关于Ubuntu18.04 linux系统使用安装JDK Mysql

一、安装JDK

step1.下载OracleJDK
step2.解压
step3.加入环境变量

具体操作如下：

lemon@ubuntu:~$ cd ~/download/
lemon@ubuntu:~/download$ wget http://download.oracle.com/otn-pub/java/jdk/8u191-b12/2787e4a523244c269598db4e85c51e0c/jdk-8u191-linux-x64.tar.gz
lemon@ubuntu:~/download$ tar vxf jdk-8u191-linux-x64.tar.gz
lemon@ubuntu:~/download$ ls  #查看当前目录下的文件
jdk1.8.0_191  jdk-8u191-linux-x64.tar.gz
lemon@ubuntu:~/download$ sudo mv jdk1.8.0_191/ /usr/local/jdk1.8/  #将jdk1.8.0_191文件夹移动到/usr/local/下并重命名为jdk1.8
lemon@ubuntu:~/download$ sudo vim /etc/profile #编辑环境变量

在环境变量末尾加入如下内容:

export JAVA_HOME=/usr/local/jdk1.8
export JRE_HOME=${JAVA_HOME}/jre
export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib
export PATH=.:${JAVA_HOME}/bin:$PATH

保存后重新加载环境变量，使生效：

lemon@ubuntu:~/download$ source /etc/profile #刷新环境变量，使生效
lemon@ubuntu:~$ java -version#输入java -version，如显示以下信息，则JDK安装成功
java version "1.8.0_191"
Java(TM) SE Runtime Environment (build 1.8.0_191-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.191-b12, mixed mode)

二、安装MySQL

step1.安装MySQL并配置
step2.创建数据库与表

由于在安装Ubuntu系统时，本人选择了安装LAMP服务，所以MySQL已安装完成，仅需设置即可启用。

测试是否安装：

lemon@ubuntu:~$ mysql #输入mysql，如出现以下提示，说明已安装mysql
ERROR 1045 (28000): Access denied for user 'lemon'@'localhost' (using password: NO)

如未安装：

lemon@ubuntu:~$ sudo apt-get install mysql-server
lemon@ubuntu:~$sudo apt isntall mysql-client
lemon@ubuntu:~$sudo apt install libmysqlclient-dev

如已安装：

lemon@ubuntu:~$ sudo mysql_secure_installation

两者都会进入MySQL设置过程，具体设置内容如下：

#1
VALIDATE PASSWORD PLUGIN can be used to test passwords...
Press y|Y for Yes, any other key for No: N(不启用弱密码检查）

#2
Please set the password for root here...
New password: (设置root密码)
Re-enter new password: (重复输入)

#3
By default, a MySQL installation has an anonymous user,
allowing anyone to log into MySQL without having to have
a user account created for them...
Remove anonymous users? (Press y|Y for Yes, any other key for No) : Y(不启用匿名用户)

#4
Normally, root should only be allowed to connect from
'localhost'. This ensures that someone cannot guess at
the root password from the network...
Disallow root login remotely? (Press y|Y for Yes, any other key for No) : Y (不允许root远程登陆)

#5
By default, MySQL comes with a database named 'test' that
anyone can access...
Remove test database and access to it? (Press y|Y for Yes, any other key for No) : N 

#6
Reloading the privilege tables will ensure that all changes
made so far will take effect immediately.
Reload privilege tables now? (Press y|Y for Yes, any other key for No) : Y (立刻刷新权限表)

All done!

接下来进入进入MySQL进行操作：

#最新版的MySQL安装之后无法使用密码进行登陆，需要sudo登录修改登录方式
lemon@ubuntu:~$ sudo mysql -uroot -p
Enter password: （空密码）
mysql>
mysql>UPDATE mysql.user SET authentication_string=PASSWORD('LEMON'), plugin='mysql_native_password' WHERE user='root';
mysql> FLUSH PRIVILEGES;
mysql>exit

lemon@ubuntu:~$ sudo service mysql restart
lemon@ubuntu:~$ mysql -u root -p
Enter password: （上一步设置的密码，PASSWORD括号内的）
mysql>CREATE DATABASE nutch;
mysql>USE nutch
mysql> CREATE TABLE `webpage` (
`id` varchar(767) NOT NULL,
`headers` blob,
`text` mediumtext DEFAULT NULL,
`status` int(11) DEFAULT NULL,
`markers` blob,
`parseStatus` blob,
`modifiedTime` bigint(20) DEFAULT NULL,
`score` float DEFAULT NULL,
`typ` varchar(32) CHARACTER SET latin1 DEFAULT NULL,
`baseUrl` varchar(767) DEFAULT NULL,
`content` longblob,
`title` varchar(2048) DEFAULT NULL,
`reprUrl` varchar(767) DEFAULT NULL,
`fetchInterval` int(11) DEFAULT NULL,
`prevFetchTime` bigint(20) DEFAULT NULL,
`inlinks` mediumblob,
`prevSignature` blob,
`outlinks` mediumblob,
`fetchTime` bigint(20) DEFAULT NULL,
`retriesSinceFetch` int(11) DEFAULT NULL,
`protocolStatus` blob,
`signature` blob,
`metadata` blob,
`batchId`varchar(767)DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB
ROW_FORMAT=COMPRESSED
DEFAULT CHARSET=utf8mb4;
mysql>exit

*最新版本默认情况下，MySQL是不允许远程登录的，如需远程访问需要做一些修改：

lemon@ubuntu:~$sudo vim /etc/mysql/mysql.conf.d/mysqld.cnf
#将bind-address = 127.0.0.1注释掉，重启MySQL服务
lemon@ubuntu:~$sudo service mysqld start

接下来就可以通过Navicat等软件，在其他计算机访问数据库了。