JSP Request 中文亂碼徹底解決：全站 UTF-8 統一編碼最佳實踐

亂碼根因

瀏覽器發送請求參數預設以 ISO-8859-1 編碼；伺服器若以 GBK/UTF-8 解碼即產生亂碼。解決核心：統一雙端編碼為 UTF-8。

一、前端頁面統一 UTF-8

<%@ page contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

所有 .jsp/.java 檔案以 UTF-8 儲存（IDE 設定 File Encoding = UTF-8）。

二、web.xml 配置 EncodingFilter（核心）

<filter>
    <filter-name>SetCharacterEncodingFilter</filter-name>
    <filter-class>com.example.filter.SetCharacterEncodingFilter</filter-class>
    <init-param>
        <param-name>encoding</param-name>
        <param-value>UTF-8</param-value>
    </init-param>
    <init-param>
        <param-name>ignore</param-name>
        <param-value>true</param-value>
    </init-param>
</filter>
<filter-mapping>
    <filter-name>SetCharacterEncodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

三、Filter 實作（支援 GET/POST 自動轉碼）

package com.example.filter;

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.IOException;

public class SetCharacterEncodingFilter implements Filter {
    private String encoding = "UTF-8";
    private boolean ignore = true;

    public void init(FilterConfig config) {
        String e = config.getInitParameter("encoding");
        if (e != null) encoding = e;
        String ig = config.getInitParameter("ignore");
        if (ig != null) ignore = Boolean.parseBoolean(ig);
    }

    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
            throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) req;
        if (ignore || request.getCharacterEncoding() == null) {
            request.setCharacterEncoding(encoding); // POST 直接生效
        }
        // GET 參數需包裝 Request 覆寫 getParameter
        if ("GET".equalsIgnoreCase(request.getMethod())) {
            request = new Utf8RequestWrapper(request);
        }
        chain.doFilter(request, res);
    }

    public void destroy() {}
}

// 包裝類：自動將 ISO-8859-1 -> UTF-8
class Utf8RequestWrapper extends HttpServletRequestWrapper {
    public Utf8RequestWrapper(HttpServletRequest request) { super(request); }

    private String decode(String s) {
        try { return new String(s.getBytes("ISO-8859-1"), "UTF-8"); }
        catch (Exception e) { return s; }
    }
    @Override public String getParameter(String name) { return decode(super.getParameter(name)); }
    @Override public String[] getParameterValues(String name) {
        String[] vals = super.getParameterValues(name);
        if (vals != null) for (int i=0;i

<Connector port="8080" protocol="HTTP/1.1"
           URIEncoding="UTF-8" useBodyEncodingForURI="true" />

jdbc:mysql://localhost:3306/mydb?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Taipei

// 取得原始 Connection
Connection raw = dataSource.getConnection();
// 包裝為自動轉碼 Connection
Connection conn = new EncodingConnection(raw, true, "ISO-8859-1", "UTF-8");
// 後續 setString/getString 直接用中文，內部自動雙向轉碼