CDI（Contexts and Dependency Injection 上下文依赖注入），是JAVA官方提供的依赖注入实现，可用于Dynamic Web Module中，先给3篇老外的文章，写得很不错
1、Java EE CDI Dependency Injection (@Inject) tutorial
2、Java EE CDI Producer methods tutorial
3、Java EE CDI bean scopes
此外，还有jboss官方的参考文档：http://docs.jboss.org/weld/reference/latest/en-US/html/
如果不想啃洋文，也可以继续往下看：
一、基本的Inject注入
1.1 在eclipse中先创建一个常规的maven Dynamic Web项目（不熟悉maven的，可以先看看这里），下面是完整的项目截图
里面各package的代码，后面会给出。 项目的属性中，注意有几个属性要勾上（默认情况下，应该已经自动勾上了），如下图：
上图右侧的圆圈，其实就是CDI 1.0使用的先决条件。
Pom.xml的内容如下:
<?xml version="1.0" encoding="UTF-8"?>
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<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/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion> <groupId>cnblogs</groupId>
<artifactId>cdi-web-sample</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>war</packaging>
<name>cdi-web-sample</name>
<description>A starter Java EE 6 webapp project for use on JBoss AS 7 / EAP 6, generated from the jboss-javaee6-webapp archetype</description> <url>http://jboss.org/jbossas</url>
<licenses>
<license>
<name>Apache License, Version 2.0</name>
<distribution>repo</distribution>
<url>http://www.apache.org/licenses/LICENSE-2.0.html</url>
</license>
</licenses> <properties>
<!-- Explicitly declaring the source encoding eliminates the following
message: -->
<!-- [WARNING] Using platform encoding (UTF-8 actually) to copy filtered
resources, i.e. build is platform dependent! -->
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <!-- JBoss dependency versions -->
<version.jboss.maven.plugin>7.4.Final</version.jboss.maven.plugin> <!-- Define the version of the JBoss BOMs we want to import to specify
tested stacks. -->
<version.jboss.bom>1.0.7.Final</version.jboss.bom>
<!-- Alternatively, comment out the above line, and un-comment the line
below to use version 1.0.4.Final-redhat-4 which is a release certified to
work with JBoss EAP 6. It requires you have access to the JBoss EAP 6
maven repository. -->
<!-- <version.jboss.bom>1.0.4.Final-redhat-4</version.jboss.bom>> --> <!-- other plugin versions -->
<version.surefire.plugin>2.10</version.surefire.plugin>
<version.war.plugin>2.1.1</version.war.plugin> <!-- maven-compiler-plugin -->
<maven.compiler.target>1.6</maven.compiler.target>
<maven.compiler.source>1.6</maven.compiler.source>
</properties> <dependencyManagement>
<dependencies>
<!-- JBoss distributes a complete set of Java EE 6 APIs including a Bill
of Materials (BOM). A BOM specifies the versions of a "stack" (or a collection)
of artifacts. We use this here so that we always get the correct versions
of artifacts. Here we use the jboss-javaee-6.0-with-tools stack (you can
read this as the JBoss stack of the Java EE 6 APIs, with some extras tools
for your project, such as Arquillian for testing) and the jboss-javaee-6.0-with-hibernate
stack you can read this as the JBoss stack of the Java EE 6 APIs, with extras
from the Hibernate family of projects) -->
<dependency>
<groupId>org.jboss.bom</groupId>
<artifactId>jboss-javaee-6.0-with-tools</artifactId>
<version>${version.jboss.bom}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
<dependency>
<groupId>org.jboss.bom</groupId>
<artifactId>jboss-javaee-6.0-with-hibernate</artifactId>
<version>${version.jboss.bom}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement> <dependencies> <!-- First declare the APIs we depend on and need for compilation. All
of them are provided by JBoss AS 7 --> <!-- Import the CDI API, we use provided scope as the API is included in
JBoss AS 7 -->
<dependency>
<groupId>javax.enterprise</groupId>
<artifactId>cdi-api</artifactId>
<scope>provided</scope>
</dependency> <!-- Import the Common Annotations API (JSR-250), we use provided scope
as the API is included in JBoss AS 7 -->
<dependency>
<groupId>org.jboss.spec.javax.annotation</groupId>
<artifactId>jboss-annotations-api_1.1_spec</artifactId>
<scope>provided</scope>
</dependency> <!-- Import the JAX-RS API, we use provided scope as the API is included
in JBoss AS 7 -->
<dependency>
<groupId>org.jboss.spec.javax.ws.rs</groupId>
<artifactId>jboss-jaxrs-api_1.1_spec</artifactId>
<scope>provided</scope>
</dependency> <!-- Import the JPA API, we use provided scope as the API is included in
JBoss AS 7 -->
<dependency>
<groupId>org.hibernate.javax.persistence</groupId>
<artifactId>hibernate-jpa-2.0-api</artifactId>
<scope>provided</scope>
</dependency> <!-- Import the EJB API, we use provided scope as the API is included in
JBoss AS 7 -->
<dependency>
<groupId>org.jboss.spec.javax.ejb</groupId>
<artifactId>jboss-ejb-api_3.1_spec</artifactId>
<scope>provided</scope>
</dependency> <!-- JSR-303 (Bean Validation) Implementation -->
<!-- Provides portable constraints such as @Email -->
<!-- Hibernate Validator is shipped in JBoss AS 7 -->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-validator</artifactId>
<scope>provided</scope>
<exclusions>
<exclusion>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
</exclusion>
</exclusions>
</dependency> <!-- Import the JSF API, we use provided scope as the API is included in
JBoss AS 7 -->
<dependency>
<groupId>org.jboss.spec.javax.faces</groupId>
<artifactId>jboss-jsf-api_2.1_spec</artifactId>
<scope>provided</scope>
</dependency> <!-- Now we declare any tools needed --> <!-- Annotation processor to generate the JPA 2.0 metamodel classes for
typesafe criteria queries -->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-jpamodelgen</artifactId>
<scope>provided</scope>
</dependency> <!-- Annotation processor that raising compilation errors whenever constraint
annotations are incorrectly used. -->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-validator-annotation-processor</artifactId>
<scope>provided</scope>
</dependency> <!-- Needed for running tests (you may also use TestNG) -->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<scope>test</scope>
</dependency> <!-- Optional, but highly recommended -->
<!-- Arquillian allows you to test enterprise code such as EJBs and Transactional(JTA)
JPA from JUnit/TestNG -->
<dependency>
<groupId>org.jboss.arquillian.junit</groupId>
<artifactId>arquillian-junit-container</artifactId>
<scope>test</scope>
</dependency> <dependency>
<groupId>org.jboss.arquillian.protocol</groupId>
<artifactId>arquillian-protocol-servlet</artifactId>
<scope>test</scope>
</dependency> </dependencies> <build>
<!-- Maven will append the version to the finalName (which is the name
given to the generated war, and hence the context root) -->
<finalName>${project.artifactId}</finalName>
<plugins>
<plugin>
<artifactId>maven-war-plugin</artifactId>
<version>${version.war.plugin}</version>
<configuration>
<!-- Java EE 6 doesn't require web.xml, Maven needs to catch up! -->
<failOnMissingWebXml>false</failOnMissingWebXml>
</configuration>
</plugin>
<!-- The JBoss AS plugin deploys your war to a local JBoss AS container -->
<!-- To use, run: mvn package jboss-as:deploy -->
<plugin>
<groupId>org.jboss.as.plugins</groupId>
<artifactId>jboss-as-maven-plugin</artifactId>
<version>${version.jboss.maven.plugin}</version>
</plugin>
</plugins>
</build> <profiles>
<profile>
<!-- The default profile skips all tests, though you can tune it to run
just unit tests based on a custom pattern -->
<!-- Seperate profiles are provided for running all tests, including Arquillian
tests that execute in the specified container -->
<id>default</id>
<activation>
<activeByDefault>true</activeByDefault>
</activation>
<build>
<plugins>
<plugin>
<artifactId>maven-surefire-plugin</artifactId>
<version>${version.surefire.plugin}</version>
<configuration>
<skip>true</skip>
</configuration>
</plugin>
</plugins>
</build>
</profile> <profile>
<!-- An optional Arquillian testing profile that executes tests in your
JBoss AS instance -->
<!-- This profile will start a new JBoss AS instance, and execute the
test, shutting it down when done -->
<!-- Run with: mvn clean test -Parq-jbossas-managed -->
<id>arq-jbossas-managed</id>
<dependencies>
<dependency>
<groupId>org.jboss.as</groupId>
<artifactId>jboss-as-arquillian-container-managed</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
</profile> <profile>
<!-- An optional Arquillian testing profile that executes tests in a remote
JBoss AS instance -->
<!-- Run with: mvn clean test -Parq-jbossas-remote -->
<id>arq-jbossas-remote</id>
<dependencies>
<dependency>
<groupId>org.jboss.as</groupId>
<artifactId>jboss-as-arquillian-container-remote</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
</profile> <profile>
<!-- When built in OpenShift the 'openshift' profile will be used when
invoking mvn. -->
<!-- Use this profile for any OpenShift specific customization your app
will need. -->
<!-- By default that is to put the resulting archive into the 'deployments'
folder. -->
<!-- http://maven.apache.org/guides/mini/guide-building-for-different-environments.html -->
<id>openshift</id>
<build>
<plugins>
<plugin>
<artifactId>maven-war-plugin</artifactId>
<version>${version.war.plugin}</version>
<configuration>
<outputDirectory>deployments</outputDirectory>
<warName>ROOT</warName>
</configuration>
</plugin>
</plugins>
</build>
</profile> </profiles>
</project>
pom.xml
1.2 model包下，会创建Product类
package model;
public class Product {
private String productName;
private String productNo;
public String getProductNo() {
return productNo;
}
public void setProductNo(String productNo) {
this.productNo = productNo;
}
public String getProductName() {
return productName;
}
public void setProductName(String productName) {
this.productName = productName;
}
public String toString() {
return this.productName + " " + this.productNo;
}
}
Product
这个类其实是打酱油的
1.3 service包下，建一个ProductService接口
package service;
import model.Product;
public interface ProductService {
Product getNewProduct();
}
ProductService
1.4 service包下，再来几个实现
package service;
import javax.inject.Inject;
import model.Product;
public abstract class BaseProductServiceImpl implements ProductService {
@Inject
protected Product product;
public abstract Product getNewProduct();
}
BaseProductServiceImpl
这个是实现类的基类，注意这里私有成员上打了一个注解@Inject，表示运行时将动态注入(实例化)一个Product
再来二个具体的实现类，BookProductServiceImpl生成"书籍"
package service; import annotation.Book;
import model.Product; @Book
public class BookProductServiceImpl extends BaseProductServiceImpl { public Product getNewProduct() {
product.setProductName("论程序员的自我修养");
product.setProductNo("ISBN 999");
return product;
} }
BookProductServiceImpl
TelephoneProductServiceImpl生成“电话”
package service; import annotation.Telephone;
import model.Product; @Telephone
public class TeletephoneProductServiceImpl extends BaseProductServiceImpl { public Product getNewProduct() {
product.setProductName("NOKIA LUMIA");
product.setProductNo("920");
return product;
} }
TeletephoneProductServiceImpl
可能有朋友注意到了，里面用到了二个自己写的注释@Book和@Telephone，接下来会讲到，这里先忽略
1.5 controller包下，添加IndexController类
为了能跟JSF的前台页面交互，这里需要添加一个Controller
package controller; import javax.faces.bean.ManagedBean;
import javax.inject.Inject; import annotation.*;
import service.*; @ManagedBean(name = "Index")
public class IndexController { @Inject
@Book
private ProductService bookProductService; @Inject
@Telephone
private ProductService telephoneProductService; public ProductService getBookProductService() {
return bookProductService;
} public ProductService getTelephoneProductService() {
return telephoneProductService;
} }
IndexController
IndexController
好了，一下子搞了这么多代码，先停下来消化一下，这里我们模拟了分层架构：
model - 代表了业务模型层(本例中，为了简单起见，没有细分 业务模型、实体模型、以及web中的ViewModel)
service - 代表了服务层(为了简单起见，我们把接口+实现都放在一起了，实际中，可能会把这二个分开来)
controller - 这是web层MVC中的控制器层
当然，为了能展示最终的效果，我们会在后面加一个页面做为View层来提供UI
1.6 webapp下，新建一个index.xhtml文件，内容如下：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:ui="http://java.sun.com/jsf/facelets"> <h:head></h:head>
<body>
Book:
<br /> #{Index.bookProductService.newProduct.toString()}
<br />
<br /> Telephone:
<br /> #{Index.telephoneProductService.newProduct.toString()}
</body>
index.xhtml
页面里几乎没啥代码，就是调用IndexController实例中的getBookProductService、getTelephoneProductService方法，进而得到相应的"服务实现类实例"，最终输出产品信息
1.7 Inject用在什么地方了？
a) 页面显示时，IndexController里，bookProductService和telephoneProductService这二个私有成员上，都加了@Inject注解，所以运行时，这二个成员都能被实例化，但是问题来了，它们都是ProductService的接口类型，而这个接口有二个具体的实现(BookProductServiceImpl和TeletephoneProductServiceImpl)，最终运行时，应该实现化哪一个呢？
关键在于另一个注解@Book和@Telephone，观察一下：BookProductServiceImpl类上我们也加了@Book，而TeletephoneProductServiceImpl上加了@Telephone，这样正好可以跟IndexControll中这二个私成成员的注释“匹配”上，所以最终系统知道私有成员bookProductService应该被实例化成BookProductServiceImpl，telephoneProductService被实例化成TeletephoneProductServiceImpl
@Book和@Telephone的代码如下：
package annotation; import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy; import javax.inject.Qualifier; @Qualifier
@Retention(RetentionPolicy.RUNTIME)
public @interface Book { }
Book
package annotation; import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import javax.inject.Qualifier; @Qualifier
@Retention(RetentionPolicy.RUNTIME)
public @interface Telephone { }
Telephone
b) BaseProductServiceImpl中，在私成成员product上加了@Inject，这样运行时，能自动实例化Product对象
1.8 运行结果
jboss中部署后，浏览http://localhost:8080/cdi-web-sample/faces/index.xhtml 或http://localhost:8080/cdi-web-sample/index.jsf
1.9 Method(方法)注入及Constructor(构造器)注入
刚才我们看到的都是在Field(成员)上注入，除了这种方式，也可以在Method或Constructor上注入
private Product product ;
/**
* 演示在方法上使用@Inject注入
* @param p
*/
@Inject
public void setProduct(Product p){
product = p;
}
public Product getProduct(){
return product;
}
Method Inject
上面的代码即是Method注入的示例，最后来看下构造器注入，我们再新建一个ClothProductServiceImpl用于生产服装
package service; import javax.inject.Inject; import annotation.*;
import model.Product; @Cloth
public class ClothProductServiceImpl implements ProductService { private Product product; /**
* 构造器注入
* @param p
*/
@Inject
public ClothProductServiceImpl(Product p ){
p.setProductName("A New Dress");
p.setProductNo("SPRIT-001");
product = p; } public Product getNewProduct() {
return product;
} }
Constructor Inject
运行时，系统会自动给构造器ClothProductServiceImpl传递一个实例化的Product对象作为参数，以实现Product实例的注入
附文中示例源码下载：cdi-web-sample.zip
下一节，我们将学习Bean注入后的生命周期管理