How to Properly Configure UTF-8 Encoding in Java Web Applications?

How to Enable UTF-8 in Java Web Applications

Overview

To support diverse character sets like Finnish (äöå) and Cyrillic (ЦжФ), enabling UTF-8 in Java web applications is crucial. This article provides step-by-step instructions for configuring Tomcat, database, and other components to ensure proper UTF-8 handling.

Tomcat Configuration

1. Configure server.xml for UTF-8 Encoding:

   <Connector URIEncoding="UTF-8" ... />

2. Add CharacterSetFilter:

   public class CharsetFilter implements Filter {
       ...
       if (null == request.getCharacterEncoding()) {
           request.setCharacterEncoding("UTF-8");
       }
       ...
   }

3. Add CharsetFilter to web.xml:

   <filter>
       <filter-name>CharsetFilter</filter-name>
       <filter-class>fi.foo.filters.CharsetFilter</filter-class>
       ...
   </filter>
   
   <filter-mapping>
       <filter-name>CharsetFilter</filter-name>
       <url-pattern>/*</url-pattern>
   </filter-mapping>

JSP and HTML

1. Configure Web.xml for JSP Encoding:

   <jsp-config>
       <jsp-property-group>
           <page-encoding>UTF-8</page-encoding>
       </jsp-property-group>
   </jsp-config>

2. Declare Page Encoding in JSP:

   <%@page pageEncoding="UTF-8" contentType="text/html; charset=UTF-8"%>

3. Add HTML Meta Tag:

   <meta http-equiv='Content-Type' content='text/html; charset=UTF-8' />

JDBC Connection

1. Configure JDBC Datasource with UTF-8 Encoding:

   <Resource>
       ...
       url="jdbc:mysql://...useEncoding=true&amp;characterEncoding=UTF-8"...
   </Resource>

MySQL Configuration

1. Create UTF-8 Database:

   CREATE DATABASE ... CHARSET=utf8 ...

2. Create UTF-8 Tables:

   CREATE TABLE ... CHARSET=utf8 COLLATE=utf8_swedish_ci ...

3. Configure MySQL Server for UTF-8:

   [mysql]
   default-character-set=utf8

Functions and Procedures

1. Declare Functions and Procedures with UTF-8 Character Set:

   CREATE FUNCTION `pathToNode` RETURNS TEXT CHARACTER SET utf8 ...

Handling GET Requests

1. Consider Latin1 Encoding in URLs:
   Browsers may encode URLs in Latin1, which affects GET parameters.

Important Note

MySQL supports UTF-8 with 3-byte characters. For extended character sets, consider using utf8mb4 (requires MySQL 5.5.3 or later) or VARBINARY columns.

Tomcat with Apache

If using Apache Tomcat mod_JK connector:

1. Enable UTF-8 in Tomcat's server.xml:

   <Connector ... URIEncoding="UTF-8" ... />

2. Set Apache Default Charset:

   AddDefaultCharset utf-8

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