Java Servlet无法显示变音符号（Umlaut）该如何解决？

Hey there! I see you're having trouble getting umlauts (like ä, ö, ü) to display correctly in your Java Servlet. Let's break down the fixes step by step:

1. Set Request Character Encoding First #

The main issue here is that you're not configuring the character encoding for incoming request parameters. By default, most servlet containers use ISO-8859-1 for request data, which will mangle UTF-8 characters like umlauts.

Add this line BEFORE you retrieve any parameters from the request:

request.setCharacterEncoding("UTF-8");

2. Strengthen Response Encoding Settings #

You already set the response content type with UTF-8, which is great. To make it more robust, explicitly set the response character encoding too (some containers infer this from setContentType, but explicit configuration avoids edge cases):

response.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");

3. Updated doPost Method with Umlaut Example #

Here's your modified code with all fixes applied, plus a sample umlaut-rich sentence to test display:

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
    // Set request encoding FIRST
    request.setCharacterEncoding("UTF-8");
    
    // Configure response encodings
    response.setCharacterEncoding("UTF-8");
    response.setContentType("text/html;charset=UTF-8"); 
    
    String myname = request.getParameter("benutzer"); 
    String mypass = request.getParameter("pass"); 
    PrintWriter myaus = response.getWriter(); 
    
    // Display submitted credentials
    myaus.println("Deine Benutzername und pass ist : " + myname + " :: " + mypass);
    // Add a test sentence with umlauts
    myaus.println("<br><p>Heute esse ich ein leckeres Käsespätzle mit frischem Kraut!</p>");
} 

Extra Tips #

• If your HTML form uses POST (which it does here), add accept-charset="UTF-8" to the <form> tag to ensure the browser sends data in UTF-8:

  <form method="post" accept-charset="UTF-8">
      <!-- Your form fields here -->
  </form>
  

• If you ever use GET requests later, you'll need to modify your servlet container's config (e.g., Tomcat's server.xml) to add URIEncoding="UTF-8" to the Connector element, but this isn't needed for your current POST setup.

That should get your umlauts displaying perfectly!

内容的提问来源于stack exchange，提问作者sunita