使用Filter和包装模式解决request/response乱码问题

package filter;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.Map;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;
/**
 * 使用此过滤器解决reqeust/response乱码问题
 * @author 马隆博
 */
public class CharacterFilter implements Filter {
    @Override
    public void init(FilterConfig fConfig) throws ServletException {}

    @Override
    public void doFilter(ServletRequest req, ServletResponse resp,
            FilterChain chain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) resp;

        req.setCharacterEncoding( "utf-8" ); // 解决request乱码
        resp.setContentType( "text/html;charset=utf-8" ); // 解决response乱码

        if ( "get" .equalsIgnoreCase(request.getMethod())) {
            CharacterRequest characterRequest = new CharacterRequest(request); // 使用包装的request
            chain.doFilter(characterRequest, response); // 放行
            return ;
        }
        doFilter(request, response, chain);
    }

    @Override
    public void destroy() {}
}

/**
 * 包装后的Request
 * @author 马隆博
 */
class CharacterRequest extends HttpServletRequestWrapper {
    public CharacterRequest(HttpServletRequest request) {
        super (request);
    }

    @SuppressWarnings ( "finally" )
    private String convertCharacter(String value) {
        String resultValue = value;
        try {
            resultValue = new String(value.getBytes( "ISO-8859-1" ), "utf-8" ); //转换为utf-8
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } finally {
            return resultValue;
        }
    }

    @Override
    public String getParameter(String name) {
        String value = super .getParameter(name); // 调用被包装对象的方法
        if (value != null ){
            value = convertCharacter(value); //转换字符
        }
        return value;
    }

    @Override
    public Map<String, String[]> getParameterMap() {
        Map<String, String[]> map = super .getParameterMap();
        if (map != null ) {
            // 遍历转换字符
            for (String[] values : map.values()) {
                for (String value : values) {
                    value = convertCharacter(value);
                }
            }
        }
        return map;
    }

    @Override
    public String[] getParameterValues(String name) {
        String[] values = super .getParameterValues(name);
        if (values != null ) {
            // 遍历转换字符
            for (String value : values) {
                value = convertCharacter(value);
            }
        }
        return values;
    }
}