程序实现启动和停止嵌入式Tomcat Web服务器

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这阵子，由于实验的需要，需要通过程序启动和停止Tomcat Web Server。很早以前就知道有Embedded tomcat。如果不使用嵌入式服务器，直接调用命令行

startup.bat, shutdown.bat，将输入输出重定向，是比较容易的，但是这样的tomcat比较臃肿，也不好看。

网上也有一些实例，但只是告诉我们启动tomcat，却没有合适的停止tomcat的示例。

于是就尝试写一个TomcatServer.java， 用于启动和停止嵌入式的tomcat server。

原理很简单：

一个启动线程，一个停止线程。停止线程不断监听$TOMCAT_HOME/tomcat.stop 标志文件，如果有这个文件，直接stop tomcat engine，然后删除这个文件。

嵌入式tomcat作用还是蛮大的，你可以拿它做一个Web admin console工具，嵌入到你的任何系统当中。

准备工作：

1. 下载tomcat5.0.28embed.zip，能google到。总共也就4M的样子：

http://archive.apache.org/dist/tomcat/tomcat-5/v5.0.28/bin/jakarta-tomcat-5.0.28-embed.zip

2. 将它解压缩到d:\, 这样得到目录d:\jakarta-tomcat-5.0.28-embed

3. 准备一个demo.war，将其解压到d:\jakarta-tomcat-5.0.28-embed\webapps\下边，确保有一个demo目录，用作webapp。因为下边的程序要用到。

4. 在d:\jakarta-tomcat-5.0.28-embed下边编辑一个java源程序TomcatServer.java, 内容如下：

这个程序使用很简单，TomcatServer.start()启动，TomcatServer.stop()停止。

import java.io.File;
import java.io.IOException;
import java.net.InetAddress;
import java.net.UnknownHostException;

import org.apache.catalina.Context;
import org.apache.catalina.Engine;
import org.apache.catalina.Host;
import org.apache.catalina.startup.Embedded;

/***
* A very simple embedded tomcat server, which launches a single webapp: demo.
* The flag file : tomcat.stop locates at $CATALINA_HOME/ is used to notify the 
* control thread to stop tomcat engine or noe. 
*/
public class TomcatServer
{
 
 public static void stop()
 {
 final String path = System.getProperty("tomcat.home", "d:/jakarta-tomcat-5.0.28-embed");
 try
 {
 new File(path).createNewFile();
 }
 catch (IOException ex)
 {
 throw new RuntimeException(ex);
 }
 }
 
 public static void start()
 {
 // set the path for tomcat embed
 final String path = System.getProperty("tomcat.home", "d:/jakarta-tomcat-5.0.28-embed");

 final Embedded tc = createTomcat(path);
 Thread startThread = new Thread()
 {
 public void run()
 {
 try
 {
 tc.start();
 System.out.println("Tomcat Server 5.0.28 started .....");
 }
 catch (Exception e)
 {
 e.printStackTrace();
 throw new RuntimeException(e);
 }
 }
 };
 startThread.start();
 try
 {
 startThread.join();
 }
 catch (Exception ex)
 {
 ex.printStackTrace();
 }
 
 Thread controlThread = new Thread() 
 {
 public void run()
 {
 for (;;)
 {
 try
 {
 Thread.sleep(2000);
 File f = new File(path + "/tomcat.stop");
 if (f.exists())
 {
 try
 {
 tc.stop();
 System.out.println("Tomcat Server 5.0.28 stopped .....");
 }
 catch (Exception e)
 {
 e.printStackTrace();
 throw new RuntimeException(e);
 }
 f.delete();
 break;
 }
 }
 catch (Exception ex)
 {
 ex.printStackTrace();
 }
 }
 }
 };
 controlThread.start();
 try
 {
 controlThread.join();
 }
 catch (Exception ex)
 {
 ex.printStackTrace();
 } 
 }
 

 private static Embedded createTomcat(String path)
 {
 // create Tomcat Server Instance
 Embedded tomcat = new Embedded();
 // set the tomcat home
 tomcat.setCatalinaHome(path);
 // create the Tomcat engine
 Engine engine = tomcat.createEngine();
 engine.setName("TomcatServer of ProxyTest");
 // create the host
 Host host = tomcat.createHost("localhost", tomcat.getCatalinaHome() + "/webapps");
 // put the host into engine
 engine.addChild(host);
 engine.setDefaultHost(host.getName());

 String contextPath = host.getAppBase() + "/demo";
 if (!new File(contextPath).exists())
 {
 System.err.println("Please test if the contextPath exists");
 return null;
 }
 System.out.println("contextPath: " + contextPath);
 Context context = tomcat.createContext("/demo", contextPath);
 host.addChild(context);

 tomcat.addEngine(engine);
 try
 {
 tomcat.addConnector(tomcat.createConnector(InetAddress.getByName("127.0.0.1"), 8080,
 false));
 }
 catch (UnknownHostException e)
 {
 System.err
 .println("can not bind tomcat Server to the localhost 127.0.0.1:8080;test the host is free");
 e.printStackTrace();
 tomcat = null;
 throw new RuntimeException(e);
 }
 return tomcat;
 }
 
 public static void main(String[] args)
 {
 start();
 }
}