在Java类中使用ServletContext [英] Using ServletContext in java class

问题描述

我在 web.xml 中将数据保存为

I have the data in the web.xml as

<context-param>
      <param-name>vDriver</param-name>
      <param-value>com.mysql.jdbc.Driver</param-value>
     <!-- <description> ClassLoader of Driver </description>-->
 </context-param>

 <context-param>
      <param-name>vConnection</param-name>
      <param-value>jdbc:mysql://localhost:3306/cdr555</param-value>
<!--      <description> Connection to Database </description>-->
 </context-param>

 <context-param>
      <param-name>vConnectionA</param-name>
      <param-value>jdbc:mysql://localhost:3306/maindata</param-value>
<!--      <description> Connection to Database </description>-->
 </context-param>

 <context-param>
      <param-name>vConnectionB</param-name>
      <param-value>jdbc:mysql://localhost:3306/states_ap</param-value>
<!--      <description> Connection to Database </description>-->
 </context-param>

 <context-param>
      <param-name>vConnectionP</param-name>
      <param-value>jdbc:mysql://localhost:3306/personal</param-value>
<!--      <description> Connection to Database </description>-->
 </context-param>


 <context-param>
      <param-name>vUsername</param-name>
      <param-value>root</param-value>
<!--      <description> Username of Database </description>-->
 </context-param>

 <context-param>
      <param-name>vPassword</param-name>
      <param-value>sigma</param-value>
<!--      <description> Password of Database </description>-->
 </context-param>

现在，我想使用以下代码在Java类文件中访问这些值:

Now, I want to access these values in the java class file by using the code:

ServletContext sc =getServletConfig().getServletContext();
String vDriver = sc.getInitParameter("vDriver");
String vConnection = sc.getInitParameter("vConnection");
String vConnectionA = sc.getInitParameter("vConnectionA");
String vConnectionB = sc.getInitParameter("vConnectionB");
String vConnectionP = sc.getInitParameter("vConnectionP");
String vUsername = sc.getInitParameter("vUsername");
String vPassword = sc.getInitParameter("vPassword");

使用上面的代码，我正在检索值.但是值并没有出现，而是给出了空值.

请给答复. 非常紧急

Using above code, I am retriving the values. But the values are not coming instead of that it is giving null values.

Please give the reply. its very urgent

推荐答案

您尝试读取的参数是上下文参数，但是您正在使用，而是将其存储为init参数:

The parameters you''re trying to read are context parameters, but you''re reading them using getInitParameter, store them as init-parameters instead:

<init-param>
    <param-name>local-server-port</param-name>
    <param-value>4242</param-value>
</init-param

希望这会有所帮助，
弗雷德里克(Fredrik)

Hope this helps,
Fredrik

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