269 lines
9.0 KiB
Markdown
269 lines
9.0 KiB
Markdown
# 如何在 windows环境下使用jdbc进行TDengine应用开发
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本文以windows环境为例，介绍java如何进行TDengine开发应用
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## 环境准备
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（1）安装jdk
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官网下载jdk-1.8，下载页面：https://www.oracle.com/java/technologies/javase/javase-jdk8-downloads.html
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安装，配置环境变量，把jdk加入到环境变量里。
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命令行内查看java的版本。
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```shell
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>java -version
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java version "1.8.0_131"
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Java(TM) SE Runtime Environment (build 1.8.0_131-b11)
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Java HotSpot(TM) 64-Bit Server VM (build 25.131-b11, mixed mode)
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```
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（2）安装配置maven
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官网下载maven，下载地址：http://maven.apache.org/download.cgi
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配置环境变量MAVEN_HOME，将MAVEN_HOME/bin添加到PATH
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命令行里查看maven的版本
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```shell
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>mvn --version
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Apache Maven 3.5.0 (ff8f5e7444045639af65f6095c62210b5713f426; 2017-04-04T03:39:06+08:00)
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Maven home: D:\apache-maven-3.5.0\bin\..
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Java version: 1.8.0_131, vendor: Oracle Corporation
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Java home: C:\Program Files\Java\jdk1.8.0_131\jre
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Default locale: zh_CN, platform encoding: GBK
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OS name: "windows 10", version: "10.0", arch: "amd64", family: "windows"
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```
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为了加快maven下载依赖的速度，可以为maven配置mirror，修改MAVEN_HOME\config\settings.xml文件
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```xml
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<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0"
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0 http://maven.apache.org/xsd/settings-1.0.0.xsd">
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<!-- 配置本地maven仓库的路径 -->
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<localRepository>D:\apache-maven-localRepository</localRepository>
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<mirrors>
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<!-- 配置阿里云Maven镜像仓库 -->
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<mirror>
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<id>alimaven</id>
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<name>aliyun maven</name>
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<url>http://maven.aliyun.com/nexus/content/groups/public/</url>
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<mirrorOf>central</mirrorOf>
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</mirror>
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</mirrors>
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<profiles>
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<!-- 配置jdk，maven会默认使用java1.8 -->
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<profile>
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<id>jdk-1.8</id>
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<activation>
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<activeByDefault>true</activeByDefault>
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<jdk>1.8</jdk>
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</activation>
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<properties>
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<maven.compiler.source>1.8</maven.compiler.source>
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<maven.compiler.target>1.8</maven.compiler.target>
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<maven.compiler.compilerVersion>1.8</maven.compiler.compilerVersion>
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</properties>
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</profile>
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</profiles>
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</settings>
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```
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（3）在linux服务器上安装TDengine-server
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在taosdata官网下载TDengine-server，下载地址：https://www.taosdata.com/cn/all-downloads/
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在linux服务器上安装TDengine-server
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```shell
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# tar -zxvf package/TDengine-server-2.0.1.1-Linux-x64.tar.gz
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# cd TDengine-server/
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# ./install.sh
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```
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启动taosd
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```shell
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# systemctl start taosd
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```
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在server上用taos连接taosd
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```shell
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# taos
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taos> show dnodes;
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id | end_point | vnodes | cores | status | role | create_time |
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==================================================================================================================
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1 | td01:6030 | 2 | 4 | ready | any | 2020-08-19 18:40:25.045 |
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Query OK, 1 row(s) in set (0.005765s)
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```
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如果可以正确连接到taosd实例，并打印出databases的信息，说明TDengine的server已经正确启动。这里查看server的hostname
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```shell
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# hostname -f
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td01
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```
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注意，如果安装TDengine后，使用默认的taos.cfg配置文件，taosd会使用当前server的hostname创建dnode实例。之后，在client也需要使用这个hostname来连接taosd。
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（4）在windows上安装TDengine-client
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在taosdata官网下载taos客户端，下载地址：
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https://www.taosdata.com/cn/all-downloads/
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下载后，双击exe安装。
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修改client的hosts文件（C:\Windows\System32\drivers\etc\hosts），将server的hostname和ip配置到client的hosts文件中
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```
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192.168.236.136 td01
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```
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配置完成后，在命令行内使用TDengine CLI连接server端
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```shell
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C:\TDengine>taos -h td01
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Welcome to the TDengine shell from Linux, Client Version:2.0.1.1
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Copyright (c) 2017 by TAOS Data, Inc. All rights reserved.
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taos> show databases;
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name | created_time | ntables | vgroups | replica | quorum | days | keep0,keep1,keep(D) | cache(MB) | blocks | minrows | maxrows | wallevel | fsync | comp | precision | status |
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===================================================================================================================================================================================================================================================================
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test | 2020-08-19 18:43:50.731 | 1 | 1 | 1 | 1 | 2 | 3650,3650,3650 | 16 | 6 | 100 | 4096 | 1 | 3000 | 2 | ms | ready |
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log | 2020-08-19 18:40:28.064 | 4 | 1 | 1 | 1 | 10 | 30,30,30 | 1 | 3 | 100 | 4096 | 1 | 3000 | 2 | us | ready |
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Query OK, 2 row(s) in set (0.068000s)
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```
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如果windows上的client能够正常连接，并打印database信息，说明client可以正常连接server了。
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## 应用开发
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（1）新建maven工程，在pom.xml中引入taos-jdbcdriver依赖。
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```xml
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<?xml version="1.0" encoding="UTF-8"?>
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<project xmlns="http://maven.apache.org/POM/4.0.0"
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
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<modelVersion>4.0.0</modelVersion>
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<groupId>com.taosdata.demo</groupId>
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<artifactId>JdbcDemo</artifactId>
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<version>1.0-SNAPSHOT</version>
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<dependencies>
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<dependency>
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<groupId>com.taosdata.jdbc</groupId>
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<artifactId>taos-jdbcdriver</artifactId>
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<version>2.0.8</version>
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</dependency>
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</dependencies>
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</project>
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```
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（2）使用jdbc查询TDengine数据库
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下面是示例代码：
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```java
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public class JdbcDemo {
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public static void main(String[] args) throws Exception {
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Connection conn = getConn();
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Statement stmt = conn.createStatement();
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// create database
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stmt.executeUpdate("create database if not exists db");
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// use database
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stmt.executeUpdate("use db");
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// create table
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stmt.executeUpdate("create table if not exists tb (ts timestamp, temperature int, humidity float)");
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// insert data
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int affectedRows = stmt.executeUpdate("insert into tb values(now, 23, 10.3) (now + 1s, 20, 9.3)");
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System.out.println("insert " + affectedRows + " rows.");
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// query data
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ResultSet resultSet = stmt.executeQuery("select * from tb");
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Timestamp ts = null;
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int temperature = 0;
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float humidity = 0;
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while(resultSet.next()){
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ts = resultSet.getTimestamp(1);
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temperature = resultSet.getInt(2);
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humidity = resultSet.getFloat("humidity");
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System.out.printf("%s, %d, %s\n", ts, temperature, humidity);
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}
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}
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public static Connection getConn() throws Exception{
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Class.forName("com.taosdata.jdbc.TSDBDriver");
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String jdbcUrl = "jdbc:TAOS://td01:0/log?user=root&password=taosdata";
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Properties connProps = new Properties();
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connProps.setProperty(TSDBDriver.PROPERTY_KEY_CHARSET, "UTF-8");
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connProps.setProperty(TSDBDriver.PROPERTY_KEY_LOCALE, "en_US.UTF-8");
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connProps.setProperty(TSDBDriver.PROPERTY_KEY_TIME_ZONE, "UTC-8");
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Connection conn = DriverManager.getConnection(jdbcUrl, connProps);
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return conn;
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}
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}
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```
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（3）测试jdbc访问tdengine的sever实例
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console输出：
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```
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insert 2 rows.
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2020-08-26 00:06:34.575, 23, 10.3
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2020-08-26 00:06:35.575, 20, 9.3
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```
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## 指南
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（1）如何设置主机名和hosts
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在server上查看hostname和fqdn
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```shell
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查看hostname
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# hostname
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taos-server
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查看fqdn
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# hostname -f
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taos-server
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```
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windows下hosts文件位于：
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C:\\Windows\System32\drivers\etc\hosts
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修改hosts文件，添加server的ip和hostname
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```s
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192.168.56.101 node5
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```
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（2）什么是fqdn？
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> 什么是FQDN？
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>
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> FQDN（Full qualified domain name）全限定域名，fqdn由2部分组成：hostname+domainname。
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>
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> 例如，一个邮件服务器的fqdn可能是：mymail.somecollege.edu，其中mymail是hostname（主机名），somcollege.edu是domainname（域名）。本例中，.edu是顶级域名，.somecollege是二级域名。
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>
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> 当连接服务器时，必须指定fqdn，然后，dns服务器通过查看dns表，将hostname解析为相应的ip地址。如果只指定hostname（不指定domainname），应用程序可能服务解析主机名。因为如果你试图访问不在本地的远程服务器时，本地的dns服务器和可能没有远程服务器的hostname列表。
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>
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> 参考：https://kb.iu.edu/d/aiuv
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