文章目录

springboot：集成Kaptcha实现图片验证码
- 一、导入依赖
- - 系统配置文件
- 二、生成验证码
- - 1、Kaptcha的配置
  - 2、自定义验证码文本生成器
  - 3、具体实现
- 三、校验验证码
- - 1、controller接口
  - 2、自定义前端过滤器
  - 3、自定义验证码处理过滤器
  - 4、自定义BodyReaderFilter解决读取body错误问题
  - 5、注意

springboot：集成Kaptcha实现图片验证码

系统环境：

windows 10

jdk 1.8

springboot版本: 2.1.10.RELEASE

一、导入依赖

        <dependency>
            <groupId>com.github.penggle</groupId>
            <artifactId>kaptcha</artifactId>
            <version>2.3.2</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>

系统配置文件

server:
  port: 81
spring:
  redis:
    database: 1
    host: 127.0.0.1
    port: 6379
    password:      # 密码（默认为空）
    timeout: 6000ms  # 连接超时时长（毫秒）
    lettuce:
      pool:
        max-active: 1000  # 连接池最大连接数（使用负值表示没有限制）
        max-wait: -1ms      # 连接池最大阻塞等待时间（使用负值表示没有限制）
        max-idle: 10      # 连接池中的最大空闲连接
        min-idle: 5       # 连接池中的最小空闲连接

二、生成验证码

1、Kaptcha的配置

验证码文本生成器：这个需要自己生成并且修改下面的配置文件为你文件的路径

package com.yolo.springboot.kaptcha.config;

import com.google.code.kaptcha.impl.DefaultKaptcha;
import com.google.code.kaptcha.util.Config;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.util.Properties;

/**
 * @ClassName CaptchaConfig
 * @Description 验证码配置
 * @Author hl
 * @Date 2022/12/6 9:37
 * @Version 1.0
 */
@Configuration
public class CaptchaConfig {

    @Bean(name = "captchaProducerMath")
    public DefaultKaptcha getKaptchaBeanMath() {
        DefaultKaptcha defaultKaptcha = new DefaultKaptcha();
        Properties properties = new Properties();
        // 是否有边框 默认为true 我们可以自己设置yes，no
        properties.setProperty("kaptcha.border", "yes");
        // 边框颜色 默认为Color.BLACK
        properties.setProperty("kaptcha.border.color", "105,179,90");
        // 验证码文本字符颜色 默认为Color.BLACK
        properties.setProperty("kaptcha.textproducer.font.color", "blue");
        // 验证码图片宽度 默认为200
        properties.setProperty("kaptcha.image.width", "160");
        // 验证码图片高度 默认为50
        properties.setProperty("kaptcha.image.height", "60");
        // 验证码文本字符大小 默认为40
        properties.setProperty("kaptcha.textproducer.font.size", "35");
        // KAPTCHA_SESSION_KEY
        properties.setProperty("kaptcha.session.key", "kaptchaCodeMath");
        // 验证码文本生成器
        properties.setProperty("kaptcha.textproducer.impl", "com.yolo.springboot.kaptcha.config.KaptchaTextCreator");
        // 验证码文本字符间距 默认为2
        properties.setProperty("kaptcha.textproducer.char.space", "3");
        // 验证码文本字符长度 默认为5
        properties.setProperty("kaptcha.textproducer.char.length", "6");
        // 验证码文本字体样式 默认为new Font("Arial", 1, fontSize), new Font("Courier", 1,
        // fontSize)
        properties.setProperty("kaptcha.textproducer.font.names", "Arial,Courier");
        // 验证码噪点颜色 默认为Color.BLACK
        properties.setProperty("kaptcha.noise.color", "white");
        // 干扰实现类
        properties.setProperty("kaptcha.noise.impl", "com.google.code.kaptcha.impl.NoNoise");
        // 图片样式 水纹com.google.code.kaptcha.impl.WaterRipple
        // 鱼眼com.google.code.kaptcha.impl.FishEyeGimpy
        // 阴影com.google.code.kaptcha.impl.ShadowGimpy
        properties.setProperty("kaptcha.obscurificator.impl", "com.google.code.kaptcha.impl.ShadowGimpy");
        Config config = new Config(properties);
        defaultKaptcha.setConfig(config);
        return defaultKaptcha;
    }
}

2、自定义验证码文本生成器

package com.yolo.springboot.kaptcha.config;

import com.google.code.kaptcha.text.impl.DefaultTextCreator;

import java.util.Random;

/**
 * @ClassName KaptchaTextCreator
 * @Description 验证码文本生成器
 * @Author hl
 * @Date 2022/12/6 10:14
 * @Version 1.0
 */
public class KaptchaTextCreator extends DefaultTextCreator {

    private static final String[] Number = "0,1,2,3,4,5,6,7,8,9,10".split(",");
    @Override
    public String getText()
    {
        int result;
        Random random = new Random();
        int x = random.nextInt(10);
        int y = random.nextInt(10);
        StringBuilder suChinese = new StringBuilder();
        int randomOperand = (int) Math.round(Math.random() * 2);
        if (randomOperand == 0) {
            result = x * y;
            suChinese.append(Number[x]);
            suChinese.append("*");
            suChinese.append(Number[y]);
        } else if (randomOperand == 1) {
            if (!(x == 0) && y % x == 0) {
                result = y / x;
                suChinese.append(Number[y]);
                suChinese.append("/");
                suChinese.append(Number[x]);
            } else {
                result = x + y;
                suChinese.append(Number[x]);
                suChinese.append("+");
                suChinese.append(Number[y]);
            }
        } else if (randomOperand == 2) {
            if (x >= y) {
                result = x - y;
                suChinese.append(Number[x]);
                suChinese.append("-");
                suChinese.append(Number[y]);
            } else {
                result = y - x;
                suChinese.append(Number[y]);
                suChinese.append("-");
                suChinese.append(Number[x]);
            }
        } else {
            result = x + y;
            suChinese.append(Number[x]);
            suChinese.append("+");
            suChinese.append(Number[y]);
        }
        suChinese.append("=?@").append(result);
        return suChinese.toString();
    }
}

3、具体实现

package com.yolo.springboot.kaptcha.controller;

import cn.hutool.json.JSONUtil;
import com.google.code.kaptcha.Producer;
import com.hl.springbootcommon.common.HttpResponseTemp;
import com.hl.springbootcommon.common.ResultStat;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.http.MediaType;
import org.springframework.util.FastByteArrayOutputStream;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;
import javax.imageio.ImageIO;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.UUID;
import java.util.concurrent.TimeUnit;

/**
 * @ClassName CaptchaController
 * @Description 验证码
 * @Author hl
 * @Date 2022/12/6 9:45
 * @Version 1.0
 */
@RestController
@Slf4j
public class CaptchaController {

    @Autowired
    private Producer producer;

    @Autowired
    private StringRedisTemplate redisTemplate;

    public static final String DEFAULT_CODE_KEY = "random_code_";

   /**
      * @MethodName createCaptcha
      * @Description  生成验证码
      * @param httpServletResponse 响应流
      * @Author hl
      * @Date 2022/12/6 10:30
      */
    @GetMapping("/create/captcha")
    public void createCaptcha(HttpServletResponse httpServletResponse) throws IOException {
        // 生成验证码
        String capText = producer.createText();
        String capStr = capText.substring(0, capText.lastIndexOf("@"));
        String result = capText.substring(capText.lastIndexOf("@") + 1);
        BufferedImage image = producer.createImage(capStr);
        // 保存验证码信息
        String randomStr = UUID.randomUUID().toString().replaceAll("-", "");
        System.out.println("随机数为:" + randomStr);
        redisTemplate.opsForValue().set(DEFAULT_CODE_KEY + randomStr, result, 3600, TimeUnit.SECONDS);
        // 转换流信息写出
        FastByteArrayOutputStream os = new FastByteArrayOutputStream();
        try {
            ImageIO.write(image, "jpg", os);
        } catch (IOException e) {
            log.error("ImageIO write err", e);
            httpServletResponse.sendError(HttpServletResponse.SC_NOT_FOUND);
            return;
        }

        // 定义response输出类型为image/jpeg类型，使用response输出流输出图片的byte数组
        byte[] bytes = os.toByteArray();
        //设置响应头
        httpServletResponse.setHeader("Cache-Control", "no-store");
        //设置响应头
        httpServletResponse.setHeader("randomstr",randomStr);
        //设置响应头
        httpServletResponse.setHeader("Pragma", "no-cache");
        //在代理服务器端防止缓冲
        httpServletResponse.setDateHeader("Expires", 0);
        //设置响应内容类型
        ServletOutputStream responseOutputStream = httpServletResponse.getOutputStream();
        responseOutputStream.write(bytes);
        responseOutputStream.flush();
        responseOutputStream.close();
    }
}

在这里插入图片描述

三、校验验证码

这里校验验证码，我用了过滤器来实现的，其中遇到了很多问题，下面有我详细的解决方法

1、controller接口

    @PostMapping("/login")
    public HttpResponseTemp<?> login(@RequestBody LoginDto loginDto){

        System.out.println(JSONUtil.toJsonStr(loginDto));
        return ResultStat.OK.wrap("","成功");
    }

@Data
public class LoginDto {

    private String captcha;
    private String randomStr;
}

2、自定义前端过滤器

这里是我写了一个简单的前端页面，然后发现这里会有一些前端的文件，所以需要过滤一下

package com.yolo.springboot.kaptcha.filter;

import cn.hutool.core.collection.ListUtil;
import org.apache.commons.lang3.StringUtils;
import org.springframework.web.filter.ShallowEtagHeaderFilter;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.List;

/**
 * @ClassName SuffixFilter
 * @Description 前端文件过滤
 * @Author hl
 * @Date 2022/12/6 12:40
 * @Version 1.0
 */
public class FrontFilter extends ShallowEtagHeaderFilter implements Filter {

    private static final List<String> suffix = ListUtil.of(".css",".eot",".gif",".ico",".js",".map",".png",".svg",".swf",".ttf",".TTF",".woff",".woff2");


    @Override
    protected boolean shouldNotFilterAsyncDispatch() {
        return false;
    }

    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
            throws ServletException, IOException {
        response.setHeader("Server", "Apache-Coyote/1.1");
        response.setHeader("Cache-Control", "max-age=0");
        String uri = request.getRequestURI();
        if (!StringUtils.isBlank(uri)) {
            int index = uri.lastIndexOf(".");
            if (index > 0 && suffix.contains(uri.substring(index))) {
                response.setHeader("Cache-Control", "max-age=3600");
            }
            if (uri.startsWith("/lib")) {
                response.setHeader("Cache-Control", "max-age=3600, immutable");
            }
        }
        super.doFilterInternal(request, response, filterChain);
    }
}

然后需要把我们自定的过滤器加入到spring中让他生效

package com.yolo.springboot.kaptcha.config;

import com.yolo.springboot.kaptcha.filter.FrontFilter;
import com.yolo.springboot.kaptcha.filter.ImgCodeFilter;
import com.yolo.springboot.kaptcha.filter.BodyReaderFilter;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.core.StringRedisTemplate;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

@Configuration
public class FilterConfig {

    @Bean
    public FilterRegistrationBean<?> frontFilterRegistration() {
        FilterRegistrationBean<FrontFilter> registration = new FilterRegistrationBean<>();
        // 将过滤器配置到FilterRegistrationBean对象中
        registration.setFilter(new FrontFilter());
        // 给过滤器取名
        registration.setName("frontFilter");
        // 设置过滤器优先级，该值越小越优先被执行
        registration.setOrder(0);
        List<String> urlPatterns = new ArrayList<>();
        urlPatterns.add("/*");
        // 设置urlPatterns参数
        registration.setUrlPatterns(urlPatterns);
        return registration;
    }
}

这里我给他设置的拦截全部请求，并且优先级是第一位的

3、自定义验证码处理过滤器

package com.yolo.springboot.kaptcha.filter;

import com.alibaba.fastjson.JSONObject;
import lombok.AllArgsConstructor;
import lombok.SneakyThrows;
import org.apache.commons.lang3.StringUtils;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.http.HttpStatus;
import org.springframework.stereotype.Component;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.stream.Collectors;

/**
 * @ClassName ImgCodeFilter
 * @Description 验证码处理
 * @Author hl
 * @Date 2022/12/6 10:35
 * @Version 1.0
 */
@AllArgsConstructor
public class ImgCodeFilter implements Filter {

    private final StringRedisTemplate redisTemplate;

    private final static String AUTH_URL = "/login";

    public static final String DEFAULT_CODE_KEY = "random_code_";


    /**
     * filter对象只会创建一次，init方法也只会执行一次。
     */
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        Filter.super.init(filterConfig);
    }

    /**
     * 主要的业务代码编写方法
     */
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        //只有转换为HttpServletRequest 对象才可以获取路径参数
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        String requestURI = request.getRequestURI();
        if (!AUTH_URL.equalsIgnoreCase(requestURI)){
            //放行
            filterChain.doFilter(servletRequest, servletResponse);
        }

        try {
            String bodyStr = resolveBodyFromRequest(request);
            JSONObject bodyJson=JSONObject.parseObject(bodyStr);
            String code = (String) bodyJson.get("captcha");
            String randomStr = (String) bodyJson.get("randomStr");
            // 校验验证码
            checkCode(code, randomStr);
        } catch (Exception e) {
            HttpServletResponse response = (HttpServletResponse) servletResponse;
            response.setStatus(HttpStatus.INTERNAL_SERVER_ERROR.value());
            response.setHeader("Content-Type", "application/json;charset=UTF-8");
            response.sendError(HttpStatus.UNAUTHORIZED.value(),"验证码认证失败或者过期");
        }
        filterChain.doFilter(servletRequest, servletResponse);
    }

    /**
     * 检查code
     */
    @SneakyThrows
    private void checkCode(String code, String randomStr) {
        if (StringUtils.isBlank(code)) {
            throw new RuntimeException("验证码不能为空");
        }
        if (StringUtils.isBlank(randomStr)) {
            throw new RuntimeException("验证码不合法");
        }
        String key = DEFAULT_CODE_KEY + randomStr;
        String result = redisTemplate.opsForValue().get(key);
        redisTemplate.delete(key);
        if (!code.equalsIgnoreCase(result)) {
            throw new RuntimeException("验证码不合法");
        }
    }

    /**
       * @MethodName resolveBodyFromRequest
       * @Description  不能和@Requestbody搭配使用
       * 原因: getInputStream() has already been called for this request,流不能读取第二次,@Requestbody已经读取过一次了
       * @param request 请求流
       * 解决方案: 重写HttpServletRequestWrapper类,将HttpServletRequest的数据读到wrapper的缓存中去(用 byte[] 存储),再次读取时读缓存就可以了
       * 当接口涉及到上传下载时,会有一些异常问题,最好在过滤器中排除这些路径
       * @return: java.lang.String
       * @Author hl
       * @Date 2022/12/6 15:18
       */

    private String resolveBodyFromRequest(HttpServletRequest request){
        String bodyStr = null;
        // 获取请求体
        if ("POST".equalsIgnoreCase(request.getMethod())){
            try {
                bodyStr = request.getReader().lines().collect(Collectors.joining(System.lineSeparator()));
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return bodyStr;
    }

    /**
     * 在销毁Filter时自动调用。
     */
    @Override
    public void destroy() {
        Filter.super.destroy();
    }
}

加入到配置中

这里校验需要用到redis，用构造方法给他注入

    @Autowired
    private StringRedisTemplate redisTemplate;
    @Bean
    public FilterRegistrationBean<?> imgCodeFilterRegistration() {
        FilterRegistrationBean<ImgCodeFilter> registration = new FilterRegistrationBean<>();
        // 将过滤器配置到FilterRegistrationBean对象中
        registration.setFilter(new ImgCodeFilter(redisTemplate));
        // 给过滤器取名
        registration.setName("imgCodeFilter");
        // 设置过滤器优先级，该值越小越优先被执行
        registration.setOrder(2);
        List<String> urlPatterns = new ArrayList<>();
        urlPatterns.add("/login");
        // 设置urlPatterns参数
        registration.setUrlPatterns(urlPatterns);
        return registration;
    }

遇到的问题及解决思路

问题：流不能多次被调用

ERROR m.e.handler.GlobalExceptionHandler - getInputStream() has already been called for this request
java.lang.IllegalStateException: getInputStream() has already been called for this request
    at org.apache.catalina.connector.Request.getReader(Request.java:1212)
    at org.apache.catalina.connector.RequestFacade.getReader(RequestFacade.java:504)

根据报错信息分析简单来说，就是getInputStream()已经被调用了，不能再次调用。可是我看代码上，我也没调用。经过一番检索，原来@RequestBody注解配置后，默认会使用流来读取数据

具体原因：

默认配置时，getInputStream()和getReader()一起使用会报错，使用两遍getInputStream()，第二遍会为空
当存在@RequestBody等注解时，springMVC已读取过一遍流，默认单独使用getInputStream()或getReader()都为空。

实测，不加@RequestBody注解，可以如期获得请求中的json参数，但是又不得不加@RequestBody注解。这样就需要新的思路

解决思路：

写filter继承HttpServletRequestWrapper，缓存InputStream，覆盖getInputStream()和getReader()方法，使用ByteArrayInputStream is = new ByteArrayInputStream(body.getBytes());读取InputStream。下面自定义BodyReaderFilter和BodyReaderWrapper就是具体解决方法

4、自定义BodyReaderFilter解决读取body错误问题

BodyReaderWrapper

package com.yolo.springboot.kaptcha.filter;

import org.springframework.util.StreamUtils;

import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;

/**
 * 自定义 BodyReaderWrapper
 * 问题原因：在controller中我们通过@RequestBody注解来获取前端传过来的json数据，这里已经使用了一次request来获取body中的值。再次通过request获取body中的值，就会报错
 * 使用场景：通过request能获取到一次body中的值，有时候我们需要多次获取body中的值的需求，因此需要对流再次封装再次传递
 */
public class BodyReaderWrapper extends HttpServletRequestWrapper {
    private byte[] body;

    public BodyReaderWrapper(HttpServletRequest request) throws IOException {
        super(request);
        //保存一份InputStream，将其转换为字节数组
        body = StreamUtils.copyToByteArray(request.getInputStream());
    }

    //转换成String
    public String getBodyString(){
        return new String(body,StandardCharsets.UTF_8);
    }


    @Override
    public BufferedReader getReader() {
        return new BufferedReader(new InputStreamReader(getInputStream()));
    }
	//把保存好的InputStream，传下去
    @Override
    public ServletInputStream getInputStream() {
        final ByteArrayInputStream bais = new ByteArrayInputStream(body);
        return new ServletInputStream() {
            @Override
            public int read() {
                return bais.read();
            }
            @Override
            public boolean isFinished() {
                return false;
            }
            @Override
            public boolean isReady() {
                return false;
            }
            @Override
            public void setReadListener(ReadListener readListener) {
            }
        };
    }
    public void setInputStream(byte[] body) {
        this.body = body;
    }
}

BodyReaderFilter

package com.yolo.springboot.kaptcha.filter;

import cn.hutool.core.collection.CollUtil;
import cn.hutool.core.util.StrUtil;
import org.apache.commons.lang3.StringUtils;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 * @ClassName RequestFilter
 * @Description 自定义BodyReaderFilter解决读取controller中使用@Requestbody重复读取流错误问题
 * @Author hl
 * @Date 2022/12/6 15:44
 * @Version 1.0
 */
public class BodyReaderFilter implements Filter {
    private List<String> noFilterUrls;

    @Override
    public void init(FilterConfig filterConfig){
        // 从过滤器配置中获取initParams参数
        String noFilterUrl = filterConfig.getInitParameter("noFilterUrl");
        // 将排除的URL放入成员变量noFilterUrls中
        if (StringUtils.isNotBlank(noFilterUrl)) {
            noFilterUrls = new ArrayList<>(Arrays.asList(noFilterUrl.split(",")));
        }
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain chain) throws IOException, ServletException {
        ServletRequest requestWrapper = null;
        String requestURI = null;

        if (servletRequest instanceof HttpServletRequest) {
            //获取请求中的流如何，将取出来的字符串，再次转换成流，然后把它放入到新request对象中。
            requestWrapper = new BodyReaderWrapper((HttpServletRequest) servletRequest);
            requestURI = ((HttpServletRequest) servletRequest).getRequestURI();
        }

        //如果请求是需要排除的，直接放行，例如上传文件
        if ((CollUtil.isNotEmpty(noFilterUrls) && StrUtil.isNotBlank(requestURI) && noFilterUrls.contains(requestURI)) || requestWrapper == null){
            chain.doFilter(servletRequest, servletResponse);
        }else {
            // 在chain.doFiler方法中传递新的request对象
            chain.doFilter(requestWrapper, servletResponse);
        }
    }

    @Override
    public void destroy() {
        Filter.super.destroy();
    }
}

加入到配置中

这里需要注意，拦截的是所有请求，上传文件的时候需要排除，上传文件的路径

    @Bean
    public FilterRegistrationBean<?> bodyReaderFilterRegistration() {
        FilterRegistrationBean<BodyReaderFilter> registration = new FilterRegistrationBean<>();
        // 将过滤器配置到FilterRegistrationBean对象中
        registration.setFilter(new BodyReaderFilter());
        // 给过滤器取名
        registration.setName("bodyReaderFilter");
        // 设置过滤器优先级，该值越小越优先被执行
        registration.setOrder(1);
        List<String> urlPatterns = new ArrayList<>();
        //这里需要填写排除上传文件的接口
        Map<String, String> paramMap = new HashMap<>();
        paramMap.put("noFilterUrl", "/test");
        // 设置initParams参数
        registration.setInitParameters(paramMap);
        urlPatterns.add("/*");
        // 设置urlPatterns参数
        registration.setUrlPatterns(urlPatterns);
        return registration;
    }

在这里插入图片描述

测试成功：这里我原本用的form-data传参，然后一直获取到body为空，用这种方法是需要在raw中进行填写的

获取form表单的数据

		//方式一：getParameterMap()，获得请求参数map
        Map<String,String[]> map= request.getParameterMap();  //key 参数名称 value:具体值
		//方式二：getParameterNames()：获取所有参数名称
        Enumeration a = request.getParameterNames();