【Spring Framework】5、依赖注入
1、构造器注入
User 实体类
package com.xg.pojo;
public class User {
private String name;
public User(String name) {
this.name = name;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public void show() {
System.out.println("name:" + name);
}
}
1.1、使用下标创建
<?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
https://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="user" class="com.xg.pojo.User">
<constructor-arg index="0" value="遇见星光"/>
</bean>
</beans>
1.2、使用类型创建
不建议使用
<?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
https://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="user" class="com.xg.pojo.User">
<constructor-arg type="java.lang.String" value="遇见星光"/>
</bean>
</beans>
1.3、通过参数名直接创建
<?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
https://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="user" class="com.xg.pojo.User">
<constructor-arg name="name" value="遇见星光"/>
</bean>
</beans>
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对象的所有属性，由容器来注入
2.1、环境搭建
1、复杂类型
Student
package com.xg.pojo;
import java.util.*;
public class Student {
private String name;
private Address address;
private String[] books;
private List<String> hobby;
private Map<String,String> card;
private Set<String> game;
private Properties info;
private String wife;
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> getHobby() {
return hobby;
}
public void setHobby(List<String> hobby) {
this.hobby = hobby;
}
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 Properties getInfo() {
return info;
}
public void setInfo(Properties info) {
this.info = info;
}
public String getWife() {
return wife;
}
public void setWife(String wife) {
this.wife = wife;
}
@Override
public String toString() {
return "Student{" +
"name='" + name + '\'' +
", address=" + address +
", books=" + Arrays.toString(books) +
", hobby=" + hobby +
", card=" + card +
", game=" + game +
", info=" + info +
", wife='" + wife + '\'' +
'}';
}
}
2、真实测试对象
Address
package com.xg.pojo;
public class Address {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Override
public String toString() {
return "Address{" +
"name='" + name + '\'' +
'}';
}
}
3、beans.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
https://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="address" class="com.xg.pojo.Address">
<property name="name" value="默认地址"/>
</bean>
<bean id="student" class="com.xg.pojo.Student">
<!-- 普通注入 value-->
<property name="name" value="遇见星光"/>
<!-- bean注入 ref-->
<property name="address" ref="address"/>
<!-- 数组-->
<property name="books">
<array>
<value>红楼梦</value>
<value>三国演义</value>
<value>西游记</value>
<value>水浒传</value>
</array>
</property>
<!-- List -->
<property name="hobby">
<list>
<value>听歌</value>
<value>看电影</value>
<value>敲代码</value>
</list>
</property>
<!-- Map-->
<property name="card">
<map>
<entry key="身份证" value="***************************"/>
<entry key="手机" value="123****1231"/>
</map>
</property>
<!-- Set-->
<property name="game">
<set>
<value>LOL</value>
<value>COC</value>
</set>
</property>
<!-- null-->
<property name="wife">
<null/>
</property>
<!-- Properties-->
<property name="info">
<props>
<prop key="user">Admin</prop>
<prop key="password">123456</prop>
<prop key="sex">男</prop>
</props>
</property>
</bean>
</beans>
4、测试类
import com.xg.pojo.Student;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class MyTest {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
Student student = context.getBean("student", Student.class);
System.out.println(student.toString());
}
}
/*
Student{
name='遇见星光',
address=Address{name='默认地址'},
books=[红楼梦, 三国演义, 西游记, 水浒传],
hobby=[听歌, 看电影, 敲代码],
card={
身份证=***************************,
手机=123****1231
},
game=[LOL, COC],
info={user=Admin, password=123456, sex=男},
wife='null'
}
*/
3、拓展方式注入
可以使用p命名空间和c命名空间进行注入
userBeans.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"
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">
<!-- p命名空间注入, 可以直接注入一些简单的值： property-->
<bean id="user" class="com.xg.pojo.User" p:name="遇见星光"/>
<!-- c命名空间注入, 通过构造器注入： constructor-arg-->
<bean id="user2" class="com.xg.pojo.User" c:name="遇见星光" c:age="18"/>
</beans>
测试
@Test
public void userTest() {
ApplicationContext context = new ClassPathXmlApplicationContext("userBeans.xml");
User user = context.getBean("user", User.class);
System.out.println(user.toString());
}
@Test
public void user2Test(){
ApplicationContext context = new ClassPathXmlApplicationContext("userBeans.xml");
User user = context.getBean("user2", User.class);
System.out.println(user.toString());
}
注意点
使用p命名空间和c命名空间需要导入对应的xml约束!
-
p命名空间
-
xmlns:p="http://www.springframework.org/schema/p"
-
-
c命名空间
-
xmlns:c="http://www.springframework.org/schema/c"
-
