【SpringBoot】环境准备-编程知识

一.SpringBoot准备

1.下载idea

社区版 2021.1 - 2022.1.4

专业版无要求

2.Maven

是一个工具,和Java没有关系 .

主要功能是项目构建和依赖管理.

项目构建

上述对应的都是maven命令 .

依赖管理

添加坐标之后,点击刷新,右侧就会载入依赖.

Maven还有依赖传递和依赖排除功能.

依赖传递

比如要使用mysql依赖,mysql所需要的依赖protobuf -java的也会传递过来 .

依赖排除

如果不需要引入的依赖的依赖,可以手动的排除

使用场景: 为了解决冲突 . 如果项目中引入的多个相同但版本不一致的依赖. 就可以使用依赖排除删掉冲突的依赖.

安装插件:maven helper

在idea插件市场搜索安装.

依赖分析

仓库

1.中央仓库 (全球唯一)

仓库地址: Central Repository: (maven.org)

可以通过: https://mvnrepository.com 来查询并下载

2.本地仓库

项目所需要的依赖会先在本地仓库查找.

如果找到了直接获取.

如果找不到 , 本地仓库就会到中央仓库去下载,并且保存到本地仓库. 然后再返回给项目.

查看本地仓库地址

这个地址最好不要包括中文 .

修改本地仓库的地址

1.将原来默认的.m2文件夹一键复制到一个你想到存的地方.

2.点击override . 重新输入路径

3.私服

由于中央仓库的下载速度较慢 , 现在一些企业为了提高下载速度. 有自己的私有服务器 , 一般是企业的. 通常具有一定权限.

有了私服,如果项目需要引入依赖,仍然会先从本地仓库查找.

*如果找到了,就返回.

*如果没找到,就从私服查找.

* 如果从私服找到了,就返回给本地仓库, 再返回给项目.

(公司里只要有一个人下载了,其他人都可以从私服中访问了)

* 如果没找到,私服再去中央仓库下载. 如此一层层返回.

私服的配置

可以使用自己公司的私服

maven国内源有很多 , 这里使用的是阿里的私服.

如果没有settings文件,创建一个settings.xml 文件 , 写入以下内容

This XML file does not appear to have any style information associated with it. The document tree is shown below.
<!-- 
Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements.  See the NOTICE file
distributed with this work for additional information
regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License.  You may obtain a copy of the License athttp://www.apache.org/licenses/LICENSE-2.0Unless required by applicable law or agreed to in writing,
software distributed under the License is distributed on an
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
KIND, either express or implied.  See the License for the
specific language governing permissions and limitations
under the License.-->
<!-- | This is the configuration file for Maven. It can be specified at two levels:||  1. User Level. This settings.xml file provides configuration for a single user,|                 and is normally provided in ${user.home}/.m2/settings.xml.||                 NOTE: This location can be overridden with the CLI option:||                 -s /path/to/user/settings.xml||  2. Global Level. This settings.xml file provides configuration for all Maven|                 users on a machine (assuming they're all using the same Maven|                 installation). It's normally provided in|                 ${maven.conf}/settings.xml.||                 NOTE: This location can be overridden with the CLI option:||                 -gs /path/to/global/settings.xml|| The sections in this sample file are intended to give you a running start at| getting the most out of your Maven installation. Where appropriate, the default| values (values used when the setting is not specified) are provided.|| -->
<settings xmlns="http://maven.apache.org/SETTINGS/1.2.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.2.0 https://maven.apache.org/xsd/settings-1.2.0.xsd">
<!--  localRepository| The path to the local repository maven will use to store artifacts.|| Default: ${user.home}/.m2/repository<localRepository>/path/to/local/repo</localRepository>-->
<!--  interactiveMode| This will determine whether maven prompts you when it needs input. If set to false,| maven will use a sensible default value, perhaps based on some other setting, for| the parameter in question.|| Default: true<interactiveMode>true</interactiveMode>-->
<!--  offline| Determines whether maven should attempt to connect to the network when executing a build.| This will have an effect on artifact downloads, artifact deployment, and others.|| Default: false<offline>false</offline>-->
<!--  pluginGroups| This is a list of additional group identifiers that will be searched when resolving plugins by their prefix, i.e.| when invoking a command line like "mvn prefix:goal". Maven will automatically add the group identifiers| "org.apache.maven.plugins" and "org.codehaus.mojo" if these are not already contained in the list.| -->
<pluginGroups>
<!--  pluginGroup| Specifies a further group identifier to use for plugin lookup.<pluginGroup>com.your.plugins</pluginGroup>-->
</pluginGroups>
<!--  proxies| This is a list of proxies which can be used on this machine to connect to the network.| Unless otherwise specified (by system property or command-line switch), the first proxy| specification in this list marked as active will be used.| -->
<proxies>
<!--  proxy| Specification for one proxy, to be used in connecting to the network.|<proxy><id>optional</id><active>true</active><protocol>http</protocol><username>proxyuser</username><password>proxypass</password><host>proxy.host.net</host><port>80</port><nonProxyHosts>local.net|some.host.com</nonProxyHosts></proxy>-->
</proxies>
<!--  servers| This is a list of authentication profiles, keyed by the server-id used within the system.| Authentication profiles can be used whenever maven must make a connection to a remote server.| -->
<servers>
<!--  server| Specifies the authentication information to use when connecting to a particular server, identified by| a unique name within the system (referred to by the 'id' attribute below).|| NOTE: You should either specify username/password OR privateKey/passphrase, since these pairings are|       used together.|<server><id>deploymentRepo</id><username>repouser</username><password>repopwd</password></server>-->
<!--  Another sample, using keys to authenticate.<server><id>siteServer</id><privateKey>/path/to/private/key</privateKey><passphrase>optional; leave empty if not used.</passphrase></server>-->
</servers>
<!--  mirrors| This is a list of mirrors to be used in downloading artifacts from remote repositories.|| It works like this: a POM may declare a repository to use in resolving certain artifacts.| However, this repository may have problems with heavy traffic at times, so people have mirrored| it to several places.|| That repository definition will have a unique id, so we can create a mirror reference for that| repository, to be used as an alternate download site. The mirror site will be the preferred| server for that repository.| -->
<mirrors>
<!--  mirror| Specifies a repository mirror site to use instead of a given repository. The repository that| this mirror serves has an ID that matches the mirrorOf element of this mirror. IDs are used| for inheritance and direct lookup purposes, and must be unique across the set of mirrors.|<mirror><id>mirrorId</id><mirrorOf>repositoryId</mirrorOf><name>Human Readable Name for this Mirror.</name><url>http://my.repository.com/repo/path</url></mirror>-->
<mirror>
<id>aliyunmaven</id>
<mirrorOf>*</mirrorOf>
<name>阿里云公共仓库</name>
<url>https://maven.aliyun.com/repository/public</url>
</mirror>
</mirrors>
<!--  profiles| This is a list of profiles which can be activated in a variety of ways, and which can modify| the build process. Profiles provided in the settings.xml are intended to provide local machine-| specific paths and repository locations which allow the build to work in the local environment.|| For example, if you have an integration testing plugin - like cactus - that needs to know where| your Tomcat instance is installed, you can provide a variable here such that the variable is| dereferenced during the build process to configure the cactus plugin.|| As noted above, profiles can be activated in a variety of ways. One way - the activeProfiles| section of this document (settings.xml) - will be discussed later. Another way essentially| relies on the detection of a system property, either matching a particular value for the property,| or merely testing its existence. Profiles can also be activated by JDK version prefix, where a| value of '1.4' might activate a profile when the build is executed on a JDK version of '1.4.2_07'.| Finally, the list of active profiles can be specified directly from the command line.|| NOTE: For profiles defined in the settings.xml, you are restricted to specifying only artifact|       repositories, plugin repositories, and free-form properties to be used as configuration|       variables for plugins in the POM.|| -->
<profiles>
<!--  profile| Specifies a set of introductions to the build process, to be activated using one or more of the| mechanisms described above. For inheritance purposes, and to activate profiles via <activatedProfiles/>| or the command line, profiles have to have an ID that is unique.|| An encouraged best practice for profile identification is to use a consistent naming convention| for profiles, such as 'env-dev', 'env-test', 'env-production', 'user-jdcasey', 'user-brett', etc.| This will make it more intuitive to understand what the set of introduced profiles is attempting| to accomplish, particularly when you only have a list of profile id's for debug.|| This profile example uses the JDK version to trigger activation, and provides a JDK-specific repo.<profile><id>jdk-1.4</id><activation><jdk>1.4</jdk></activation><repositories><repository><id>jdk14</id><name>Repository for JDK 1.4 builds</name><url>http://www.myhost.com/maven/jdk14</url><layout>default</layout><snapshotPolicy>always</snapshotPolicy></repository></repositories></profile>-->
<!-- | Here is another profile, activated by the system property 'target-env' with a value of 'dev',| which provides a specific path to the Tomcat instance. To use this, your plugin configuration| might hypothetically look like:|| ...| <plugin>|   <groupId>org.myco.myplugins</groupId>|   <artifactId>myplugin</artifactId>||   <configuration>|     <tomcatLocation>${tomcatPath}</tomcatLocation>|   </configuration>| </plugin>| ...|| NOTE: If you just wanted to inject this configuration whenever someone set 'target-env' to|       anything, you could just leave off the <value/> inside the activation-property.|<profile><id>env-dev</id><activation><property><name>target-env</name><value>dev</value></property></activation><properties><tomcatPath>/path/to/tomcat/instance</tomcatPath></properties></profile>-->
</profiles>
<!--  activeProfiles| List of profiles that are active for all builds.|<activeProfiles><activeProfile>alwaysActiveProfile</activeProfile><activeProfile>anotherAlwaysActiveProfile</activeProfile></activeProfiles>-->
</settings>

如果有,就修改settings文件.