The first Spring application

POM

Create a project called  hello-spring project pom.xml file as follows:

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <project xmlns="http://maven.apache.org/POM/4.0.0"
 3          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 5     <modelVersion>4.0.0</modelVersion>
 6 
 7     <groupId>com.snake</groupId>
 8     <artifactId>hello-spring</artifactId>
 9     <version>1.0.0-SNAPSHOT</version>
10     <packaging>jar</packaging>
11 
12     <dependencies>
13         <dependency>
14             <groupId>org.springframework</groupId>
15             <artifactId>spring-context</artifactId>
16             <version>4.3.17.RELEASE</version>
17         </dependency>
18     </dependencies>
19 </project>

Creating an interface and implementation

# Creating  UserService interfaces

1 package com.snake.hello.spring.service;
2 
3 public interface UserService {
4     public void sayHi();
5 }

Creating  UserServiceImpl achieve

package com.snake.hello.spring.service.impl;

import com.snake.hello.spring.service.UserService;

public class UserServiceImpl implements UserService {
    public void sayHi() {
        System.out.println("Hello Spring");
    }
}

 

# Create a Spring configuration file

In  src/main/resources Creating directory  spring-context.xml profiles, from now instantiate the class work to the Spring container management (IoC), the configuration file as follows:

<?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="userService" class="com.funtl.hello.spring.service.impl.UserServiceImpl" />
</beans>

 

 

• <bean />: Used to define an instance of the object. One example of a bean element corresponds.

• id: This attribute is a unique identifier Bean instance, to access the id attribute Bean, Bean and dependencies between Bean is also associated with the id attribute.

• class: Bean belongs to the specified class, pay attention here can only be a class, not an interface.

# Test Spring IoC

Create a  MyTest test class, can be created if the test object by Spring, code is as follows:

package com.snake.hello.spring;

import com.snaek.hello.spring.service.UserService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MyTest {

    public static void main(String[] args) {
        // 获取 Spring 容器
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-context.xml");
        
        // 从 Spring 容器中获取对象
        UserService userService = (UserService) applicationContext.getBean("userService");
        userService.sayHi();
    }
}