #endregion #region 删除 Console.WriteLine("-----------------删除-------------------"); string deleteSql = "delete from student where studentname=@studentName"; var result = await dapper.ExecuteAsync(deleteSql, new {studentName = "小红帽"}); Console.WriteLine($"结果：{result}"); #endregion #region 修改 Console.WriteLine("-----------------修改-------------------"); string updateSql = "update student set studentname=@NewStudentName where studentName=@OldStudentName"; var result = await dapper.ExecuteAsync(updateSql, new {NewStudentName = "杜甫", OldStudentName = "李白" }); Console.WriteLine($"结果：{result}"); #endregion #endregion 原生dapper封装 } }
}
三、Dapper的二次封装（基于上一个）
利用反射对Dapper进行二次封装：DapperSuperHelper<T>.cs，通过继承继承dapper的封装，我们可以即可用使用原始封装又可以使用通用的对单表的增删改查。
该封装可以实现对单个表的增删改查，以及分页查询，修改、删除、查询都是基于id查询，id支持任意类型。
注意：修改的时候建议先查出数据再执行修改，因为目前封装的代码无法实现只更改某个字段，暂时是全部更改，必填项必须有值。非必填，不传值，即为null。
using System; using System.Collections.Generic; using System.Linq; using System.Reflection; using System.Threading.Tasks;namespace Model
{
public class DapperSuperHelper<T>:DapperHelper
{
/// <summary>
/// 查询所有
/// </summary>
/// <returns></returns>
public async Task<List<T>> GetAllAsync()
{
var sql = $"select * from {typeof(T).Name}";
return await QueryAsync<T>(sql);
}
public List<T> GetAll()
{
var sql = $"select * from {typeof(T).Name}";
return Query<T>(sql);
}
/// <summary>
/// 按id查询
/// </summary>
/// <param name="id"></param>
/// <returns></returns>
public T Get(object id)
{
var sql = $"select * from {typeof(T).Name} where id=@Id";
return QueryFirstOrDefault<T>(sql, new {Id = id});
}public async Task<T> GetAsync(object id) { var sql = $"select * from {typeof(T).Name} where id=@Id"; return await QueryFirstOrDefaultAsync<T>(sql, new { Id = id }); } /// <summary> /// 新增 /// </summary> /// <param name="t"></param> /// <returns></returns> public async Task<int> InsertAsync(T t) { Type type = t.GetType(); var sql = $"insert into {type.Name}" + $"({string.Join(",",type.GetProperties().Select(n=>n.Name))})"+ $" values({string.Join(",",type.GetProperties().Select(n=>$"@{n.Name}"))})"; return await ExecuteAsync(sql,t); } public int Insert(T t) { Type type = t.GetType(); var sql = $"insert into {type.Name}" + $"({string.Join(",", type.GetProperties().Select(n => n.Name))})" + $" values({string.Join(",", type.GetProperties().Select(n => $"@{n.Name}"))})"; return Execute(sql, t); } /// <summary> /// 修改 /// </summary> /// <param name="t"></param> /// <returns></returns> public async Task<int> UpdateAsync(T t) { Type type = t.GetType(); var sql = $"update {type.Name} set " + $"{string.Join(",", type.GetProperties().Select(n => $"{n.Name}=@{n.Name}"))} " + $"where id=@Id"; return await ExecuteAsync(sql,t); } public int Update(T t) { Type type = t.GetType(); var sql = $"update {type.Name} set " + $"{string.Join(",", type.GetProperties().Select(n => $"{n.Name}=@{n.Name}"))} " + $"where id=@Id"; return Execute(sql, t); } /// <summary> /// 按id删除 /// </summary> /// <param name="id"></param> /// <returns></returns> public async Task<bool> DeleteAsync(object id) { var sql = $"delete from {typeof(T).Name} where id=@Id"; return await ExecuteAsync(sql, new { Id = id }) > 0; } public bool Delete(object id) { var sql = $"delete from {typeof(T).Name} where id=@Id"; return Execute(sql, new { Id = id }) > 0; } /// <summary> /// 删除全部 /// </summary> /// <returns></returns> public async Task<bool> DeleteAllAsync() { var sql = $"delete from {typeof(T).Name}"; return await ExecuteAsync(sql) > 0; } public bool DeleteAll() { var sql = $"delete from {typeof(T).Name}"; return Execute(sql) > 0; } /// <summary> /// 单表分页查询 /// </summary> /// <param name="pageIndex"></param> /// <param name="pageSize"></param> /// <returns></returns> public async Task<List<T>> GetPagedAsync(int pageIndex,int pageSize) { var skipRow = (pageIndex - 1) * pageSize; var sql = $"select * from {typeof(T).Name} order by Id " + $"offset @skipRow rows fetch next @PageSize rows only"; return await QueryAsync<T>(sql, new {skipRow, pageSize}); } /// <summary> /// 单表分页查询 /// </summary> /// <param name="pageIndex"></param> /// <param name="pageSize"></param> /// <returns></returns> public List<T> GetPaged(int pageIndex, int pageSize) { var skipRow = (pageIndex - 1) * pageSize; var sql = $"select * from {typeof(T).Name} order by Id " + $"offset @skipRow rows fetch next @PageSize rows only"; return Query<T>(sql, new { skipRow, pageSize }); } }
}
使用：
using Model; using Newtonsoft.Json; using System; using System.Collections.Generic; using System.IO; using System.Linq; using System.Threading.Tasks;namespace dapperDemo
{
class Program
{
static async Task Main(string[] args)
{#region dapper二次封装 DapperSuperHelper<Student> superDapper = new DapperSuperHelper<Student>(); //查询所有 List<Student> students = await superDapper.GetAllAsync(); Console.WriteLine(JsonConvert.SerializeObject(students)); //按id查询 var id = Guid.Parse("b2847592-90d6-40a4-b3b0-c1ebf514e258"); var stu = await superDapper.GetAsync(id); Console.WriteLine(JsonConvert.SerializeObject(stu)); //新增 Student entity = new Student() { Id = Guid.NewGuid(), Birthday = DateTime.Now, CreateTime = DateTime.Now, Email = "hello@163.com", IsDelete = false, Sex = SexType.Female, StudentName = "夏花" }; var result = await superDapper.InsertAsync(entity); Console.WriteLine($"新增结果，受影响的行数：{result}"); //修改 entity.StudentName = "小燕子"; var updateResult = await superDapper.UpdateAsync(entity); Console.WriteLine($"修改结果，受影响的行数：{updateResult}"); //删除 var did = Guid.Parse("b2847592-90d6-40a4-b3b0-c1ebf514e258"); var deleteResult = await superDapper.DeleteAsync(did); Console.WriteLine($"删除结果：{deleteResult}"); //分页查询 var pagedResult = await superDapper.GetPagedAsync(2, 2); Console.WriteLine(JsonConvert.SerializeObject(pagedResult)); #endregion } }
}
四、Dapper官方提供的扩展包
原理和我通过反射进行的二次封装差不多，但是肯定比我写的更安全和规范、更复杂，不过官方的id我看了一下，好像只支持int类型。
可以看到我上面的二次封装和官方的封装其实差不多的功能，不过我还多了一个分页，嘿嘿。
using System.Collections.Generic; using System.Data; using System.Data.SqlClient; using System.IO; using System.Threading.Tasks; using Dapper.Contrib.Extensions; using Microsoft.Extensions.Configuration;namespace Model
{
public class DapperExtHelper<T> where T:class
{
static DapperExtHelper()
{
_dbConnection = new SqlConnection();
_dbConnection.ConnectionString = new ConfigurationBuilder()
.SetBasePath(Directory.GetCurrentDirectory())
.AddJsonFile("appsettings.json").Build().GetConnectionString("Default");
}private static readonly IDbConnection _dbConnection; public List<T> GetAll() { return _dbConnection.GetAll<T>().ToList(); } public async Task<List<T>> GetAllAsync() { return (await _dbConnection.GetAllAsync<T>()).ToList(); } public T Get(int id) { return _dbConnection.Get<T>(id); } public bool Update(T entity) { return _dbConnection.Update(entity); } public async Task<bool> UpdateAsync(T entity) { return await _dbConnection.UpdateAsync(entity); } public long Insert(T entity) { return _dbConnection.Insert(entity); } public async Task<long> InsertAsync(T entity) { return await _dbConnection.InsertAsync(entity); } public bool Delete(T entity) { return _dbConnection.Delete(entity); } public async Task<bool> DeleteAsync(T entity) { return await _dbConnection.DeleteAsync(entity); } public bool DeleteAll() { return _dbConnection.DeleteAll<T>(); } public async Task<bool> DeleteAllAsync() { return await _dbConnection.DeleteAllAsync<T>(); } }
}
使用：
using Model; using Newtonsoft.Json; using System; using System.Collections.Generic; using System.IO; using System.Linq; using System.Threading.Tasks;namespace dapperDemo
{
class Program
{
static async Task Main(string[] args)
{#region dapper官方自带的扩展包 //查全部，官方默认会以类名后面加个s，我们最好指定[Table("Student")] DapperExtHelper<Student> dapperExtHelper = new DapperExtHelper<Student>(); var students = dapperExtHelper.GetAll(); Console.WriteLine(JsonConvert.SerializeObject(students)); //id查询 只支持id为int //var stu = dapperExtHelper.Get(1); //删除全部 //dapperExtHelper.DeleteAll(); //删除 var delEntity = new Student() { Id = Guid.Parse("c066dfce-d7cd-46b5-9fa3-d0aa4b165dde") }; //dapperExtHelper.Delete(delEntity); //修改 全部字段修改，需要传递必填的参数，否则报错，未传的参数修改为空，因此最好是先查出当实体，再修改单独字段 var updEntity = new Student() { Id = Guid.Parse("b2847592-90d6-40a4-b3b0-c1ebf514e257"), StudentName = "李白222", CreateTime = DateTime.Now, Birthday = DateTime.Now }; dapperExtHelper.Update(updEntity); //新增 这居然报错，id不能传null，就离谱，估计和类型有关 Student InsertEntity = new Student() { Id = Guid.NewGuid(), Birthday = DateTime.Now, CreateTime = DateTime.Now, Email = "hello@163.com", IsDelete = false, Sex = SexType.Female, StudentName = "夏花" }; dapperExtHelper.Insert(InsertEntity); #endregion } }
}
以上就是我对dapper的简单的封装。大家也可以自行封装。
需要源代码的可以加群831181779@群主哦