Spring学习笔记（一）
1.简介
简介：(作者：Rod Johnson)
Spring的主要特性仅仅是依赖注入(DI)和面向切面编程(AOP),最根本使命是：简化Java开发
为了降低Java开发的复杂性，Spring采用了一下四种关键策略：
- 基于POJO的轻量级和最小侵入性编程
- 通过依赖注入和面向接口实现松耦合
- 基于切面和惯例进行声明式编程
- 通过切面和模版减少样板式代码
IOC(Inversion of Controler):控制反转
控制：指谁来控制对象的创建；传统的应用程序对象的创建是由程序本身控制的，使用Spring后，是由Spring来创建对象的
反转：正转是指由程序来创建，反转指程序本身不去创建对象，而变为被动接收的对象
总结：以前对象是由程序本身来创建，使用Spring后，程序变为被动接收Spring创建好的对象
IOC的实现是通过ioc容器来实现的，ioc容器其实就是一个BeanFactory
2.IOC创建对象的三种方式
通过无参数的构造方法来创建
//User类
package com.spring.learning.vo;
public class User{
private String name;
public User(){
System.out.println("User的无参数构造方法");
}
public void setName(String name) {
this.name = name;
}
public void show(){
System.out.println("name = " + name);
}
}//测试类
package com.spring.learning.test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.spring.learning.vo.User;
public class Test {
public static void main(String[] args) {
ApplicationContext ac = new ClassPathXmlApplicationContext("bean.xml");
User user = (User)ac.getBean("user");
user.show();
}
}
<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.spring.learning.vo.User">
<property name="name" value="张三">property>
bean>
beans>通过有参数的构造方法来创建
//User类
package com.spring.learning.vo;
public class User{
private String name;
public User(String name){
super();
this.name = name;
}
public void show(){
System.out.println("name = " + name);
}
}
<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.spring.learning.vo.User">
<constructor-arg index="0" value="李四" />
bean>
<bean id="user" class="com.spring.learning.User">
<constructor-arg name="name" value="李四">constructor-arg>
bean>
<bean id="user" class="com.spring.learning.User">
<constructor-arg type="java.lang.String" value="李四">constructor-arg>
bean>
beans>通过工厂方式来创建
静态工厂：
在第二种有参数构造方法的基础上，新建一个UserFactory类
package com.spring.learning.factory;
import com.spring.learning.vo.User;
public class UserFactory {
public static User newInstance(String name){
return new User(name);
}
}
<bean id="user" class="com.spring.learning.factory.UserFactory" factory-method="newInstance">
<constructor-arg index="0" value="王五">constructor-arg>
bean>动态工厂：
在第二种有参数构造方法的基础上，新建一个UserDynamicFactory类
package com.spring.learning.factory;
import com.spring.learning.vo.User;
public class UserDynamicFactory {
public User newInstance(String name){
return new User(name);
}
}
<bean id="userFactory" class="com.spring.learning.factory.UserDynamicFactory" />
<bean id="user" factory-bean="userFactory" factory-method="newInstance">
<constructor-arg index="0" value="王五">constructor-arg>
bean> bean.xml的配置
-- id是bean的标识符，是唯一的，如果没有配置id，则name为默认标识符
如果配置了id，又配置了name，则name是别名
name可以设置多个别名，分隔符可以是空格，分号，逗号
如果没有配置id和name，也可以根据applicationContext.getBean(class)获取对象
-->
id="h1" name="helo"class="com.spring.learning.Hello">
<property name="name" value="aaa">property>
3.DI注入的几种方式
DI —— 依赖注入
依赖是指：bean对象的创建依赖容器，bean对象的依赖资源
注入：指bean对象依赖的资源由容器来设置和装配
Spring注入
构造器注入：与IOC的对象的创建类似
setter注入：要求被注入的属性必须有set方法，方法名由set+属性首字母大写。如果属性是boolean，则没有set方法，是is方法
- 常量注入
id="user" class="com.spring.learning.vo.User">
<property name="name" value="张三">property>
- bean注入
id="addr" class="com.spring.learning.vo.Address">
id="user" class="com.spring.learning.vo.User">
<property name="name" value="张三">property>
<property name="addr" ref="addr">property>
- 数组注入
<bean id="addr" class="com.spring.learning.vo.Address">
<bean id="user" class="com.spring.learning.vo.User">
<property name="name" value="张三">property>
<property name="addr" ref="addr">property>
<property name="books">
<array>
<value>aaavalue>
<value>bbbvalue>
<value>cccvalue>
array>
property>
bean>- list注入
<bean id="addr" class="com.spring.learning.vo.Address">
<bean id="user" class="com.spring.learning.vo.User">
<property name="name" value="张三">property>
<property name="addr" ref="addr">property>
<property name="books">
<array>
<value>aaavalue>
<value>bbbvalue>
<value>cccvalue>
array>
property>
<property name="hobbies">
<list>
<value>dddvalue>
<value>eeevalue>
<value>fffvalue>
list>
property>
bean>- map注入
<bean id="addr" class="com.spring.learning.vo.Address">
<bean id="user" class="com.spring.learning.vo.User">
<property name="name" value="张三">property>
<property name="addr" ref="addr">property>
<property name="books">
<array>
<value>aaavalue>
<value>bbbvalue>
<value>cccvalue>
array>
property>
<property name="hobbies">
<list>
<value>dddvalue>
<value>eeevalue>
<value>fffvalue>
list>
property>
<property name="cards">
<map>
<entry key="aaa" value="bbb">entry>
<entry>
<key><value>mmmvalue>key>
<value>nnnvalue>
entry>
<entry key="ccc" value="ddd">entry>
map>
property>
bean>- set注入
<bean id="addr" class="com.spring.learning.vo.Address">
<bean id="user" class="com.spring.learning.vo.User">
<property name="name" value="张三">property>
<property name="addr" ref="addr">property>
<property name="books">
<array>
<value>aaavalue>
<value>bbbvalue>
<value>cccvalue>
array>
property>
<property name="hobbies">
<list>
<value>dddvalue>
<value>eeevalue>
<value>fffvalue>
list>
property>
<property name="cards">
<map>
<entry key="aaa" value="bbb">entry>
<entry>
<key><value>mmmvalue>key>
<value>nnnvalue>
entry>
<entry key="ccc" value="ddd">entry>
map>
property>
<property name="games">
<set>
<value>dddvalue>
<value>eeevalue>
<value>fffvalue>
set>
property>
bean>- null注入
<bean id="addr" class="com.spring.learning.vo.Address">
<bean id="user" class="com.spring.learning.vo.User">
<property name="name" value="张三">property>
<property name="addr" ref="addr">property>
<property name="books">
<array>
<value>aaavalue>
<value>bbbvalue>
<value>cccvalue>
array>
property>
<property name="hobbies">
<list>
<value>dddvalue>
<value>eeevalue>
<value>fffvalue>
list>
property>
<property name="cards">
<map>
<entry key="aaa" value="bbb">entry>
<entry>
<key><value>mmmvalue>key>
<value>nnnvalue>
entry>
<entry key="ccc" value="ddd">entry>
map>
property>
<property name="games">
<set>
<value>dddvalue>
<value>eeevalue>
<value>fffvalue>
set>
property>
<property name="yyy">
<null>null>
set>
property>
bean>- properties注入
<bean id="addr" class="com.spring.learning.vo.Address">
<bean id="user" class="com.spring.learning.vo.User">
<property name="name" value="张三">property>
<property name="addr" ref="addr">property>
<property name="books">
<array>
<value>aaavalue>
<value>bbbvalue>
<value>cccvalue>
array>
property>
<property name="hobbies">
<list>
<value>dddvalue>
<value>eeevalue>
<value>fffvalue>
list>
property>
<property name="cards">
<map>
<entry key="aaa" value="bbb">entry>
<entry>
<key><value>mmmvalue>key>
<value>nnnvalue>
entry>
<entry key="ccc" value="ddd">entry>
map>
property>
<property name="games">
<set>
<value>dddvalue>
<value>eeevalue>
<value>fffvalue>
set>
property>
<property name="yyy">
<null>null>
set>
property>
<property name="info">
<props>
<prop key="no">2015prop>
<prop key="sex">maleprop>
<prop key="name">aaaprop>
props>
property>
bean>- p命名空间注入
需要在头文件中加入：
xmlns:p=”http://www.springframework.org/schema/p”
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p" xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="user" class="com.spring.learning.vo.User"
p:name="aaa" p:age="20">bean>- c命名空间注入
需要在头文件中加入：
xmlns:p=”http://www.springframework.org/schema/c”
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p"
xmlns:p="http://www.springframework.org/schema/c" xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="user" class="com.spring.learning.vo.User"
c:name="aaa" c:age="20">bean>4.bean的作用域
--bean的作用域
scope="singleton"----单例模式 ，整个容器中只有一个对象实例(默认)
scope="prototype"-----原型模式,每次获取bean都产生一个新的对象
scope="request"----每次请求时产生一个新的对象
scope="session"----在会话范围内产生一个新的对象
scope="global session"----只在portlet下有用，表示application
scope="application"----在应用范围内产生一个新的对象
-->
id="user" class="com.spring.learning.vo.User" scope="singleton">
<property name="name" value="张三">property>
注意：在整合structs2和spring时需要将action设为scope=”prototype”;
5.bean的自动装配
bean的自动装配—–简化spring配置
在配置bean时，可以配置bean的autowire属性，用于指定装配类型
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p"
xmlns:p="http://www.springframework.org/schema/c" xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd" >
<bean id="user" class="com.spring.learning.vo.User" autowire="byName">
<property name="name" value="张三">property>
bean>
beans>可以配置全局的自动装配类型，在头部default-autowire
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p"
xmlns:p="http://www.springframework.org/schema/c" xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd" default-autowire="byName">