Spring中IoC

说明：Spring IoC其实就是在Service的实现中定义了一些以来的策略类，这些策略类不是通过 初始化、Setter、工厂方法来确定的。而是通过一个叫做上下文的(ApplicationContext)组建来加载进来的。这里介绍两种Context组建的构件过程

前提条件：在Gradle工程的build.gradle文件中引入对Spring framework 的支持

repositories {
    mavenCentral()
}

dependencies {
    compile group: 'org.springframework',name: 'spring-context', version: '4.1.5.RELEASE'
    compile group: 'org.springframework',name: 'spring-core', version: '4.1.5.RELEASE'
    testCompile group: 'junit', name: 'junit', version: '4.11'
}

第一种方式：通过ClassPathXmlApplicationContext加载xml配置文件

这里使用greenmail做测试邮件的例子来介绍：

1. 依赖管理

<?xml version="1.0" encoding="UTF-8"?>
<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.ygshen.mvnbook.account</groupId>
    <artifactId>account-service</artifactId>
    <version>1.0-SNAPSHOT</version>
    <dependencies>
        <!-- https://mvnrepository.com/artifact/org.springframework/spring-context -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>4.3.3.RELEASE</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.springframework/spring-beans -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</artifactId>
            <version>4.3.3.RELEASE</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.springframework/spring-core -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>4.3.3.RELEASE</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.springframework/spring-context-support -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>4.3.3.RELEASE</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/javax.mail/mail -->
        <dependency>
            <groupId>javax.mail</groupId>
            <artifactId>mail</artifactId>
            <version>1.4.1</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/junit/junit -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.7</version>
            <scope>test</scope>

        </dependency>

        <!-- https://mvnrepository.com/artifact/com.icegreen/greenmail -->
        <dependency>
            <groupId>com.icegreen</groupId>
            <artifactId>greenmail</artifactId>
            <version>1.5.2</version>
            <scope>test</scope>
        </dependency>


    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.5</source>
                    <target>1.5</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

 2. 接口定义

public interface emailService {
    public void sendMail(String to, String subject,String htmlText) throws MessagingException;
}

 3. 接口实现

public class emailServiceImp implements emailService{
      //这里有两个IOC的变量，后面将通过bean＋property的方式进行依赖管理
  private JavaMailSender javaMailSender;
    private String systemAccount;

／／ Get和Set时必须的
    public JavaMailSender getJavaMailSender() {
        return javaMailSender;
    }

    public void setJavaMailSender(JavaMailSender javaMailSender) {
        this.javaMailSender = javaMailSender;
    }

    public String getSystemAccount() {
        return systemAccount;
    }

    public void setSystemAccount(String systemAccount) {
        this.systemAccount = systemAccount;
    }

／／发送邮件主题函数，javamailsender是 spring的邮件类。这个mail sender就是发送邮件的smtp服务器。
／／ 如Gmail等，这里将在测试用例中使用greenemail代替他门
    public void sendMail(String to, String subject, String htmlText) throws MessagingException {
        MimeMessage message = javaMailSender.createMimeMessage();
        MimeMessageHelper helper = new MimeMessageHelper(message);
        helper.setFrom(systemAccount);
        helper.setTo(to);
        helper.setSubject(subject);
        helper.setText(htmlText);

        javaMailSender.send(message);
    }
}

 4. Bean文件定义：

<?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">

<!--定义自动获取property配置-->
    <bean id="propertyConfigure" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="location" value="classpath:service.properties"></property>
    </bean>
<!--定义java mail sender bean 对象，这个bean后边将作为依赖注入到service中-->
    <bean id="javaMailSender" class="org.springframework.mail.javamail.JavaMailSenderImpl">
        <property name="protocol" value="${email.protocol}"></property>
        <property name="port" value="${email.port}"></property>
        <property name="host" value="${email.host}"></property>
        <property name="username" value="${email.username}"></property>
        <property name="password" value="${email.password}"></property>
        <property name="javaMailProperties">
            <props>
                <prop key="mail.${email.protocol}.auth">${email.auth}</prop>
            </props>
        </property>

    </bean>
<!--真正负责发送邮件的类定义bean-->
    <bean id="accountService" class="com.ygshen.mvnbook.account.email.emailServiceImp">
        <property name="javaMailSender" ref="javaMailSender"></property>
        <property name="systemAccount" value="${email.systemAccount}"></property>
    </bean>
</beans>

 5. Property 文件

email.protocol=smtps
email.host=smtp.gmail.com
email.port=465
email.username=shenyuangong@gmail.com
email.password=111111
email.auth=true
email.systemAccount=ygshen@163.com

初始化javamailsender的配置文件。 main／Resources目录下。注意这个配置文件将在test／resource中 重新定义目的是模拟测试

6. 测试代码：

package com.ygshen.mvnbook.account;

import com.icegreen.greenmail.util.GreenMail;
import com.icegreen.greenmail.util.ServerSetup;
import com.ygshen.mvnbook.account.email.emailService;
import org.junit.After;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import javax.mail.Message;
import javax.mail.MessagingException;

/**
 * Created by ygshen on 16/10/31.
 */
／／这里需要注意junit的测试文件必须以Test结尾 否则 mvn clean test 的时候将没有办法获取到测试用例
public class emailServiceTest {
／／这里初始化一个本地的greenmail作为测试邮箱服务器    
private GreenMail mail;
    @Before
    public void startMailBox(){
        mail = new GreenMail(new ServerSetup(12000,null,"smtp"));
        mail.setUser("shenyuangong@gmail.com", "123456");
        mail.start();
    }
    @Test
    public void sendMail() throws MessagingException {
        ApplicationContext context = new ClassPathXmlApplicationContext("account-service.xml");
／／ 这里将初始化发送邮件的service，而service所依赖的javamailsender初始化所配置的邮箱服务器和start中 定义的port、protocol也是一样的。 在测试test/resources中定义。这里greenmail起到模拟gmail服务器的能力
        emailService service = (emailService)context.getBean("accountService");
        service.sendMail("test2@163.com","Test Subject","<h1>test</h1>");
        mail.waitForIncomingEmail(2000,1);
        Message[] msgs = mail.getReceivedMessages();
        Assert.assertEquals(1,msgs.length);
    }
    @After
    public void closeMail(){
        mail.stop();
    }

}

 7. 测试用的Properties文件

email.protocol=smtp
email.host=localhost
email.port=12000
＃ 注意这里的邮箱登陆的帐号要和Greenmail中 setUser使用的相同才行。
email.username=shenyuangong@gmail.com
email.password=123456
email.auth=true
email.systemAccount=ygshen@163.com

第二种方式：AnnotationConfigApplicationContext类加载JavaClass File的配置文件

配置文件JavaClass如下：

@Configuration：表示这是一个配置文件

@Bean: 表示这是一个Bean（名字为方法名），将来他要用来与Service中的@Autowired属性配对，注意配对的时候是根据返回类型来对应的，也就是说所有的Service中但凡有@Autowired的属性，他们都是从这个配置文件中拿到的。

@Configuration
public class ApplicationContextConfiguration {
    @Bean
    public AccountRepoisitory accountRepoisitory() {
        return new AccountRepositoryImp();
    }

    @Bean
    public TransactionService transactionService() {
        return new TransactionServiceImp();
    }

    @Bean
    public TransferService transferService() {
        return new TransferServiceImp();
    }
}

再来看一下使用@AutoWired的Service类。这个AutoWired将与上面配置文件中的@Bean结成一对儿

public class TransactionServiceImp implements TransactionService {

    @Autowired
    public  AccountRepoisitory accountRepoisitory;
    @Override
    public void NewTransaction(String accountId1, String accountId2, double money) {
        Account account1=accountRepoisitory.GetAccountByAccountId(accountId1);
        Account account2=accountRepoisitory.GetAccountByAccountId(accountId2);
        Transaction transaction=new Transaction(){ };
        transaction.fromAccount=account1;
        transaction.toAccount=account2;
        transaction.moneyTransfered=money;
        transaction.transactionDate= Calendar.getInstance().getTime();

        BankFactory.Transactions.add(transaction);
    }
}

最后来看Main函数是如何将配置文件与Service文件结合在一起的。 很简单

  ApplicationContext context=
                new AnnotationConfigApplicationContext(
                        com.ctrip.configuration.ApplicationContextConfiguration.class
                );

// 接下来我们就可以使用任何Service中定义的方法了

AccountRepoisitory accountRepoisitory=context.getBean("accountRepoisitory",
        AccountRepositoryImp.class);

TransactionService transactionService=context.getBean("transactionService",
        TransactionServiceImp.class);

TransferService transferService=context.getBean("transferService",
        TransferServiceImp.class
        );
transferService.Transfer("1","2",234);