spring的i o c简单回顾
1.springIOC是一个创建对象的容器,他负责将我们需要的对象帮我们创建出来,创建时间是:当我们从上下文环境中读取此对象时就会帮我们创建,严格意义上来讲它是一种编程思想不是一种技术。
2.依赖注入:对象中有引用其他对象,但只是声明(依赖),并没有创建,创建是交给spring的IOC容器去帮我们做的,当我们调用此对象时spring就会创建好给我们(注入)。
1)构造器id注入:
package x.y; public class ThingOne { public ThingOne(ThingTwo thingTwo, ThingThree thingThree) { // ... } } <beans> <bean id="beanOne" class="x.y.ThingOne"> <constructor-arg ref="beanTwo"/> <constructor-arg ref="beanThree"/> </bean> <bean id="beanTwo" class="x.y.ThingTwo"/> <bean id="beanThree" class="x.y.ThingThree"/> </beans>
2)构造器参数类型注入:
package examples; public class ExampleBean { // Number of years to calculate the Ultimate Answer private int years; // The Answer to Life, the Universe, and Everything private String ultimateAnswer; public ExampleBean(int years, String ultimateAnswer) { this.years = years; this.ultimateAnswer = ultimateAnswer; } } <bean id="exampleBean" class="examples.ExampleBean"> <constructor-arg type="int" value="7500000"/> <constructor-arg type="java.lang.String" value="42"/> </bean>
3)按照带参构造器,参数下标注入:
<bean id="exampleBean" class="examples.ExampleBean">
<constructor-arg index="0" value="7500000"/>
<constructor-arg index="1" value="42"/>
</bean>
4)按照构造器参数名称注入:
<bean id="exampleBean" class="examples.ExampleBean">
<constructor-arg name="years" value="7500000"/>
<constructor-arg name="ultimateAnswer" value="42"/>
</bean>
1)通过set方法给成员赋值:
public class ExampleBean { private AnotherBean beanOne; private YetAnotherBean beanTwo; private int i; public void setBeanOne(AnotherBean beanOne) { this.beanOne = beanOne; } public void setBeanTwo(YetAnotherBean beanTwo) { this.beanTwo = beanTwo; } public void setIntegerProperty(int i) { this.i = i; } } <bean id="exampleBean" class="examples.ExampleBean"> <!-- setter injection using the nested ref element --> <property name="beanOne"> <ref bean="anotherExampleBean"/> </property> <!-- setter injection using the neater ref attribute --> <property name="beanTwo" ref="yetAnotherBean"/> <property name="integerProperty" value="1"/> </bean>
1)通过静态工厂方式创建对象:
public class ExampleBean { // a private constructor private ExampleBean(...) { ... } // a static factory method; the arguments to this method can be // considered the dependencies of the bean that is returned, // regardless of how those arguments are actually used. public static ExampleBean createInstance ( AnotherBean anotherBean, YetAnotherBean yetAnotherBean, int i) { ExampleBean eb = new ExampleBean (...); // some other operations... return eb; } } <bean id="exampleBean" class="examples.ExampleBean" factory-method="createInstance"> <constructor-arg ref="anotherExampleBean"/> <constructor-arg ref="yetAnotherBean"/> <constructor-arg value="1"/> </bean>
2).通过动态工厂方式创建对象:
//和静态工厂方式一样,不过没有被调用的方法上static而已,这里是创建了一个apache包下的一个类
<bean id="myDataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close"> <!-- results in a setDriverClassName(String) call --> <property name="driverClassName" value="com.mysql.jdbc.Driver"/> <property name="url" value="jdbc:mysql://localhost:3306/mydb"/> <property name="username" value="root"/> <property name="password" value="masterkaoli"/> </bean>
1)通过命名空间 p标签创建:实际是用set方法去创建的:
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <bean id="myDataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close" p:driverClassName="com.mysql.jdbc.Driver" p:url="jdbc:mysql://localhost:3306/mydb" p:username="root" p:password="masterkaoli"/> </beans>
2)通过命名空间的 “c” 标签去创建:实际是通过构造器去创建的(对应的无参和带参的):
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:c="http://www.springframework.org/schema/c" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <bean id="beanTwo" class="x.y.ThingTwo"/> <bean id="beanThree" class="x.y.ThingThree"/> <!-- traditional declaration with optional argument names --> <bean id="beanOne" class="x.y.ThingOne"> <constructor-arg name="thingTwo" ref="beanTwo"/> <constructor-arg name="thingThree" ref="beanThree"/> <constructor-arg name="email" value="something@somewhere.com"/> </bean> <!-- c-namespace declaration with argument names --> <bean id="beanOne" class="x.y.ThingOne" c:thingTwo-ref="beanTwo" c:thingThree-ref="beanThree" c:email="something@somewhere.com"/> </beans>
1)map:
public class SomeClass {
private Map<String, Float> accounts;
public void setAccounts(Map<String, Float> accounts) {
this.accounts = accounts;
}
}
<beans>
<bean id="something" class="x.y.SomeClass">
<property name="accounts">
<map>
<entry key="one" value="9.99"/>
<entry key="two" value="2.75"/>
<entry key="six" value="3.99"/>
</map>
</property>
</bean>
</beans>
1)property:
<beans> <bean id="parent" abstract="true" class="example.ComplexObject"> <property name="adminEmails"> <props> <prop key="administrator">administrator@example.com</prop> <prop key="support">support@example.com</prop> </props> </property> </bean> <bean id="child" parent="parent"> <property name="adminEmails"> <!-- the merge is specified on the child collection definition --> <props merge="true"> <prop key="sales">sales@example.com</prop> <prop key="support">support@example.co.uk</prop> </props> </property> </bean> <beans>
1)list, set, map, property:
<bean id="moreComplexObject" class="example.ComplexObject">
<!-- results in a setAdminEmails(java.util.Properties) call -->
<property name="adminEmails">
<props>
<prop key="administrator">administrator@example.org</prop>
<prop key="support">support@example.org</prop>
<prop key="development">development@example.org</prop>
</props>
</property>
<!-- results in a setSomeList(java.util.List) call -->
<property name="someList">
<list>
<value>a list element followed by a reference</value>
<ref bean="myDataSource" />
</list>
</property>
<!-- results in a setSomeMap(java.util.Map) call -->
<property name="someMap">
<map>
<entry key="an entry" value="just some string"/>
<entry key ="a ref" value-ref="myDataSource"/>
</map>
</property>
<!-- results in a setSomeSet(java.util.Set) call -->
<property name="someSet">
<set>
<value>just some string</value>
<ref bean="myDataSource" />
</set>
</property>
</bean>
本文来自博客园,作者:~~mr.li~~,转载请注明原文链接:https://www.cnblogs.com/li-yan-long/p/10527703.html