web.xml

<filter>
    <filter-name>encodeFilter</filter-name>
    <filter-class>lx.servlet.filter.GenericEncodingFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>encodeFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>
 

/**
 * 通用編碼解決方案
 * 
 */
public class GenericEncodingFilter implements Filter {	
	public void destroy() {
	}
	
	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
		// 轉型為與協議相關物件
		HttpServletRequest httpServletRequest = (HttpServletRequest) request;
		// 對request包裝增強
		HttpServletRequest myrequest = new MyRequest(httpServletRequest);
		chain.doFilter(myrequest, response);
	}

	public void init(FilterConfig filterConfig) throws ServletException {
	}

}

// 自定義request物件
class MyRequest extends HttpServletRequestWrapper {

	private HttpServletRequest request;

	private boolean hasEncode;

	public MyRequest(HttpServletRequest request) {
		super(request);// super必須寫
		this.request = request;
	}

	// 對需要增強方法 進行覆蓋
	@Override
	public Map getParameterMap() {
		// 先獲得請求方式
		String method = request.getMethod();
		if (method.equalsIgnoreCase("post")) {
			// post請求
			try {
				// 處理post亂碼
				request.setCharacterEncoding("utf-8");
				return request.getParameterMap();
			} catch (UnsupportedEncodingException e) {
				e.printStackTrace();
			}
		} else if (method.equalsIgnoreCase("get")) {
			// get請求
			Map<String, String[]> parameterMap = request.getParameterMap();
			if (!hasEncode) { // 確保get手動編碼邏輯只執行一次
				for (String parameterName : parameterMap.keySet()) {
					String[] values = parameterMap.get(parameterName);
					if (values != null) {
						for (int i = 0; i < values.length; i++) {
							try {
								// 處理get亂碼
								values[i] = new String(values[i].getBytes("ISO-8859-1"), "utf-8");
							} catch (UnsupportedEncodingException e) {
								e.printStackTrace();
							}
						}
					}
				}
				hasEncode = true;
			}
			return parameterMap;
		}

		return super.getParameterMap();
	}

	@Override
	public String getParameter(String name) {
		Map<String, String[]> parameterMap = getParameterMap();
		String[] values = parameterMap.get(name);
		if (values == null) {
			return null;
		}
		return values[0]; // 取回引數的第一個值
	}

	@Override
	public String[] getParameterValues(String name) {
		Map<String, String[]> parameterMap = getParameterMap();
		String[] values = parameterMap.get(name);
		return values;
	}

}