Spring DI(依赖注入)
1.依赖注入(DI)
- 依赖注入(Dependency Injection,DI)。
- 依赖 : 指Bean对象的创建依赖于容器 . Bean对象的依赖资源 .
- 注入 : 指Bean对象所依赖的资源 , 由容器来设置和装配 .
1.1 构造器注入
<bean id="user2" class="com.zhang.pojo.User">
<constructor-arg index="0" value="zhang" />
<constructor-arg index="1" value="18" />
</bean>
1.2 Set方式注入(重点)
依赖注入:set注入
依赖:bean对象的创建依赖于容器
注入:bean对象中所有的属性,由容器来注入
普通值注入,基于set注入
环境搭建
Address类
package com.zhang.pojo;
public class Address {
private String address;
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
@Override
public String toString() {
return "Address{" +
"address='" + address + '\'' +
'}';
}
}
Student类
package com.zhang.pojo;
import java.util.*;
public class Student {
private String name;
private Address address;
private String[] books;
private List<String> hobbys;
private Map<String ,String > card;
private Set<String> game;
private String wife;
private Properties info;
@Override
public String toString() {
return "Student{" +
"name='" + name + '\'' +
", address=" + address +
", books=" + Arrays.toString(books) +
", hobbys=" + hobbys +
", card=" + card +
", game=" + game +
", wife='" + wife + '\'' +
", info=" + info +
'}';
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
public String[] getBooks() {
return books;
}
public void setBooks(String[] books) {
this.books = books;
}
public List<String> getHobbys() {
return hobbys;
}
public void setHobbys(List<String> hobbys) {
this.hobbys = hobbys;
}
public Map<String, String> getCard() {
return card;
}
public void setCard(Map<String, String> card) {
this.card = card;
}
public Set<String> getGame() {
return game;
}
public void setGame(Set<String> game) {
this.game = game;
}
public String getWife() {
return wife;
}
public void setWife(String wife) {
this.wife = wife;
}
public Properties getInfo() {
return info;
}
public void setInfo(Properties info) {
this.info = info;
}
}
applicationContext.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="address" class="com.zhang.pojo.Address">
<property name="address" value="北京中南海"/>
</bean>
<bean id="student" class="com.zhang.pojo.Student">
</bean>
</beans>
1.2.1 常量注入
<!--第一种:普通值注入,value-->
<property name="name" value="cnfalltime" />
1.2.2 数组注入
<!--第二种:数组注入,array-->
<property name="books">
<array>
<value>红楼梦</value>
<value>西游记</value>
<value>水浒传</value>
</array>
</property>
1.2.3 列表注入
<!--第三种:List注入,list-->
<property name="hobbys">
<list>
<value>听歌</value>
<value>看电影</value>
<value>敲代码</value>
</list>
</property>
1.2.4 map注入
<!--第四种:Map注入,map-->
<property name="card">
<map>
<entry key="身份证" value="141414144144414141" />
<entry key="银行卡" value="1234567891234567891" />
<entry key="电话号" value="12345698765" />
</map>
</property>
1.2.5 set注入
<!--第五种:Set注入,value-->
<property name="game">
<set>
<value>LOL</value>
<value>COC</value>
<value>BOB</value>
</set>
</property>
1.2.6 null注入
<!--第六种:null注入,value-->
<!-- <property name="wife" value="" />-->//方式1
<property name="wife">//方式二
<null></null>
</property>
1.2.7 properties注入
<!--第七种:Properties注入,props-->
<property name="info">
<props>
<prop key="driver">com.jdbc.cj.JDBC</prop>
<prop key="url">localhost:3306</prop>
<prop key="username">root</prop>
<prop key="password">123456</prop>
</props>
</property>
1.2.8 bean注入(引用)
<!--第八种:Bean注入,ref-->
<property name="address" ref="address" />
完善注入信息
1.3 拓展方式注入
p命名和c命名不能直接使用,需要在头部导入xml约束
<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
https://www.springframework.org/schema/beans/spring-beans.xsd">
</beans>
xmlns:p="http://www.springframework.org/schema/p"
xmlns:c="http://www.springframework.org/schema/c"
package com.zhang.pojo;
public class User {
private String name;
private int age;
public User() {
}
public User(String name, int age) {
this.name = name;
this.age = age;
}
@Override
public String toString() {
return "User{" +
"name='" + name + '\'' +
", age=" + age +
'}';
}
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;
}
}
p命名注入 property
<!--p命名空间注入可以直接注入简单属性的值(相当于property注入)-->
<bean id="user" class="com.zhang.pojo.User" p:name="zhang" p:age="18" />
c命名空间注入 constructor
<!--c命名空间注入可以直接注入简单属性的值(相当于构造器注入)-->
<bean id="user" class="com.zhang.pojo.User" c:_0="CnFallTime" c:_1="22" />
注意点:p命名和c命名不能直接使用,需要导入xml约束
本文来自博客园,作者:Cn_FallTime,转载请注明原文链接:https://www.cnblogs.com/CnFallTime/p/16060995.html