关于Spring中基于xml文件配置bean的详细总结（spring 4.1.0）
来源：https://www.cnblogs.com/albertrui/p/8279682.html
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());
}
}