【譯】Spring 4 @Profile註解示例

時間 2019-11-18

標籤 spring profile 註解示例欄目 Spring 简体版

原文原文鏈接

前言

譯文連接：http://websystique.com/spring/spring-profile-example/java

本文將探索Spring中的@Profile註解，能夠實現不一樣環境（開發、測試、部署等）使用不一樣的配置。一樣，除了使用註解也會給出基於XML配置的示例做爲對比。mysql

假設你有一個應用涉及數據庫交互，你可能但願在開發環境上使用mysql數據庫，在生產環境上使用oracle數據庫，那麼使用Spring的Profiles，能夠輕鬆達到這個目的，接下來咱們將給出一個實例詳細介紹這種狀況。web

涉及技術及開發工具

Spring 4.0.6.RELEASE
Maven 3
JDK 1.6
Eclipse JUNO Service Release 2

工程目錄結構

步驟一：往pom.xml中添加依賴

<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.websystique.spring</groupId>
    <artifactId>Spring4ProfilesExample</artifactId>
    <version>1.0.0</version>
    <packaging>jar</packaging>
 
    <name>Spring4ProfilesExample</name>
 
    <properties>
        <springframework.version>4.0.6.RELEASE</springframework.version>
    </properties>
 
    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${springframework.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${springframework.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>${springframework.version}</version>
        </dependency>
 
    </dependencies>
    <build>
        <pluginManagement>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <version>3.2</version>
                    <configuration>
                        <source>1.6</source>
                        <target>1.6</target>
                    </configuration>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>
 
</project>

步驟二：建立Spring配置類

Spring配置類是指用@Configuration註解標註的類，這些類包含了用@Bean標註的方法。這些被@Bean標註的方法能夠生成bean並交由spring容器管理。spring

package com.websystique.spring.configuration;
 
import javax.sql.DataSource;
 
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
 
@Configuration
@ComponentScan(basePackages = "com.websystique.spring")
public class AppConfig {
     
    @Autowired
    public DataSource dataSource;
     
 
}

以上配置只有一個屬性被自動注入，接下來咱們將展現這個dataSource屬性能夠根據不一樣的環境（開發環境或生產環境）注入不一樣的bean。sql

package com.websystique.spring.configuration;
 
import javax.sql.DataSource;
 
public interface DatabaseConfig {
 
    DataSource createDataSource();
     
}

一個簡單的接口，能夠被全部可能的環境配置實現數據庫

package com.websystique.spring.configuration;
 
import javax.sql.DataSource;
 
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Profile;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
 
@Profile("Development")
@Configuration
public class DevDatabaseConfig implements DatabaseConfig {
 
    @Override
    @Bean
    public DataSource createDataSource() {
        System.out.println("Creating DEV database");
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        /*
         * Set MySQL specific properties for Development Environment
         */
        return dataSource;
    }
 
}

package com.websystique.spring.configuration;
 
import javax.sql.DataSource;
 
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Profile;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
 
@Profile("Production")
@Configuration
public class ProductionDatabaseConfig implements DatabaseConfig {
 
    @Override
    @Bean
    public DataSource createDataSource() {
        System.out.println("Creating Production database");
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        /*
         * Set ORACLE specific properties for Production environment
         */
        return dataSource;
    }
 
}

以上兩個配置類都實現了DatabaseConfig接口，特殊的地方在於它們都用@Profile標註。apache

被@Profile標註的組件只有當指定profile值匹配時才生效。oracle

能夠經過如下方式設置profile值：app

一、設置spring.profiles.active屬性（經過JVM參數、環境變量或者web.xml中的Servlet context參數）maven

二、ApplicationContext.getEnvironment().setActiveProfiles(「ProfileName」)

根據你的實際環境設置profile值，而後被profile標註（並且value=設置值）的bean纔會被註冊到spring容器。

步驟三：運行main方法測試

package com.websystique.spring;
 
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 
public class AppMain {
     
    public static void main(String args[]){
        AnnotationConfigApplicationContext  context = new AnnotationConfigApplicationContext();
        //Sets the active profiles
        context.getEnvironment().setActiveProfiles("Development");
        //Scans the mentioned package[s] and register all the @Component available to Spring
        context.scan("com.websystique.spring"); 
        context.refresh();
        context.close();
    }
 
}

注意以上代碼，context.scan("com.websystique.spring")掃描到該包並開始註冊全部被@Component標註的bean時，若是同時遇到被@Profile註解標註的bean時，會與profile值作比較，profile值匹配則註冊到spring容器，不然直接跳過。

在咱們這個例子中，DevDatabaseConfig會被註冊到Spring容器中。

運行以上程序，結果以下：

Creating DEV database

附：基於XML的配置

替換DevelopmentDatabaseConfig配置爲dev-config-context.xml (src/main/resources/dev-config-context.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"
        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd">
 
     
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="com.mysql.jdbc.Driver" />
        <property name="url" value="jdbc:mysql://localhost:3306/websystique" />
        <property name="username" value="myuser" />
        <property name="password" value="mypassword" />
    </bean>
 
</beans>

替換ProductionDatabaseConfig配置爲prod-config-context.xml (src/main/resources/prod-config-context.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"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd">
 
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value=" oracle.jdbc.driver.OracleDriver" />
        <property name="url"     value="jdbc:oracle:thin:@PRODHOST:PRODPORT/websystique" />
        <property name="username" value="myproduser" />
        <property name="password" value="myprodpassword" />
    </bean>
 
</beans>

替換AppConfig配置爲app-config.xml (src/main/resources/app-config.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-4.0.xsd
                            http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">
 
     
    <context:component-scan base-package="com.websystique.spring"/>
     
    <beans profile="Development">
        <import resource="dev-config-context.xml"/>
    </beans>
 
    <beans profile="Production">
        <import resource="prod-config-context.xml"/>
    </beans>
 
</beans>

根據實際的profile配置，相應的config-context.xml文件會被加載，其它的會被忽略。

最後，main方法以下：

package com.websystique.spring;
 
import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
 
public class AppMain {
     
    public static void main(String args[]){
        AbstractApplicationContext  context = new ClassPathXmlApplicationContext("app-config.xml");
        //Sets the active profiles
        context.getEnvironment().setActiveProfiles("Development");
        /*
         * Perform any logic here
         */
        context.close();
    }
 
}