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這篇文章將為大家詳細講解有關怎么在Spring框架中注入依賴，文章內容質量較高，因此小編分享給大家做個參考，希望大家閱讀完這篇文章后對相關知識有一定的了解。
三種依賴注入的方式
屬性注入，通過setter方法注入bean的屬性值或依賴的對象 構造注入 工廠方法注入（很少使用）
例子
這里我們使用了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：標識容器中bean對象 class：bean的全類名，通過反射的方式在IOC容器中創建Bean，所以要求Bean類必須有無參構造器 --> <bean class="com.spring.test.HelloWorld" id="helloWorld"> <property name="name" value="crystal"></property> </bean> <!-- 通過構造方法配置bean,可以指定參數的位置和類型，以區分重載的構造函數 --> <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[]]>包裹起來 屬性值可以使用value子節點來配置 --> <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建立引用之間的關系 --> <!-- <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> --> <!-- 測試賦值null --> <!-- <property name="car"><null/></property> --> <property name="car" ref="car1"></property> <!-- 為級聯屬性賦值，注意：屬性需要先初始化后才能為級聯屬性賦值，和structs2不同 --> <property name="car.price" value="400000"></property> </bean> <!-- 測試配置集合屬性 --> <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的屬性值 --> <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節點及map的entry子節點配置Map類型的成員變量 --><map> <entry key="AA" value-ref="car"></entry> <entry key="BB" value-ref="car1"></entry></map> </property> </bean> <!-- 配置Properties屬性值 --> <bean class="com.spring.test.collections.DataSource" id="dataSource"> <property name="properties"> <!-- 使用props和prop子節點來為Properties屬性賦值 --> <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> <!-- 配置單例的集合bean，以供多個bean進行引用，需要導入util命名空間 --> <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> <!-- 通過p命名空間為bean的屬性賦值，需要先導入p命名空間，相對于傳統配置方式更為簡潔 --> <bean class="com.spring.test.collections.Person" id="person5" p:age="32" p:cars-ref="cars" p:name="Queue"></bean> </beans>
1. 下面是簡單的屬性注入、構造注入的測試類
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");
// 裝入 Spring 配置文件
/**
* 裝入 Spring 配置文件
* ApplicationContext是IOC容器，它有兩個主要實現類（ClassPathXmlApplicationContext和FileSystemXmlApplicationContext）
* ApplicationContext在初始化上下文時就實例化所有單例的Bean
*/
ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
//HelloWorld hello1 = (HelloWorld) context.getBean("helloWorld"); // 通過id獲取bean對象
HelloWorld hello1 = context.getBean(HelloWorld.class);
// 通過類型獲取bean對象（要求在IOC容器里該類型的對象只能有一個）
System.out.println(hello1);
}
@Test
public void testContructor() {
ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
Car car = (Car) context.getBean("car");
// 通過類型獲取bean對象（要求在IOC容器里該類型的對象只能有一個）
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. 下面是集合的測試類
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);
}
}關于怎么在Spring框架中注入依賴就分享到這里了，希望以上內容可以對大家有一定的幫助，可以學到更多知識。如果覺得文章不錯，可以把它分享出去讓更多的人看到。
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