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Spring属性注入、构造方法注入、工厂注入以及注入参数（转）

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12/02
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Spring 是一个开源框架.

Spring 为简化企业级应用开发而生（对比EJB2.0来说）. 使用 Spring 可以使简单的 JavaBean 实现以前只有 EJB 才能实现的功能。
Spring 是一个 IOC(DI) 和 AOP 容器框架。

具体描述 Spring:
轻量级：Spring 是非侵入性的 - 基于 Spring 开发的应用中的对象可以不依赖于 Spring 的 API
控制反转（依赖注入） (IOC----inverse of control 、DI --- dependency injection)
面向切面编程(AOP --- aspect oriented programming)
容器: Spring 是一个容器, 因为它包含并且管理应用对象的生命周期
框架: Spring 实现了使用简单的组件配置组合成一个复杂的应用. 在 Spring 中可以使用 XML 和 Java 注解组合这些对象
一站式：在 IOC 和 AOP 的基础上可以整合各种企业应用的开源框架和优秀的第三方类库 （实际上 Spring 自身也提供了展现层的 SpringMVC 和 持久层的 Spring JDBC）

所需jar包

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<? xml version="1.0" encoding="UTF-8"?>
< beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd">
< bean name="dog" class="com.zhiqi.entity.Dog"></ bean >
</ beans >

装配一个Bean

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package com.zhiqi.entity;
public class Dog {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this .name = name;
}
}

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package com.zhiqi.test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.zhiqi.entity.Dog;
public class T {
public static void main(String[] args) {
ApplicationContext ac= new ClassPathXmlApplicationContext( "beans.xml" );
Dog dog=(Dog)ac.getBean( "dog" );
System.out.println(dog.getName());
}
}

此时装配了Dog这个类，但是为null

需要进行依赖注入（属性注入、构造方法注入，工厂注入）

1、属性注入：

装配一个员工类

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package com.zhiqi.entity;
public class Employee {
private int id;
private String name;
private String sex;
public int getId() {
return id;
}
public void setId( int id) {
this .id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this .name = name;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this .sex = sex;
}
}

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package com.zhiqi.test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.zhiqi.entity.Dog;
import com.zhiqi.entity.Employee;
public class T {
public static void main(String[] args) {
ApplicationContext ac= new ClassPathXmlApplicationContext( "beans.xml" );
Employee employee=(Employee)ac.getBean( "employee" );
System.out.println(employee.getName());
}
}

属性注入如下：<property name="" value=""></property>

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< bean name="employee" class="com.zhiqi.entity.Employee">
< property name="id" value="10050"></ property >
< property name="name" value="小鲜肉"></ property >
< property name="sex" value="男"></ property >
</ bean >

构造方法注入一（通过类型）：<constructor-arg type="" value=""></constructor-arg>

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< bean name="employee" class="com.zhiqi.entity.Employee">
< constructor-arg type="int" value="10010"></ constructor-arg >
< constructor-arg type="String" value="小萝莉"></ constructor-arg >
< constructor-arg type="String" value="女"></ constructor-arg >
</ bean >

此时需要写构造函数否则会报错：

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public class Employee {
private int id;
private String name;
private String sex;
public Employee() {
super ();
// TODO Auto-generated constructor stub
}
public Employee( int id, String name, String sex) {
super ();
this .id = id;
this .name = name;
this .sex = sex;
}
}

构造方法注入二（通过索引）：<constructor-arg index="" value=""></constructor-arg>   索引从0开始

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< bean name="employee" class="com.zhiqi.entity.Employee">
< constructor-arg index="0" value="10010"></ constructor-arg >
< constructor-arg index="1" value="小萝莉"></ constructor-arg >
< constructor-arg index="2" value="女"></ constructor-arg >
</ bean >

可以混合使用　类型+索引

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< bean name="employee" class="com.zhiqi.entity.Employee">
< constructor-arg type="int" index="0" value="10010"></ constructor-arg >
< constructor-arg type="String" index="1" value="小萝莉"></ constructor-arg >
< constructor-arg type="String" index="2" value="女"></ constructor-arg >
</ bean >

通过工厂注入：<bean name="employee" factory-bean="" factory-method=""></bean>

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package com.zhiqi.factory;
import com.zhiqi.entity.Employee;
public class EmployeeFactory {
public Employee createEmployee(){
Employee employee= new Employee();
employee.setId( 10080 );
employee.setName( "小霸王" );
employee.setSex( "男" );
return employee;
}
}

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<? xml version="1.0" encoding="UTF-8"?>
< beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd">
< bean name="dog" class="com.zhiqi.entity.Dog"></ bean >
< bean name="employeeFactory" class="com.zhiqi.factory.EmployeeFactory"></ bean >
< bean name="employee" factory-bean="employeeFactory" factory-method="createEmployee"></ bean >
</ beans >

通过静态工厂注入：

注入参数：

1、基本类型值

2、注入bean

3、内部bean

4、null值

5、级联属性

6、集合注入（List、Set、Map）

员工有一辆车

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< bean id="employee" class="com.zhiqi.entity.Employee">
< property name="id" value="10060"></ property >
< property name="name" value="脑残粉"></ property >
< property name="sex" value="女"></ property >
< property name="car" ref="car"></ property >
</ bean >
< bean id="car" class="com.zhiqi.entity.Car">
< property name="name" value="别克"></ property >
</ bean >

一辆车只属于某员工，内部bean

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< bean id="employee" class="com.zhiqi.entity.Employee">
< property name="id" value="10060"></ property >
< property name="name" value="脑残粉"></ property >
< property name="sex" value="女"></ property >
< property name="car">
< bean class="com.zhiqi.entity.Car">
< property name="name" value="雪佛兰"></ property >
</ bean >
</ property >
</ bean >

有一个员工没有车

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< bean id="employee" class="com.zhiqi.entity.Employee">
< property name="id" value="10060"></ property >
< property name="name" value="脑残粉"></ property >
< property name="sex" value="女"></ property >
< property name="car">
< null ></ null >
</ property >
</ bean >

级联

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< bean id="employee" class="com.zhiqi.entity.Employee">
< property name="id" value="10060"></ property >
< property name="name" value="脑残粉"></ property >
< property name="sex" value="女"></ property >
< property name="car.name" value="好车"></ property >
</ bean >

此时在Car中new一个

一个员工有多个girlFriend

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private int id;
private String name;
private String sex;
private Car car;
private List<String> girlFriend= new ArrayList<String>();

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<? xml version="1.0" encoding="UTF-8"?>
< beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd">
< bean id="employee" class="com.zhiqi.entity.Employee">
< property name="id" value="10060"></ property >
< property name="name" value="脑残粉"></ property >
< property name="sex" value="女"></ property >
< property name="car" value="宾利"></ property >
< property name="girlFriend">
< list >
< value >琪琪</ value >
< value >丽丽</ value >
< value >小莫</ value >
</ list >
</ property >
</ bean >
</ beans >

一个员工有多套房子

private Set<String> house=new HashSet<String>();

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<?xml version= "1.0" encoding= "UTF-8" ?>
<beans xmlns= "http://www.springframework.org/schema/beans"
xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http: //www.springframework.org/schema/beans
http: //www.springframework.org/schema/beans/spring-beans.xsd">
<bean id= "employee" class = "com.zhiqi.entity.Employee" >
<property name= "id" value= "10060" ></property>
<property name= "name" value= "脑残粉" ></property>
<property name= "sex" value= "女" ></property>
<property name= "car" value= "宾利" ></property>
<property name= "girlFriend" >
<list>
<value>琪琪</value>
<value>丽丽</value>
<value>小莫</value>
</list>
</property>
<property name= "house" >
<set>
<value>房子 1 </value>
<value>别墅 2 </value>
</set>
</property>
</bean>
</beans>

一个员工的工作

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<? xml version="1.0" encoding="UTF-8"?>
< beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd">
< bean id="employee" class="com.zhiqi.entity.Employee">
< property name="id" value="10060"></ property >
< property name="name" value="脑残粉"></ property >
< property name="sex" value="女"></ property >
< property name="car" value="宾利"></ property >
< property name="girlFriend">
< list >
< value >琪琪</ value >
< value >丽丽</ value >
< value >小莫</ value >
</ list >
</ property >
< property name="house">
< set >
< value >房子1</ value >
< value >别墅2</ value >
</ set >
</ property >
< property name="works">
< map >
< entry >
< key >< value >上午</ value ></ key >
< value >撸代码</ value >
</ entry >
< entry >
< key >< value >下午</ value ></ key >
< value >找BUG</ value >
</ entry >
</ map >
</ property >
</ bean >
</ beans >

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package com.zhiqi.test;
import java.util.Iterator;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.zhiqi.entity.Employee;
public class T {
public static void main(String[] args) {
ApplicationContext ac= new ClassPathXmlApplicationContext( "beans.xml" );
Employee employee=(Employee)ac.getBean( "employee" );
for (String str:employee.getHouse()){
System.out.println(str);
}
//entrySet()将map转为set，然后迭代器遍历
Iterator it=employee.getWorks().entrySet().iterator();
while (it.hasNext()){
System.out.println(it.next());
}
}
}

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