Question

我正在尝试（学习如何）使用由OSGi提供的声明性服务（DS）创建Servlet（javax.servlet.Servlet），如下所示：

import java.io.IOException;

import javax.servlet.Servlet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.osgi.service.component.annotations.Component;

@Component(service = Servlet.class, property = { "alias:String=/hello" }, immediate = true)
public class LogsHTTPServlet extends HttpServlet {

    private static final long serialVersionUID = 2302372200114479484L;

    @Override
    public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        try {
            resp.setContentType("text/plain");
            resp.getWriter().println("It works!");
        } catch (Exception e) {
            e.printStackTrace();
        }
        resp.setStatus(200);
    }
}

当我在the project上运行Eclipse ^{（2019-03（4.11.0），build id：20190314-1200）}时，使用this target platform，在我用custom run configuration（org.eclipse.jetty.server）设置-Dorg.osgi.service.http.port=8080（和其他必需的依赖项）的情况下，我在osgi控制台中看到类似以下的内容：

osgi> 2019-05-07 18:22:28.236:INFO::Start Level: Equinox Container: 0d7d3d67-401b-48eb-b016-6e6c0c16352c: Logging initialized @1590ms to org.eclipse.jetty.util.log.StdErrLog
2019-05-07 18:22:28.388:INFO:oejs.session:Start Level: Equinox Container: 0d7d3d67-401b-48eb-b016-6e6c0c16352c: DefaultSessionIdManager workerName=node0
2019-05-07 18:22:28.388:INFO:oejs.session:Start Level: Equinox Container: 0d7d3d67-401b-48eb-b016-6e6c0c16352c: No SessionScavenger set, using defaults
2019-05-07 18:22:28.389:INFO:oejs.session:Start Level: Equinox Container: 0d7d3d67-401b-48eb-b016-6e6c0c16352c: node0 Scavenging every 660000ms
2019-05-07 18:22:28.427:INFO:oejs.session:Start Level: Equinox Container: 0d7d3d67-401b-48eb-b016-6e6c0c16352c: node0 Scavenging every 660000ms

现在，当我使用this VM argument（http://127.0.0.1:8080/hello）执行此请求时，我得到：

<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html;charset=utf-8"/>
        <title>Error 404 ProxyServlet: /hello</title>
    </head>
    <body>
        <h2>HTTP ERROR 404</h2>
        <p>Problem accessing /hello. Reason:

            <pre>    ProxyServlet: /hello</pre>
        </p>
        <hr>
        <a href="http://eclipse.org/jetty">Powered by Jetty:// 9.4.15.v20190215</a>
        <hr/>
    </body>
</html>

如何解决此问题？

Answer 1

使用 alias 属性代替osgi.http.whiteboard.servlet.pattern：

@Component(service = Servlet.class, property = {"osgi.http.whiteboard.servlet.pattern=/hello/*" })

或者，根据当前的osgi Compendium依赖关系（版本7.0.0），您可以使用@org.osgi.service.http.whiteboard.propertytypes.HttpWhiteboardServletPattern注释，如下所示：

@Component(service=Servlet.class)
@org.osgi.service.http.whiteboard.propertytypes.HttpWhiteboardServletPattern("/hello/*")

请参见https://osgi.org/specification/osgi.cmpn/7.0.0/service.http.whiteboard.html#service.http.whiteboard-i21223311

如何使用OSGi声明式服务正确实现servlet？

1 个答案: