Spring框架之IoC（ Inversion of Control ）基础知识入门
1、IoC创建对象的方式
-
使用无参构造创建对象
-
假如要使用有参构造创建：
-
下标赋值constructor-arg
<!--有参--> <bean id="User" class="com.reliable.pojo.User" > <constructor-arg index="0" value="靠谱杨"></constructor-arg> </bean>public User(String name){ System.out.println("User的有参构造！"); this.name=name; } -
通过类型type="java.lang.String"
<bean id="User" class="com.reliable.pojo.User" > <constructor-arg type="java.lang.String" value="靠谱杨"></constructor-arg> </bean>- 通过参数名name="name" value="reliable"
<bean id="User" class="com.reliable.pojo.User" > <constructor-arg name="name" value="reliable"></constructor-arg> </bean>总结：在配置文件加载的时候，Spring容器中管理的对象就已经初始化成功了！
-
2、Spring的配置
2.1、别名
<!--别名-->
<alias name="User" alias="new_user"></alias>
2.2、Bean的配置
<?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">
<!--
类型 变量名 = new 类型();
Hello hello = new Hello();
bean就是java对象 , 由Spring创建和管理
bean = 一个对象
其中
id = 变量名
class = new的对象类型
property相当于给对象里的属性设置一个值
-->
<bean id="Hello" class="com.reliable.pojo.Hello">
<property name="name" value="Spring"/>
</bean>
<!-- 无参 -->
<!--<bean id="User" class="com.reliable.pojo.User">-->
<!--<property name="name" value="靠谱"></property>-->
<!--</bean>-->
<!--有参第一种，index-->
<!--<bean id="User" class="com.reliable.pojo.User" >
<constructor-arg index="0" value="靠谱杨"></constructor-arg>
</bean>-->
<!-- 2 类型-->
<!-- <bean id="User" class="com.reliable.pojo.User" >
<constructor-arg type="java.lang.String" value="靠谱杨"></constructor-arg>
</bean>-->
<!-- 3 参数名字 -->
<bean id="User" class="com.reliable.pojo.User" >
<constructor-arg name="name" value="User"></constructor-arg>
</bean>
<bean id="User1" class="com.reliable.pojo.User1">
<constructor-arg name="name" value="User1"></constructor-arg>
</bean>
<!--别名 如果添加的别名 都可以使用-->
<alias name="User" alias="new_user"></alias>
</beans>
2.3、import
一般用于团队开发使用，可以将多个配置文件导入合并为一个
<!--import -->
<import resource="beans1.xml"></import>
3、依赖注入（DI）
3.1 构造器注入
- 依赖注入：Set注入
- 依赖：bean对象的创建依赖于容器
- 注入：bean对象中的所有属性，由容器来注入！
3.2、Set方式注入【重点】
- 复杂类型
public class Address {
private String address;
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
}
- 实体对象
import java.util.*;
public class Student {
public String getName() {
return name;
}
public Address getAddress() {
return address;
}
public String[] getBooks() {
return books;
}
public List<String> getHobbies() {
return hobbies;
}
public Map<String, String> getCard() {
return card;
}
public Set<String> getGames() {
return games;
}
public String getWife() {
return wife;
}
public Properties getInfo() {
return info;
}
private String name;
private Address address;
private String[] books;
private List<String> hobbies;
private Map<String,String> card;
private Set<String> games;
private String wife;
private Properties info;
public void setName(String name) {
this.name = name;
}
public void setAddress(Address address) {
this.address = address;
}
public void setBooks(String[] books) {
this.books = books;
}
public void setHobbies(List<String> hobbies) {
this.hobbies = hobbies;
}
public void setCard(Map<String, String> card) {
this.card = card;
}
public void setGames(Set<String> games) {
this.games = games;
}
public void setWife(String wife) {
this.wife = wife;
}
public void setInfo(Properties info) {
this.info = info;
}
@Override
public String toString() {
return "Student{" +
"name='" + name + '\'' +
", address=" + address +
", books=" + Arrays.toString(books) +
", hobbies=" + hobbies +
", card=" + card +
", games=" + games +
", wife='" + wife + '\'' +
", info=" + info +
'}';
}
//show方法
public void show(){
System.out.println("name="+ name
+ ",address="+ address.getAddress()
+ ",books="
);
for (String book:books){
System.out.print("<<"+book+">>\t");
}
System.out.println("\n爱好:"+ hobbies);
System.out.println("card:"+card);
System.out.println("games:"+games);
System.out.println("wife:"+wife);
System.out.println("info:"+info);
}
}
xml配置文件
<?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="Address" class="com.kuang.pojo.Address">
<property name="address" value="石家庄"></property>
</bean>
<bean id="Student" class="com.kuang.pojo.Student">
<!-- 第一种：普通值注入 -->
<property name="name" value="杨传伟"></property>
<!-- 第二种：ref注入 -->
<property name="address" ref="Address"></property>
<!-- 第三种：数组注入 -->
<property name="books">
<array>
<value>《红楼梦》</value>
<value>《西游记》</value>
<value>《水浒传》</value>
<value>《三国演义》</value>
</array>
</property>
<!-- 第四种：List注入 -->
<property name="hobbies">
<list>
<value>听音乐</value>
<value>看电影</value>
<value>敲代码</value>
<value>摄影</value>
</list>
</property>
<!-- 第五种：Map注入 -->
<property name="card">
<map>
<entry key="IDcard" value="1234567"></entry>
<entry key="STcard" value="7654321"></entry>
</map>
</property>
<!-- 第六种：Set注入 -->
<property name="games">
<set>
<value>跑跑卡丁车官方竞速版</value>
<value>王者荣耀</value>
</set>
</property>
<!-- 第七种：设置空值 -->
<property name="wife">
<null></null>
</property>
<!--properties-->
<property name="info">
<props>
<prop key="学号">20194074</prop>
<prop key="性别">男</prop>
<prop key="姓名">杨传伟</prop>
<prop key="username">reliable</prop>
<prop key="userpass">resetpass01</prop>
</props>
</property>
</bean>
</beans>
3.3、拓展方式注入
使用p命名空间和c命名空间
使用：
package com.kuang.pojo;
public class User {
private String name;
private int age;
public User(String name,int age) {
this.name = name;
this.age=age;
}
public User(){};
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;
}
@Override
public String toString() {
return "User{" +
"name='" + name + '\'' +
", age=" + age +
'}';
}
}
配置文件：
<?xml version="1.0" encoding="UTF-8"?>
<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"
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">
<!--P(属性: properties)命名空间 , 属性依然要设置set方法-->
<bean id="user" class="com.kuang.pojo.User" p:name="靠谱" p:age="21"/>
<!--C(构造: Constructor)命名空间 , 属性依然要设置set方法-->
<bean id="user2" class="com.kuang.pojo.User" c:name="狂神" c:age="18"/>
</beans>
测试：
public void test2(){
ApplicationContext context=new ClassPathXmlApplicationContext("beans03.xml");
User user = context.getBean("user", User.class);
System.out.println(user);
User user2 = context.getBean("user2", User.class);
System.out.println(user2);
}
注意
要引入c和p命名空间：
xmlns:p="http://www.springframework.org/schema/p"
xmlns:c="http://www.springframework.org/schema/c"
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