How to Handle UTF-8 Encoding for Servlet Form Submissions in Tomcat

How can I ensure that my servlet correctly handles UTF-8 encoded form submissions in Tomcat?

request.setCharacterEncoding("UTF-8");

When dealing with form submissions in servlets hosted on Tomcat, it's crucial to handle character encoding correctly to avoid issues with special characters. This guide explains how to ensure that your servlet can properly process UTF-8 encoded form data.

<form action="/submit" method="post" accept-charset="UTF-8">
    <input type="text" name="name" />
    <input type="submit" value="Submit" />
</form>

Causes

• Incorrect encoding on submission forms.
• Tomcat's default encoding is not set to UTF-8.
• Lack of 'setCharacterEncoding' in servlet.
• HTML form doesn't specify the character set.

Solutions

• Add `request.setCharacterEncoding("UTF-8");` in the servlet to process UTF-8 data.
• Set the correct content type in HTML forms: `<form accept-charset="UTF-8">`.
• Configure the Tomcat `server.xml` file to set `URIEncoding="UTF-8"` under the `<Connector>` element.

Mistake: Not calling `setCharacterEncoding` before reading request parameters.

Solution: Always call `request.setCharacterEncoding("UTF-8");` before accessing request parameters.

Mistake: Forgetting to set `accept-charset` in the form.

Solution: Add the attribute `accept-charset="UTF-8"` to the form element.

Mistake: Not configuring Tomcat for UTF-8 encoding at server level.

Solution: Update the Tomcat `server.xml` to have `URIEncoding="UTF-8"` in the `<Connector>`.