@Configuration 和 @Bean
Spring的Java配置方式是通过 @Configuration 和 @Bean 这两个注解实现的:
1、@Configuration 作用于类上,相当于一个xml配置文件;
2、@Bean 作用于方法上,相当于xml配置中的<bean>;
pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>demo.springboot</groupId>
<artifactId>springboot</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>war</packaging>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>4.3.11.RELEASE</version>
</dependency>
<!-- 连接池 -->
<dependency>
<groupId>com.jolbox</groupId>
<artifactId>bonecp-spring</artifactId>
<version>0.8.0.RELEASE</version>
</dependency>
</dependencies>
<build>
<finalName>${project.artifactId}</finalName>
<plugins>
<!-- 资源文件拷贝插件 -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-resources-plugin</artifactId>
<configuration>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
<!-- java编译插件 -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.7</source>
<target>1.7</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
</plugins>
<pluginManagement>
<plugins>
<!-- 配置Tomcat插件 -->
<plugin>
<groupId>org.apache.tomcat.maven</groupId>
<artifactId>tomcat7-maven-plugin</artifactId>
<version>2.2</version>
</plugin>
</plugins>
</pluginManagement>
</build>
</project>
pojo
package demo.pojo;
public class User {
private String username;
private String password;
private Integer age;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
}
dao
package demo.dao;
import java.util.ArrayList;
import java.util.List;
import demo.pojo.User;
public class UserDao {
public List<User> queryUserList(){
List<User> result = new ArrayList<User>();
// 模拟数据库的查询
for (int i = 0; i < 10; i++) {
User user = new User();
user.setUsername("username_" + i);
user.setPassword("password_" + i);
user.setAge(i + 1);
result.add(user);
}
return result;
}
}
service
package demo.service;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import demo.dao.UserDao;
import demo.pojo.User;
@Service
public class UserService {
@Autowired
private UserDao dao;
public List<User> queryUserList() {
return dao.queryUserList();
}
}
config:java配置
package demo.config;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import demo.dao.UserDao;
@Configuration //相当于一个spring.xml
@ComponentScan(basePackages="demo")//配置扫描包
public class SpringConfig {
@Bean // 通过该注解来表明是一个Bean对象,相当于xml中的<bean>
public UserDao getUserDao(){
return new UserDao(); // 直接new对象
}
}
测试类
package test;
import java.util.List;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import demo.config.SpringConfig;
import demo.pojo.User;
import demo.service.UserService;
public class SpringBootTest {
public static void main(String[] args) {
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(SpringConfig.class);
UserService userService = context.getBean(UserService.class);
List<User> queryUserList = userService.queryUserList();
for (User user : queryUserList) {
System.out.println(user);
}
//销毁容器
context.destroy();
}
}
使用Java代码就完美的替代xml配置文件,并且结构更加的清晰。