基于XMl的DI
1.设值注入
2.构造注入
3.p命名空间设值注入
4.c命名空间构造注入


​官方文档​

设值注入


调用属性的set方法,使用​​<property name="name" value="FutaoSmile"/>​​设值注入


环境搭建​ -- 属性需要set方法,类不需要构造方法

Bean-Student

/**
* Created by futao on 2017/10/10.
*/
public class Student {
private String name;
private int age;

public String getName() {
return name;
}

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

public int getAge() {
return age;
}

public void setAge(int age) {
this.age = age;
}

@Override
public String toString() {
return "Student{" +
"name='" + name + '\'' +
", age=" + age +
'}';
}
}

配置文件-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"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="student" class="Student">

</bean>
</beans>

测试

import org.junit.Test
import org.springframework.context.support.ClassPathXmlApplicationContext

/**
* Created by futao on 2017/10/10.
*/
class Mytest {
@Test
fun forTest() {
val xml = ClassPathXmlApplicationContext("applicationContext.xml")
val student = xml.getBean("student") as Student
println(student)
}
}

输出结果

Student{name='null', age=0}

修改配置文件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"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="student" class="Student">
<!--设值注入,实际上是通过调用set方法实现-->
<property name="name" value="FutaoSmile"/>
<property name="age" value="18"/>
</bean>
</beans>

测试结果:

Student{name='FutaoSmile', age=18}

新建School类

/**
* Created by futao on 2017/10/10.
*/
public class School {
private String schoolName;

public String getSchoolName() {
return schoolName;
}

public void setSchoolName(String schoolName) {
this.schoolName = schoolName;
}

@Override
public String toString() {
return "School{" +
"schoolName='" + schoolName + '\'' +
'}';
}
}

School在Student类中作为属性存在

/**
* Created by futao on 2017/10/10.
*/
public class Student {
private String name;
private int age;
private School school;

public String getName() {
return name;
}

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

public int getAge() {
return age;
}

public void setAge(int age) {
this.age = age;
}

public School getSchool() {
return school;
}

public void setSchool(School school) {
this.school = school;
}


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

修改配置文件applicationContext.xml注入school属性值

<?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="student" class="Student">
<!--设值注入,实际上是通过调用set方法实现-->
<!-- 即:property标签调用到的是set方法 -->
<property name="name" value="FutaoSmile"/>
<property name="age" value="18"/>
<!-- 添加school的引用 -->
<property name="school" ref="school"/>
</bean>
<bean id="school" class="School">
<property name="schoolName" value="Ecjtu"/>
</bean>
</beans>

测试结果

Student{name='FutaoSmile', age=18, school=School{schoolName='Ecjtu'}}


基于XMl的DI-构造注入


直接调用带参构造器 - 使用​​<constructor-arg name="0" value="李四"/>​​构造注入
环境搭建​ -- 属性不需要set方法,类需要带参的构造方法
Student类


package gouzaoDI;

/**
* Created by futao on 2017/10/10.
*/
public class Student {
private String name;
private int age;
private School school;

/**
* 带参构造器
*
* @param name 姓名
* @param age 年龄
* @param school 学校
*/
public Student(String name, int age, School school) {
this.name = name;
this.age = age;
this.school = school;
}

/**
* 无参构造器
*/
public Student() {
}

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

School类

package gouzaoDI;

/**
* Created by futao on 2017/10/10.
*/
public class School {
private String schoolName;

/**
* 带参构造方法
*
* @param schoolName 学校名称
*/
public School(String schoolName) {
this.schoolName = schoolName;
}

/**
* 无参构造方法
*/
public School() {
}

@Override
public String toString() {
return "School{" +
"schoolName='" + schoolName + '\'' +
'}';
}
}

配置文件applicationContextGouzaoDI.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 http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="student" class="gouzaoDI.Student">
<!--构造注入方式1,用index,实际上是通过构造方法注入,index表示构造方法的参数索引-->
<!--<constructor-arg index="0" value="李四"/>-->
<!--<constructor-arg index="1" value="18"/>-->
<!--<constructor-arg index="2" ref="school"/>-->
<!--构造注入方式2,用name-->
<!--<constructor-arg name="name" value="李四"/>-->
<!--<constructor-arg name="age" value="18"/>-->
<!--<constructor-arg name="school" ref="school"/>-->
<!--构造注入方式3,省略index和name,但是这样要保证顺序与构造方法中参数的顺序是一样的-->
<constructor-arg value="李四"/>
<constructor-arg value="18"/>
<constructor-arg ref="school"/>

</bean>
<bean id="school" class="gouzaoDI.School">
<constructor-arg index="0" value="华东交通大学"/>
</bean>
</beans>

测试

/**
* 构造注入- 通过类的带参构造方法
*/
@Test
fun test4gouzaoDI() {
val xml = ClassPathXmlApplicationContext("applicationContextGouzaoDI.xml")
val student = xml.getBean("student") as gouzaoDI.Student
println(student)
}

结果

Student{name='李四', age=18, school=School{schoolName='华东交通大学'}}

P名字空间设值注入 p:schoolName="East China JiaoTong University"


实际上是通过属性的set方法实现的,所以如果要通过p名字空间进行设只注入的属性,需要为该属性设置setter



XML shortcut with the p-namespace
The p-namespace enables you to use the bean element’s attributes, instead of nested ​​<property/>​​ elements(property), to describe your property values and/or collaborating beans.


配置文件applicationContextPnamespaceDI.xml

注意:需要添加约束​​xmlns:p="http://www.springframework.org/schema/p"​

<?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">
<!--p名字空间设值注入的原理其实是通过属性的set方法实现的,通过追踪代码可以出来-->
<bean id="student" class="PnamespaceDI.Student" p:name="麻子" p:age="18" p:school-ref="school"/>
<bean id="school" class="PnamespaceDI.School" p:schoolName="East China JiaoTong University"/>
</beans>

测试

/**
* p命名空间设值注入
*/
@Test
fun test4pNamespaceDI() {
val xml = ClassPathXmlApplicationContext("applicationContextPnamespaceDI.xml")
val student = xml.getBean("student") as PnamespaceDI.Student
println(student)
}

结果

Student{name='麻子', age=18, school=School{schoolName='East China Jiao Tong University'}}

c名字空间构造注入 - c:schoolName="华东交通大学"

添加约束​​xmlns:c="http://www.springframework.org/schema/c"​


原理:c名字空间构造注入,原理实际上是通过类的构造方法实现的,所以要使用c名字空间注入就需要为类添加带参的构造方法



XML shortcut with the c-namespace
Similar to the the section called “XML shortcut with the p-namespace”, the c-namespace, newly introduced in Spring 3.1, allows usage of inlined attributes for configuring the constructor arguments rather then nested constructor-arg elements.


applicationContextCnamespaceDI.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:c="http://www.springframework.org/schema/c"


xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<!--p名字空间设值注入的原理其实是通过属性的set方法实现的,通过追踪代码可以出来-->
<!--<bean id="student" class="PnamespaceDI.Student" p:name="麻子" p:age="18" p:school-ref="school"/>-->
<!--<bean id="school" class="PnamespaceDI.School" p:schoolName="East China JiaoTong University"/>-->
<!--c名字空间构造注入,原理实际上是通过类的构造方法实现的-->
<bean id="student" class="PnamespaceDI.Student" c:name="coder" c:age="18" c:school-ref="school"/>
<bean id="school" class="PnamespaceDI.School" c:schoolName="华东交通大学"/>
</beans>

测试结果:

​Student{name='coder', age=18, school=School{schoolName='华东交通大学'}}​