IoC(2)

依赖注入

常用：构造方法注入、setter注入
注意：实例注入和静态工厂注入

构造方法注入

构造方法可以根据参数索引、参数类型、参数名注入(有限制)或者使用@ConstructorProperties在构造方法上来指定参数名

HelloImpl.java

package com.hello.dao.Impl;import java.beans.ConstructorProperties;import com.hello.dao.HelloDao;public class HelloImpl implements HelloDao{private int id;private String password;//@ConstructorProperties(value = { "id","password" })    public HelloImpl(int id,String password) {    this.id=id;    this.password=password;}@Overridepublic void sayHello() {    System.out.println("id:"+id+"/password:"+password);}}

applicationContext.xml

       <!--id为组件名 class为组件类  -->       <bean id="byIndex" class="com.hello.dao.Impl.HelloImpl">       <!--index为索引从0开始  -->       <constructor-arg index="0" value="1"></constructor-arg>       <constructor-arg index="1" value="111"></constructor-arg>       </bean>       <!--除了基本类型以外 其余必须填写全限定类名  -->       <bean id="byType" class="com.hello.dao.Impl.HelloImpl">       <constructor-arg type="int" value="2"></constructor-arg>       <constructor-arg type="java.lang.String" value="222"></constructor-arg>       </bean>       <!--构造函数的参数名  -->       <bean id="byName" class="com.hello.dao.Impl.HelloImpl">       <constructor-arg name="id" value="3"></constructor-arg>       <constructor-arg name="password" value="333"></constructor-arg>            </bean>

HelloTest.java

package com.test;import junit.framework.TestCase;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;import com.hello.dao.HelloDao;public class HelloTest extends TestCase {public void testHelloWorld(){//实例化IoC容器ApplicationContext context =new ClassPathXmlApplicationContext("applicationContext.xml");//获取bean 这里是实现接口HelloDao helloDao1=context.getBean("byIndex",HelloDao.class);HelloDao helloDao2=context.getBean("byType",HelloDao.class);HelloDao helloDao3=context.getBean("byName",HelloDao.class);//执行业务helloDao1.sayHello();helloDao2.sayHello();helloDao3.sayHello();}}

setter注入

对Bean类的setter方法进行注入

HelloImpl.java

package com.hello.dao.Impl;import com.hello.dao.HelloDao;public class HelloImpl implements HelloDao{private int id;private String password;@Overridepublic void sayHello() {    System.out.println("id:"+id+"/password:"+password);}public void setId(int id) {this.id = id;}public void setPassword(String password) {this.password = password;}}

applicationContext.xml

       <!--id为组件名 class为组件类  -->       <bean id="bySet" class="com.hello.dao.Impl.HelloImpl">       <!--setId()则name为id  -->       <property name="id"><value>4</value></property>       <property name="password" value="444"></property>       </bean>

HelloTest.java

package com.test;import junit.framework.TestCase;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;import com.hello.dao.HelloDao;public class HelloTest extends TestCase {public void testHelloWorld(){//实例化IoC容器ApplicationContext context =new ClassPathXmlApplicationContext("applicationContext.xml");//获取bean 这里是实现接口HelloDao helloDao1=context.getBean("bySet",HelloDao.class);//执行业务helloDao1.sayHello();}}

常量注入

       <property name="id"><value>4</value></property>       <property name="password" value="444"></property>

两种写法均可以,第二种较为简洁

value中的是字符串,IoC容器会自动进行类型转换,如果类型转换出错则抛出异常

注意:对于String转boolean,Spring有容错机制"true/false"可以写成"yes/no"、“on/off”、“1/0”

集合数组字典properties注入

• 集合

ListBean.java

package com.list;import java.util.List;public class ListBean {private List<String> list;public int listLength(){return this.list.size();}public List<String> getList() {return list;}public void setList(List<String> list) {this.list = list;}}

application.xml

       <bean id="listBean" class="com.list.ListBean">        <!--name依然为set注入  -->        <property name="list">        <!-- 1 value-type指定条目的数据类型 -->        <!-- 2 Spring会根据泛型指定条目的数据类型 -->        <!-- 3 若没有value-type也没有泛型,则默认为String类型 -->         <list value-type="java.lang.String">           <value>!1!</value>           <value>!2!</value>           <value>!3!</value>         </list>        </property>       </bean>

Test.java

package com.test;import junit.framework.TestCase;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;import com.hello.dao.HelloDao;import com.list.ListBean;public class Test extends TestCase{public void testBean(){//实例化IoC容器ApplicationContext context =new ClassPathXmlApplicationContext("applicationContext.xml");//获取bean 这里是实现接口ListBean listBean=context.getBean("listBean",ListBean.class);//执行业务System.out.println(listBean.listLength());}}

set类型注入是xml中需要用<set>替换<list>,用法和list一样

而collection则<set>和<list>都能使用

• 数组

• map

properties

Bean的引用

可以通过构造方法注入和setter注入引用其他Bean

1. <constructor-arg index="0" value="1">和<span style="font-family: Arial, Helvetica, sans-serif; font-size: 12px;"><property name="password" value="444">用bean属性替换value属性,bean属性填写别的bean的id或者别名</span>

2. 用<ref bean="">替换<value>,<span style="font-family: Arial, Helvetica, sans-serif; font-size: 12px;">bean属性填写别的bean的id或者别名</span>

其他方式的引用

<ref local="">和<ref parent="">

1. <ref local="">引用的是当前配置文件中用id属性(不会找name和别名)指定的bean即<bean id="">,找不到则抛出异常
2. <ref parent="">查找父容器不会查找本地容器

HelloImpl.java

package com.hello.dao.Impl;import com.hello.dao.HelloDao;public class HelloImpl implements HelloDao{private HelloParent helloParent;private HelloLocal helloLocal;@Overridepublic void sayHello() {System.out.println("parent=name:"+helloParent.getName()+";msg:"+helloParent.getMsg());System.out.println("local=name:"+helloLocal.getName()+";msg:"+helloLocal.getMsg());}public HelloParent getHelloParent() {return helloParent;}public void setHelloParent(HelloParent helloParent) {this.helloParent = helloParent;}public HelloLocal getHelloLocal() {return helloLocal;}public void setHelloLocal(HelloLocal helloLocal) {this.helloLocal = helloLocal;}}

applicationContextParent.xml

       <!--父容器 bean  -->       <bean id="beanParent" class="com.hello.dao.Impl.HelloParent">        <!--name依然为set注入  -->        <property name="name" value="parent"></property>        <property name="msg" value="hello this is parent"/>       </bean>

applicationContext.xml

       <!--id为组件名 class为组件类  -->       <bean id="byRefPandL" class="com.hello.dao.Impl.HelloImpl">        <!--name依然为set注入  -->        <property name="helloParent"><ref parent="beanParent"/> </property>        <property name="helloLocal"><ref local="beanLocal"/></property>       </bean>              <!--本地容器 bean  -->       <bean id="beanParent" class="com.hello.dao.Impl.HelloParent">        <!--name依然为set注入  -->        <property name="name" value="parent"/>        <property name="msg" value="hello this is Local"/>       </bean>        <bean id="beanLocal" class="com.hello.dao.Impl.HelloLocal">        <!-- name依然为set注入 -->         <property name="name" value="local"/>        <property name="msg" value="hello this is Local"/>       </bean>

ParentLocalTest.java

package com.test;import junit.framework.TestCase;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;import com.hello.dao.HelloDao;public class ParentLocalTest extends TestCase {public void testHelloWorld(){//实例化IoC容器ApplicationContext parentContext =new ClassPathXmlApplicationContext("applicationContextParent.xml");ApplicationContext context=new ClassPathXmlApplicationContext(new String[]{"applicationContext.xml"}, parentContext);//获取bean 这里是实现接口HelloDao helloDao1=context.getBean("byRefPandL",HelloDao.class);//执行业务helloDao1.sayHello();}}