Servlet在客戶端中出現亂碼是是常見現象，參見Servlet中文亂碼原因 解決 Get 和 Post 和客戶端，以下兩行語句要在獲取輸出流之前執行，纔會生效。問題解決。
response.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=utf-8");
//以上兩行語句要在獲取輸出流之前執行。纔會生效。
PrintWriter out = response.getWriter();
完整代碼：
package com.xionghuilin;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class HelloWorld extends HttpServlet {
public void doGet(HttpServletRequest request,HttpServletResponse response)throws IOException,ServletException {
//以下兩行語句要在獲取輸出流之前執行。纔會生效。
response.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=utf-8");
//以上兩行語句要在獲取輸出流之前執行。纔會生效。
PrintWriter out = response.getWriter();
response.setContentType("text/html;charset=UTF-8");
response.setCharacterEncoding("UTF-8");
request.setCharacterEncoding("UTF-8");
response.setHeader("content-type","text/html;charset=UTF-8");
//以下語句無法解決問題，位置不對
//out.write("<meta http-equiv=\"Content-Type\" content=\"text/html; charset=UTF-8\">\r\n");
//<%@ page contentType="text/html; charset=UTF-8" language="java" import="java.sql.*" errorPage="" %>
//out.write("<%@ page contentType=\"text/html; charset=UTF-8\" language=\"java\" import=\"java.sql.*\" errorPage=\"\" %>\r\n");
out.write("<html>\r\n");
out.write("<head>\r\n");
//以下語句無法解決問題，位置不對
//設定解碼方式
//out.write("<meta http-equiv=\"Content-Type\" content=\"text/html; charset=GBK\">\r\n");
//out.write("<meta http-equiv=\"Content-Type\" content=\"text/html; charset=UTF-8\">\r\n");
//out.write("<meta http-equiv=\"Content-Type\" content=\"text/html; charset=gb2312\">\r\n");
out.write("<title>該文件放在根目錄下</title>\r\n");
out.write("</head>\r\n");
out.write("\r\n");
out.write("<body>\r\n");
out.write("<font size=20>\r\n");
//以下語句無法解決問題，位置不對
//out.print("採用Servlet實現HelloWorld".getBytes("UTF-8"));
out.print("採用Servlet實現HelloWorld");
out.write("\r\n");
out.write("</font>\r\n");
out.write("</body>\r\n");
out.write("</html>");
}
}
Reference
Servlet 中文亂碼問題及解決方案剖析
Servlet解決中文亂碼
Servlet頁面中文亂碼問題
解決servlet亂碼問題
Servlet中文亂碼原因 解決 Get 和 Post 和客戶端