Spring框架总结

Posted 2020-09-03 北极的大企鹅

开发一个简单的Spring项目:

一、开发环境搭建:
1、引入源码jar ：3.0以前的版本含有依赖jar包，3.0以后只有spring的核心jar
包
core的jar包
commons-logging-1.1.3.jar
spring-beans-3.2.5.RELEASE.jar
spring-context-3.2.5.RELEASE.jar
spring-core-3.2.5.RELEASE.jar
spring-expression-3.2.5.RELEASE.jar

jar包可以在官网下载：http://repo.spring.io/release/org/springframework/spring/

2、创建一个xml文档，命名为applicationContext.xml

导入必须的schema

 1     <beans xmlns="http://www.springframework.org/schema/beans"
 2     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 3     xmlns:p="http://www.springframework.org/schema/p"
 4     xmlns:context="http://www.springframework.org/schema/context"
 5     xsi:schemaLocation="
 6         http://www.springframework.org/schema/beans
 7         http://www.springframework.org/schema/beans/spring-beans.xsd
 8         http://www.springframework.org/schema/context
 9         http://www.springframework.org/schema/context/spring-context.xsd">
10     
11 </beans>   

这些都需要，就不必删减了。留着吧。

3、创建例子

user

 1 package com.liuyang.spring;
 2 
 3 public class User {
 4     String _id;
 5     String _username;
 6 
 7     public User() {
 8         System.out.println("========创建类========");
 9     }
10 
11     public String get_id() {
12         return _id;
13     }
14 
15     public void set_id(String _id) {
16         this._id = _id;
17     }
18 
19     public String get_username() {
20         return _username;
21     }
22 
23     public void set_username(String _username) {
24         this._username = _username;
25     }
26 }

4、创建xml

 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" xmlns:p="http://www.springframework.org/schema/p"
 4     xmlns:context="http://www.springframework.org/schema/context"
 5     xsi:schemaLocation="
 6         http://www.springframework.org/schema/beans
 7         http://www.springframework.org/schema/beans/spring-beans.xsd
 8         http://www.springframework.org/schema/context
 9         http://www.springframework.org/schema/context/spring-context.xsd">
10     <bean id="user" class="com.liuyang.spring.User"></bean>
11     
12 
13 
14 </beans>

5、创建测试类

 1 @SuppressWarnings({ "resource", "deprecation" })
 2 public class TestApplication {
 3 
 4     // 通过工厂类创建IOC工程类对象
 5     @Test
 6     public void test1() {
 7         // 把对象创建交给IOC
 8         Resource resource = new ClassPathResource("com/liuyang/spring/applicationContext.xml");
 9         // 创建器对象
10         BeanFactory beanFactory = new XmlBeanFactory(resource);
11         // 的到容器对象 IOC=工厂类+ApplicationContext.xml
12         User user = (User) beanFactory.getBean("user");
13 
14         System.out.println(user);
15     }
16 
17     // 2.直接获取ApplicationContext.xml()方便
18     @Test
19     public void test2() {
20 
21         ApplicationContext aContext = new ClassPathXmlApplicationContext(
22                 "com/liuyang/spring/applicationContext.xml");
23 
24         // 的到容器对象 IOC=工厂类+ApplicationContext.xml
25         User user = (User) aContext.getBean("user");
26 
27         System.out.println(user);
28     }
29 
30     @Test
31     public void test3() {
32         /*
33          * (1)修改
34          * <bean id="user" class="com.liuyang.spring.User" scope="singleton"></bean> 
35          * // scope="singleton"   加不加无影响,默认是单例模式
36          * (2)[service/dao/工具类]   只需创建一次 scope="prototype" 多例
37          * [action对象]选有多次创建对象时用         用到对象时创建        启动容器之前,整个应用只有一个
38          * (3)是否延迟创建
39          *        scope="singleton" 才有效
40          * (4)懒加载问题 lazy-init="false" 默认为false,
41          *    不延迟创建，
42          *        即在启动时候就创建对象 lazy-init="true" 延迟初始化， 在用到对象的时候才创建对象
43          * 
44          * 
45          * (5)  lazy-init="true"+scope="singleton"   ==    scope="prototype"
46          */
47         ApplicationContext aContext = new ClassPathXmlApplicationContext(
48                 "com/liuyang/spring/applicationContext.xml");
49         System.out.println("========创建容器========");
50         // 得到容器对象 IOC=工厂类+ApplicationContext.xml
51         User user1 = (User) aContext.getBean("user");
52         User user2 = (User) aContext.getBean("user");
53 
54         System.out.println(user1);
55         System.out.println(user2);
56     }
57 
58 }