Spring框架之IoC（ Inversion of Control ）基礎知識入門
阿新 • • 發佈：2021-10-30
1、IoC建立物件的方式
-
使用無參構造建立物件
-
假如要使用有參構造建立：
-
下標賦值constructor-arg
<!--有參--> <bean id="User" class="com.reliable.pojo.User" > <constructor-arg index="0" value="靠譜楊"></constructor-arg> </bean>public User(String name){ System.out.println("User的有參構造！"); this.name=name; } -
通過型別type="java.lang.String"
<bean id="User" class="com.reliable.pojo.User" > <constructor-arg type="java.lang.String" value="靠譜楊"></constructor-arg> </bean>- 通過引數名name="name" value="reliable"
<bean id="User" class="com.reliable.pojo.User" > <constructor-arg name="name" value="reliable"></constructor-arg> </bean>總結：在配置檔案載入的時候，Spring容器中管理的物件就已經初始化成功了！
-
2、Spring的配置
2.1、別名
<!--別名-->
<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"> <!-- 型別 變數名 = new 型別(); Hello hello = new Hello(); bean就是java物件 , 由Spring建立和管理 bean = 一個物件 其中 id = 變數名 class = new的物件型別 property相當於給物件裡的屬性設定一個值 --> <bean id="Hello" class="com.reliable.pojo.Hello"> <property name="name" value="Spring"/> </bean> <!-- 無參 --> <!--<bean id="User" class="com.reliable.pojo.User">--> <!--<property name="name" value="靠譜"></property>--> <!--</bean>--> <!--有參第一種，index--> <!--<bean id="User" class="com.reliable.pojo.User" > <constructor-arg index="0" value="靠譜楊"></constructor-arg> </bean>--> <!-- 2 型別--> <!-- <bean id="User" class="com.reliable.pojo.User" > <constructor-arg type="java.lang.String" value="靠譜楊"></constructor-arg> </bean>--> <!-- 3 引數名字 --> <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> <!--別名 如果新增的別名 都可以使用--> <alias name="User" alias="new_user"></alias> </beans>
2.3、import
一般用於團隊開發使用，可以將多個配置檔案匯入合併為一個
<!--import -->
<import resource="beans1.xml"></import>
3、依賴注入（DI）
3.1 構造器注入
- 依賴注入：Set注入
- 依賴：bean物件的建立依賴於容器
- 注入：bean物件中的所有屬性，由容器來注入！
3.2、Set方式注入【重點】
- 複雜型別
public class Address {
private String address;
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
}
- 實體物件
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愛好:"+ hobbies);
System.out.println("card:"+card);
System.out.println("games:"+games);
System.out.println("wife:"+wife);
System.out.println("info:"+info);
}
}
xml配置檔案
<?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="石家莊"></property>
</bean>
<bean id="Student" class="com.kuang.pojo.Student">
<!-- 第一種：普通值注入 -->
<property name="name" value="楊傳偉"></property>
<!-- 第二種：ref注入 -->
<property name="address" ref="Address"></property>
<!-- 第三種：陣列注入 -->
<property name="books">
<array>
<value>《紅樓夢》</value>
<value>《西遊記》</value>
<value>《水滸傳》</value>
<value>《三國演義》</value>
</array>
</property>
<!-- 第四種：List注入 -->
<property name="hobbies">
<list>
<value>聽音樂</value>
<value>看電影</value>
<value>敲程式碼</value>
<value>攝影</value>
</list>
</property>
<!-- 第五種：Map注入 -->
<property name="card">
<map>
<entry key="IDcard" value="1234567"></entry>
<entry key="STcard" value="7654321"></entry>
</map>
</property>
<!-- 第六種：Set注入 -->
<property name="games">
<set>
<value>跑跑卡丁車官方競速版</value>
<value>王者榮耀</value>
</set>
</property>
<!-- 第七種：設定空值 -->
<property name="wife">
<null></null>
</property>
<!--properties-->
<property name="info">
<props>
<prop key="學號">20194074</prop>
<prop key="性別">男</prop>
<prop key="姓名">楊傳偉</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名稱空間和c名稱空間
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 +
'}';
}
}
配置檔案：
<?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(屬性: properties)名稱空間 , 屬性依然要設定set方法-->
<bean id="user" class="com.kuang.pojo.User" p:name="靠譜" p:age="21"/>
<!--C(構造: Constructor)名稱空間 , 屬性依然要設定set方法-->
<bean id="user2" class="com.kuang.pojo.User" c:name="狂神" c:age="18"/>
</beans>
測試：
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名稱空間：
xmlns:p="http://www.springframework.org/schema/p"
xmlns:c="http://www.springframework.org/schema/c"