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
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<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
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<!--?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 class="com.spring.test.HelloWorld" 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 class="com.spring.test.Car" id="car"> <constructor-arg index="0" value="BENCHI"></constructor-arg> <constructor-arg index="1" type="double" value="200000.0"></constructor-arg> </bean> <bean class="com.spring.test.Car" 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 class="com.spring.test.Person" 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 class="com.spring.test.Car"> <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 class="com.spring.test.collections.Person" 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 class="com.spring.test.Car"> <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 class="com.spring.test.collections.NewPerson" 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 class="com.spring.test.collections.DataSource" 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 class="com.spring.test.collections.Person" 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 class="com.spring.test.collections.Person" 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
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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
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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
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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
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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
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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
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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
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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
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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！
原文链接：https://www.2cto.com/kf/201608/539381.html
