依赖注入框架Autofac的简单使用

Autofac是一款IOC框架,比较于其他的IOC框架,如Spring.NET,Unity,Castle等等所包含的,它很轻量级性能上也是很高的。于是,今天抽空研究了下它。下载地址:http://code.google.com/p/autofac/downloads/list

1)解压它的压缩包,主要看到Autofac.dll,Autofac.Configuration.dll,这也是本篇文章重点使用的Autofac的类库。

2)创建一个控制台工程,并且引用以上的DLL文件。创建一个数据库操作接口IDatabase.cs:

///<summary>///

Database operate interface

///publicinterface

IDatabase

{

string Name { get

; }

void Select(string

commandText);

void Insert(string

commandText);

void Update(string

commandText);

void Delete(string

commandText);

}

这里包含CRUD四种操作的方法。

3)创建两种数据库的操作类,SqlDatabase.cs以及OracleDatabase.cs:

publicclass

SqlDatabase : IDatabase

{

publicstring

Name

{

get { return“sqlserver”

; }

}

publicvoid Select(string

commandText)

{

Console.WriteLine(
string.Format(“{0} is a query sql in {1}!”

, commandText, Name));

}

publicvoid Insert(string

commandText)

{

Console.WriteLine(
string.Format(“{0} is a insert sql in {1}!”

, commandText, Name));

}

publicvoid Update(string

commandText)

{

Console.WriteLine(
string.Format(“{0} is a update sql in {1}!”

, commandText, Name));

}

publicvoid Delete(string

commandText)

{

Console.WriteLine(
string.Format(“{0} is a delete sql in {1}!”

, commandText, Name));

}

}

以及

publicclass

OracleDatabase : IDatabase

{

publicstring

Name

{

get { return“oracle”

; }

}

publicvoid Select(string

commandText)

{

Console.WriteLine(
string.Format(“{0} is a query sql in {1}!”

, commandText, Name));

}

publicvoid Insert(string

commandText)

{

Console.WriteLine(
string.Format(“{0} is a insert sql in {1}!”

, commandText, Name));

}

publicvoid Update(string

commandText)

{

Console.WriteLine(
string.Format(“{0} is a update sql in {1}!”

, commandText, Name));

}

publicvoid Delete(string

commandText)

{

Console.WriteLine(
string.Format(“{0} is a delete sql in {1}!”

, commandText, Name));

}

}

4)接着创建一个数据库管理器DatabaseManager.cs:

publicclass

DatabaseManager

{

IDatabase _database;

public

DatabaseManager(IDatabase database)

{

_database = database;

}

publicvoid Search(string

commandText)

{

_database.Select(commandText);

}

publicvoid Add(string

commandText)

{

_database.Insert(commandText);

}

publicvoid Save(string

commandText)

{

_database.Update(commandText);

}

publicvoid Remove(string

commandText)

{

_database.Delete(commandText);

}

}

5)在控制台中,编写以下测试程序:

var builder = new

ContainerBuilder();

builder.RegisterType();

builder.RegisterType().As();

using

(var container = builder.Build())

{

var manager = container.Resolve();

manager.Search(
“SELECT * FORM USER”

);

}

运行结果:

分析:

这里通过ContainerBuilder方法RegisterType对DatabaseManager进行注册,当注册的类型在相应得到的容器中可以Resolve你的DatabaseManager实例。

builder.RegisterType<SqlDatabase>().As<IDatabase>();通过AS可以让DatabaseManager类中通过构造函数依赖注入类型相应的接口。

Build()方法生成一个对应的Container实例,这样,就可以通过Resolve解析到注册的类型实例。

同样地,如果你修改数据库类型注册为:

builder.RegisterType<OracleDatabase>().As<IDatabase>();

运行结果:

6)显然以上的程序中,SqlDatabase或者OracleDatabase已经暴露于客户程序中了,现在我想将该类型选择通过文件配置进行读取。Autofac自带了一个Autofac.Configuration.dll 非常方便地对类型进行配置,避免了程序的重新编译。

修改App.config:

<configuration><configSections><section name=”autofac” type=”Autofac.Configuration.SectionHandler, Autofac.Configuration”/></configSections><autofac defaultAssembly=”AutofacDemo”><components><component type=”AutofacDemo.SqlDatabase, AutofacDemo” service=”AutofacDemo.IDatabase”/></components></autofac></configuration>

通过Autofac.Configuration.SectionHandler配置节点对组件进行处理。

对应的客户端程序改为:

var builder = new

ContainerBuilder();

builder.RegisterType();

builder.RegisterModule( new ConfigurationSettingsReader(“autofac”

));

using

(var container = builder.Build())

{

var manager = container.Resolve();

manager.Search(
“SELECT * FORM USER”

);

}

运行结果:

7)另外还有一种方式,通过Register方法进行注册:

var builder = new

ContainerBuilder();

//builder.RegisterType();

builder.RegisterModule(new ConfigurationSettingsReader(“autofac”

));

builder.Register(c =>
new

DatabaseManager(c.Resolve()));

using

(var container = builder.Build())

{

var manager = container.Resolve();

manager.Search(
“SELECT * FORM USER”

);

}

得到的结果也是一样的。

8)现在我想通过一个用户类来控制操作权限,比如增删改的权限,创建一个用户类:

///<summary>///

Id Identity Interface

///</summary>publicinterface

Identity

{

int Id { get; set

; }

}

publicclass

User : Identity

{

publicint Id { get; set

; }

publicstring Name { get; set

; }

}

修改DatabaseManager.cs代码:

publicclass

DatabaseManager

{

IDatabase _database;

User _user;

public DatabaseManager(IDatabase database) : this(database, null

)

{

}

public

DatabaseManager(IDatabase database, User user)

{

_database = database;

_user = user;

}

///<summary>///

Check Authority

///</summary>///<returns></returns>publicbool

IsAuthority()

{

bool result = _user != null && _user.Id == 1 && _user.Name == “leepy” ? true : false

;

if

(!result)

Console.WriteLine(
“Not authority!”

);

return

result;

}

publicvoid Search(string

commandText)

{

_database.Select(commandText);

}

publicvoid Add(string

commandText)

{

if

(IsAuthority())

_database.Insert(commandText);

}

publicvoid Save(string

commandText)

{

if

(IsAuthority())

_database.Update(commandText);

}

publicvoid Remove(string

commandText)

{

if

(IsAuthority())

_database.Delete(commandText);

}

}

在构造函数中增加了一个参数User,而Add,Save,Remove增加了权限判断。

修改客户端程序:

User user = new User { Id = 1, Name = “leepy”

};

var builder = new

ContainerBuilder();

builder.RegisterModule(
new ConfigurationSettingsReader(“autofac”

));

builder.RegisterInstance(user).As();

builder.Register(c =>
new

DatabaseManager(c.Resolve(), c.Resolve()));

using

(var container = builder.Build())

{

var manager = container.Resolve();

manager.Add(
“INSERT INTO USER …”

);

}

运行结果:

分析:

builder.RegisterInstance(user).As<User>();注册User实例。

builder.Register(c => new DatabaseManager(c.Resolve<IDatabase>(), c.Resolve<User>()));通过Lampda表达式注册DatabaseManager实例。

如果这里我修改User的属性值:

User user = new User { Id = 2, Name = “zhangsan” };

运行结果:

说明该用户无权限操作。

源代码下载:https://files.cnblogs.com/liping13599168/AutofacDemo.rar

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