《Javac、Java、Jar命令》第三篇

这篇随笔主要写启动 jar 时，如果需要依赖其他的 jar 包该怎么处理，我会以 rabbitMQ 客服端启动为例。

package com.rockcode.www.rabbitmq;

import java.io.IOException;
import java.util.concurrent.TimeoutException;
import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;
import com.rabbitmq.client.DefaultConsumer;
import com.rabbitmq.client.Envelope;

public class Consumer {
    private final static String QUEUE_NAME = "rock";

    public static void main(String[] args) {
        
        ConnectionFactory factory = new ConnectionFactory();
        factory.setUsername("guest");
        factory.setPassword("guest");
        factory.setHost("localhost");
        
        Connection conn;
        try {
            conn = factory.newConnection();
            Channel channel = conn.createChannel();
            channel.queueDeclare(QUEUE_NAME, false, false, false, null);
            System.out.println(" [*] Waiting for messages. To exit press CTRL+C");
            
            com.rabbitmq.client.Consumer con = new DefaultConsumer(channel) {
                  @Override
                  public void handleDelivery(String consumerTag, Envelope envelope,
                                             AMQP.BasicProperties properties, byte[] body)
                      throws IOException {
                    String message = new String(body, "UTF-8");
                    System.out.println(" [x] Received '" + message + "'");
                    
                        try {
                            doWork(message);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                      finally {
                        System.out.println(" [x] Done");
                      }
                    
                  }
                };
            
            channel.basicConsume(QUEUE_NAME, true, con);
            
        } catch (IOException e) {
        } catch (TimeoutException e) {
        }
    
        
    }
    
    private static void doWork(String task) throws InterruptedException {
        for (char ch: task.toCharArray()) {
            if (ch == '.') Thread.sleep(1000);
        }
    }

}

客服端依赖 amqp-client-5.0.0.jar 和 slf4j-api-1.7.25.jar，先看看 MANIFEST.MF 文件

再看看目录结构

lib 下面就是所依赖的 jar 文件 amqp-client-5.0.0.jar 和 slf4j-api-1.7.25.jar。

我们在打开 CMD，先设置路径 set CP=.;lib/amqp-client-5.0.0.jar;lib/slf4j-api-1.7.25.jar;再执行 java -cp %CP% -jar consumer.jar

[x] Received 'hello.'
[x] Done

没错，收到了消息。但是上面有报错， Failed to load class "org.slf4j.impl.StaticLoggerBinder".

我们将 slf4j-nop-1.7.21.jar 加入 lib 目录下，重新设置路径，set CP=.;lib/amqp-client-5.0.0.jar;lib/slf4j-api-1.7.25.jar;lib/slf4j-nop-1.7.21.jar;

同时修改 MANIFEST.MF 文件

再试下 java -cp %CP% -jar consumer.jar

这样就没问题了。

下一篇我会将 producer 和 consumer 分别打包成 jar，通过命令行和脚本来执行，谢谢大家，希望有所帮助！