Spring（1）：配置文件（IOC）与Annotation的使用（上集）

日期：2017/12/9

       spring是目前最流行的java开源框架。很容易可以知道，它整合了7大组件（spring mvc + spring web + spring aop + spring orm + spring core + spring dao + spring content）如何进行开发呢？下载了 spring-framework-4.1.3.BUILD-SNAPSHOT-dist.zip 后解压，可以查看官方文档：Spring Framework Reference Documentation。

       学习spring，不能一脑瓜子的直接copy他人的配置文件，否则会给各个配置文件搞得神魂颠倒，出了问题还一头雾水。通过阅读官方文档，对整个spring框架的主体有了个清晰的把握，开发起来更加得心应手。

1.常规注入（DI）： （1）需要在类里面 声明一个成员变量，并且写了一个它的setter方法。这样框架底层才能读取成员变量，并且在配置文件中注入。

                               （2）利用了类名的反射方式，创建类。class必须具体到包下的类（全类名）；

                               （3）由于使用了反射机制，因此，凡是利用bean配置的类都要设置一个无参构造器；

2.<beans></beans>包含多个<bean></bean>；

3.<bean id=“ ” class=“ ”></bean>，里面可以加入<propertities></propertities>元素。

例子：

三个.java 文件：

（1）Address.java

package com.spring.beans.autowire;public class Address {private String province;private String city;public String getProvince() {return province;}public void setProvince(String province) {this.province = province;}public String getCity() {return city;}public void setCity(String city) {this.city = city;}@Overridepublic String toString() {return "Address [province=" + province + ", city=" + city + "]";}public Address(String province, String city) {super();this.province = province;this.city = city;}public Address() {super();// TODO 自动生成的构造函数存根}}

（2）Car.java

package com.spring.beans.autowire;public class Car {private String brand;private String number;public String getBrand() {return brand;}public void setBrand(String brand) {this.brand = brand;}public String getNumber() {return number;}public void setNumber(String number) {this.number = number;}@Overridepublic String toString() {return "Car [brand=" + brand + ", number=" + number + "]";}public Car(String brand, String number) {super();this.brand = brand;this.number = number;}public Car() {super();// TODO 自动生成的构造函数存根}}

（3）Person .java

package com.spring.beans.autowire;public class Person {private String name;private Car car;private Address address;public String getName() {return name;}public void setName(String name) {this.name = name;}public Car getCar() {return car;}public void setCar(Car car) {this.car = car;}public Address getAddress() {return address;}public void setAddress(Address address) {this.address = address;}@Overridepublic String toString() {return "Person [name=" + name + ", car=" + car + ", address=" + address + "]";}public Person(String name, Car car, Address address) {super();this.name = name;this.car = car;this.address = address;}

public Person() {super();// TODO 自动生成的构造函数存根}}

（4）spring_autowire.xml

<?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="car" class="com.spring.beans.autowire.Car"></bean><bean id="address" class="com.spring.beans.autowire.Address"></bean><bean id="person" class="com.spring.beans.autowire.Person"><property name="address" ref="address"></property><property name="car" ref="car"></property><property name="name" value="mmb"></property></bean></beans>