使用Jetty在Oracle中实现连接池

Question

我正在尝试在使用Jetty服务器时，在Oracle中实现ConnectionPooling的概念。我尝试了一个教程上的以下方法。如果我使用Tomcat服务器部署，它可以正常工作，但是Jetty似乎给我一个不寻常的错误。详细信息如下 -

我有一个名为TestServlet.java的类定义如下 -

import java.io.IOException;
import java.sql.*;
import javax.naming.*;
import javax.servlet.*;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.*;
import javax.sql.DataSource;


@SuppressWarnings("serial")
@WebServlet("/TestServlet")
public class TestServlet extends HttpServlet {
public TestServlet() throws ServletException{
    System.out.println("Constructor");
    init();
}
public DataSource dataSource;
private Connection con;
private Statement statement;

public void init() throws ServletException {
    System.out.println("inside init method");
    try {
        // Get DataSource
        Context initContext  = new InitialContext();
        System.out.println("Before envcontext");
        Context envContext  = (Context)initContext.lookup("java:comp/env");
        System.out.println("After envcontext");
        dataSource = (DataSource)envContext.lookup("jdbc/DSTest");
        System.out.println(dataSource.toString());
    } catch (NamingException e) {
        System.out.println("Exception in try");
        e.printStackTrace();
    }
}

public void doGet(HttpServletRequest req, HttpServletResponse resp)
        throws ServletException, IOException {
    System.out.println("Request: "+req+"\tResponse: "+resp);
     int i=0;
    ResultSet resultSet = null;
    try {
        // Get Connection and Statement
        con = dataSource.getConnection();
        statement = con.createStatement();
        String query = "SELECT * FROM USER";
        resultSet = statement.executeQuery(query);
        while (resultSet.next()) {
            ++i;
            System.out.println(i+":\nID:"+resultSet.getString("ID") +"\nEmail:"+ resultSet.getString("UEMAIL") +"\nPassword:" + resultSet.getString("PASSWORD")+"\nFlag:"+resultSet.getShort("FLAG")
                    +"\n");

        }
    } catch (SQLException e) {
        System.out.println("EXCEPTIOn");
        e.printStackTrace();
    }finally {
        try { if(null!=resultSet)resultSet.close();} catch (SQLException e) 
        {e.printStackTrace();System.out.println("1");}
        try { if(null!=statement)statement.close();} catch (SQLException e) 
        {e.printStackTrace();System.out.println("2");}
        try { if(null!=con)con.close();} catch (SQLException e) 
        {e.printStackTrace();System.out.println("3");}
    }
}

我的Jetty-web.xml文件如下：

<?xml version="1.0" encoding="UTF-8"?>
<Configure class="org.eclipse.jetty.webapp.WebAppContext">
<New id="DSTest" class="org.eclipse.jetty.plus.jndi.Resource">
 <Arg>java:comp/env</Arg>
 <Arg>jdbc/DSTest</Arg>
 <Arg>
     <New class="org.apache.commons.dbcp.BasicDataSource">
        <Set name="driverClassName">oracle.jdbc.OracleDriver</Set>
        <Set  name="url">ConnectionUrl</Set>
        <Set name="username">app_user</Set>
        <Set name="password">abcd</Set>
     </New>
 </Arg>
</New>
</Configure>

当我运行servlet类时，出现错误提示 -

java.lang.NoClassDefFoundError: org/apache/commons/pool/impl/GenericObjectPool
at java.lang.Class.getDeclaredConstructors0(Native Method)
at java.lang.Class.privateGetDeclaredConstructors(Class.java:2658)
at java.lang.Class.getConstructors(Class.java:1638)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.newObj(XmlConfiguration.java:748)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.itemValue(XmlConfiguration.java:1078)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.value(XmlConfiguration.java:993)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.newObj(XmlConfiguration.java:741)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.configure(XmlConfiguration.java:383)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.configure(XmlConfiguration.java:317)
at org.eclipse.jetty.xml.XmlConfiguration.configure(XmlConfiguration.java:276)
at org.eclipse.jetty.webapp.JettyWebXmlConfiguration.configure(JettyWebXmlConfiguration.java:100)
at org.eclipse.jetty.webapp.WebAppContext.configure(WebAppContext.java:427)
at org.eclipse.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1207)
at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:610)
at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:453)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
at org.eclipse.jetty.server.handler.HandlerWrapper.doStart(HandlerWrapper.java:89)
at org.eclipse.jetty.server.Server.doStart(Server.java:262)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
at runjettyrun.Bootstrap.main(Bootstrap.java:80)
Caused by: 
java.lang.ClassNotFoundException: org.apache.commons.pool.impl.GenericObjectPool
at java.net.URLClassLoader$1.run(URLClassLoader.java:372)
at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:360)
at org.eclipse.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:415)
at runjettyrun.ProjectClassLoader.loadClass(ProjectClassLoader.java:92)
at java.lang.Class.getDeclaredConstructors0(Native Method)
at java.lang.Class.privateGetDeclaredConstructors(Class.java:2658)
at java.lang.Class.getConstructors(Class.java:1638)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.newObj(XmlConfiguration.java:748)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.itemValue(XmlConfiguration.java:1078)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.value(XmlConfiguration.java:993)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.newObj(XmlConfiguration.java:741)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.configure(XmlConfiguration.java:383)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.configure(XmlConfiguration.java:317)
at org.eclipse.jetty.xml.XmlConfiguration.configure(XmlConfiguration.java:276)
at org.eclipse.jetty.webapp.JettyWebXmlConfiguration.configure(JettyWebXmlConfiguration.java:100)
at org.eclipse.jetty.webapp.WebAppContext.configure(WebAppContext.java:427)
at org.eclipse.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1207)
at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:610)
at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:453)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
at org.eclipse.jetty.server.handler.HandlerWrapper.doStart(HandlerWrapper.java:89)
at org.eclipse.jetty.server.Server.doStart(Server.java:262)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
at runjettyrun.Bootstrap.main(Bootstrap.java:80)
2015-10-30 14:22:51.172:INFO:oejs.AbstractConnector:Started     SelectChannelConnector@0.0.0.0:8081 STARTING
2015-10-30 14:22:51.172:WARN:oejuc.AbstractLifeCycle:FAILED   org.eclipse.jetty.server.Server@7857fe2: java.lang.NoClassDefFoundError:   org/apache/commons/pool/impl/GenericObjectPool
java.lang.NoClassDefFoundError: org/apache/commons/pool/impl/GenericObjectPool
at java.lang.Class.getDeclaredConstructors0(Native Method)
at java.lang.Class.privateGetDeclaredConstructors(Class.java:2658)
at java.lang.Class.getConstructors(Class.java:1638)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.newObj(XmlConfiguration.java:748)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.itemValue(XmlConfiguration.java:1078)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.value(XmlConfiguration.java:993)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.newObj(XmlConfiguration.java:741)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.configure(XmlConfiguration.java:383)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.configure(XmlConfiguration.java:317)
at org.eclipse.jetty.xml.XmlConfiguration.configure(XmlConfiguration.java:276)
at org.eclipse.jetty.webapp.JettyWebXmlConfiguration.configure(JettyWebXmlConfiguration.java:100)
at org.eclipse.jetty.webapp.WebAppContext.configure(WebAppContext.java:427)
at org.eclipse.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1207)
at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:610)
at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:453)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
at org.eclipse.jetty.server.handler.HandlerWrapper.doStart(HandlerWrapper.java:89)
at org.eclipse.jetty.server.Server.doStart(Server.java:262)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
at runjettyrun.Bootstrap.main(Bootstrap.java:80)
Caused by: 
java.lang.ClassNotFoundException: org.apache.commons.pool.impl.GenericObjectPool
at java.net.URLClassLoader$1.run(URLClassLoader.java:372)
at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:360)
at org.eclipse.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:415)
at runjettyrun.ProjectClassLoader.loadClass(ProjectClassLoader.java:92)
at java.lang.Class.getDeclaredConstructors0(Native Method)
at java.lang.Class.privateGetDeclaredConstructors(Class.java:2658)
at java.lang.Class.getConstructors(Class.java:1638)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.newObj(XmlConfiguration.java:748)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.itemValue(XmlConfiguration.java:1078)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.value(XmlConfiguration.java:993)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.newObj(XmlConfiguration.java:741)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.configure(XmlConfiguration.java:383)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.configure(XmlConfiguration.java:317)
at org.eclipse.jetty.xml.XmlConfiguration.configure(XmlConfiguration.java:276)
at org.eclipse.jetty.webapp.JettyWebXmlConfiguration.configure(JettyWebXmlConfiguration.java:100)
at org.eclipse.jetty.webapp.WebAppContext.configure(WebAppContext.java:427)
at org.eclipse.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1207)
at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:610)
at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:453)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
at org.eclipse.jetty.server.handler.HandlerWrapper.doStart(HandlerWrapper.java:89)
at org.eclipse.jetty.server.Server.doStart(Server.java:262)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
at runjettyrun.Bootstrap.main(Bootstrap.java:80)
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/pool/impl/GenericObjectPool
at java.lang.Class.getDeclaredConstructors0(Native Method)
at java.lang.Class.privateGetDeclaredConstructors(Class.java:2658)
at java.lang.Class.getConstructors(Class.java:1638)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.newObj(XmlConfiguration.java:748)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.itemValue(XmlConfiguration.java:1078)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.value(XmlConfiguration.java:993)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.newObj(XmlConfiguration.java:741)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.configure(XmlConfiguration.java:383)
at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.configure(XmlConfiguration.java:317)
at org.eclipse.jetty.xml.XmlConfiguration.configure(XmlConfiguration.java:276)
at org.eclipse.jetty.webapp.JettyWebXmlConfiguration.configure(JettyWebXmlConfiguration.java:100)
at org.eclipse.jetty.webapp.WebAppContext.configure(WebAppContext.java:427)
at org.eclipse.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1207)
at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:610)
at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:453)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
at org.eclipse.jetty.server.handler.HandlerWrapper.doStart(HandlerWrapper.java:89)
at org.eclipse.jetty.server.Server.doStart(Server.java:262)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
at runjettyrun.Bootstrap.main(Bootstrap.java:80)
Caused by: java.lang.ClassNotFoundException: org.apache.commons.pool.impl.GenericObjectPool
at java.net.URLClassLoader$1.run(URLClassLoader.java:372)
at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:360)
at org.eclipse.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:415)
at runjettyrun.ProjectClassLoader.loadClass(ProjectClassLoader.java:92)
... 20 more

在查看其他stackoverflow线程后，我已将commons-dbcp-1.4.jar添加到我的WEB-INF/lib文件夹中。即使这样做了，当我在Jetty上部署时仍然会出现相同的错误。

我正在使用与eclipse luna 4.4.1集成的jetty服务器版本8。

非常感谢任何帮助。

- tpsaitwal

---

commons-pool和commons-dbcp是否在不同的JAR文件中？以前是这样的，你需要两个都要。 - Thilo

我添加了两个版本。但是对我没有用。你有其他聪明的想法吗？@Thilo - tpsaitwal

如果是Jetty本身使用池（而不是您的Web应用程序），则需要将jar文件放置在Jetty自己的“lib”文件夹中（而不是放置在“WEB-INF / lib”中）。 - Thilo

你不能随意将任意的JAR文件放入Jetty发行版的${jetty.home}/lib目录中并期望它们被使用。如果你正在使用Jetty 9，那么需要在${jetty.base}中添加ext模块，然后将额外的服务器端JAR文件添加到${jetty.base}/lib/ext/目录中。 - Joakim Erdfelt

我知道你已经添加了common-pool，但是你能否按照https://dev59.com/cXvaa4cB1Zd3GeqPDG9p#21191623中的建议进行检查？（部署组件） - VonC

Answer 1

你有三种方法来完成它：

1. 如果你的项目中使用了Maven或Gradle，只需在pom.xml或build.gradle文件中添加commons-pool依赖项即可（推荐方式）
2. 如果你没有使用上述工具之一，请将正确的JAR包放置在WEB-INF / lib目录中
3. 最后一种方法是将JAR包放置在$ {jettyHome} / lib目录中

请确保你正在使用适用于当前commons-dbcp实现的正确版本的commons-pool。

- burovmarley

---

是的，我做了，但我不知道它在哪里找到剩余名称“env”的上下文。 - tpsaitwal

@Tejas Saitwal。在这里有一个类似的JNDI问题（https://dev59.com/L4Tba4cB1Zd3GeqP0ATo）。如果您已经正确配置了所有内容，您应该能够通过使用`datasource =（DataSource）new InitialContext（）。lookup（“java：comp / env / jdbc / DSTest”）;`来查找数据源。 - burovmarley

Answer 2

你为什么不使用Tomcat呢？在这里找到http://tomcat.apache.org/ :) 注意，Jetty只适合用于需要简化本地应用程序开发的情况。 https://tomcat.apache.org/tomcat-7.0-doc/jdbc-pool.html 我建议你开始学习基础的Tomcat知识，并在你开始获得基本的理解时开始实现连接池 :) 希望这可以帮到你。

- TheLuminor

---

这并没有回答问题。Jetty在生产环境中被广泛采用，并具有连接池功能。通常，在部署到嵌入式/资源受限环境时，这是一种更可取的服务器。说Jetty仅用于简化本地应用程序开发是绝对不正确的，这只是其中一个使用情况。 - Scot Matson

Answer 3

对于Jetty 10.x，您可以按照以下方式解决此问题：

1. 启用ext模块 -> java -jar start.jar --add-modules=ext
2. 在执行1）后，将在$JETTY_BASE/start.d/ext.ini中创建
3. 将您的Oracle JDBC jar文件放置在位置$JETTY_HOME/lib/ext/
4. 再次启动您的应用程序 -> java -jar start.jar

- Ashok Vijayakumar

Answer 4

当我需要 Oracle 连接池时，我总是使用 ojdbcx.jar 和 ucp.jar。你可以从这里下载它们。

你可以从 Google 上找到很多教程，但这里有一个简单的（适用于 Jetty 6） 链接。

- Orcun Yucel