Exception in thread "main" java.lang.RuntimeException: java.lang.RuntimeException: ognl.OgnlException: source is null for getProperty(null, "showapi_res_body")

at com.imooc.weather.impl.WeatherUtilsImpl.w24h(WeatherUtilsImpl.java:82)

at com.imooc.weather.Application.main(Application.java:39)

Caused by: java.lang.RuntimeException: ognl.OgnlException: source is null for getProperty(null, "showapi_res_body")

at com.imooc.weather.impl.WeatherUtilsImpl.getValue(WeatherUtilsImpl.java:34)

at com.imooc.weather.impl.WeatherUtilsImpl.w24h(WeatherUtilsImpl.java:63)

... 1 more

Caused by: ognl.OgnlException: source is null for getProperty(null, "showapi_res_body")

at ognl.OgnlRuntime.getProperty(OgnlRuntime.java:2410)

at ognl.ASTProperty.getValueBody(ASTProperty.java:114)

at ognl.SimpleNode.evaluateGetValueBody(SimpleNode.java:212)

at ognl.SimpleNode.getValue(SimpleNode.java:258)

at ognl.ASTChain.getValueBody(ASTChain.java:141)

at ognl.SimpleNode.evaluateGetValueBody(SimpleNode.java:212)

at ognl.SimpleNode.getValue(SimpleNode.java:258)

at ognl.Ognl.getValue(Ognl.java:467)

at ognl.Ognl.getValue(Ognl.java:569)

at ognl.Ognl.getValue(Ognl.java:539)

at com.imooc.weather.impl.WeatherUtilsImpl.getValue(WeatherUtilsImpl.java:31)

... 2 more

 这是怎么回事？