getinit.html

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<TITLE>Getting and Setting Initialization Parameters for a Servlet
(Java Developers Almanac Example)
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  <h3>
    e1035.  
    Getting and Setting Initialization Parameters for a Servlet</h3>

The servlet container supports the ability to store startup and
configuration information for a servlet. After the container
instantiates the servlet, it makes this information available to the
servlet instance.  This example demonstrates a servlet that retrieves
some initialization parameters in its <code>init()</code> method:


<pre>
    // See also <a href="../javax.servlet/com_mycompany_MyServlet.html" class="eglink"><font size="-1"><b>e1034</b> The Quintessential Servlet</font></a>
    
    // This method is called by the servlet container just before this servlet
    // is put into service.
    public void init() throws ServletException {
        getServletContext().log("getinit init");
        // Get the value of an initialization parameter
        String value = getServletConfig().getInitParameter(<font color="#0066ff"><i>"param1"</i></font>);
    
        // Get all available intialization parameters
        java.util.Enumeration enum = getServletConfig().getInitParameterNames();
        for (; enum.hasMoreElements(); ) {
            // Get the name of the init parameter
            String name = (String)enum.nextElement();
    
            // Get the value of the init parameter
            value = getServletConfig().getInitParameter(name);
        }
    
    
        // The int parameters can also be retrieved using the servlet context
        value = getServletContext().getInitParameter(<font color="#0066ff"><i>"param1"</i></font>);
    }
</pre>

The initialization parameters for the servlet are specified in the
deployment descriptor (i.e. web.xml file). Here is an example of a
deployment descriptor that specifies two initialization parameters:


<pre>
    &lt;web-app&gt;
        &lt;servlet&gt;
            &lt;servlet-name&gt;<font color="#0066ff"><i>MyServletName</i></font>&lt;/servlet-name&gt;
            &lt;servlet-class&gt;<font color="#0066ff"><i>com.mycompany.MyServlet</i></font>&lt;/servlet-class&gt;
    
            &lt;init-param&gt;
                &lt;param-name&gt; <font color="#0066ff"><i>param1</i></font> &lt;/param-name&gt;
                &lt;param-value&gt; <font color="#0066ff"><i>value1</i></font> &lt;/param-value&gt;
            &lt;/init-param&gt;
            &lt;init-param&gt;
                &lt;param-name&gt; <font color="#0066ff"><i>param2</i></font> &lt;/param-name&gt;
                &lt;param-value&gt; <font color="#0066ff"><i>value2</i></font> &lt;/param-value&gt;
            &lt;/init-param&gt;
            ...
        &lt;/servlet&gt;
        ...
    &lt;/web-app&gt;
</pre>

Note that the leading and trailing space around the parameter value is
trimmed.


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            &nbsp;Related Examples
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e1034. <a class="eglink" href="com_mycompany_MyServlet.html?l=rel">
    The Quintessential Servlet
</a>
<br>

e1036. <a class="eglink" href="GetImage.html?l=rel">
    Returning an Image in a Servlet
</a>
<br>

e1037. <a class="eglink" href="State.html?l=rel">
    Saving Data in a Servlet
</a>
<br>

e1038. <a class="eglink" href="Log.html?l=rel">
    Logging a Message in a Servlet
</a>
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