Spring.NET学习笔记(2)依赖注入细节

    你会发现学一个灵活的框架，往往是在学一些概念，而这些概念的技术构成都是基于xml的，就导致了我们得对着一堆的xml来看.试着配置完成让框架来解析。

1.构造注入细节constructor-arg

(1)与类构造函数参数一一对应原则，既然注入，肯定需要知道构造函数的参数

构造注入的关键字

<object id="foo" type="X.Y.Foo, Example">
  <constructor-arg ref="bar"/>
  <constructor-arg ref="baz"/>
</object>

<object id="bar" type="X.Y.Bar, Example"/>
<object id="baz" type="X.Y.Baz, Example"/>

(3)相关attribute

index指定参数索引
ref指定参数引用

<object id="rod2" type="Spring.Objects.Factory.Xml.ConstructorDependenciesObject, Spring.Core.Tests"
    autowire="constructor">
    <constructor-arg index="1" ref="kerry1"/>
    <constructor-arg index="0" ref="kerry2"/>
    <constructor-arg ref="other"/>
</object>

type显示指定参数类型
value指定简单类型值
name按参数命名指定

<object id="objectWithCtorArgValueShortcuts" type="Spring.Objects.TestObject, Spring.Core.Tests"
    singleton="false">
    <constructor-arg name="name" type="string" value="Rick" />
    <constructor-arg name="age" type="int" value="30" />
</object>

2.属性注入property
 

与上面相似

3.直接属性写法

也可称为嵌套属性,特别是集合属性，是必须要这么写的，这也是xml标记写法的缺陷。只要去理解xml的特性就能理解其写法.

<constructor-arg type="bool" value="true"/>

<constructor-arg type="bool">
  <value>true</value>
</constructor-arg>

<property name="target">
  <object type="ExampleApp.Person, ExampleApp">
    <property name="name" value="Tony"/>
    <property name="age" value="51"/>
  </object>
</property>

<property name="myProperty">
  <value>hello</value>
</property>
<constructor-arg>
  <value>hello</value>
</constructor-arg>
<entry key="myKey">
  <value>hello</value>
</entry>

<property name="myProperty" value="hello"/>
<constructor-arg value="hello"/>
<entry key="myKey" value="hello"/>

4.集合属性(list, set, name-values and dictionary)

<property name="SomeList">
  <list>
    <value>a list element followed by a reference</value>
    <ref object="myConnection"/>
  </list>
</property>
<!--
  results in a call to the setter of the SomeDictionary (System.Collections.IDictionary) property
  -->
<property name="SomeDictionary">
  <dictionary>
    <entry key="a string => string entry" value="just some string"/>
    <entry key-ref="myKeyObject" value-ref="myConnection"/>
  </dictionary>
</property>
<!--
  results in a call to the setter of the SomeNameValue (System.Collections.NameValueCollection) property
  -->
<property name="SomeNameValue">
  <name-values>
    <add key="HarryPotter" value="The magic property"/>
    <add key="JerrySeinfeld" value="The funny (to Americans) property"/>
  </name-values>
</property>
<!-- 
  results in a call to the setter of the SomeSet (Spring.Collections.ISet) property 
  -->
<property name="someSet">
  <set>
    <value>just some string</value>
    <ref object="myConnection"/>
  </set>
</property>

4.1泛型集合支持

public class GenericExpressionHolder
   {
       private System.Collections.Generic.IList<IExpression> expressionsList;
       private System.Collections.Generic.IDictionary<string, IExpression> expressionsDictionary;

       public System.Collections.Generic.IList<IExpression> ExpressionsList
       {
           set { this.expressionsList = value; }
       }

       public System.Collections.Generic.IDictionary<string,IExpression> ExpressionsDictionary
       {
           set { this.expressionsDictionary = value; }
       }

       public IExpression this[int index]
       {
           get { return this.expressionsList[index]; }
       }

       public IExpression this[string key]
       {
           get { return this.expressionsDictionary[key]; }
       }
   }

<object id="genericExpressionHolder" type="Spring.Objects.Factory.Xml.GenericExpressionHolder, Spring.Core.Tests">
  <property name="ExpressionsList">
    <list element-type="Spring.Expressions.IExpression, Spring.Core">
      <value>1 + 1</value>
      <value>date('1974-8-24').Month</value>
      <value>'Aleksandar Seovic'.ToUpper()</value>
      <value>DateTime.Today > date('1974-8-24')</value>
    </list>
  </property>
  <property name="ExpressionsDictionary">
    <dictionary key-type="string" value-type="Spring.Expressions.IExpression, Spring.Core">
      <entry key="0">
        <value>1 + 1</value>
      </entry>
      <entry key="1">
        <value>date('1974-8-24').Month</value>
      </entry>
      <entry key="2">
        <value>'Aleksandar Seovic'.ToUpper()</value>
      </entry>
      <entry key="3">
        <value>DateTime.Today > date('1974-8-24')</value>
      </entry>
    </dictionary>
  </property>
</object>

4.2集合合并

<object id="parent" abstract="true" type="Example.ComplexObject, Examples">
  <property name="AdminEmails">
    <name-values>
      <add key="administrator" value="administrator@example.com"/>
      <add key="support" value="support@example.com"/>
    </name-values>
  </property>
</object>

<object id="child" parent="parent" >
  <property name="AdminEmails">
    <!-- the merge is specified on the *child* collection definition -->
    <name-values merge="true">
      <add key="sales" value="sales@example.com"/>
      <add key="support" value="support@example.co.uk"/>
    </name-values>
  </property>
</object>

结果是
administrator=administrator@example.com
sales=sales@example.com
support=support@example.co.uk

5.空字符串值与Null

注意不同概念

<object type="Examples.ExampleObject, ExamplesLibrary">
  <property name="email" value=""/>
  <property name="email">
    <null/>
  </property>
</object>