Spring原始註解

Spring是輕程式碼而重配置的框架，配置比較繁重，影響開發效率，所以註解開發是一種趨勢，註解代替xml配置檔案可以簡化配置，提高開發效率。 

 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:context="http://www.springframework.org/schema/context"
 

 5        xsi:schemaLocation="
 6        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
 7        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
 8 
 9 
10     <bean id="dataSource_c3p0" class
 
="com.mchange.v2.c3p0.ComboPooledDataSource">
11         <property name="driverClass" value="com.mysql.jdbc.Driver"></property>
12         <property name="jdbcUrl" value="jdbc:mysql://localhost:3306/test"></property>
13         <property name="user" value="root"></property
 
>
14         <property name="password" value="root"></property>
15     </bean>
16 
17     <!--載入外部的properties檔案-->
18     <!--需要在頂部beans中配置名稱空間context，並在xsi中新增對應的約束路徑-->
19     <context:property-placeholder location="classpath:jdbc.properties"/>
20     <bean id="dataSource_druid" class="com.alibaba.druid.pool.DruidDataSource">
21         <property name="driverClassName" value="${jdbc.driver}"></property>
22         <property name="url" value="${jdbc.url}"></property>
23         <property name="username" value="${jdbc.username}"></property>
24         <property name="password" value="${jdbc.password}"></property>
25     </bean>
26 
27 
28     <!--<bean id="userDao" class="com.haifei.dao.impl.UserDaoImpl"></bean>-->
29     <!--<bean id="userService" class="com.haifei.service.impl.UserServiceImpl">-->
30         <!--<property name="userDao" ref="userDao"></property>-->
31     <!--</bean>-->
32 
33     <!--配置元件掃描-->
34     <!--使用註解進行開發時（代替配置bean方式開發），需要在applicationContext.xml中配置元件掃描，
35     作用是指定哪個包及其子包下的Bean需要進行掃描以便識別使用註解配置的類、欄位和方法
36     不配置這個的話，執行會報異常NoSuchBeanDefinitionException-->
37     <context:component-scan base-package="com.haifei" />
38 
39 </beans>

1 package com.haifei.dao;
2 
3 public interface UserDao {
4 
5     public void save();
6 }

 1 package com.haifei.dao.impl;
 2 
 3 import com.haifei.dao.UserDao;
 4 import org.springframework.stereotype.Component;
 5 import org.springframework.stereotype.Repository;
 6 
 7 //<bean id="userDao" class="com.haifei.dao.impl.UserDaoImpl"></bean>
 8 //@Component("userDao")
 9 @Repository("userDao")
10 public class UserDaoImpl implements UserDao {
11 
12     @Override
13     public void save() {
14         System.out.println("UserDaoImpl: save running...");
15     }
16 }

1 package com.haifei.service;
2 
3 public interface UserService {
4 
5     public void save();
6 }

 1 package com.haifei.service.impl;
 2 
 3 import com.haifei.dao.UserDao;
 4 import com.haifei.dao.impl.UserDaoImpl;
 5 import com.haifei.service.UserService;
 6 import org.springframework.beans.factory.annotation.Autowired;
 7 import org.springframework.beans.factory.annotation.Qualifier;
 8 import org.springframework.beans.factory.annotation.Value;
 9 import org.springframework.context.annotation.Scope;
10 import org.springframework.stereotype.Component;
11 import org.springframework.stereotype.Service;
12 
13 import javax.annotation.PostConstruct;
14 import javax.annotation.PreDestroy;
15 import javax.annotation.Resource;
16 
17 //<bean id="userService" class="com.haifei.service.impl.UserServiceImpl"></bean>
18 //@Component("userService")
19 @Service("userService")
20 @Scope("prototype") //預設（不設定時也是）是singleton單例；可以設定為prototype多例
21 public class UserServiceImpl implements UserService {
22 
23     //<property name="userDao" ref="userDao"></property>
24     /*@Autowired //按照資料型別從Spring容器中進行匹配的（只寫Autowired，不寫Qualifier，也能注入）
25 //    @Qualifier("userDao") //是按照id值從容器中進行匹配的 但是主要此處@Qualifier結合@Autowired一起使用*/
26     @Resource(name="userDao") //@Resource相當於@Qualifier+@Autowired
27     private UserDao userDao;
28 
29     /*public void setUserDao(UserDao userDao) {
30         this.userDao = userDao;
31     }*/
32     /*
33     通過xml配置bean的方式開發時：
34         如果使用set進行依賴注入，則set方法必須有，不能省略
35     通過註解的方式開發時：
36         set方法可以省略，因為註解可以通過反射給userDao賦值
37      */
38 
39 
40     //通過註解注入普通資料型別
41     @Value("itcast")
42     private String heima; // private String heima = "itcast"
43     @Value("${jdbc.driver}") //通過鍵從jdbc.properties中獲取值
44     private String driver;
45 
46 
47     @Override
48     public void save() {
49         System.out.println(heima); //itcast
50         System.out.println(driver); //com.mysql.jdbc.Driver
51         userDao.save();
52     }
53 
54 
55     @PostConstruct
56     public void init(){
57         System.out.println("UserServiceImpl: 初始化方法");
58     }
59     @PreDestroy
60     public void destory(){
61         System.out.println("UserServiceImpl: 銷燬方法");
62     }
63 }

 1 package com.haifei.web;
 2 
 3 import com.haifei.service.UserService;
 4 import org.springframework.context.ApplicationContext;
 5 import org.springframework.context.support.ClassPathXmlApplicationContext;
 6 import org.springframework.stereotype.Controller;
 7 
 8 /**
 9  * 假的servlet
10  * 用於測試
11  */
12 //@Controller
13 public class UserController {
14 
15     public static void main(String[] args) {
16 //        ApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
17         ClassPathXmlApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
18         UserService userService = app.getBean(UserService.class);
19         userService.save();
20         app.close();
21 
22         /*
23             UserServiceImpl: 初始化方法
24             itcast
25             com.mysql.jdbc.Driver
26             UserDaoImpl: save running...
27             七月 15, 2021 7:37:53 下午 org.springframework.context.support.AbstractApplicationContext doClose
28             資訊: Closing org.springframework.context.support.ClassPathXmlApplicationContext@e2144e4: startup date [Thu Jul 15 19:37:52 CST 2021]; root of context hierarchy
29          */
30     }
31 
32 }

Spring新註解