Servlet encoding globally using maven + guice

Question

In my project, I'm using Maven + Google Guice + Java 8, and I checked that my webpage responses were not encoded and the problem is from the backend side.

The solution I found to fix it was to update the HttpServletResponse:

@Override
public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
...
resp.setContentType("text/html; charset=UTF-8");
resp.setCharacterEncoding("UTF-8");
}

But I would like to configure it globally and not only for one Servlet, to do it I tried what they explained here adding encoding to the pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <groupId>YOUR_COMPANY</groupId>
    <artifactId>YOUR_APP</artifactId>
    <version>1.0.0-SNAPSHOT</version>

    <properties>
        <project.java.version>1.8</project.java.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    </properties>

    <dependencies>
        <!-- Your dependencies -->
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.7.0</version>
                <configuration>
                    <source>${project.java.version}</source>
                    <target>${project.java.version}</target>
                    <encoding>${project.build.sourceEncoding}</encoding>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-resources-plugin</artifactId>
                <version>3.0.2</version>
                <configuration>
                    <encoding>${project.build.sourceEncoding}</encoding>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

But it didn't work. Could someone help with it? Configuring it globally in my project?

Answer 1

Firstly, thank you @Robert for your answer and help.

As he pointed out:

The maven configuration only affects how strings present in your source code are read and written into the class files. You can't configure a servlet response encoding this way.

To solve it using Guice, we need to create a filter in our ServletModule as we can find in the documentation.

I did it adding the filter to configureServlets():

filter("/*").through(createServletFilter());

And the filter create was:

protected Filter createServletFilter() {
 return new Filter() {
   @Override
   public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
       throws IOException, ServletException {
     response.setContentType("text/html; charset=UTF-8");
     response.setCharacterEncoding("UTF-8");
     chain.doFilter(request, response);
   }

   @Override
   public void init(FilterConfig filterConfig) throws ServletException {}

   @Override
   public void destroy() {}
 };
}