Guice笔记

1、Hello World!

1、定义ServiceService.javapublic interface Service{ public void sayHello();}2、定义实现类ServiceImpl.javapublic class ServiceImpl implements Service{ @Override public String sayHello() { return "Hello World!"; }}3、客户端Client.javapublic class Client { //@Inject 也可以再这里注入 public Service service; /*这里是在构造函数中注入了 优点是可以再构造函数中完成一些初始化工作 缺点是类的实例化与参数绑定，限制了实例化类的方式 */ @Inject public Client(Service service){ this.service = service; } public void print(){ System.out.println(service.say()); }}4、测试类public class Test extends TestCase{ public void testGuice(){ Injector inj = Guice.createInjector(new Module(){ @Override public void configure(Binder binder){ binder.bind(Service.class).to(ServiceImpl.class); } }); Client client = inj.getInstance(Client.class); client.print(); }}

 

2、单例问题

 

在测试类中直接拿Service对象比较

 

Service service = inj.getInstance(Service.class);Service service2 =inj.getInstance(Service.class);Assert.assertEquals(service.hashCode(),service2.hashCode());//不等，每次都会返回一个新的实例修改代码Module中的方法...binder.bind(Service.class).to(Serviceimpl.class).in(Scopes.SINGLETON);...//再次测试Service service = inj.getInstance(Service.class);Service service2 =inj.getInstance(Service.class);Assert.assertEquals(service.hashCode(),service2.hashCode());//相等，返回是同一个实例//--------------------我是分割线 -----------------------------//也可以通过在实现类上添加@Singleton标注来完成，@Singletonpublic class ServiceImpl implements Service{ ...}

 

3、返回的是正常的实例，未做转换和代理。

 

Service service = inj.getInstance(Service.class);System.out.println(service.getClass().getName());//输出Service,是正常的实例，未做转换和代理。

 

 

4、无法绑定多个实现到一个借口

 

再建一个实现类public class ServiceImplAgain implements Service{ ...}然后修改Module类...binder.bind(Service.class).to(ServiceImpl.class);binder.bind(Service.class).to(ServiceImplAgain.class);..//系统报错

 

5、不可以自己绑定自己，但可以绑定子类到自己，也可以绑定到自己构造出来的实例上。

 

...binder.bind(ServiceImpl.class).to(ServiceImpl.class);...//报错 ，不可以自己绑定自己 Binding porins to itserlf//--------------------我是分割线---------------------------public class ServiceSubImpl extends ServiceImpl{ ...}...binder.bind(ServiceImpl.class).to(ServiceSubImpl.class);.../*运行正常，支持子类绑定，这样即使我们将一个实现类发布出去（尽管不推荐这么做），我们再后期仍然有拌饭替换实现类。*///--------------------我是分割线---------------------------...binder.bind(Service.class).to(new ServiceImpl());...//绑定到实例上

 

 

5、可以Guice提供一个方式（Provider<T>），允许自己提供构造对象的方式。

//方法一...binder.bind(Service.class).toProvider(new Provider<Service>() { @Override public Service get() { return new ServiceImpl(); }});...//方法二，或者直接编写类public class ServiceProvider implements Provider<Service>{ @Override public Service get(){ return new ServiceImpl(); }}//正常调用...binder.bind(Service.class).toProvider(ServiceProvider.class)...//方法三，也可以再借口上预定义@ProvideBy(ServiceProvider.class)public interface Service{ ...}...Service service = Guice.createInjector().getInstance(Client.class)...//方法四，当然也可以注入Provider，通过Guice获取后，调用get()获取Service的实例public class ProviderServiceDemo { @Inject private Provider<Service> provider; public static void main(String[] args) { ProviderServiceDemo psd = Guice.createInjector(new Module() { @Override public void configure(Binder binder) { binder.bind(Service.class).toProvider(WwwServiceProvider.class); }}).getInstance(ProviderServiceDemo.class); psd.provider.get().execute();//我们每次get出来都是新对象 }}

 

 

6、可以直接获取实例而不通过Modue绑定。

Injector inj= Guice.createInjector();Service service = inj.getInstance(ServiceImpl.class);System.out.println(service.sayHello());

 

 

7、使用注解实现注入，等于是默认实现类。

 

@ImplementedBy(ServiceImpl.class)public interface Service{ String sayHello();}Injector inj = Guice.createInjector();Service service = inj.getInstance(Service.class);System.out.println(service.sayHello());//使用Module关联 优先于 @ImplementedBy

 

8、静态属性注入

 

@Injectpublic Service service;//运行正常@Inject public static Service service;//如果是刚才的客户端代码，使用时报空指针异常。//要这么写public class Demo{ @Inject private static Service service; public static void main(String[] args){ Guice.createInjector(new Module(){ @Override public void configure(Binder binder){ binder.requestStaticInjection(Demo.class); }//这里请求了静态注入服务。 }); Demo.service.sayHello(): }}

 

9、构造函数注入可以自动注入多个参数

 

...@Injectpublic Client(Service service,Service2 service2){ this.service = service; this.service2 = service2;}...

 

10、使用setter注入

 

...@Injectpublic void setService(Service service){ this.service = service;}...

 

 

11、注入实例变量的属性

 

public class Demo{ @Inject private Service service; public static void main(String[] args){ final Demo demo = new Demo(); Guice.createInjector(new Module(){ @Override public void configure(Binder binder){ binder.requestInjection(demo);//想实例变量注入属性 } }); demo.service.sayHello(); }}//更简便的方法...Guice.createInjector().injectMember(demo);//一句搞定...

 

 

12、绑定多个服务

 

public interface Service{ void execute();}public class HomeService implements Service{ @Override public void execute(){ System.out.println("home"); }}public class WwwService implements Service{ @Override public void execute(){ System.out.println("www"); }}//这里需要定义2个注解@Retention(RetentionPolicy.RUNTIME)@Target({FIELD,PARAMETER})@BindingAnnotationpublic @interface Home {}@Retention(RetentionPolicy.RUNTIME)@Target({FIELD,PARAMETER})@BindingAnnotationpublic @interface Www {}public class Demo { @Inject @Www private Service wwwService; @Inject @Home private Service homeService; public static void main(String[] args) { Demo demo = Guice.createInjector(new Module() { @Override public void configure(Binder binder) { binder.bind(Service.class).annotatedWith(Www.class).to(WwwService.class); binder.bind(Service.class).annotatedWith(Home.class).to(HomeService.class); } }).getInstance(Demo.class); demo.homeService.execute(); demo.wwwService.execute();}}

 

静态注入 多个服务

 

public class StaticMultiInterfaceServiceDemo { @Inject @Www private static Service wwwService; @Inject @Home private static Service homeService; public static void main(String[] args) { Guice.createInjector(new Module() { @Override public void configure(Binder binder) { binder.bind(Service.class).annotatedWith(Www.class).to(WwwService.class); binder.bind(Service.class).annotatedWith(Home.class).to(HomeService.class); binder.requestStaticInjection(StaticMultiInterfaceServiceDemo.class); } }); StaticMultiInterfaceServiceDemo.homeService.execute(); StaticMultiInterfaceServiceDemo.wwwService.execute(); }}

 

太懒，不想写注解怎么办，用Names模板

 

public class NoAnnotationMultiInterfaceServiceDemo { @Inject @Named("Www") private static Service wwwService; @Inject @Named("Home") private static Service homeService; public static void main(String[] args) { Guice.createInjector(new Module() { @Override public void configure(Binder binder) { binder.bind(Service.class).annotatedWith(Names.named("Www")).to(WwwService.class); binder.bind(Service.class).annotatedWith(Names.named("Home")).to(HomeService.class); binder.requestStaticInjection(NoAnnotationMultiInterfaceServiceDemo.class); } }); NoAnnotationMultiInterfaceServiceDemo.homeService.execute(); NoAnnotationMultiInterfaceServiceDemo.wwwService.execute(); }}

 

 

13、绑定常量

public class ConstantInjectDemo { @Inject @Named("v") private int v; public static void main(String[] args) { ConstantInjectDemo cid = Guice.createInjector(new Module() { @Override public void configure(Binder binder) { binder.bindConstant().annotatedWith(Names.named("v")).to(12); //以下方法同样适用（其他基本类型全部适用） //binder.bind(int.class).annotatedWith(Names.named("v")).toInstance(12); } }).getInstance(ConstantInjectDemo.class); System.out.println(cid.v); }}

 

 

14、绑定Properties

@Inject@Named("web")private String web;public static void main(String[] args) { ConstantInjectDemo cid = Guice.createInjector(new Module() { @Override public void configure(Binder binder) { Properties properties= new Properties(); properties.setProperty("web", "www.imxylz.cn"); Names.bindProperties(binder, properties); } }).getInstance(ConstantInjectDemo.class); System.out.println(cid.web);}