第一种:构造方法注入
● 通过构造方法注入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》 元素里声明的属性
代码演示:
1.编写一个javaBean
package com.zhou.ioc.demo4;
public class User {
private String name;
private Integer age;
public User(String name, Integer age) {
this.name = name;
this.age = age;
}
@Override
public String toString() {
return "User{" +
"name='" + name + '\'' +
", age=" + age +
'}';
}
}
2.编写applicationContext.xml配置文件
<?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">
<bean id="user" class="com.zhou.ioc.demo4.User">
<constructor-arg name="name" value="小明"/>
<constructor-arg name="age" value="18"/>
</bean>
</beans>
3.编写测试类
package com.zhou.ioc.demo4;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class springDemo1 {
@Test
public void demo1(){
//获得工厂
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
User user = (User) applicationContext.getBean("user");
System.out.println(user);
}
}
结果:
User{name='小明', age=18}
.第二种方式 :Set 方法注入
使用set方法注入,在Spring配置文件种,通过 《property》设置注入的属性
案例演示:
- 创建一个javaBean , 里面不仅包含普通属性 还包含对象属性
——
package com.zhou.ioc.demo4;
public class Person {
private String name;
private Integer age;
private Cat cat;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public Cat getCat() {
return cat;
}
public void setCat(Cat cat) {
this.cat = cat;
}
@Override
public String toString() {
return "Person{" +
"name='" + name + '\'' +
", age=" + age +
", cat=" + cat +
'}';
}
}
2.编写Cat 对象属性
package com.zhou.ioc.demo4;
public class Cat {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Override
public String toString() {
return "Cat{" +
"name='" + name + '\'' +
'}';
}
}
3.编写 applicationContext.xml配置文件
<?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">
<bean id="person" class="com.zhou.ioc.demo4.Person">
<property name="name" value="黄大炮"/>
<property name="age" value="250"/>
<property name="cat" ref="cat"/>
</bean>
<bean id="cat" class="com.zhou.ioc.demo4.Cat">
<property name="name" value="胖橘"/>
</bean>
</beans>
小提示 : ref:是用来引入其他bean对象的id或name的
4 编写测试类
package com.zhou.ioc.demo4;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class springDemo1 {
@Test
public void demo(){
//获得工厂
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
Person person = (Person) applicationContext.getBean("person");
System.out.println(person);
}
}
Person{name='黄大炮', age=250, cat=Cat{name='胖橘'}}
第3种方式:p名称空间注入
首先得引入p名称空间,这跟beans差不多 我们可以复制一下 然后对其修改就行了
xmlns:p=“http://www.springframework.org/schema/p”
接着我们就可以直接去调用 直接在 标签里面填写 格式如下:
p:<属性名>=“xxx” 引入常量值
p:<属性名>-ref=“xxx” 引入其他Bean对象
案例演示:
我们就直接用上面set的案例对其就行修改一下
1.修改applicationContext.xml 配置文件
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:p="http://www.springframework.org/schema/p"
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">
<bean id="person" class="com.zhou.ioc.demo4.Person" p:name="大黄" p:age="18" p:cat-ref="cat"/>
<bean id="cat" class="com.zhou.ioc.demo4.Cat" p:name="小黄" />
</beans>
这里我们添加了一个p名称空间 :xmlns:p=“http://www.springframework.org/schema/p”
然后对<bean>标签进行了修改
2.直接执行测试类得到结果
Person{name='大黄', age=
Person{name='大黄', age=18, cat=Cat{name='小黄'}}
第4种: SpEL注入
即spring表达式语言,对依赖注入进行简化
语法:#{表达式}
<bean id = " " value = “#{表达式}” 》
SpEL表达式语言:
#{ ‘hello’} :使用字符串
#{topicId}:使用另一个bean
#{topicld.add()}: 使用指定名属性, 并使用属性里的方法
#{ T (java.lang.Math).PI} : 使用静态字段或方法
代码演示:
1.创建一个Product 产品类
package com.zhou.ioc.demo4;
public class Product {
private String name;
private double price;
private Category category; //商品分类
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public double getPrice() {
return price;
}
public void setPrice(double price) {
this.price = price;
}
public Category getCategory() {
return category;
}
public void setCategory(Category category) {
this.category = category;
}
@Override
public String toString() {
return "Product{" +
"name='" + name + '\'' +
", price=" + price +
", category=" + category +
'}';
}
}
2、创建 Category 商品 类
package com.zhou.ioc.demo4;
public class Category {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Override
public String toString() {
return "Category{" +
"name='" + name + '\'' +
'}';
}
}
3.编写 一个计算商品价格的ProductInfo 类
package com.zhou.ioc.demo4;
public class ProductInfo {
public Double calculatePrice(){
return Math.random() * 200;
}
}
4.编写 applicationContext.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:p="http://www.springframework.org/schema/p"
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">
<bean id="product" class="com.zhou.ioc.demo4.Product">
<property name="name" value="#{'服装'}"/>
<!--productInfo.calculatePrice() 调用productInfo中的calculatePrice()方法-->
<property name="price" value="#{productInfo.calculatePrice()}"/>
<property name="category" value="#{category}"/>
</bean>
<bean id="productInfo" class="com.zhou.ioc.demo4.ProductInfo"/>
<bean id="category" class="com.zhou.ioc.demo4.Category">
<property name="name" value="#{'女装'}"/>
</bean>
</beans>
5.结果
Product{name='服装', price=69.97578331596061, category=Category{name='女装'}}
第5种:复杂类型注入
数组类型的属性注入
List集合类型的属性注入
Set集合类型的属性注入
Map集合类型的属性注入
Properties类型的属性注入
1.编写一个demo
package com.zhou.ioc.demo5;
import java.util.*;
public class CollectionBean {
private String[] arrs; // 数组类型
private List<String> list;// List集合类型
private Set<String> set; // Set集合类型
private Map<String,Integer> map;// Map集合类型
private Properties properties; // 属性类型
public String[] getArrs() {
return arrs;
}
public void setArrs(String[] arrs) {
this.arrs = arrs;
}
public List<String> getList() {
return list;
}
public void setList(List<String> list) {
this.list = list;
}
public Set<String> getSet() {
return set;
}
public void setSet(Set<String> set) {
this.set = set;
}
public Map<String, Integer> getMap() {
return map;
}
public void setMap(Map<String, Integer> map) {
this.map = map;
}
public Properties getProperties() {
return properties;
}
public void setProperties(Properties properties) {
this.properties = properties;
}
@Override
public String toString() {
return "CollectionBean{" +
"arrs=" + Arrays.toString(arrs) +
", list=" + list +
", set=" + set +
", map=" + map +
", properties=" + properties +
'}';
}
}
2、编写applicationContext.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:p="http://www.springframework.org/schema/p"
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">
<!--集合类型的属性注入=================================-->
<bean id="collectionBean" class="com.zhou.ioc.demo5.CollectionBean">
<!--数组类型-->
<property name="arrs">
<list>
<value>aaa</value>
<value>bbb</value>
<value>ccc</value>
</list>
</property>
<!--List集合的属性注入-->
<property name="list">
<list>
<value>111</value>
<value>222</value>
<value>333</value>
</list>
</property>
<!--Set集合的属性注入-->
<property name="set">
<set>
<value>ddd</value>
<value>eee</value>
<value>fff</value>
</set>
</property>
<!--Map集合的属性注入-->
<property name="map">
<map>
<entry key="aaa" value="111"/>
<entry key="bbb" value="222"/>
<entry key="ccc" value="333"/>
</map>
</property>
<!--Properties的属性注入-->
<property name="properties">
<props>
<prop key="username">root</prop>
<prop key="password">1234</prop>
</props>
</property>
</bean>
</beans>
3.编写测试类
package com.zhou.ioc.demo5;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class SpringDemo5 {
@Test
public void demo1(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
CollectionBean collectionBean = (CollectionBean)applicationContext.getBean("collectionBean");
System.out.println(collectionBean);
}
}
4.结果
CollectionBean{arrs=[aaa, bbb, ccc], list=[111, 222, 333], set=[ddd, eee, fff], map={aaa=111, bbb=222, ccc=333}, properties={password=1234, username=root}}
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原文链接:https://blog.csdn.net/qq_42137956/article/details/90112478