Spring bean 四种注入方式详解
作者：宁在春
这篇文章主要介绍了Spring bean的实例化和IOC依赖注入详解，小编觉得挺不错的，现在分享给大家，也给大家做个参考。一起跟随小编过来看看吧
一、Set方式注入
pojo层：
/**
* @Author: crush
* @Date: 2021-06-17 16:57
* version 1.0
* xml 配置注入版本 set 方式
*/
public class Student1 {
public String name;
public String school;
public void setName(String name) {
this.name = name;
}
public void setSchool(String school) {
this.school = school;
}
@Override
public String toString() {
return "Student1{" +
"name='" + name + '\'' +
", school='" + school + '\'' +
'}';
}
}
1.xml 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">
<!--set方式注入
id是注入bean中的名字
class 是全限定类名
property 是按照set方式注入
-->
<bean id="student1" class="com.crush.pojo.Student1">
<property name="name" value="wyh1"/>
<property name="school" value="hngy1"/>
</bean>
</beans>
test测试
@Test
public void student1(){
ApplicationContext context = new ClassPathXmlApplicationContext("student1.xml");
Student1 student1 = context.getBean("student1", Student1.class);
System.out.println(student1);
}
二、构造函数方式注入
pojo层
/**
* @Author: crush
* @Date: 2021-06-17 17:02
* version 1.0
* xml 配置 构造函数方式注入
*/
public class Student2 {
private String name;
private String school;
public Student2(String name, String school) {
this.name = name;
this.school = school;
}
@Override
public String toString() {
return "Student2{" +
"name='" + name + '\'' +
", school='" + school + '\'' +
'}';
}
}
2.xml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">
<!--set方式注入
id是注入bean中的名字
class 是全限定类名
constructor 是按照构造方式注入
index 是按照成员变量在构造函数中的参数的第几个
name 表示成员变量名
type 表示类型
value 表示值
ref 表示引用 可引用另外一个注入到Spring的中的值
-->
<bean id="student2" class="com.crush.pojo.Student2">
<constructor-arg index="0" name="name" type="java.lang.String" value="wyh2"/>
<constructor-arg name="school" value="hngy2"/>
</bean>
</beans>
test测试
@Test
public void student2(){
ApplicationContext context = new ClassPathXmlApplicationContext("student2.xml");
Student2 student2 = context.getBean("student2", Student2.class);
System.out.println(student2);
}
三、注解注入
pojo层
/**
* @Author: crush
* @Date: 2021-06-17 17:08
* version 1.0
*/
@Component
public class Student3 {
@Value("wyh3")
private String name;
@Value("hngy3")
private String school;
@Override
public String toString() {
return "Student3{" +
"name='" + name + '\'' +
", school='" + school + '\'' +
'}';
}
}
3.xml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:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">
<!--注解方式注入
需要扫描注解在的包 注解才会生效
-->
<context:component-scan base-package="com.crush.pojo"/>
</beans>
test测试
@Test
public void student3(){
ApplicationContext context = new ClassPathXmlApplicationContext("student3.xml");
Student3 student3 = context.getBean("student3", Student3.class);
System.out.println(student3);
}
四、JavaConfig 方式注入
pojo层
/**
* @Author: crush
* @Date: 2021-06-17 17:16
* version 1.0
* JavaConfig 配置
*/
public class Student4 {
@Value("wyh4")
private String name;
@Value("hngy4")
private String school;
@Override
public String toString() {
return "Student4{" +
"name='" + name + '\'' +
", school='" + school + '\'' +
'}';
}
}
JavaConfig 类
@Configuration
public class Student4Config {
@Bean
public Student4 student4(){
return new Student4();
}
}
xml文件 扫描包
<?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:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">
<context:component-scan base-package="com.crush.config"/>
</beans>
测试：
@Test
public void student4(){
ApplicationContext context = new ClassPathXmlApplicationContext("student4.xml");
Student4 student4 = context.getBean("student4", Student4.class);
System.out.println(student4);
}
五、Service层注入详解
service
/**
* @Author: crush
* @Date: 2021-06-17 17:27
* version 1.0
* xml 配置
*/
public interface StudentService1 {
void test();
}
serviceImpl
/**
* @Author: crush
* @Date: 2021-06-17 17:29
* version 1.0
* xml 配置
*/
public class StudentService1Impl implements StudentService1{
@Override
public void test() {
System.out.println("===StudentDao1Impl===");
}
}
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="studentService1" class="com.crush.dao.StudentService1" />
</beans>
总结
本篇文章就到这里了，希望能给你带来帮助，也希望能够您能够关注脚本之家的更多内容！