基于XML的依赖注入

1.设值注入：底层调用属性setter方法进行赋值，一定要有setter方法。使用property.
2.构造注入：一定要有带参数的构造方法。使用constructor-arg.

通过设值注入源码为：
1.School类：

public class School {
private String sname;

public void setSname(String sname) {
	this.sname = sname;
}

@Override
public String toString() {
	return "School [sname=" + sname + "]";
}

}

2.Student类及setter方法

public class Student {
private String name; //成员变量
private int age;
private School school; //自定义类对象

public void setXxx(String name) {
	this.name = name;
}
public void setAge(int age) {
	this.age = age;
}
public void setSchool(School school) {
	this.school = school;
}
@Override
public String toString() {
	return "Student [name=" + name + ", age=" + age + ", school=" + school + "]";
}

}

3.XML配置文件

<?xml version="1.0" encoding="UTF-8"?>

<bean id="mySchool" class="com.abc.di01.School">
	<property name="sname" value="清华大学"/>
</bean>
<bean id="student" class="com.abc.di01.Student">
	<property name="xxx" value="张三"/>
	<property name="age" value="21"/>
	<property name="school" ref="mySchool"/>
</bean>

4.测试类MyTest

import org.junit.Test;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.context.support.FileSystemXmlApplicationContext;
import org.springframework.core.io.ClassPathResource;

//设值注入
public class MyTest {

@Test
public void tests01(){
	//创建Spring容器对象，加载Spring的配置文件（在类路径下）
	String config = "com/abc/di01/applicationContext.xml";
	ApplicationContext ac = new ClassPathXmlApplicationContext(config);
	Student student = (Student) ac.getBean("student");
	System.out.println(student);
}

}

测试结果为：

Student [name=张三, age=21, school=School [sname=清华大学]]

通过构造注入源码为：

1.School类：

public class School {
private String sname;

public void setSname(String sname) {
	this.sname = sname;
}

@Override
public String toString() {
	return "School [sname=" + sname + "]";
}

}
2.Student类及有参构造方法

public class Student {
private String name; //成员变量
private int age;
private School school; //自定义类对象

public Student(String name, int age, School school) {
	super();
	this.name = name;
	this.age = age;
	this.school = school;
}

@Override
public String toString() {
	return "Student [name=" + name + ", age=" + age + ", school=" + school + "]";
}

}

3.XML配置文件

<?xml version="1.0" encoding="UTF-8"?>

<bean id="mySchool" class="com.abc.di02.School">
	<property name="sname" value="清华大学"/>
</bean>
<bean id="student" class="com.abc.di02.Student">
	<constructor-arg name="name" value="李四"/>
	<constructor-arg name="age" value="22"/>
	<constructor-arg name="school" ref="mySchool"/>
</bean>

4.测试类MyTest

Student [name=李四, age=22, school=School [sname=清华大学]]