【SpringBoot】使用Java配置方式
阿新 • • 發佈：2019-01-22
Java配置是Spring4.x推薦的配置方式，完全替代xml配置
@Configuration 和 @Bean
Spring的Java配置方式是通過 @Configuration 和 @Bean 這兩個註解實現的：
1、@Configuration 作用於類上，相當於一個xml配置檔案；
2、@Bean 作用於方法上，相當於xml配置中的<bean>；
建立maven專案，匯入依賴
<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>com.dynamic.springconfig</groupId> <artifactId>dynamic-springconfig</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>war</packaging> <name>dynamic-springconfig</name> <url>http://maven.apache.org</url> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.8.1</version> <scope>test</scope> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>4.3.7.RELEASE</version> </dependency> <!-- 連線池 --> <dependency> <groupId>com.jolbox</groupId> <artifactId>bonecp-spring</artifactId> <version>0.8.0.RELEASE</version> </dependency> </dependencies> <build> <finalName>${project.artifactId}</finalName> <plugins> <!-- 資原始檔拷貝外掛 --> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-resources-plugin</artifactId> <configuration> <encoding>UTF-8</encoding> </configuration> </plugin> <!-- Java編譯外掛 --> <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外掛 --> <plugin> <groupId>org.apache.tomcat.maven</groupId> <artifactId>tomcat7-maven-plugin</artifactId> <version>2.2</version> </plugin> <!-- 新增配置，放過該錯誤提示。web.xml is missing and <failOnMissingWebXml> is set to true--> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-war-plugin</artifactId> <version>2.2</version> <configuration> <failOnMissingWebXml>false</failOnMissingWebXml> </configuration> </plugin> </plugins> </pluginManagement> </build> </project>
一.使用Java配置方式
User實體
package com.dynamic.springconfig;
public class User {
private String username;
private String password;
private Integer age;
}UserDao
package com.dynamic.springconfig; import java.util.ArrayList; import java.util.List; public class UserDao { public List<User> queryUserList() { List<User> result = new ArrayList<User>(); //模擬資料庫的查詢 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; } }
UserService
package com.dynamic.springconfig; import java.util.List; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; @Service public class UserService { @Autowired private UserDao userDao; public List<User> queryUserList() { return this.userDao.queryUserList(); } }
啟動類
package com.dynamic.springconfig;
import java.util.List;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
/**
* Hello world!
*/
@Configuration//通過該註解來表明該類是一個Spring的配置，相當於一個xml檔案
@ComponentScan(basePackages="com.dynamic.springconfig")//掃描包
@PropertySource(value= {"classpath:test.properties"},ignoreResourceNotFound = false)
public class App
{
@Value("${test}")
private String test;
@Bean //通過該註解來表明是一個Bean物件，相當於xml中的<bean>
public UserDao getUserDao()
{
System.out.println(test);
return new UserDao();
}
public static void main( String[] args )
{
//通過Java配置來例項化Spring容器
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(App.class);
//在Spring容器中獲取Bean物件
UserService userService = context.getBean(UserService.class);
//呼叫物件中的方法
List<User> List = userService.queryUserList();
for(User user:List)
{
System.out.println(user.getUsername() + ","+ user.getAge());
}
}
}
啟動類中可以看到它宣告為配置類，配置了包掃描，讀取屬性檔案。
test.properties
test=success對比使用xml配置。在原始碼的基礎上，我們加入配置檔案。
applicationContext.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd">
<context:component-scan base-package="com.dynamic.springconfig">
</context:component-scan>
<context:property-placeholder location="test.properties"/>
<bean id="userDao" class="com.dynamic.springconfig.UserDao"></bean>
</beans>
啟動類
package com.dynamic.springxml;
import java.util.List;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.dynamic.springconfig.User;
import com.dynamic.springconfig.UserService;
public class AppXml {
@Value("${test}")
private String test;
public static void main(String[] args)
{
ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
UserService userService = (UserService) context.getBean("userService");
List<User> list =userService.queryUserList();
for(User user:list)
{
System.out.println(user.getUsername() + ","+ user.getAge());
}
}
}
使用Java配置替換XML配置