How to configure encoding in Maven

Question

When I run maven install on my multi module maven project I always get the following output    WARNING  File encoding has not been set  using platform encoding UTF-8  i e  build is platform dependent    So  I googled around a bit  but all I can find is that I have to add    lt properties gt       lt project build sourceEncoding gt UTF-8 lt  project build sourceEncoding gt   lt  properties gt       to my pom xml  But it s already there  in the parent pom xml    Configuring  lt encoding gt  for the maven-resources-plugin or the maven-compiler-plugin also doesn t fix it    So what s the problem

User · Answer

It seems people mix a content encoding with a built files/resources encoding. Having only maven properties is not enough. Having -Dfile.encoding=UTF8 not effective. To avoid having issues with encoding you should follow the following simple rules

Set maven encoding, as described above:

<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>

Always set encoding explicitly, when work with files, strings, IO in your code. If you do not follow this rule, your application depend on the environment. The -Dfile.encoding=UTF8 exactly is responsible for run-time environment configuration, but we should not depend on it. If you have thousands of clients, it takes more effort to configure systems and to find issues because of it. You just have an additional dependency on it which you can avoid by setting it explicitly. Most methods in Java that use a default encoding are marked as deprecated because of it.
Make sure the content, you are working with, also is in the same encoding, that you expect. If it is not, the previous steps do not matter! For instance a file will not be processed correctly, if its encoding is not UTF8 but you expect it. To check file encoding on Linux:

$ file --mime F_PRDAUFT.dsv

Force clients/server set encoding explicitly in requests/responses, here are examples:

@Produces("application/json; charset=UTF-8")
@Consumes("application/json; charset=UTF-8")

Hope this will be useful to someone.

User · Answer

Try this    lt project gt           lt build gt       lt plugins gt         lt plugin gt           lt groupId gt org apache maven plugins lt  groupId gt           lt artifactId gt maven-resources-plugin lt  artifactId gt           lt version gt 2 7 lt  version gt           lt configuration gt                           lt encoding gt UTF-8 lt  encoding gt                         lt  configuration gt         lt  plugin gt       lt  plugins gt             lt  build gt         lt  project gt

User · Answer

This would be in addition to previous  if someone meets a problem with scandic letters that isn t solved with the solution above   If the java source files contain scandic letters they need to be interpreted correctly by the Java used for compiling   e g  scandic letters used in constants   Even that the files are stored in UTF-8 and the Maven is configured to use UTF-8  the System Java used by the Maven will still use the system default  eg  in Windows  cp1252    This will be visible only running the tests via maven  possibly printing the values of these constants in tests  The printed scandic letters would show as   lt       If not tested properly  this would corrupt the class files as compile result and be left unnoticed   To prevent this  you have to set the Java used for compiling to use UTF-8 encoding  It is not enough to have the encoding settings in the maven pom xml  you need to set the environment variable  JAVA TOOL OPTIONS   -Dfile encoding UTF8  Also  if using Eclipse in Windows  you may need to set the encoding used in addition to this  if you run individual test via eclipse

User · Answer

OK  I have found the problem  I use some reporting plugins  In the documentation of the failsafe-maven-plugin I found  that the  lt encoding gt  configuration - of course - uses   project reporting outputEncoding  by default  So I added the property as a child element of the project element and everything is fine now   lt properties gt       lt project build sourceEncoding gt UTF-8 lt  project build sourceEncoding gt       lt project reporting outputEncoding gt UTF-8 lt  project reporting outputEncoding gt   lt  properties gt   See also http   maven apache org general html encoding-warning

User · Answer

If you combine the answers above  finally a pom xml that configured for UTF-8 should seem like that   pom xml   lt  xml version  1 0  encoding  UTF-8   gt   lt 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  gt        lt modelVersion gt 4 0 0 lt  modelVersion gt        lt groupId gt YOUR COMPANY lt  groupId gt       lt artifactId gt YOUR APP lt  artifactId gt       lt version gt 1 0 0-SNAPSHOT lt  version gt        lt properties gt           lt project java version gt 1 8 lt  project java version gt           lt project build sourceEncoding gt UTF-8 lt  project build sourceEncoding gt           lt project reporting outputEncoding gt UTF-8 lt  project reporting outputEncoding gt       lt  properties gt        lt dependencies gt           lt  -- Your dependencies -- gt       lt  dependencies gt        lt build gt           lt plugins gt               lt plugin gt                   lt groupId gt org apache maven plugins lt  groupId gt                   lt artifactId gt maven-compiler-plugin lt  artifactId gt                   lt version gt 3 7 0 lt  version gt                   lt configuration gt                       lt source gt   project java version  lt  source gt                       lt target gt   project java version  lt  target gt                       lt encoding gt   project build sourceEncoding  lt  encoding gt                   lt  configuration gt               lt  plugin gt               lt plugin gt                   lt groupId gt org apache maven plugins lt  groupId gt                   lt artifactId gt maven-resources-plugin lt  artifactId gt                   lt version gt 3 0 2 lt  version gt                   lt configuration gt                       lt encoding gt   project build sourceEncoding  lt  encoding gt                   lt  configuration gt               lt  plugin gt           lt  plugins gt       lt  build gt   lt  project gt

User · Answer

In my case I was using the maven-dependency-plugin so in order to resolve the issue I had to add the following property      lt project build sourceEncoding gt UTF-8 lt  project build sourceEncoding gt    See Apache Maven Resources Plugin    Specifying a character encoding scheme

[java] How to configure encoding in Maven?

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