javaservlet和googleappengine中的编码

我正在使用谷歌应用引擎从数据库中检索数据。当我检索阿拉伯语文本时，它会返回类似于“§？？？？？？”的内容

以下是HttpServlet：

public class MyServlet extends HttpServlet {
@Override
public void doGet(HttpServletRequest request, HttpServletResponse response)
        throws IOException {
    PrintWriter writer = response.getWriter();

    final String contentType = "text/plain;charset=UTF-8";
    final String characterEncoding = "UTF-8";

    response.setContentType(contentType);
    response.setCharacterEncoding(characterEncoding);

    writer.println(response.getContentType());
    writer.println(response.getCharacterEncoding());
    writer.println("السلام عليكم:");
}
}

输出为：

text/plain; charset=iso-8859-1
ISO-8859-1
?§???³???§?? ?¹????????:

appengine-web.xml：

<?xml version="1.0" encoding="utf-8"?>

<appengine-web-app xmlns="http://appengine.google.com/ns/1.0">

    <application>myApplicationID</application>

    <use-google-connector-j>true</use-google-connector-j>

    <version>1</version>

    <threadsafe>true</threadsafe>

    <system-properties>

         <property name="java.util.logging.config.file" value="WEB-INF/logging.properties" />

         <property name="file.encoding" value="UTF-8" />

         <property name="appengine.file.encoding" value="UTF-8" />

         <property name="DEFAULT_ENCODING" value="UTF-8" />

    </system-properties>

    <env-variables>

         <env-var name="DEFAULT_ENCODING" value="UTF-8" />

    </env-variables>
</appengine-web-app>

我找到了解决办法

问题是，我在设置内容类型之前获取了writer

因此，代码应该是：

public class MyServlet extends HttpServlet {
   @Override
   public void doGet(HttpServletRequest request, HttpServletResponse response)
       throws IOException {
       final String contentType = "text/plain;charset=UTF-8";
       final String characterEncoding = "UTF-8";

       response.setContentType(contentType);
       response.setCharacterEncoding(characterEncoding);

       PrintWriter writer = response.getWriter();

       writer.println(response.getContentType());
       writer.println(response.getCharacterEncoding());
       writer.println("السلام عليكم:");
  }
}

我找到了解决办法

问题是，我在设置内容类型之前获取了writer

因此，代码应该是：

public class MyServlet extends HttpServlet {
   @Override
   public void doGet(HttpServletRequest request, HttpServletResponse response)
       throws IOException {
       final String contentType = "text/plain;charset=UTF-8";
       final String characterEncoding = "UTF-8";

       response.setContentType(contentType);
       response.setCharacterEncoding(characterEncoding);

       PrintWriter writer = response.getWriter();

       writer.println(response.getContentType());
       writer.println(response.getCharacterEncoding());
       writer.println("السلام عليكم:");
  }
}