三种注入方式:

1. setter & getter 注入
2. 构造函数注入
3. p命名空间注入

有两个实体类

student:

public class Student {String name;int number;int age;public Student() {}public Student(String name, int number, int age) {super();this.name = name;this.number = number;this.age = age;}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getNumber() {return number;}public void setNumber(int number) {this.number = number;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}@Overridepublic String toString() {return "Student [name=" + name + ", number=" + number + ", age=" + age + "]";}}

teacher:

public class Teacher {String name;Student student;public String getName() {return name;}public void setName(String name) {this.name = name;}public Student getStudent() {return student;}public void setStudent(Student student) {this.student = student;}@Overridepublic String toString() {return "Teacher [name=" + name + ", student=" + student + "]";}
}

setter & getter 注入

这个要求在实体类中有setXxxx()
比如

public void setName(String name) {this.name = name;
}

在xml中的形式:

	<bean id="student" class= "org.ljn.entity.Student"><property name="name" value="ljn" /><property name="age" value="20" /><property name="number" value="28" />	</bean>

构造方法注入

1. 直接写的方式,必须按照顺序

   <bean id="student1" class= "org.ljn.entity.Student"><!-- name,number,age --><constructor-arg value = "jack"></constructor-arg><constructor-arg value = "123"></constructor-arg><constructor-arg value = "35"></constructor-arg>
   </bean>
   

2. 不按照顺序,加上index(从0开始)

   <bean id="student2" class= "org.ljn.entity.Student"><constructor-arg index="1" value = "35"></constructor-arg><constructor-arg index="2" value = "123"></constructor-arg><constructor-arg index="0" value = "jack"></constructor-arg>
   </bean>
   

p命名空间

首先要在namespace里面加上p的那个

这么写👇

<bean id="teacher" class = "org.ljn.entity.Teacher" p:student-ref="student1" p:name="ls">
</bean>

两种写法:

• 简单类型、String：p:属性名=“属性值”
• 引用类型（除了String外）：p:属性名-ref=“引用的id”
  注意多个 p赋值的时候 要有空格。

比如上面的name是String类型就写 p:name=xxx
是引用类型:p:student-ref=xxxx

汇总

1. Student

   package org.ljn.entity;
   import org.springframework.context.ApplicationContext;
   import org.springframework.context.support.ClassPathXmlApplicationContext;
   public class Student {
   String name;
   int number;
   int age;
   public Student() {}
   public Student(String name, int number, int age) {super();this.name = name;this.number = number;this.age = age;
   }
   public String getName() {return name;
   }
   public void setName(String name) {this.name = name;
   }
   public int getNumber() {return number;
   }
   public void setNumber(int number) {this.number = number;
   }
   public int getAge() {return age;
   }
   public void setAge(int age) {this.age = age;
   }
   @Override
   public String toString() {return "Student [name=" + name + ", number=" + number + ", age=" + age + "]";}}
   

2. Teacher

package org.ljn.entity;public class Teacher {String name;Student student;public String getName() {return name;}public void setName(String name) {this.name = name;}public Student getStudent() {return student;}public void setStudent(Student student) {this.student = student;}@Overridepublic String toString() {return "Teacher [name=" + name + ", student=" + student + "]";}}

3. 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"xmlns:p="http://www.springframework.org/schema/p"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"><bean id="student" class= "org.ljn.entity.Student"><property name="name" value="ljn" /><property name="age" value="20" /><property name="number" value="28" />	</bean><bean id="student1" class= "org.ljn.entity.Student"><!-- name,number,age --><constructor-arg value = "jack"></constructor-arg><constructor-arg value = "123"></constructor-arg><constructor-arg value = "35"></constructor-arg></bean><bean id="student2" class= "org.ljn.entity.Student"><!-- name,number,age --><constructor-arg index="1" value = "35"></constructor-arg><constructor-arg index="2" value = "123"></constructor-arg><constructor-arg index="0" value = "jack"></constructor-arg></bean><bean id="teacher" class = "org.ljn.entity.Teacher" p:student-ref="student1" p:name="ls"></bean>
</beans>

4. 测试类Test

package org.ljn.test;import org.ljn.entity.Student;
import org.ljn.entity.Teacher;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;public class Test {public static void main(String[] args) {ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");Student student = (Student)context.getBean("student");Student student1 = (Student)context.getBean("student1");Student student2 = (Student)context.getBean("student2");Teacher teacher = (Teacher)context.getBean("teacher");System.out.println(student);System.out.println(student1);System.out.println(student2);System.out.println(teacher);}
}

github代码