(四)SpringIoc之Bean装配
- 在pom.xml的依赖
<dependencies>
<!--测试包-->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<scope>test</scope>
<version>4.11</version>
</dependency>
<!--spring 上下文-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>4.3.0.RELEASE</version>
</dependency>
<!--织入包-->
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
<version>1.8.9</version>
</dependency>
<!--高速代理生成包-->
<dependency>
<groupId>cglib</groupId>
<artifactId>cglib</artifactId>
<version>3.2.4</version>
</dependency>
</dependencies>
2.创建实体类Person和Computer两个实体类
package com.qf.pojo;
public class Computer {
String disk;
String cpu;
String memory;
String gpu;
public Computer() {
System.out.println("空参构造");
}
public Computer(String disk, String cpu, String memory, String gpu) {
this.disk = disk;
this.cpu = cpu;
this.memory = memory;
this.gpu = gpu;
}
public String getDisk() {
return disk;
}
public void setDisk(String disk) {
this.disk = disk;
}
public String getCpu() {
return cpu;
}
public void setCpu(String cpu) {
this.cpu = cpu;
}
public String getMemory() {
return memory;
}
public void setMemory(String memory) {
this.memory = memory;
}
public String getGpu() {
return gpu;
}
public void setGpu(String gpu) {
this.gpu = gpu;
}
@Override
public String toString() {
return "Computer{" +
"disk='" + disk + '\'' +
", cpu='" + cpu + '\'' +
", memory='" + memory + '\'' +
", gpu='" + gpu + '\'' +
'}';
}
}
package com.qf.pojo;
import java.util.List;
public class Person {
String name;
int age;
Computer computer;
List<String> girlFriend;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public Computer getComputer() {
return computer;
}
public void setComputer(Computer computer) {
this.computer = computer;
}
public List<String> getGirlFriend() {
return girlFriend;
}
public void setGirlFriend(List<String> girlFriend) {
this.girlFriend = girlFriend;
}
@Override
public String toString() {
return "Person{" +
"name='" + name + '\'' +
", age=" + age +
", computer=" + computer +
", girlFriend=" + girlFriend +
'}';
}
}
3.配置spring-config.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">
<!--Id和name：使用基本一致，name允许有一些特殊字符，name和id都唯一-->
<!--scope默认为singleton-->
<!--如果是属性注入，需要为每一个依赖类创建相应的getter和setter方法
-->
<!--属性装配-->
<bean class="com.qf.pojo.Computer" name="myComputer" scope="prototype" id="computer1">
<property name="disk" value="i7 7700HQ"></property>
<property name="memory" value="16GB"></property>
<property name="cpu" value="256G SSD 1TB"></property>
<property name="gpu" value="NVIDIA 1060"></property>
</bean>
<!--构造装配，Computer必须有有参构造和无参构造-->
<bean class="com.qf.pojo.Computer" name="computer">
<constructor-arg name="cpu" value="i9 9700HQ"></constructor-arg>
<constructor-arg name="disk" value="512G SSD"></constructor-arg>
<constructor-arg name="gpu" value="NVIDIA 2080"></constructor-arg>
<constructor-arg name="memory" value="64G"></constructor-arg>
</bean>
<!--自动装配autowire，默认按byType自动装配-->
<!--下面没有装配Computer，autowire会自动装配-->
<bean class="com.qf.pojo.Person" name="zhangsan" autowire="byName">
<property name="name" value="张三"></property>
<property name="age" value="18"></property>
<property name="girlFriend">
<!--集合装配-->
<list>
<value>小娜</value>
<value>小莎</value>
<value>小琪</value>
</list>
</property>
</bean>
</beans>
自动装配
- byName:通过
反射到Person类，找到没有装配的Computer computer,根据computer和每个bean的name/id匹配，相同就装配，如果没有相同的就抛出异常。 - byType：通过
反射到Person类，找到没有装配的Computer属性， 按Bean的包名.class的class来匹配的，如果有多个class相同抛异常。 - autowired按byType自动注入.
4.创建测试类TestSpringIoc
public class TestSpringIoc {
public static void main(String[] args) {
<!--可以初始化多个xml-->
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("spring-ioc.xml");
Computer computer1 =(Computer)context.getBean("computer1");
System.out.println(computer1);
Person person = (Person)context.getBean("zhangsan",Person.class);
System.out.println(person);
}
}
集合装配：如果对应bean的属性是一个集合则需要使用集合装配，Spring支持多种集合装配类型：
- 对应类型为java.util.List、java.util.Vector 、java.util.Collection 、数组的属性
对应类型为java.util.Set的属性 对应类型为java.util.Properties的属性
示例
<!--List装配：-->
<property name=“list">
<list>
<value>a</value>
<value>b</value>
</list>
</property>
<!--Set装配：(HashSet如何去重复,hashCode)-->
<property name=“set">
<set>
<value>a</value>
<value>b</value>
</set>
</property>
<!--Map装配：-->
<property name=“map">
<map>
<entry key="1" value=“a"></entry>
<entry key="2" value=“b"></entry>
</map>
</property>
Annotation注解模式实现装配
1.修改spring-ioc.xml文件
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
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
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
<!--声明使用注解开发-->
<context:annotation-config></context:annotation-config>
<!--组件扫描，扫描com.qf.pojo，如果含有spring组件注解，将被spring容器管理-->
<context:component-scan base-package="com.qf.pojo"></context:component-scan>
</beans>
2.创建新的PersonAnnotation类
<!--定义为spring组件-->
@Component("personAnnotation")
public class PersonAnnotation {
@Value("18")
int age;
@Value("张三")
String name;
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Override
public String toString() {
return "PersonAnnotation{" +
"age=" + age +
", name='" + name + '\'' +
'}';
}
}
3.创建新的测试类
public class AnnotationTest {
public static void main(String[] args) {
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-ioc-annotation.xml");
PersonAnnotation personAnnotation = applicationContext.getBean("personAnnotation", PersonAnnotation.class);
System.out.println(personAnnotation);
}
}
- Annotation的优缺点：
- 优点:灵活、简单、开发效率高
- 缺点：在不合适的情况下，滥用注解会违反ioc的思想
