解决java.lang.NoClassDefFoundError: org/apache/log4j/Level

现象：

java.lang.NoClassDefFoundError: org/apache/log4j/Level

    at org.slf4j.LoggerFactory.getSingleton(LoggerFactory.java:)

    at org.slf4j.LoggerFactory.bind(LoggerFactory.java:)

    at org.slf4j.LoggerFactory.performInitialization(LoggerFactory.java:)

    at org.slf4j.LoggerFactory.getILoggerFactory(LoggerFactory.java:)

    at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:)

    at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:)

    at HttpUtils2.<clinit>(HttpUtils2.java:)

原因其实是缺少log4j相关的jar，在classpath中加入log4j-1.2.14.jar即可解决问题。