4.2 Initialization Parameters

Some servlets and filters require initialization parameters. The init-param element of a filter or servlet definition contains initialization parameters for that filter or servlet instance. Each init-param contains a param-name element and a param-value element. The servlet container does not interpret the contents of the param-name and param-value. However, the contents of these elements must be legal XML. If the web.xml file is in UTF-16, the servlet container transcodes the contents of the param-name and param-value to UTF-8.

For example, the web.xml snippet below defines two initialization parameters, greeting and fontsize.

<init-param>
  <param-name>greeting</param-name>
  <param-value>Hello, World!</param-value>
</init-param>
<init-param>
  <param-name>fontsize</param-name>
  <param-value>14</param-value>
</init-param>

An init-param element must appear within a servlet or filter definition (see Section 4.7 and Section 4.8). The web.xml fragment below is a full servlet definition containing the init-param elements above:

<servlet>
  <servlet-name>helloWorld</servlet-name>
  <servlet-class>hello.createHelloWorld</servlet-class>
  <init-param>
    <param-name>greeting</param-name>
    <param-value>Hello, World!</param-value>
  </init-param>
  <init-param>
    <param-name>fontsize</param-name>
    <param-value>14</param-value>
  </init-param>
</servlet>

If a definition contains two or more parameters with the same name, the container will present one param-value and ignore the others.

Section 6.8 describes the interface a servlet or filter uses to read initialization parameters.

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