一个简单的JAVA后台程序框架

    本项目已经通过git进行版本管理，checkout：http://github.com/lettoo/orion

    项目要实现一个java后台程序，提供start()，stop()和status()的方法。

    主要的原理是：有一个Server类运行在localhost:xxxx上，当成一个RMI service，这个Server类里有一个Service List，通过Spring注入的方式，向其中注入Service，当然，也可以通过编程方式动态往里面加Service，因为项目比较简单，直接通过Spring配置已经满足要求。RMI 客户端通过调用Server.start()，遍历Service List中的service，一个个启动起来。客户端调用stop()，则遍历Service List中的server，一个个关闭，最终再关闭服务端。status()方法只是简单的提供Server是否在运行状态。

1. Server接口

public interface IServer {
    void start() throws Exception;    
    void stop() throws Exception;    
    boolean isStarted();
}

2. Server实现类

import java.util.LinkedList;
import java.util.List;

public class ServerImpl implements IServer {    
    private volatile boolean isStarted = false;
    private List<IService> serviceList = new LinkedList<IService>();
    
    public void setServiceList(List<IService> serviceList) {
        this.serviceList = serviceList;
    }

    @Override
    public void start() throws Exception {
        if (isStarted) {
            return;
        }        
        for (IService service : serviceList) {
            service.start();
        }        
        isStarted = true;
    }

    @Override
    public void stop() throws Exception{       
        for (IService service : serviceList) {
            service.stop();
        }        
        isStarted = false;
        System.exit(0);
    }

    @Override
    public boolean isStarted() {
        return isStarted;
    }
}

 
3. 通过Spring RMI，分别创建两个xml，一个是server.xml

<?xml version="1.0" encoding="UTF-8"?> 
<!DOCTYPE beans PUBLIC "-//SPRING/DTD BEAN/EN" 
  "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
    <bean id="server" class="cn.lettoo.server.ServerImpl">
        <property name="serviceList">
            <list>
                <!-- Add your service here, all service implements IService interface. -->
                <ref bean="jmsService" />
                <ref bean="jobService" />
                <ref bean="dataReaderService" />
            </list>
        </property>
    </bean>
    <bean id="orionMonitorServer" class="org.springframework.remoting.rmi.RmiServiceExporter">
        <property name="serviceInterface" value="cn.lettoo.server.IServer" />
        <property name="service" ref="server" />
        <property name="serviceName" value="OrionMonitorServer" />
        <property name="registryPort" value="1199" />
        <property name="alwaysCreateRegistry" value="true" />
    </bean>

</beans>

再创建一个client.xml

<?xml version="1.0" encoding="UTF-8"?> 
<!DOCTYPE beans PUBLIC "-//SPRING/DTD BEAN/EN" 
  "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
    <bean id="serviceProxy" class="org.springframework.remoting.rmi.RmiProxyFactoryBean">
        <property name="serviceUrl" value="rmi://localhost:1199/OrionMonitorServer" />
        <property name="serviceInterface" value="cn.lettoo.server.IServer" />
    </bean>
</beans>

4. 写一个Luncher类，通过RMI来调用Server的方法

import org.apache.commons.cli.BasicParser;
import org.apache.commons.cli.CommandLine;
import org.apache.commons.cli.CommandLineParser;
import org.apache.commons.cli.HelpFormatter;
import org.apache.commons.cli.Options;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Launcher {

    /** The Constant USAGE. */
    private static final String USAGE = "[options]";

    /** The Constant HEADER. */
    private static final String HEADER = "Options:";

    /** The Constant FOOTER. */
    private static final String FOOTER = "For more instructions, please contact golettoo@gmail.com";
    
    private IServer server;
    
    private static Log logger = LogFactory.getLog(Launcher.class);

    public static void main(String args[]) {
        Launcher launcher = new Launcher();
        try {
            launcher.execute(args);
        } catch (Exception e) {
            launcher.printUsage(launcher.createOptions());
            logger.error("launch error: ", e);
            System.exit(1);
        }
    }

    private void execute(String[] args) throws Exception {
        CommandLineParser parser = new BasicParser();
        Options options = createOptions();
        CommandLine commandLine = parser.parse(options, args);
        if (commandLine.hasOption('h')) {
            printUsage(options);
            return;
        }

        if (commandLine.hasOption('v')) {
            System.out.println("Version: 1.0");
            return;
        }
        
        if (args.length == 0) {
            start();
        } else if (commandLine.hasOption("start")) {
            start();
        } else if (commandLine.hasOption("stop")) {
            stop();
        } else if (commandLine.hasOption("status")) {
            System.out.println("Status: " + getStatus());
        } else {
            printUsage(options);
        }
    }

    private void initServer() throws Exception {
        ApplicationContext context = 
            new ClassPathXmlApplicationContext(new String[] { "server.xml" });        
    }
    
    private void initClient() throws Exception {
        ApplicationContext context = 
            new ClassPathXmlApplicationContext(new String[] { "client.xml" });        
        this.server = (IServer) context.getBean("serviceProxy");
    }
    
    private void start() throws Exception {
        initServer();
        initClient();
        server.start();
    }

    private void stop() {
        try {
            initClient();
            server.stop();
        } catch (Exception e) {
            logger.error("Stop server error: " + e.toString());
        }
    }

    private String getStatus() {
        try {     
            initClient();
            return server.isStarted() ? "started" : "stopped";
        } catch (Exception e) {
            logger.error("Get server status error: " + e.toString());
        }
        return "stopped";
    }

    private void printUsage(Options options) {
        HelpFormatter helpFormatter = new HelpFormatter();
        helpFormatter.printHelp(USAGE, HEADER, options, FOOTER);
    }

    private Options createOptions() {
        Options options = new Options();
        options.addOption("h", "help", false, "print this usage information");
        options.addOption("o", "option", true, "set option");
        options.addOption("v", "version", false, "print version");
        options.addOption("start", false, "start the application");
        options.addOption("stop", false, "stop the application");
        options.addOption("status", false, "print the status information");
        return options;
    }
}

Luncher类通过运行时的参数来决定是start还是stop，另外，还提供了一个帮助和版本信息的查看

现在可以通过运行Luncher -start来启动这个server了

再通过Luncher -status来看状态

通过Luncher -stop来关闭server