十二、消息服务（2）

本章概要

AMQP
安装 RabbitMQ

12.2.1 AMQP 简介

AMQP （Advanced Message Queuing Protocol，高级消息队列协议），是一个线路层的协议规范，而不是 API 规范（例如 JMS）。由于 AMQP 是一个线路层协议规范，因此它天然就是跨平台的，就像 SMTP、HTTP 等协议一样，只要开发者按照规范的格式发送数据，任何平台都可以通过 AMQP 进行消息交互。像目前流行的 StormMQ 、RabbitMQ 等都实现了 AMQP 。

12.2.2 Spring Boot 整合 AMQP

和 JMS 一样，使用 AMQP 也是使用 AMQP 的某个实现，此处以 RabbitMQ 为例介绍 AMQP 的使用。

1. RabbitMQ 简介

RabbitMQ 是一个实现了 AMQP 的开源消息中间件，使用高性能的 Erlang 编写。RabbitMQ 具有可靠性、支持多协议、高可用、支持消息集群以及多语言客户端等特点，在分布式系统中存储转发消息，具有不错的性能表现。

2. RabbitMQ 安装

由于 RabbitMQ 使用 Erlang 编写，因此需要先安装 Erlang 环境，在 CentOS 7 中安装 Erlang 21.0 的步骤如下（其它下载地址：otp_src_21.0.tar.gz）：
（1）下载解压安装包

wget http://erlang.org/download/otp_src_21.0.tar.gz
tar -zxvf /opt/package/otp_src_21.0.tar.gz -C /opt/soft/

（2）编译

./otp_build autoconf
./configure

报错了以下错误

configure: error: No curses library functions found
configure: error: /opt/soft/otp_src_21.0/erts/configure failed for erts

解决方案（没报错不需要）

yum -y install ncurses-devel
./otp_build autoconf
./configure

（3）安装校验

make install
erl

看到以下内容表示 Erlang 安装成功

[root@VM-12-5-centos otp_src_21.0]# erl
Erlang/OTP 21 [erts-10.0] [source] [64-bit] [smp:1:1] [ds:1:1:10] [async-threads:1] [hipe]Eshell V10.0  (abort with ^G)
1>

Erlang 安装成功后，然后开始安装 RabbitMQ
（1）下载安装文件

wget https://dl.bintray.com/rabbitmq/all/rabbitmq-server/3.7.7/rabbitmq-server-3.7.7.el7.noarch.rpm

如果提示502，在此下载：erlang-21.0.9-1.el7，rabbitmq-server-3.7.7-1.el7，还是502，直接离线安装吧：rabbitmq-server-generic-unix-3.7.7.tar

（2）解压

tar -xvf /opt/package/rabbitmq-server-generic-unix-3.7.7.tar -C /opt/soft/

修改主机名：vim /etc/hosts，追加一行 127.0.0.1 VM-12-5-centos（VM-12-5-centos改为自己的主机名），因为RabbitMQ在启动的时候会ping自己的主机名，所以这里要进行映射，然后重启网络：service network restart

（3）启动

注意：启动的时候注意查看日志（tail -f /opt/soft/rabbitmq_server-3.7.7/var/log/rabbitmq/log/crash.log）
我这报错了，原因是端口被占用

查看端口占用信息：**lsof -i:5672，然后 kill 掉，kill -9 3918

/opt/soft/rabbitmq_server-3.7.7/sbin/rabbitmq-server start

（3）查看状态

/opt/soft/rabbitmq_server-3.7.7/sbin/rabbitmqctl status

Status of node rabbit@VM-12-5-centos ...
[{pid,17978},{running_applications,[{rabbitmq_management,"RabbitMQ Management Console","3.7.7"},{rabbitmq_management_agent,"RabbitMQ Management Agent","3.7.7"},{rabbitmq_web_dispatch,"RabbitMQ Web Dispatcher","3.7.7"},{rabbit,"RabbitMQ","3.7.7"},{amqp_client,"RabbitMQ AMQP Client","3.7.7"},{rabbit_common,"Modules shared by rabbitmq-server and rabbitmq-erlang-client","3.7.7"},{recon,"Diagnostic tools for production use","2.3.2"},{cowboy,"Small, fast, modern HTTP server.","2.2.2"},{ranch_proxy_protocol,"Ranch Proxy Protocol Transport","1.5.0"},{ranch,"Socket acceptor pool for TCP protocols.","1.5.0"},{ssl,"Erlang/OTP SSL application","9.0"},{public_key,"Public key infrastructure","1.6"},{asn1,"The Erlang ASN1 compiler version 5.0.6","5.0.6"},{os_mon,"CPO  CXC 138 46","2.4.5"},{jsx,"a streaming, evented json parsing toolkit","2.8.2"},{mnesia,"MNESIA  CXC 138 12","4.15.4"},{xmerl,"XML parser","1.3.17"},{cowlib,"Support library for manipulating Web protocols.","2.1.0"},{crypto,"CRYPTO","4.3"},{inets,"INETS  CXC 138 49","7.0"},{lager,"Erlang logging framework","3.6.3"},{goldrush,"Erlang event stream processor","0.1.9"},{compiler,"ERTS  CXC 138 10","7.2"},{syntax_tools,"Syntax tools","2.1.5"},{syslog,"An RFC 3164 and RFC 5424 compliant logging framework.","3.4.2"},{sasl,"SASL  CXC 138 11","3.2"},{stdlib,"ERTS  CXC 138 10","3.5"},{kernel,"ERTS  CXC 138 10","6.0"}]},{os,{unix,linux}},{erlang_version,"Erlang/OTP 21 [erts-10.0] [source] [64-bit] [smp:1:1] [ds:1:1:10] [async-threads:64] [hipe]\n"},{memory,[{connection_readers,0},{connection_writers,0},{connection_channels,0},{connection_other,2820},{queue_procs,0},{queue_slave_procs,0},{plugins,799300},{other_proc,29727876},{metrics,195020},{mgmt_db,153256},{mnesia,73104},{other_ets,2823312},{binary,88784},{msg_index,31152},{code,23237767},{atom,1131721},{other_system,10672784},{allocated_unused,8706880},{reserved_unallocated,0},{strategy,rss},{total,[{erlang,68936896},{rss,73388032},{allocated,77643776}]}]},{alarms,[]},{listeners,[{clustering,25672,"::"},{amqp,5672,"::"},{http,15672,"::"}]},{vm_memory_calculation_strategy,rss},{vm_memory_high_watermark,0.4},{vm_memory_limit,770865561},{disk_free_limit,50000000},{disk_free,38876147712},{file_descriptors,[{total_limit,99901},{total_used,2},{sockets_limit,89908},{sockets_used,0}]},{processes,[{limit,1048576},{used,376}]},{run_queue,1},{uptime,118},{kernel,{net_ticktime,60}}]

（4）开启web插件

/opt/soft/rabbitmq_server-3.7.7/sbin/rabbitmq-plugins enable rabbitmq_management

（5）重启

/opt/soft/rabbitmq_server-3.7.7/sbin/rabbitmq-server restart

（6）添加一个用户名为 long，密码为 123 的用户

/opt/soft/rabbitmq_server-3.7.7/sbin/rabbitmqctl add_user long 123

（7）设置 long 用户的角色为管理员

/opt/soft/rabbitmq_server-3.7.7/sbin/rabbitmqctl set_user_tags long administrator

（8）配置 long 的权限

/opt/soft/rabbitmq_server-3.7.7/sbin/rabbitmqctl  set_permissions -p / long '.*' '.*' '.*'

（9）登录
浏览器访问：http://ip:15672