Guice的github地址: 

    这个例子很简单，如果会点Guice，那么不需要再往下看了。

    简单来说，它是dependeny injection框架，它与Spring相比，作者已经给出了，见

1.添加依赖

    List-1 pom.xml中添加如下依赖

        
     
      com.google.inject
         
     
      guice
         
     
      4.0
     
    

2.定义接口及实现类

2.1 CreditCardProcessor

    List-2

/** * @author dmj1161859184@126.com 2018-09-10 20:00 * @version 1.0 * @since 1.0 */public interface CreditCardProcessor {    ChargeResult charge(CreditCard credit, Object amount);}/** * @author dmj1161859184@126.com 2018-09-10 20:42 * @version 1.0 * @since 1.0 */public class PaypalCreditCardProcessorImpl implements CreditCardProcessor {    @Override    public ChargeResult charge(CreditCard credit, Object amount) {        LOG.info("charge方法");        return null;    }}

2.2 TransactionLog

    List-3

/** * @author dmj1161859184@126.com 2018-09-10 20:00 * @version 1.0 * @since 1.0 */public interface TransactionLog {    void logChargeResult(ChargeResult result);    void logConnectException(Exception e);}/** * @author dmj1161859184@126.com 2018-09-10 20:07 * @version 1.0 * @since 1.0 */public class DatabaseTransactionLogImpl implements TransactionLog {    @Override    public void logChargeResult(ChargeResult result) {        LOG.info("logChargeResult方法");    }    @Override    public void logConnectException(Exception e) {        LOG.info("logConnectException方法");    }}

2.3 BillingService

    List-4

/** * @author dmj1161859184@126.com 2018-09-10 19:59 * @version 1.0 * @since 1.0 */public interface BillingService {    Receipt chargeOrder(PizzaOrder order, CreditCard credit);}/** * @author dmj1161859184@126.com 2018-09-10 20:00 * @version 1.0 * @since 1.0 */public class BillingServiceImpl implements BillingService {    private final CreditCardProcessor processor;    private final TransactionLog transactionLog;    @Inject    public BillingServiceImpl(CreditCardProcessor processor,                              TransactionLog transactionLog) {        this.processor = processor;        this.transactionLog = transactionLog;    }    @Override    public Receipt chargeOrder(PizzaOrder order, CreditCard credit) {        try {            ChargeResult result = processor.charge(credit, order.getAmount());            transactionLog.logChargeResult(result);            return result.wasSuccessful()                    ? Receipt.forSuccessfulCharge(order.getAmount())                    : Receipt.forDeclinedCharge(result.getDeclineMessage());        } catch (Exception e) {            transactionLog.logConnectException(e);            return Receipt.forSystemFailure(e.getMessage());        }    }}

3.测试

    List-5

public class Main {    public static void main(String[] args) {        Injector injector = Guice.createInjector(new BillingModule());        BillingService billingService = injector.getInstance(BillingService.class);        billingService.chargeOrder(new PizzaOrder(), new CreditCard());    }}

    List-5的运行结果如下图1所示:

                                                  图1 List-5的运行结果