使用maven导入jar包

我们都经历过自己写代码时有时就要引用一些第三方的jar包，这个我们都会，但在公司里进行团队开发时，是不允许我们自己导入jar包的，是由项目组长之类的统一导入jar包，我们在这里来了解一下这个过程：
a、先创建一个maven工程，在pom.xml中有这样一段代码：

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.jd</groupId><artifactId>dddmaven</artifactId><packaging>war</packaging><version>0.0.1-SNAPSHOT</version><name>dddmaven Maven Webapp</name><url>http://maven.apache.org</url><dependencies></dependencies>
</project>

b、然后我们就在<dependencies></dependencies>中间添加相应的jar包的坐标<dependency></dependency>即可
其中jar包的坐标可以在这个网站上去找Maven Repository:Search/Browse/Explore

在这里写几个常用的jar包的坐标：

Junit:Test测试

    <dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>3.8.1</version><scope>test</scope></dependency>

Servlet:前端控制器

    <dependency><groupId>javax.servlet</groupId><artifactId>javax.servlet-api</artifactId><version>3.1.0</version><scope>provided</scope></dependency>

log4j:异常收集

 <dependency><groupId>log4j</groupId><artifactId>log4j</artifactId><version>1.2.17</version></dependency>

slf4j：

 <dependency><groupId>org.slf4j</groupId><artifactId>slf4j-api</artifactId><version>1.6.4</version></dependency>

slf4j-log4j12:

 <dependency><groupId>org.slf4j</groupId><artifactId>slf4j-log4j12</artifactId><version>1.6.4</version><scope>test</scope></dependency>

如果用slf4j-log4j12出现以下情况：

则在pom.xml里插入以下配置：

 <dependency><groupId>org.slf4j</groupId><artifactId>slf4j-nop</artifactId><version>1.7.2</version></dependency>

mysql:驱动

 <dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>5.1.38</version></dependency>

c、还有就是有些maven工程的版本较低（可能是1.5），可以升级到1.8，也是在pom.xml中最后（</project>之前）添加一些配置信息：

 <profiles><profile>   <id>jdk1.8</id>    <activation>   <activeByDefault>true</activeByDefault>    <jdk>1.8</jdk>   </activation>    <properties>   <maven.compiler.source>1.8</maven.compiler.source>    <maven.compiler.target>1.8</maven.compiler.target>    <maven.compiler.compilerVersion>1.8</maven.compiler.compilerVersion>   </properties>   </profile></profiles>

然后再升级一下就可以了：

或者在<build></build>里加一下东西：

<plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><configuration><source>1.8</source><target>1.8</target></configuration></plugin></plugins>

然后升级maven项目就可以了
补充：

验证码(patchca)：

<!-- https://mvnrepository.com/artifact/net.pusuo/patchca -->
<dependency><groupId>net.pusuo</groupId><artifactId>patchca</artifactId><version>0.5.0</version>
</dependency>

Gson：

<dependency><groupId>com.google.code.gson</groupId><artifactId>gson</artifactId><version>2.8.4</version>
</dependency>

jstl & taglibs：

 <dependency><groupId>jstl</groupId><artifactId>jstl</artifactId><version>1.2</version></dependency><dependency><groupId>taglibs</groupId><artifactId>standard</artifactId><version>1.1.2</version></dependency>

上传文件：

    <dependency><groupId>commons-io</groupId><artifactId>commons-io</artifactId><version>2.4</version></dependency><dependency><groupId>commons-fileupload</groupId><artifactId>commons-fileupload</artifactId><version>1.3.1</version></dependency>

jsp:

 <dependency><groupId>javax.servlet</groupId><artifactId>jsp-api</artifactId><version>2.0</version><scope>provided</scope></dependency>

Spring框架：

 <!-- spring3 --><dependency><groupId>org.springframework</groupId><artifactId>spring-core</artifactId><version>3.1.2.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>3.1.2.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-beans</artifactId><version>3.1.2.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-expression</artifactId><version>3.1.2.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-web</artifactId><version>4.3.10.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-webmvc</artifactId><version>4.3.10.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-web</artifactId><version>3.1.2.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-expression</artifactId><version>3.1.2.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-orm</artifactId><version>3.1.2.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-jdbc</artifactId><version>3.1.2.RELEASE</version></dependency>

Jackson（用于将字符串转换成json格式，为了兼顾低版本浏览器）：

 <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind --><dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-databind</artifactId><version>2.6.3</version></dependency>