Question

我刚接触服务器开发，并且从简单的教程开始 Lars Vogel。 Servlet and JSP development with Eclipse WTP

一步一步 符合本教程：

安装了Eclipse Java EE Kepler;
在Ubuntu 12.04上安装了tomcat 7 - http://localhost:8080/显示正确的tomcat页面;
将tomcat运行时环境设置为eclipse;
将tomcat服务器添加到eclipse;
创建DAO;
创建了Servlet;
run =＆gt;

在这里，我抓住了下一个提示：

Sep 15, 2013 3:40:39 PM org.apache.catalina.core.AprLifecycleListener init
INFO: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: /usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib
Sep 15, 2013 3:40:42 PM org.apache.tomcat.util.digester.SetPropertiesRule begin
WARNING: [SetPropertiesRule]{Server/Service/Engine/Host/Context} Setting property 'source' to 'org.eclipse.jst.jee.server:com.filecounter' did not find a matching property.
Sep 15, 2013 3:40:43 PM org.apache.coyote.AbstractProtocol init
INFO: Initializing ProtocolHandler ["http-bio-8080"]
Sep 15, 2013 3:40:43 PM org.apache.coyote.AbstractProtocol init
INFO: Initializing ProtocolHandler ["ajp-bio-8009"]
Sep 15, 2013 3:40:43 PM org.apache.catalina.startup.Catalina load
INFO: Initialization processed in 5203 ms
Sep 15, 2013 3:40:43 PM org.apache.catalina.core.StandardService startInternal
INFO: Starting service Catalina
Sep 15, 2013 3:40:43 PM org.apache.catalina.core.StandardEngine startInternal
INFO: Starting Servlet Engine: Apache Tomcat/7.0.42
Sep 15, 2013 3:40:45 PM org.apache.catalina.util.SessionIdGenerator createSecureRandom
INFO: Creation of SecureRandom instance for session ID generation using [SHA1PRNG] took [171] milliseconds.
Sep 15, 2013 3:40:46 PM org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler ["http-bio-8080"]
Sep 15, 2013 3:40:46 PM org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler ["ajp-bio-8009"]
Sep 15, 2013 3:40:46 PM org.apache.catalina.startup.Catalina start
INFO: Server startup in 2882 ms

以下是tomcat/lib文件夹的内容：

nazar_art@nazar-desctop:/usr/local/tomcat/apache-tomcat-7.0.42/lib$ ls -lg
total 6132
-rwxrwxrwx 1 nazar_art   15264 Jul  2 10:59 annotations-api.jar
-rwxrwxrwx 1 nazar_art   54142 Jul  2 10:59 catalina-ant.jar
-rwxrwxrwx 1 nazar_art  134215 Jul  2 10:59 catalina-ha.jar
-rwxrwxrwx 1 nazar_art 1581311 Jul  2 10:59 catalina.jar
-rwxrwxrwx 1 nazar_art  257520 Jul  2 10:59 catalina-tribes.jar
-rwxrwxrwx 1 nazar_art 1801636 Jul  2 10:59 ecj-4.2.2.jar
-rwxrwxrwx 1 nazar_art   46085 Jul  2 10:59 el-api.jar
-rwxrwxrwx 1 nazar_art  123241 Jul  2 10:59 jasper-el.jar
-rwxrwxrwx 1 nazar_art  599428 Jul  2 10:59 jasper.jar
-rwxrwxrwx 1 nazar_art   88690 Jul  2 10:59 jsp-api.jar
-rwxrwxrwx 1 nazar_art  177598 Jul  2 10:59 servlet-api.jar
-rwxrwxrwx 1 nazar_art    6873 Jul  2 10:59 tomcat-api.jar
-rwxrwxrwx 1 nazar_art  796527 Jul  2 10:59 tomcat-coyote.jar
-rwxrwxrwx 1 nazar_art  235411 Jul  2 10:59 tomcat-dbcp.jar
-rwxrwxrwx 1 nazar_art   77364 Jul  2 10:59 tomcat-i18n-es.jar
-rwxrwxrwx 1 nazar_art   48693 Jul  2 10:59 tomcat-i18n-fr.jar
-rwxrwxrwx 1 nazar_art   51678 Jul  2 10:59 tomcat-i18n-ja.jar
-rwxrwxrwx 1 nazar_art  124006 Jul  2 10:59 tomcat-jdbc.jar
-rwxrwxrwx 1 nazar_art   23201 Jul  2 10:59 tomcat-util.jar

Here is content of catalina.2013-09-15.log。

更新

这是教程：
Installing Apache Tomcat Native on Linux Ubuntu 12.04

UPDATE2：

以下是数据访问对象的内容：

public class FileDao {

  public int getCount() {
    int count = 0;
    // Load the file with the counter
    FileReader fileReader = null;
    BufferedReader bufferedReader = null;
    PrintWriter writer = null ; 
    try {
      File f = new File("FileCounter.initial");
      if (!f.exists()) {
        f.createNewFile();
        writer = new PrintWriter(new FileWriter(f));
        writer.println(0);
      }
      if (writer !=null){
        writer.close();
      }

      fileReader = new FileReader(f);
      bufferedReader = new BufferedReader(fileReader);
      String initial = bufferedReader.readLine();
      count = Integer.parseInt(initial);
    } catch (Exception ex) {
      if (writer !=null){
        writer.close();
      }
    }
    if (bufferedReader != null) {
      try {
        bufferedReader.close();
      } catch (IOException e) {
        e.printStackTrace();
      }
    }
    return count;
  }

  public void save(int count) throws Exception {
    FileWriter fileWriter = null;
    PrintWriter printWriter = null;
    fileWriter = new FileWriter("FileCounter.initial");
    printWriter = new PrintWriter(fileWriter);
    printWriter.println(count);

    // Make sure to close the file
    if (printWriter != null) {
      printWriter.close();
    }
  }

}

这里是Servlet代码：

public class FileCounter extends HttpServlet {
  private static final long serialVersionUID = 1L;

  int count;
  private FileDao dao;

  public void init() throws ServletException {
    dao = new FileDao();
    try {
      count = dao.getCount();
    } catch (Exception e) {
      getServletContext().log("An exception occurred in FileCounter", e);
      throw new ServletException("An exception occurred in FileCounter"
          + e.getMessage());
    }
  }

  protected void doGet(HttpServletRequest request,
      HttpServletResponse response) throws ServletException, IOException {
    // Set a cookie for the user, so that the counter does not increate
    // every time the user press refresh
    HttpSession session = request.getSession(true);
    // Set the session valid for 5 secs
    session.setMaxInactiveInterval(5);
    response.setContentType("text/plain");
    PrintWriter out = response.getWriter();
    if (session.isNew()) {
      count++;
    }
    out.println("This site has been accessed " + count + " times.");
  }

  public void destroy() {
    super.destroy();
    try {
      dao.save(count);
    } catch (Exception e) {
      e.printStackTrace();
    }
  }

}

我还没有web.xml。

如何解决这个问题？

Answer 1

在java.library.path上找不到：/ usr / java / packages / lib / amd64：/ usr / lib64：/ lib64：/ lib：/ usr / lib

原生lib预计会在以下某个位置

/usr/java/packages/lib/amd64
/usr/lib64
/lib64
/lib
/usr/lib

而不是

tomcat/lib

tomcat/lib中的文件都是jar文件，并由tomcat添加到classpath，以便它们可供您的应用程序使用。

tomcat需要本机lib才能在安装它的平台上表现更好，因此不能是jar，对于linux来说它可能是.so文件，对于windows来说它可能是.dll档案。

只需download the native library for your platform并将其放在tomcat所期望的位置之一。

请注意，您不需要将此lib用于开发/测试目的。 Tomcat在没有它的情况下运行得很好。

org.apache.catalina.startup.Catalina启动INFO：服务器启动时间为2882 ms

修改

您获得的输出非常正常，它只是tomcat的一些日志输出，右上方的行表示服务器已正确启动并准备好运行。

如果您在运行servlet时遇到麻烦，那么在run on sever命令eclipse打开浏览器窗口（嵌入（默认）或外部）后，取决于您的配置）。如果浏览器上没有显示任何内容，请检查浏览器的url栏以查看是否请求了servlet。

它应该是那样的

http://localhost:8080/<your-context-name>/<your-servlet-name>

编辑2

尝试使用以下网址
调用您的servlet
http://localhost:8080/com.filecounter/FileCounter

此外，每个Web项目都有一个web.xml，您可以在WebContent\WEB-INF下的项目中找到它。

最好使用servlet-name servlet-class和url-mapping在那里配置servlet。它可能看起来像那样：

<servlet> <description></description> <display-name>File counter - My first servlet</display-name> <servlet-name>file_counter</servlet-name> <servlet-class>com.filecounter.FileCounter</servlet-class> </servlet> <servlet-mapping> <servlet-name>file_counter</servlet-name> <url-pattern>/FileFounter</url-pattern> </servlet-mapping>

在eclipse动态Web项目中，默认上下文名称与项目名称相同。

http://localhost:8080/<your-context-name>/FileCounter

也会奏效。

Answer 2

关于标题中提出的原始问题......

sudo apt-get install libtcnative-1
或者您使用的是RHEL Linux yum install tomcat-native

文档说明您需要http://tomcat.apache.org/native-doc/

sudo apt-get install libapr1.0-dev libssl-dev
或RHEL yum install apr-devel openssl-devel

在java.library.path上找不到基于APR的Apache Tomcat Native库

2 个答案: