net.sf.json.JSONException: JSONO
从小程序端获取openId时，出现这样的错误net.sf.json.JSONException: JSONObject[“openId”] not found
原因：找不到openId，因为没有从小程序端获取到openId
解决办法：可在获取openId前进行判断，若没有找到openId，就设置默认值
//判断是否获取到openId
if (!json.has("openId")){
json.put("openId", "");
}
获取值的代码：
JSONObject json = AcceptUtil.acceptFile(request);
//判断是否获取到openId
if (!json.has("openId")){
json.put("openId", "");
}
String openId = json.getString("openId");
报错信息：
net.sf.json.JSONException: JSONObject[“openId”] not found.
at net.sf.json.JSONObject.get(JSONObject.java:1228)
at net.sf.json.JSONObject.getString(JSONObject.java:1353)
at servlet.weixin.History.doPost(History.java:41)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:650)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at filter.EncodeFilter.doFilter(EncodeFilter.java:37)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:218)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:110)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:506)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:962)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:452)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1087)
at org.apache.coyote.AbstractProtocolAbstractConnectionHandler.process(AbstractProtocol.java:637)atorg.apache.tomcat.util.net.AprEndpointAbstractConnectionHandler.process(AbstractProtocol.java:637)atorg.apache.tomcat.util.net.AprEndpointSocketProcessor.doRun(AprEndpoint.java:2536)
at org.apache.tomcat.util.net.AprEndpointSocketProcessor.run(AprEndpoint.java:2525)atjava.util.concurrent.ThreadPoolExecutor.runWorker(UnknownSource)atjava.util.concurrent.ThreadPoolExecutorSocketProcessor.run(AprEndpoint.java:2525)atjava.util.concurrent.ThreadPoolExecutor.runWorker(UnknownSource)atjava.util.concurrent.ThreadPoolExecutorWorker.run(Unknown Source)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Unknown Source)
