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();
    }
}