Java Web实战04--Spring之属性注入和构造器注入

和前面一样，建立maven工程，然后进行以下操作过程，

1、新建一个bag类，设置四个字段，如下所示：

package com.yefeng.spring.spring2;/** * @author yefengzhichen * 2016年7月3日 */public class Bag {private String brand;private String country;private double price;private int capacity;public Bag() {super();}public Bag(String brand, String country, double price) {super();this.brand = brand;this.country = country;this.price = price;}public Bag(String brand, String country, double price, int capacity) {super();this.brand = brand;this.country = country;this.price = price;this.capacity = capacity;}public String getBrand() {return brand;}public void setBrand(String brand) {this.brand = brand;}public String getCountry() {return country;}public void setCountry(String country) {this.country = country;}public double getPrice() {return price;}public void setPrice(double price) {this.price = price;}public int getCapacity() {return capacity;}public void setCapacity(int capacity) {this.capacity = capacity;}@Overridepublic String toString() {return "Bag [brand=" + brand + ", country=" + country + ", price=" + price + ", capacity=" + capacity + "]";}}

在本bag类中，建立了三个构造器，其中无参数的构造器，是属性注入必须建立的。分别设置所有参数的setter和getter方法，并重新toString方法。

2、同上一篇博客，在pom.xml中增加以下依赖：

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.yefeng.spring</groupId><artifactId>spring1</artifactId><version>0.0.1-SNAPSHOT</version><packaging>jar</packaging><name>spring1</name><url>http://maven.apache.org</url><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding></properties><dependencies><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>3.8.1</version><scope>test</scope></dependency><!-- https://mvnrepository.com/artifact/org.springframework/spring-context --><dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>4.3.0.RELEASE</version></dependency><!-- https://mvnrepository.com/artifact/org.springframework/spring-core --><dependency><groupId>org.springframework</groupId><artifactId>spring-core</artifactId><version>4.3.0.RELEASE</version></dependency><!-- https://mvnrepository.com/artifact/org.springframework/spring-beans --><dependency><groupId>org.springframework</groupId><artifactId>spring-beans</artifactId><version>4.3.0.RELEASE</version></dependency><!-- https://mvnrepository.com/artifact/org.springframework/spring-expression --><dependency><groupId>org.springframework</groupId><artifactId>spring-expression</artifactId><version>4.3.0.RELEASE</version></dependency></dependencies></project>

3、建立Spring的bean配置文件，并增加如下内容：

<?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"><!-- 属性注入，需要无参构造器 --><bean id="adi" class="com.yefeng.spring.spring2.Bag"><property name="brand" value="adi"></property><property name="country" value="America"></property><property name="price" value="250"></property></bean><!-- 构造器注入，可以指定index或者type --><bean id="nike" class="com.yefeng.spring.spring2.Bag"><constructor-arg value="nike" index="0"></constructor-arg><constructor-arg value="America" index="1"></constructor-arg><!-- <constructor-arg value="10" index="3"></constructor-arg> --><constructor-arg value="10" type="int"></constructor-arg><constructor-arg value="200.0" type="double"></constructor-arg></bean><bean id="ata" class="com.yefeng.spring.spring2.Bag"><constructor-arg value="ata" type="java.lang.String"></constructor-arg><constructor-arg value="China"></constructor-arg><constructor-arg value="120"></constructor-arg><constructor-arg value="5"></constructor-arg></bean></beans>

4、测试代码,在app类中代码如下：

package com.yefeng.spring.spring2;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;/** * @author yefengzhichen * 2016年7月3日 */public class App {    public static void main( String[] args )    {        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");        Bag adi = (Bag) applicationContext.getBean("adi");        System.out.println(adi);                Bag nike = (Bag) applicationContext.getBean("nike");        System.out.println(nike);                Bag ata = (Bag) applicationContext.getBean("ata");        System.out.println(ata);        }}

结果如下：