关于Spring中基于xml文件配置bean的详细总结（spring 4.1.0）
一、Spring中的依赖注入方式介绍
依赖注入有三种方式
- 属性注入
- 构造方法注入
- 工厂方法注入（很少使用，不推荐，本文不再介绍）
属性注入
通过 setter 方法注入Bean 的属性值或依赖的对象。属性注入使用 <property>元素, 使用 name 属性指定 Bean 的属性名称，value 属性或 <value> 子节点指定属性值 。属性注入是实际应用中最常用的注入方式。HelloWorld类中的setName()方法，对应上边代码中的name属性，例如：把setName()方法名改为setName2()，property中的name属性值为name时则会报错，需要将name属性改为name2。
构造方法
构造方法注入Bean 的属性值或依赖的对象，它保证了 Bean 实例在实例化后就可以使用。
构造器注入在 <constructor-arg> 元素里声明属性, <constructor-arg> 中没有 name 属性。使用value属性值或value子节点为属性赋值。可以同时使用索引 index 和type属性对应为哪个属性赋值。index的值表示构造函数中参数的位置。type表示成员属性的类型，例如type=“double”
二、属性注入和构造方法注入详解：
1.applicationContext.xml文件配置如下
1 <?xml version="1.0" encoding="UTF-8"?>
2 <beans xmlns="http://www.springframework.org/schema/beans"
3 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4 xmlns:p="http://www.springframework.org/schema/p"
5 xmlns:util="http://www.springframework.org/schema/util"
6 xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.1.xsd
7 http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.1.xsd">
8
9 <!--
10 配置bean
11 class:bean的全类名，通过反射的方式在IOC容器中创建bean
12 id：表示容器中的bean，id唯一
13 -->
14 <!-- 通过setter注入配置bean的属性 -->
15 <bean id="helloWorld" class="me.spring.beans.HelloWorld">
16 <property name="name" value="Spring"></property>
17 </bean>
18 <!-- 通过构造方法配置bean的属性 -->
19 <bean id="car" class="me.spring.beans.Car">
20 <constructor-arg value="Audi"></constructor-arg>
21 <constructor-arg value="ShangHai"></constructor-arg>
22 <constructor-arg value="300000"></constructor-arg>
23 </bean>
24
25 <!--
26 使用构造器注入的属性值可以指定参数的类型和参数的位置，以区分重载的构造器
27 如果字面值包含特殊字符，可以使用<![CDATA[]]>包裹起来
28 属性值也可以使用value子节点进行配置
29 -->
30 <bean id="car2" class="me.spring.beans.Car">
31 <constructor-arg value="Baoma"></constructor-arg>
32 <constructor-arg type="java.lang.String">
33 <value><![CDATA[<Beijing>]]></value>
34 </constructor-arg>
35 <constructor-arg value="240" type="int"></constructor-arg>
36 </bean>
37
38 <!-- 可以使用property的ref属性建立bean之间的引用关系 -->
39 <bean id="person" class="me.spring.beans.Person">
40 <property name="name" value="Tom"></property>
41 <property name="age" value="24"></property>
42 <!--
43 <property name="car" ref="car2"></property>
44 -->
45
46 <!--
47 <property name="car">
48 <ref bean="car2"/>
49 </property>
50 -->
51
52 <!-- 内部bean，不能被外部引用 -->
53 <property name="car">
54 <bean class="me.spring.beans.Car">
55 <constructor-arg value="Ford"></constructor-arg>
56 <constructor-arg value="ChangAn"></constructor-arg>
57 <constructor-arg value="2354395" type="double"></constructor-arg>
58 </bean>
59 </property>
60 </bean>
61
62 <bean id="person2" class="me.spring.beans.Person">
63 <constructor-arg value="Jerry"></constructor-arg>
64 <constructor-arg value="25"></constructor-arg>
65 <constructor-arg ref="car2"></constructor-arg>
66
67 <!-- 测试赋值null -->
68 <!--
69 <constructor-arg><null/></constructor-arg>
70 -->
71 <!--
72 为级联属性赋值
73 注意:属性需要初始化后才可以为级联属性赋值，和Struts2不同
74 这里必须依据person的setter和getter方法，不能为car2
75 -->
76 <property name="car.price" value="4546"></property>
77 </bean>
78
79 <!-- 测试如何配置集合属性 -->
80 <bean id="person3" class="me.spring.beans.collections.Person">
81 <property name="name" value="Mike"></property>
82 <property name="age" value="34"></property>
83 <property name="cars">
84 <!-- 使用list结点为属性为list的属性赋值 -->
85 <list>
86 <ref bean="car"/>
87 <ref bean="car2"/>
88 <bean class="me.spring.beans.Car">
89 <constructor-arg value="Ford"></constructor-arg>
90 <constructor-arg value="ChangAn"></constructor-arg>
91 <constructor-arg value="2354395" type="double"></constructor-arg>
92 </bean>
93 </list>
94 </property>
95 </bean>
96 <bean id="newPerson" class="me.spring.beans.collections.NewPerson">
97 <property name="name" value="Rose"></property>
98 <property name="age" value="23"></property>
99 <property name="cars">
100 <!-- 使用map结点及map的entry子节点配置Map类型的成员变量 -->
101 <map>
102 <entry key="AA" value-ref="car"></entry>
103 <entry key="BB" value-ref="car2"></entry>
104 </map>
105 </property>
106 </bean>
107
108 <!-- 配置properties属性值 -->
109 <bean id="dataSource" class="me.spring.beans.collections.DataSource">
110 <property name="properties">
111 <!-- 使用props和prop子节点来为properties属性值赋值 -->
112 <props>
113 <prop key="user">root</prop>
114 <prop key="password">123456</prop>
115 <prop key="jdbcURL">jdbc:mysql://localhost:3306/test</prop>
116 <prop key="driverClass">com.mysql.jdbc.Driver</prop>
117 </props>
118 </property>
119 </bean>
120
121 <!-- 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 -->
122 <util:list id="cars">
123 <ref bean="car"/>
124 <ref bean="car2"/>
125 </util:list>
126
127 <bean id="person4" class="me.spring.beans.collections.Person">
128 <property name="name" value="Jack"></property>
129 <property name="age" value="34"></property>
130 <property name="cars" ref="cars"></property>
131 </bean>
132
133 <!-- 通过p命名空间为bean的属性赋值，需要导入p命名空间,相对于传统的配置较为简洁 -->
134 <bean id="person5" class="me.spring.beans.collections.Person" p:name="Queen" p:age="45" p:cars-ref="cars"></bean>
135 </beans>
2.相关的实体类：
(1)me.spring.beans 包下：
1 package me.spring.beans;
2
3 public class Car {
4
5 private String brand;
6 private String corp;
7 private double price;
8 private int maxSpeed;
9 public Car(String brand, String corp, double price) {
10 super();
11 this.brand = brand;
12 this.corp = corp;
13 this.price = price;
14 }
15
16 public Car(String brand, String corp, int maxSpeed) {
17 super();
18 this.brand = brand;
19 this.corp = corp;
20 this.maxSpeed = maxSpeed;
21 }
22
23 public void setPrice(double price) {
24 this.price = price;
25 }
26
27 public double getPrice() {
28 return price;
29 }
30 @Override
31 public String toString() {
32 return "Car [brand=" + brand + ", corp=" + corp + ", price=" + price + ", maxSpeed=" + maxSpeed + "]";
33 }
34
35 }
36
37 package me.spring.beans;
38
39 public class Person {
40
41 private String name;
42 private int age;
43 private Car car;
44
45 public String getName() {
46 return name;
47 }
48
49 public void setName(String name) {
50 this.name = name;
51 }
52
53 public int getAge() {
54 return age;
55 }
56
57 public void setAge(int age) {
58 this.age = age;
59 }
60
61 public Car getCar() {
62 return car;
63 }
64
65 public void setCar(Car car) {
66 this.car = car;
67 }
68
69 public Person() {
70
71 }
72 public Person(String name, int age, Car car) {
73 super();
74 this.name = name;
75 this.age = age;
76 this.car = car;
77 }
78
79 @Override
80 public String toString() {
81 return "Person [name=" + name + ", age=" + age + ", car=" + car + "]";
82 }
83
84 }
85
86 package me.spring.beans;
87
88 public class HelloWorld {
89
90 private String name;
91 public void setName(String name) {
92 this.name = name;
93 }
94 public void hello() {
95 System.out.println("hello:" + name);
96 }
97 }
98
99 package me.spring.beans;
100
101 import org.springframework.context.ApplicationContext;
102 import org.springframework.context.support.ClassPathXmlApplicationContext;
103
104 public class Main {
105
106 public static void main(String[] args) {
107 // HelloWorld helloWorld = new HelloWorld();
108 // helloWorld.setName("Spring");
109 // helloWorld.hello();
110
111 //1.创建Spring的IOC容器对象
112 //ApplicationContext代表IOC容器
113 //ClassPathXmlApplicationContext是ApplicationContext的实现类，该实现类从类路径下加载配置文件
114 ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
115 //2.从IOC容器中获取bean实例
116 //利用id定位到IOC容器中的bean
117 HelloWorld helloWorld = (HelloWorld) ctx.getBean("helloWorld");
118 //利用类型返回IOC容器中的bean，担忧求IOC容器中只能有一个该类型的bean
119 //HelloWorld helloWorld = ctx.getBean(HelloWorld.class);
120 //3.调用hello方法
121 helloWorld.hello();
122 Car car = (Car) ctx.getBean("car");
123 System.out.println(car);
124 car = (Car) ctx.getBean("car2");
125 System.out.println(car);
126 Person person = (Person) ctx.getBean("person2");
127 System.out.println(person);
128 }
129
130 }
(2)me.spring.beans.collections 测试集和属性
1 package me.spring.beans.collections; 2 3 import java.util.List; 4 5 import me.spring.beans.Car; 6 7 public class Person { 8 9 private String name; 10 private int age; 11 12 private List<Car> cars; 13 14 public String getName() { 15 return name; 16 } 17 18 public void setName(String name) { 19 this.name = name; 20 } 21 22 public int getAge() { 23 return age; 24 } 25 26 public void setAge(int age) { 27 this.age = age; 28 } 29 30 31 public Person() { 32 33 } 34 35 public List<Car> getCars() { 36 return cars; 37 } 38 39 public void setCars(List<Car> cars) { 40 this.cars = cars; 41 } 42 43 public Person(String name, int age, List<Car> cars) { 44 super(); 45 this.name = name; 46 this.age = age; 47 this.cars = cars; 48 } 49 50 @Override 51 public String toString() { 52 return "Person [name=" + name + ", age=" + age + ", cars=" + cars + "]"; 53 } 54 } 55 56 package me.spring.beans.collections; 57 58 import java.util.Map; 59 60 import me.spring.beans.Car; 61 62 public class NewPerson { 63 64 private String name; 65 private int age; 66 private Map<String, Car> cars; 67 public String getName() { 68 return name; 69 } 70 public void setName(String name) { 71 this.name = name; 72 } 73 public int getAge() { 74 return age; 75 } 76 public void setAge(int age) { 77 this.age = age; 78 } 79 public Map<String, Car> getCars() { 80 return cars; 81 } 82 public void setCars(Map<String, Car> cars) { 83 this.cars = cars; 84 } 85 86 public NewPerson() { 87 // TODO Auto-generated constructor stub 88 } 89 public NewPerson(String name, int age, Map<String, Car> cars) { 90 super(); 91 this.name = name; 92 this.age = age; 93 this.cars = cars; 94 } 95 @Override 96 public String toString() { 97 return "NewPerson [name=" + name + ", age=" + age + ", cars=" + cars + "]"; 98 } 99 100 } 101 102 package me.spring.beans.collections; 103 104 import java.util.Properties; 105 106 public class DataSource { 107 108 private Properties properties; 109 110 public Properties getProperties() { 111 return properties; 112 } 113 114 public void setProperties(Properties properties) { 115 this.properties = properties; 116 } 117 118 @Override 119 public String toString() { 120 return "DataSource [properties=" + properties + "]"; 121 } 122 123 } 124 package me.spring.beans.collections;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Main {
public static void main(String[] args) {
ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
Person person = (Person) ctx.getBean("person5");
System.out.println(person);
NewPerson newPerson = (NewPerson) ctx.getBean("newPerson");
System.out.println(newPerson);
DataSource dataSource = ctx.getBean(DataSource.class);
System.out.println(dataSource.getProperties());
}
}