@WebServlet("/cdiservlet")      ||url映射public class NewServlet extends HttpServlet {    private Message message;    @Override             ||重写doGet方法    public void init() {        message = new MessageB();    ||对message初始化    }    @Override    public void doGet(HttpServletRequest request, HttpServletResponse response)                  throws IOException {              ||抛出可能出现IO异常        response.getWriter().write(message.get());   ||捕获可能发生的异常    }}

public interface Message {         ||servlet实现Message接口的一个对象实例    public String get();}

public class MessageB implements Message {          ||servlet创建对象的实例    public MessageB() { }    @Override    public String get() {        return "message B";    }}

@WebServlet("/cdiservlet")              ||使用CDI，servlet声明它对Message实例的依赖性，并让它由CDI运行时自动注入public class NewServlet extends HttpServlet {    @Inject private Message message;    @Override    public void doGet(HttpServletRequest request, HttpServletResponse response)                  throws IOException {       ||抛出可能出现的IO异常

response.getWriter().write(message.get());  ||捕获可能发生的异常  } }