根据阿里云的配置修改，另附阿里云提供的配置。

<?xml version="1.0" encoding="UTF-8"?>
<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0 http://maven.apache.org/xsd/settings-1.0.0.xsd">
  <localRepository>D:\maven\repository</localRepository>
  <!-- Nexus 镜像配置 -->
  <mirrors>
    <mirror>
      <id>nexus</id>
      <name>Nexus Repository Mirror</name>
      <mirrorOf>central,jcenter</mirrorOf>
      <url>http://ip:8081/repository/maven-public/</url>
      <blocked>false</blocked>
    </mirror>
  </mirrors>
  <!-- Nexus 认证配置 -->
<servers>
  <server>
    <id>nexus-releases</id>
    <username>admin</username>
    <password>Dfd152389</password>
  </server>
  <server>
    <id>nexus-snapshots</id>
    <username>admin</username>
    <password>admin123</password>
  </server>
</servers>

  <profiles>
    <profile>
      <id>rdc</id>
      <properties>
        <altDeploymentRepository>nexus-releases::default::http://ip:8081/repository/maven-releases/</altDeploymentRepository>
        <altSnapshotDeploymentRepository>nexus-snapshots::default::http://ip:8081/repository/maven-snapshots/</altSnapshotDeploymentRepository>
      </properties>
      <repositories>
        <repository>
          <id>nexus-releases</id>
          <url>http://ip:8081/repository/maven-public/</url>
          <releases>
            <enabled>true</enabled>
          </releases>
          <snapshots>
            <enabled>false</enabled>
          </snapshots>
        </repository>
        <repository>
          <id>nexus-snapshots</id>
          <url>http://ip:8081/repository/maven-public/</url>
          <releases>
            <enabled>false</enabled>
          </releases>
          <snapshots>
            <enabled>true</enabled>
          </snapshots>
        </repository>
      </repositories>
      <pluginRepositories>
        <pluginRepository>
          <id>central</id>
          <url>http://ip:8081/repository/maven-public/</url>
          <releases>
            <enabled>true</enabled>
          </releases>
          <snapshots>
            <enabled>false</enabled>
          </snapshots>
        </pluginRepository>
      </pluginRepositories>
    </profile>
  </profiles>
  <activeProfiles>
    <activeProfile>rdc</activeProfile>
  </activeProfiles>
</settings>

PS:阿里云提供配置

进入阿里云官网，点击生产库-release，左侧列表有个仓库指南，进去后可以看到Maven和Gradle的相关配置。