1.创建需要的实体类
public class Student { //学生实体类
private String name; //姓名
private Integer age; //年龄
private Grade grade; //年级
@Override
public String toString() {
return "Student [name=" + name + ", age=" + age + ", grade=" + grade
+ "]";
}
public Student() {
super();
}
public Student(String name, Integer age, Grade grade) {
super();
this.name = name;
this.age = age;
this.grade = grade;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public Grade getGrade() {
return grade;
}
public void setGrade(Grade grade) {
this.grade = grade;
}
}
Student实体类
public class Grade { //年级实体类
private String name; //年级名称
@Override
public String toString() {
return "Grade [name=" + name + "]";
}
public Grade() {
super();
}
public Grade(String name) {
super();
this.name = name;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
Grade实体类
public class SmallGrade extends Grade {
//只是为了 验证 autowire="byType"
}
SmallGrade实体类
2.创建对应的配置文件
<?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"> <bean id="grade" class="cn.bdqn.bean.Grade" p:name="2年级"/> <!--autowire="byName" 将域属性名称 作为ID 到容器中查询相同名称的Bean进行注入 -->
<bean id="student" class="cn.bdqn.bean.Student" autowire="byName"/>
</beans>
autowire="byName"
<?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"> <bean id="gradeaaaaa" class="cn.bdqn.bean.Grade" p:name="2年级"/>
<!-- autowire="byType" 根据域属性的类型 到容器中查询 相同类型并且具有is-a关系的一个Bean进行注入
相同类型的bean不能多于一个 -->
<bean id="student" class="cn.bdqn.bean.Student" autowire="byType"/> </beans>
autowire="byType"
3.创建测试类分类运行
public class StudentTest {
@Test
public void test01(){
ApplicationContext context=
new ClassPathXmlApplicationContext("applicationContext.xml");
Student student=(Student) context.getBean("student");
System.out.println(student);
}
}
测试类
4.如果在autowire="byType" 的时候 在容器中在增加一个相同类型的bean或者有is-a的关系 会报错！
如下的代码 运行会报错
<?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"> <bean id="gradeaaa" class="cn.bdqn.bean.Grade" p:name="2年级"/>
<bean id="smallgrade" class="cn.bdqn.bean.SmallGrade"/>
<!-- autowire="byType" 根据域属性的类型 到容器中查询 相同类型并且具有is-a关系的一个Bean进行注入
相同类型的bean不能多于一个 -->
<bean id="student" class="cn.bdqn.bean.Student" autowire="byType"/> </beans>
报错代码1
<?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"> <bean id="grade1" class="cn.bdqn.bean.Grade" p:name="1年级"/>
<bean id="grade2" class="cn.bdqn.bean.Grade" p:name="2年级"/> <!-- autowire="byType" 根据域属性的类型 到容器中查询 相同类型并且具有is-a关系的一个Bean进行注入
相同类型的bean不能多于一个 -->
<bean id="student" class="cn.bdqn.bean.Student" autowire="byType"/> </beans>
报错代码2