Spring框架依赖注入方法示例

在阅读这篇文章之前，大家可以先参阅《理解Spring中的依赖注入和控制反转》一文，了解下依赖注入和控制反转的相关内容。

三种依赖注入的方式

属性注入，通过setter方法注入bean的属性值或依赖的对象 构造注入 工厂方法注入（很少使用）
例子

这里我们使用了spring-4.3.2，maven配置文件

<dependency> <groupid>org.springframework</groupid> spring-core</artifactid> <version>${org.springframework-version}</version> <exclusions>  <exclusion>   <groupid>commons-logging</groupid>   commons-logging</artifactid>  </exclusion> </exclusions></dependency><dependency> <groupid>org.springframework</groupid> spring-beans</artifactid> <version>${org.springframework-version}</version></dependency><dependency> <groupid>org.springframework</groupid> spring-aop</artifactid> <version>${org.springframework-version}</version></dependency><dependency> <groupid>org.springframework</groupid> spring-context</artifactid> <version>${org.springframework-version}</version></dependency><dependency> <groupid>commons-logging</groupid> commons-logging</artifactid> <version>1.2</version></dependency><!-- Junit --><dependency> <groupid>junit</groupid> junit</artifactid> <version>3.8.1</version> <scope>test</scope></dependency>

applicationContext.xml配置文件

<!--?xml version="1.0" encoding="UTF-8"?--><beans xmlns="https://www.springframework.org/schema/beans" xmlns:p="https://www.springframework.org/schema/p" xmlns:util="https://www.springframework.org/schema/util" xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance" xsi:schemalocation="https://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd  https://www.springframework.org/schema/util https://www.springframework.org/schema/util/spring-util.xsd">  <!--   配置bean  id：标识容器中bean对象  class：bean的全类名，通过反射的方式在IOC容器中创建Bean，所以要求Bean类必须有无参构造器  --> <bean id="helloWorld">  <property name="name" value="crystal"></property> </bean>  <!-- 通过构造方法配置bean,可以指定参数的位置和类型，以区分重载的构造函数 --> <bean id="car">  <constructor-arg index="0" value="BENCHI"></constructor-arg>  <constructor-arg index="1" type="double" value="200000.0"></constructor-arg> </bean> <bean id="car1">  <!-- 如果字面值包含特殊字符，使用<![CDATA[]]>包裹起来   属性值可以使用value子节点来配置   -->  <constructor-arg type="java.lang.String">   <value><!--[CDATA[<shanghai-->]]></value>  </constructor-arg>  <constructor-arg index="1" type="int" value="200"></constructor-arg> </bean>  <bean id="person">  <property name="name" value="Crystal"></property>  <property name="age" value="20"></property>  <!-- 可以使用ref建立引用之间的关系 -->  <!--   <property name="car" ref="car"></property>   -->  <!--    <property name="car">    <ref bean="car2"/>   </property>   -->   <!--    <property name="car">   <bean>    <constructor-arg value="changanFute"></constructor-arg>    <constructor-arg value="3000000"></constructor-arg>    <constructor-arg value="240"></constructor-arg>   </bean>   </property>    -->   <!-- 测试赋值null -->   <!-- <property name="car"><null/></property> -->   <property name="car" ref="car1"></property>   <!-- 为级联属性赋值，注意：属性需要先初始化后才能为级联属性赋值，和structs2不同 -->   <property name="car.price" value="400000"></property> </bean>  <!-- 测试配置集合属性 --> <bean id="person3">  <property name="name" value="barry"></property>  <property name="age" value="21"></property>  <property name="cars">   <list>    <ref bean="car">    <ref bean="car1">    <bean>     <constructor-arg value="changanFute"></constructor-arg>     <constructor-arg value="3000000"></constructor-arg>     <constructor-arg value="240"></constructor-arg>    </bean>   </ref></ref></list>  </property> </bean>  <!-- 配置Map的属性值 --> <bean id="newPerson">  <property name="name" value="lina"></property>  <property name="age" value="22"></property>  <property name="cars">   <!-- 使用map节点及map的entry子节点配置Map类型的成员变量 --><map>    <entry key="AA" value-ref="car"></entry>    <entry key="BB" value-ref="car1"></entry></map>  </property> </bean>   <!-- 配置Properties属性值 --> <bean id="dataSource">  <property name="properties">   <!-- 使用props和prop子节点来为Properties属性赋值 -->   <props>    <prop key="user">root</prop>    <prop key="password">1234</prop>    <prop key="jdbcUrl">jdbc:mysql://test</prop>    <prop key="jdbcDriver">com.mysql.jdbc.Driver</prop>   </props>  </property> </bean>  <!-- 配置单例的集合bean，以供多个bean进行引用，需要导入util命名空间 --> <util:list id="cars">  <ref bean="car">  <ref bean="car1"> </ref></ref></util:list>  <bean id="person4">  <property name="name" value="Jackie"></property>  <property name="age" value="30"></property>  <property name="cars" ref="cars"></property> </bean>  <!-- 通过p命名空间为bean的属性赋值，需要先导入p命名空间，相对于传统配置方式更为简洁 --> <bean id="person5" p:age="32" p:cars-ref="cars" p:name="Queue"></bean></beans>

1. 下面是简单的属性注入、构造注入的测试类

Car.java

package com.spring.test;public class Car {private String name;private int maxSpeed;private double price;public Car() {}public Car(String name, double price) {this.name = name;this.price = price;}public Car(String name, int maxSpeed) {this.name = name;this.maxSpeed = maxSpeed;}public Car(String name, double price, int maxSpeed) {this.name = name;this.price = price;this.maxSpeed = maxSpeed;}public void setPrice(double price) {this.price = price;}@Override public String toString() {return "Car [name:" + name + ", price:" + price + ", maxSpeed:" + maxSpeed + "]";}}

HelloWorld.java

package com.spring.test;public class HelloWorld {private String name;public HelloWorld() {System.out.println("HelloWorld constructor...");}public String getName() {return name;}public void setName(String name) {System.out.println("setName:" + name);this.name = name;}@Override public String toString() {return "hello," + name;}}

Person.java

package com.spring.test;public class Person {private String name;private int age;private Car car;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 Car getCar() {return car;}public void setCar(Car car) {this.car = car;}@Override public String toString() {return "Person: [name=" + name + ", age=" + age + ", car=" + car + "]";}}

Main.java

package com.spring.test;import org.junit.Test;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;public class Main {public static void main(String[] args) {HelloWorld hello = new HelloWorld();hello.setName("barry");System.out.println("print:"+ hello + "/n");// 装入 Spring 配置文件/**   * 装入 Spring 配置文件   * ApplicationContext是IOC容器，它有两个主要实现类（ClassPathXmlApplicationContext和FileSystemXmlApplicationContext）   * ApplicationContext在初始化上下文时就实例化所有单例的Bean   */ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");//HelloWorld hello1 = (HelloWorld) context.getBean("helloWorld"); // 通过id获取bean对象HelloWorld hello1 = context.getBean(HelloWorld.class);// 通过类型获取bean对象（要求在IOC容器里该类型的对象只能有一个）System.out.println(hello1);}@Test public void testContructor() {ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");Car car = (Car) context.getBean("car");// 通过类型获取bean对象（要求在IOC容器里该类型的对象只能有一个）Car car1 = (Car) context.getBean("car1");System.out.println(car);System.out.println(car1);Person person = (Person) context.getBean("person");System.out.println(person);}}

2. 下面是集合的测试类
NewPerson.java

package com.spring.test.collections;import java.util.Map;import com.spring.test.Car;public class NewPerson {private String name;private int age;private Map<string, car=""> cars;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 Map<string, car=""> getCars() {return cars;}public void setCars(Map<string, car=""> cars) {this.cars = cars;}@Override public String toString() {return "Person: [name=" + name + ", age=" + age + ", cars=" + cars + "]";}}

Person.java

package com.spring.test.collections;import java.util.List;import com.spring.test.Car;public class Person {private String name;private int age;private List<car> cars;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 List<car> getCars() {return cars;}public void setCars(List<car> cars) {this.cars = cars;}@Override public String toString() {return "Person: [name=" + name + ", age=" + age + ", cars=" + cars + "]";}}

DataSource.java

package com.spring.test.collections;import java.util.Properties;public class DataSource {private Properties properties;public Properties getProperties() {return properties;}public void setProperties(Properties properties) {this.properties = properties;}@Override public String toString() {return "DataSource: [properties:" + properties + "]";}}

Main.java

package com.spring.test.collections;import org.junit.Test;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;public class Main {@Test public void testCollections() {ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");Person person = (Person) context.getBean("person3");System.out.println(person);NewPerson newPerson = (NewPerson) context.getBean("newPerson");System.out.println(newPerson);DataSource dataSource = (DataSource) context.getBean("dataSource");System.out.println(dataSource);Person person4 = (Person) context.getBean("person4");System.out.println(person4);Person person5 = (Person) context.getBean("person5");System.out.println(person5);}}

总结

以上就是本文关于Spring框架依赖注入方法示例的全部内容，希望对大家有所帮助。如有不足之处，欢迎留言指出。感谢朋友们对本站的支持！