一、案例演示

说明：如下案例通过springboot的方式演示拦截器是如何使用的，以获取Controller中的请求参数为切入点进行演示

1.1、前置准备工作

1.1.1、pom

<dependencies><!-- spring-boot --><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-devtools</artifactId><scope>runtime</scope><optional>true</optional></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><!-- 工具 --><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency><dependency><groupId>com.alibaba</groupId><artifactId>fastjson</artifactId><version>1.2.76</version></dependency><dependency><groupId>commons-beanutils</groupId><artifactId>commons-beanutils</artifactId><version>1.9.3</version></dependency><dependency><groupId>org.apache.httpcomponents</groupId><artifactId>httpclient</artifactId><version>4.5.6</version></dependency><dependency><groupId>org.apache.commons</groupId><artifactId>commons-lang3</artifactId><version>3.4</version></dependency><dependency><groupId>org.apache.commons</groupId><artifactId>commons-collections4</artifactId><version>4.3</version></dependency><!-- servlet --><dependency><groupId>javax.servlet</groupId><artifactId>javax.servlet-api</artifactId><version>3.1.0</version><scope>provided</scope></dependency></dependencies>

1.1.2、WebRequestConstant

/*** @Author : 一叶浮萍归大海* @Date: 2023/11/5 11:39* @Description:*/
public class WebRequestConstant {/*** 请求方法：POST*/public static final String METHOD_TYPE_POST = "POST";/*** 数据类型：application/json*/public static final String CONTENT_TYPE_APPLICATION_JSON = "application/json";/*** 字符解码*/public static final String CHARACTER_U = "%u";}

1.1.3、EncodeUtil 

/*** @Author : 一叶浮萍归大海* @Date: 2023/11/5 11:12* @Description:*/
public class EncodeUtil {private static final String DEFAULT_URL_ENCODING = "UTF-8";private static final char[] BASE62 = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz".toCharArray();/*** Hex编码.*/public static String encodeHex(byte[] input) {return Hex.encodeHexString(input);}/*** Hex解码.*/public static byte[] decodeHex(String input) {try {return Hex.decodeHex(input.toCharArray());} catch (DecoderException e) {return null;}}/*** Base64编码.*/public static String encodeBase64(byte[] input) {return Base64.encodeBase64String(input);}/*** Base64编码, URL安全(将Base64中的URL非法字符'+'和'/'转为'-'和'_', 见RFC3548).*/public static String encodeUrlSafeBase64(byte[] input) {return Base64.encodeBase64URLSafeString(input);}/*** Base64解码.*/public static byte[] decodeBase64(String input) {return Base64.decodeBase64(input);}/*** Base62编码。*/public static String encodeBase62(byte[] input) {char[] chars = new char[input.length];for (int i = 0; i < input.length; i++) {chars[i] = BASE62[(input[i] & 0xFF) % BASE62.length];}return new String(chars);}/*** Html 转码.*/public static String escapeHtml(String html) {return StringEscapeUtils.escapeHtml4(html);}/*** Html 解码.*/public static String unescapeHtml(String htmlEscaped) {return StringEscapeUtils.unescapeHtml4(htmlEscaped);}/*** Xml 转码.*/public static String escapeXml(String xml) {return StringEscapeUtils.escapeXml(xml);}/*** Xml 解码.*/public static String unescapeXml(String xmlEscaped) {return StringEscapeUtils.unescapeXml(xmlEscaped);}/*** URL 编码, Encode默认为UTF-8.*/public static String urlEncode(String part) {try {return URLEncoder.encode(part, DEFAULT_URL_ENCODING);} catch (UnsupportedEncodingException e) {e.printStackTrace();return null;}}/*** URL 解码, Encode默认为UTF-8.*/public static String urlDecode(String part) {try {return URLDecoder.decode(part, DEFAULT_URL_ENCODING);} catch (UnsupportedEncodingException e) {e.printStackTrace();return null;}}
}

1.1.4、StreamUtil

/*** @Author : 一叶浮萍归大海* @Date: 2023/11/5 1:15* @Description:*/
public class StreamUtil {public static String getRequestBody(InputStream inputStream) {String line = "";StringBuilder body = new StringBuilder();int counter = 0;// 读取POST提交的数据内容BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));try {while ((line = reader.readLine()) != null) {if (counter > 0) {body.append("rn");}body.append(line);counter++;}} catch (IOException e) {e.printStackTrace();}return body.toString();}public static HashMap<String, String[]> parseQueryString(String source) {String[] valueArray = null;if (source == null) {throw new IllegalArgumentException();}HashMap<String, String[]> hashMap = new HashMap<String, String[]>(16);StringTokenizer st = new StringTokenizer(source, "&");while (st.hasMoreTokens()) {String pair = (String) st.nextToken();int pos = pair.indexOf('=');if (pos == -1) {continue;}String key = pair.substring(0, pos);String val = pair.substring(pos + 1, pair.length());if (hashMap.containsKey(key)) {String[] oldValues = (String[]) hashMap.get(key);valueArray = new String[oldValues.length + 1];for (int i = 0; i < oldValues.length; i++) {valueArray[i] = oldValues[i];}valueArray[oldValues.length] = decodeValue(val);} else {valueArray = new String[1];valueArray[0] = decodeValue(val);}hashMap.put(key, valueArray);}return hashMap;}/*** 自定义解码函数** @param value* @return*/private static String decodeValue(String value) {if (value.contains(WebRequestConstant.CHARACTER_U)) {return EncodeUtil.urlDecode(value);} else {try {return URLDecoder.decode(value, "UTF-8");} catch (UnsupportedEncodingException e) {// 非UTF-8编码return "";}}}public static ServletInputStream getServletInputStream(ByteArrayInputStream bais) {return new ServletInputStream() {@Overridepublic int read() throws IOException {return bais.read();}@Overridepublic boolean isFinished() {return false;}@Overridepublic boolean isReady() {return false;}@Overridepublic void setReadListener(ReadListener arg0) {}};}public static byte[] readBytes(InputStream in) throws IOException {BufferedInputStream bufin = new BufferedInputStream(in);int buffSize = 1024;ByteArrayOutputStream out = new ByteArrayOutputStream(buffSize);byte[] temp = new byte[buffSize];int size = 0;while ((size = bufin.read(temp)) != -1) {out.write(temp, 0, size);}bufin.close();byte[] content = out.toByteArray();return content;}}

1.1.5、MyHttpServletRequestWrapper

/*** @Author : 一叶浮萍归大海* @Date: 2023/11/4 20:50* @Description:*/
@Getter
@Setter
public class MyHttpServletRequestWrapper extends HttpServletRequestWrapper {/*** 用于保存读取到的body中的数据*/private byte[] body;private Map<String, String[]> paramsMap;@Overridepublic Map getParameterMap() {return paramsMap;}@Overridepublic String getParameter(String name) {String[] values = paramsMap.get(name);if (values == null || values.length == 0) {return null;}return values[0];}@Overridepublic String[] getParameterValues(String name) {return paramsMap.get(name);}@Overridepublic Enumeration getParameterNames() {return Collections.enumeration(paramsMap.keySet());}private HashMap<String, String[]> getParamMapFromPost(HttpServletRequest request) {String body = "";try {body = StreamUtil.getRequestBody(request.getInputStream());} catch (IOException e) {e.printStackTrace();}HashMap<String, String[]> result = new HashMap<String, String[]>(16);if (null == body || 0 == body.length()) {return result;}return StreamUtil.parseQueryString(body);}private Map<String, String[]> getParamMapFromGet(HttpServletRequest request) {return StreamUtil.parseQueryString(request.getQueryString());}public String getBody(){return new String(body);}public MyHttpServletRequestWrapper(HttpServletRequest request) throws Exception {super(request);body = StreamUtil.readBytes(request.getInputStream());}@Overridepublic BufferedReader getReader() throws IOException {return new BufferedReader(new InputStreamReader(getInputStream()));}@Overridepublic ServletInputStream getInputStream() throws IOException {final ByteArrayInputStream bais = new ByteArrayInputStream(body);return StreamUtil.getServletInputStream(bais);}}

1.1.6、UserDTO

@Data
@AllArgsConstructor
@NoArgsConstructor
@Accessors(chain = true)
public class UserDTO implements Serializable {/*** 用户名*/private String username;/*** 密码*/private String password;}

二、创建过滤器

2.1、MyFilter

/*** @Author : 一叶浮萍归大海* @Date: 2023/11/4 20:37* @Description:*/
@Slf4j
@Component
@WebFilter(urlPatterns = "/*", filterName = "channelFilter")
public class MyFilter implements Filter {@Overridepublic void init(FilterConfig filterConfig) throws ServletException {log.info("============= MyFilter init =============");}/***      普通的参数可以通过request.getParameterMap中获取，而Controller层被@RequestBody修饰的参数需要从request的InputStream中获取，* 但是由于InputStream只能读取一次，如果过滤器读取了参数，那么后面的拦截器和Controller层就读取不到参数了，所以这类参数需要单独获取，可以把* request封装一下，copy一份request，一个用于在拦截器（过滤器）中读取参数，一个放行给Controller使用* * @param request* @param response* @param chain* @throws ServletException* @throws IOException*/@Overridepublic void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws ServletException, IOException {ServletRequest requestWrapper = null;String param = "";if (request instanceof HttpServletRequest) {HttpServletRequest httpServletRequest = (HttpServletRequest) request;String method = httpServletRequest.getMethod().toUpperCase();String type = httpServletRequest.getContentType();if (WebRequestConstant.METHOD_TYPE_POST.equals(method) && WebRequestConstant.CONTENT_TYPE_APPLICATION_JSON.equalsIgnoreCase(type)) {try {requestWrapper = new MyHttpServletRequestWrapper((HttpServletRequest) request);} catch (Exception e) {throw new RuntimeException(e);}}}if (requestWrapper == null) {Map<String, String[]> originRequestMap = request.getParameterMap();Map<String, String> requestMap = new HashMap<String, String>(16);for (String key : originRequestMap.keySet()) {String[] values = originRequestMap.get(key);requestMap.put(key, values[0]);}param = JSON.toJSONString(requestMap);} else {param = ((MyHttpServletRequestWrapper) requestWrapper).getBody();}log.info("过滤器param:{}", param);//放行if (requestWrapper == null) {chain.doFilter(request, response);} else {chain.doFilter(requestWrapper, response);}}@Overridepublic void destroy() {log.info("============= MyFilter destroy =============");}}

三、拦截器

3.1、创建拦截器

/*** @Author : 一叶浮萍归大海* @Date: 2023/11/4 18:29* @Description: 自定义的登录拦截器*/
@Slf4j
@Component
public class MyLoginHandlerInterceptor implements HandlerInterceptor {@Overridepublic boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse response, Object handler) throws Exception {log.info("============= MyLoginHandlerInterceptor preHandle =============");try {String requestUrl = httpServletRequest.getRequestURI();ServletRequest requestWrapper = null;String param = "";String method = httpServletRequest.getMethod().toUpperCase();String type = httpServletRequest.getContentType();if (WebRequestConstant.METHOD_TYPE_POST.equals(method) && WebRequestConstant.CONTENT_TYPE_APPLICATION_JSON.equalsIgnoreCase(type)) {requestWrapper = new MyHttpServletRequestWrapper(httpServletRequest);}if (requestWrapper == null) {Map<String, String[]> originRequestMap = httpServletRequest.getParameterMap();Map<String, String> requestMap = new HashMap<String, String>(16);for (String key : originRequestMap.keySet()) {String[] values = originRequestMap.get(key);requestMap.put(key, values[0]);}param = JSON.toJSONString(requestMap);} else {param = ((MyHttpServletRequestWrapper) requestWrapper).getBody();}log.info("拦截器param:{}", param);} catch (Exception e) {e.printStackTrace();}return true;}@Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {log.info("============= MyLoginHandlerInterceptor postHandle =============");}@Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {log.info("============= MyLoginHandlerInterceptor afterCompletion =============");}
}

3.2、注册拦截器

/*** @Author : 一叶浮萍归大海* @Date: 2023/11/4 18:37* @Description:*/
@Configuration
public class MyWebMvcConfigurer implements WebMvcConfigurer {/*** 引入自定义的拦截器对象*/@Resourceprivate MyLoginHandlerInterceptor loginHandlerInterceptor;/*** 注册拦截器* @param registry*      addPathPatterns("/**")：拦截所有*      excludePathPatterns("/business/*")：放行以/business打头的请求*/@Overridepublic void addInterceptors(InterceptorRegistry registry) {registry.addInterceptor(loginHandlerInterceptor).addPathPatterns("/**").excludePathPatterns("/business/*").order(1);// registry.addInterceptor(loginHandlerInterceptor).addPathPatterns("/**");}
}

四、使用拦截器（案例）

4.1、获取Controller层@RequestBody中的对象参数

4.1.1、LoginController#login()

@PostMapping("/login")
public String login(@RequestBody UserDTO param) {log.info("LoginController login param:{}", param);return "OK";
}

4.1.2、测试

4.2、获取Controller层普通的对象参数

4.2.1、LoginController#login2()

@PostMapping("/login2")
public String login2(UserDTO param) {log.info("LoginController login2 param:{}", param);return "OK";
}

4.2.2、测试#form-data

4.2.3、测试#x-www-form-urlencoded

4.3、获取Controller层字符串参数

4.3.1、LoginController#login3()

@GetMapping("/login3")
public String login3(String username,String password) {log.info("LoginController login3 param username:{},password:{}", username,password);return "OK";
}

4.3.2、测试

五、参考

https://blog.csdn.net/w_t_y_y/article/details/103407841https://blog.csdn.net/weixin_45100881/article/details/128660421