解决eclipse安装maven的问题:Unable to update index for central|http://repo1.maven.org/maven2

copy一个settings.xml到C:/Documents and Settings/username/.m2目录，并修改settings.xml文件，添加一个http代理:

  <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>
    -->
    <proxy>
      <id>optional</id>
      <active>true</active>
      <protocol>http</protocol>
      <host>www.yourproxy.com</host>
      <port>8080</port>
    </proxy>
  </proxies>

然后，重启就可以了。