guice的学习

由于Spring太过庞大，所以本人也一直都不太喜欢，当guice1出来时，就关注过一阵子，但始终没有行动去试用，听说2.0出来了，最近闲着也没事，就去试用了一下，单从IOC方面来说，做得的确比较出色。
于是做了一个例子，把常用的功能都试了一下，其中需要的JAR包只有两个：
aopalliance.jar
guice-2.0.jar

下面是例子的代码：

public interface Service {
	public void sayHello();
}

public class ServiceImp implements Service {
	public void sayHello() {
		System.out.println("ServiceImp say Hello !");
	}
}

然后需要一个Model建立接口与类之间的映射关系,
由于包含的功能比较多，所以代码相对有一点复杂,不过这个类是最重要的

import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

import com.google.inject.AbstractModule;
import com.google.inject.Binder;
import com.google.inject.Provides;
import com.google.inject.name.Names;

import demo.HeroModule;

public class ServiceModel extends AbstractModule {

	@Override
	protected void configure() {

		// 与在Service接口上声明@ImplementedBy(ServiceImp.class)等价
		// 手工实例化想绑定的对象
		// this.bind(Service.class).toInstance(new ServiceImp());
		// this.bind(Service.class).to(ServiceImp.class);
		// When your @Provides methods start to grow complex, you may consider
		// moving them to a class of their own
		this.bind(Service.class).toProvider(ServiceProvider.class);
		// this.bind(String.class).annotatedWith(Names.named("username")).toInstance("qiuqiu");
		this.bindConstant().annotatedWith(Names.named("username")).to("qiuqiu");
		loadProperties();
	}

	/*
	 * When you need code to create an object, use an @Provides method. The
	 * method must be defined within a module, and it must have an @Provides
	 * annotation. The method's return type is the bound type. Whenever the
	 * injector needs an instance of that type, it will invoke the method.
	 */
	@Provides
	public User provide() {
		System.out.println("++++++++=============");
		User user = new User();
		user.setUsername("myprovide");
		return user;
	}

	private void loadProperties() {
		InputStream stream = this.getClass().getResourceAsStream(
				"/app.properties");
		Properties appProperties = new Properties();

		try {
			appProperties.load(stream);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		Names.bindProperties(this.binder(), appProperties);

	}
}

Provider在管理手工创建对象时会比@Provides灵活一些:

import com.google.inject.Provider;

public class ServiceProvider implements Provider<Service> {

	@Override
	public Service get() {
		System.out.println("ServiceProvider==-=-=-=-=_+_+_+_+_+_+_+_+");
		// TODO Auto-generated method stub
		Service service = new ServiceImp();
		return service;
	}

}

还有一辅助类：

public class User{
	private String username;
	public String getUsername() {
		return username;
	}
	public void setUsername(String username) {
		this.username = username;
	}
}

还有一属性文件app.properties，很简单：
db.user=mysql
db.pwd=2009
经过上面一系列的准备，就可以进行测试了了：

import org.testng.Assert;
import org.testng.annotations.Test;

import com.google.inject.Guice;
import com.google.inject.Inject;
import com.google.inject.Injector;
import com.google.inject.name.Named;

public class Client {

	private Service service;
	private User user;
	private String username;
	private String db_user;
	private String db_pwd;

	@Inject
	public void setDB(@Named("db.user") String db_user,
			@Named("db.pwd") String db_pwd) {
		this.db_user = db_user;
		this.db_pwd = db_pwd;
	}

	@Inject
	public void setUsername(@Named("username") String username) {
		this.username = username;
	}

	@Inject
	public void setUser(User user) {
		this.user = user;
	}

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

	@Test
	public void testGuice() {
		Injector injector = Guice.createInjector(new ServiceModel());
		// 如果不用@Inject注入，则用这种方法
		// Service service = injector.getInstance(ServiceImp.class);
		injector.injectMembers(this);
		service.sayHello();

	}

	@Test
	public void testBindConstant() {
		System.out.println("username=" + username);
	}

	@Test
	public void testBindProvides() {
		Injector injector = Guice.createInjector(new ServiceModel());
		injector.injectMembers(this);
		// 必须要调用上面的注入方法
		Assert.assertEquals(user.getUsername(), "myprovide");
	}

	@Test
	public void testProperties() {
		Injector injector = Guice.createInjector(new ServiceModel());
		injector.injectMembers(this);
		Assert.assertEquals(db_user, "mysql");
		Assert.assertEquals(db_pwd, "2009");
	}
}

大体过程就这样，还有一些细小的功能没有仔细去体会，以后有时间再来完善吧！