java配置多个过滤器优先级以及几个常用过滤器操作

一个项目中不出意外的话会有两个以上的过滤器，但是直接不配置的话他会按照你的过滤器名字排序执行，这样的话可能会导致一些性能上或者逻辑上的问题。那么，控制一下执行顺序是我们所必须要做的。

java封装了一个FilterRegistrationBean对象，可以把他比作一个容器，将过滤器套入这个对象中，可以对这个对象进行优先级设置、过滤规则设置等属性，下面是几个常用的过滤器以及过滤器配置。

过滤器配置：

package cn.ask.filter;
import javax.servlet.DispatcherType;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.filter.DelegatingFilterProxy;

/**
* Title:      FilterConfig
* @date       2018年10月25日
* @version    V1.0
* Description: 过滤器配置
*/
@SuppressWarnings("all")
@Configuration
public class FilterConfig {
/**
* @Description 防xss攻击过滤器
* @date 2018年8月16日下午4:55:44
*/
@Bean
public FilterRegistrationBean xssFilterRegistration() {
FilterRegistrationBean registration = new FilterRegistrationBean();
registration.setDispatcherTypes(DispatcherType.REQUEST);
registration.setFilter(new XssFilter());
registration.addUrlPatterns("/*");
registration.setName("xssFilter");
       //order数字越小越先执行
registration.setOrder(1);
return registration;
}

/**  
* @Description 获取登录信息
* @date 2018年10月25日上午9:14:48
*/
@Bean
public FilterRegistrationBean cookieRegistration() {
FilterRegistrationBean registration = new FilterRegistrationBean();
registration.setDispatcherTypes(DispatcherType.REQUEST);
registration.setFilter(new CookieFilter());
registration.addUrlPatterns("/*");
registration.setName("firstFilter");
registration.setOrder(2);
return registration;
}
}

常用过滤器之一：

sso单点登录（使用cookie记录跨站数据）

package cn.ask.filter;
import java.io.IOException;
import java.net.URLDecoder;
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.Cookie;
import javax.servlet.http.HttpServletRequest;
import org.apache.commons.lang3.StringUtils;

/**
* Servlet Filter implementation class FirstFilter
*/
public class CookieFilter implements Filter {

/**
    * Default constructor.
    */
   public CookieFilter() {
       // TODO Auto-generated constructor stub
   }

/**
* @see Filter#destroy()
*/
public void destroy() {
// TODO Auto-generated method stub
}

/**
* @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)
*/
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
HttpServletRequest req = (HttpServletRequest) request;
String tokenHeader = req.getHeader("token");
if(StringUtils.isBlank(tokenHeader)) {
Cookie[] cookies = req.getCookies();
if (cookies != null && cookies.length > 0) {
for (int i = 0; i < cookies.length; i++) {
String name = cookies[i].getName();
String value = cookies[i].getValue();
if ("user_accesstoken".equals(name)) { // 用户token
req.setAttribute("token", URLDecoder.decode(value, "utf-8"));
}
if ("user_avatar".equals(name)) { // 头像
req.setAttribute("avatar", URLDecoder.decode(value, "utf-8"));
}
if ("user_nickname".equals(name)) { // 昵称
req.setAttribute("nickname", URLDecoder.decode(value, "utf-8"));
}
String token = (String) req.getAttribute("token");
if (StringUtils.isBlank(token)) {
req.setAttribute("isLogin", "no");
} else {
req.setAttribute("isLogin", "yes");
}
}
}else {
req.removeAttribute("token");
req.removeAttribute("avatar");
req.removeAttribute("nickname");
req.setAttribute("isLogin", "no");
}
} else {
req.setAttribute("token", tokenHeader);
}

chain.doFilter(request, response);
}

/**
* @see Filter#init(FilterConfig)
*/
public void init(FilterConfig fConfig) throws ServletException {
// TODO Auto-generated method stub
}
}

常用过滤器之二：

xss过滤以及防html注入过滤（包括过滤敏感词）

package cn.ask.filter;
import java.io.IOException;
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;  
/**
* Title:      XssFilter
* @date       2018年8月16日
* @version    V1.0
* Description: xss过滤
*/
public class XssFilter implements Filter {

@Override
public void init(FilterConfig config) throws ServletException {
}

@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
           throws IOException, ServletException {
XssHttpServletRequestWrapper xssRequest = new XssHttpServletRequestWrapper((HttpServletRequest) request);
chain.doFilter(xssRequest, response);
}

@Override
public void destroy() {
}
}

package cn.ask.filter;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.LinkedHashMap;
import java.util.Map;
import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.StringUtils;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;

/**
* Title:      XssHttpServletRequestWrapper
* @date       2018年8月16日
* @version    V1.0
* Description:  XSS过滤处理
*/
public class XssHttpServletRequestWrapper extends HttpServletRequestWrapper {
   /**没被包装过的HttpServletRequest（特殊场景，需要自己过滤*/
   HttpServletRequest orgRequest;
   /**html过滤*/
   private final static HtmlFilter HTMLFILTER = new HtmlFilter();

public XssHttpServletRequestWrapper(HttpServletRequest request) {
       super(request);
       orgRequest = request;
   }

@Override
   public ServletInputStream getInputStream() throws IOException {
       //非json类型，直接返回
       if(!super.getHeader(HttpHeaders.CONTENT_TYPE).equalsIgnoreCase(MediaType.APPLICATION_JSON_VALUE)){
           return super.getInputStream();
       }

//为空，直接返回
       String json = IOUtils.toString(super.getInputStream(), "utf-8");
       if (StringUtils.isBlank(json)) {
           return super.getInputStream();
       }

//xss过滤
       json = xssEncode(json);
       final ByteArrayInputStream bis = new ByteArrayInputStream(json.getBytes());
       return new ServletInputStream() {
           @Override
           public boolean isFinished() {
               return true;
           }

@Override
           public boolean isReady() {
               return true;
           }

@Override
           public void setReadListener(ReadListener readListener) {

}

@Override
           public int read() throws IOException {
               return bis.read();
           }
       };
   }
   @Override
   public String getParameter(String name) {
       String value = super.getParameter(xssEncode(name));
       if (StringUtils.isNotBlank(value)) {
           value = xssEncode(value);
       }
       return value;
   }
   @Override
   public String[] getParameterValues(String name) {
       String[] parameters = super.getParameterValues(name);
       if (parameters == null || parameters.length == 0) {
           return null;
       }

for (int i = 0; i < parameters.length; i++) {
           parameters[i] = xssEncode(parameters[i]);
       }
       return parameters;
   }
   @Override
   public Map<String,String[]> getParameterMap() {
       Map<String,String[]> map = new LinkedHashMap<>();
       Map<String,String[]> parameters = super.getParameterMap();
       for (String key : parameters.keySet()) {
           String[] values = parameters.get(key);
           for (int i = 0; i < values.length; i++) {
               values[i] = xssEncode(values[i]);
           }
           map.put(key, values);
       }
       return map;
   }
   @Override
   public String getHeader(String name) {
       String value = super.getHeader(xssEncode(name));
       if (StringUtils.isNotBlank(value)) {
           value = xssEncode(value);
       }
       return value;
   }
   //富文本内容放行
   private String xssEncode(String input) {
   if(!input.startsWith("<p")&&!input.startsWith("<ol")&&!input.startsWith("<ul")&&!input.startsWith("<hr/>")) {
   input=HTMLFILTER.filter(input);
   }
       //敏感词过滤
       input=SensitiveWordUtils.getSensitiveWordUtils().replaceSensitiveWord(input, '*', 2);
       return input;        
   }
   /**
    * 获取最原始的request
    */
   public HttpServletRequest getOrgRequest() {
       return orgRequest;
   }
   /**
    * 获取最原始的request
    */
   public static HttpServletRequest getOrgRequest(HttpServletRequest request) {
       if (request instanceof XssHttpServletRequestWrapper) {
           return ((XssHttpServletRequestWrapper) request).getOrgRequest();
       }
       return request;
   }
}

package cn.ask.filter;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.logging.Logger;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* Title:      HTMLFilter
* @date       2018年8月16日
* @version    V1.0
* Description: 防html注入
*/
public final class HtmlFilter {
   /** regex flag union representing /si modifiers in php **/
   private static final int REGEX_FLAGS_SI = Pattern.CASE_INSENSITIVE | Pattern.DOTALL;
   private static final Pattern P_COMMENTS = Pattern.compile("<!--(.*?)-->", Pattern.DOTALL);
   private static final Pattern P_COMMENT = Pattern.compile("^!--(.*)--$", REGEX_FLAGS_SI);
   private static final Pattern P_TAGS = Pattern.compile("<(.*?)>", Pattern.DOTALL);
   private static final Pattern P_END_TAG = Pattern.compile("^/([a-z0-9]+)", REGEX_FLAGS_SI);
   private static final Pattern P_START_TAG = Pattern.compile("^([a-z0-9]+)(.*?)(/?)$", REGEX_FLAGS_SI);
   private static final Pattern P_QUOTED_ATTRIBUTES = Pattern.compile("([a-z0-9]+)=([\"'])(.*?)\\2", REGEX_FLAGS_SI);
   private static final Pattern P_UNQUOTED_ATTRIBUTES = Pattern.compile("([a-z0-9]+)(=)([^\"\\s']+)", REGEX_FLAGS_SI);
   private static final Pattern P_PROTOCOL = Pattern.compile("^([^:]+):", REGEX_FLAGS_SI);
   private static final Pattern P_ENTITY = Pattern.compile("&#(\\d+);?");
   private static final Pattern P_ENTITY_UNICODE = Pattern.compile("&#x([0-9a-f]+);?");
   private static final Pattern P_ENCODE = Pattern.compile("％([0-9a-f]{2});?");
   private static final Pattern P_VALID_ENTITIES = Pattern.compile("&([^&;]*)(?=(;|&|$))");
   private static final Pattern P_VALID_QUOTES = Pattern.compile("(>|^)([^<]+?)(<|$)", Pattern.DOTALL);
   private static final Pattern P_END_ARROW = Pattern.compile("^>");
   private static final Pattern P_BODY_TO_END = Pattern.compile("<([^>]*?)(?=<|$)");
   private static final Pattern P_XML_CONTENT = Pattern.compile("(^|>)([^<]*?)(?=>)");
   private static final Pattern P_STRAY_LEFT_ARROW = Pattern.compile("<([^>]*?)(?=<|$)");
   private static final Pattern P_STRAY_RIGHT_ARROW = Pattern.compile("(^|>)([^<]*?)(?=>)");
   private static final Pattern P_AMP = Pattern.compile("&");
   private static final Pattern P_QUOTE = Pattern.compile("<");
   private static final Pattern P_LEFT_ARROW = Pattern.compile("<");
   private static final Pattern P_RIGHT_ARROW = Pattern.compile(">");
   private static final Pattern P_BOTH_ARROWS = Pattern.compile("<>");
   private static final String SS="#//";

/** @xxx could grow large... maybe use sesat's ReferenceMap */
   private static final ConcurrentMap<String,Pattern> P_REMOVE_PAIR_BLANKS = new ConcurrentHashMap<String, Pattern>();
   private static final ConcurrentMap<String,Pattern> P_REMOVE_SELF_BLANKS = new ConcurrentHashMap<String, Pattern>();

/** set of allowed html elements, along with allowed attributes for each element **/
   private final Map<String, List<String>> vAllowed;
   /** counts of open tags for each (allowable) html element **/
   private final Map<String, Integer> vTagCounts = new HashMap<String, Integer>();

/** html elements which must always be self-closing (e.g. "<img />") **/
   private final String[] vSelfClosingTags;
   /** html elements which must always have separate opening and closing tags (e.g. "<b></b>") **/
   private final String[] vNeedClosingTags;
   /** set of disallowed html elements **/
   private final String[] vDisallowed;
   /** attributes which should be checked for valid protocols **/
   private final String[] vProtocolAtts;
   /** allowed protocols **/
   private final String[] vAllowedProtocols;
   /** tags which should be removed if they contain no content (e.g. "<b></b>" or "<b />") **/
   private final String[] vRemoveBlanks;
   /** entities allowed within html markup **/
   private final String[] vAllowedEntities;
   /** flag determining whether comments are allowed in input String. */
   private final boolean stripComment;
   private final boolean encodeQuotes;
   private boolean vDebug = false;
   /**
    * flag determining whether to try to make tags when presented with "unbalanced"
    * angle brackets (e.g. "<b text </b>" becomes "<b> text </b>").  If set to false,
    * unbalanced angle brackets will be html escaped.
    */
   private final boolean alwaysMakeTags;

/** Default constructor.
    *
    */
   public HtmlFilter() {
       vAllowed = new HashMap<>();

final ArrayList<String> aAtts = new ArrayList<String>();
       aAtts.add("href");
       aAtts.add("target");
       vAllowed.put("a", aAtts);

final ArrayList<String> imgAtts = new ArrayList<String>();
       imgAtts.add("src");
       imgAtts.add("width");
       imgAtts.add("height");
       imgAtts.add("alt");
       vAllowed.put("img", imgAtts);

final ArrayList<String> noAtts = new ArrayList<String>();
       vAllowed.put("b", noAtts);
       vAllowed.put("strong", noAtts);
       vAllowed.put("i", noAtts);
       vAllowed.put("em", noAtts);

vSelfClosingTags = new String[]{"img"};
       vNeedClosingTags = new String[]{"a", "b", "strong", "i", "em"};
       vDisallowed = new String[]{};
       /**no ftp*/
       vAllowedProtocols = new String[]{"http", "mailto", "https"};
       vProtocolAtts = new String[]{"src", "href"};
       vRemoveBlanks = new String[]{"a", "b", "strong", "i", "em"};
       vAllowedEntities = new String[]{"amp", "gt", "lt", "quot"};
       stripComment = true;
       encodeQuotes = true;
       alwaysMakeTags = true;
   }
   /** Set debug flag to true. Otherwise use default settings. See the default constructor.
    *
    * @param debug turn debug on with a true argument
    */
   public HtmlFilter(final boolean debug) {
       this();
       vDebug = debug;
   }
   /** Map-parameter configurable constructor.
    *
    * @param conf map containing configuration. keys match field names.
    */
   @SuppressWarnings("unchecked")
public HtmlFilter(final Map<String,Object> conf) {

assert conf.containsKey("vAllowed") : "configuration requires vAllowed";
       assert conf.containsKey("vSelfClosingTags") : "configuration requires vSelfClosingTags";
       assert conf.containsKey("vNeedClosingTags") : "configuration requires vNeedClosingTags";
       assert conf.containsKey("vDisallowed") : "configuration requires vDisallowed";
       assert conf.containsKey("vAllowedProtocols") : "configuration requires vAllowedProtocols";
       assert conf.containsKey("vProtocolAtts") : "configuration requires vProtocolAtts";
       assert conf.containsKey("vRemoveBlanks") : "configuration requires vRemoveBlanks";
       assert conf.containsKey("vAllowedEntities") : "configuration requires vAllowedEntities";

vAllowed = Collections.unmodifiableMap((HashMap<String, List<String>>) conf.get("vAllowed"));
       vSelfClosingTags = (String[]) conf.get("vSelfClosingTags");
       vNeedClosingTags = (String[]) conf.get("vNeedClosingTags");
       vDisallowed = (String[]) conf.get("vDisallowed");
       vAllowedProtocols = (String[]) conf.get("vAllowedProtocols");
       vProtocolAtts = (String[]) conf.get("vProtocolAtts");
       vRemoveBlanks = (String[]) conf.get("vRemoveBlanks");
       vAllowedEntities = (String[]) conf.get("vAllowedEntities");
       stripComment =  conf.containsKey("stripComment") ? (Boolean) conf.get("stripComment") : true;
       encodeQuotes = conf.containsKey("encodeQuotes") ? (Boolean) conf.get("encodeQuotes") : true;
       alwaysMakeTags = conf.containsKey("alwaysMakeTags") ? (Boolean) conf.get("alwaysMakeTags") : true;
   }
   private void reset() {
       vTagCounts.clear();
   }
   private void debug(final String msg) {
       if (vDebug) {
           Logger.getAnonymousLogger().info(msg);
       }
   }
   //---------------------------------------------------------------
   /**my versions of some PHP library functions*/
   public static String chr(final int decimal) {
       return String.valueOf((char) decimal);
   }

public static String htmlSpecialChars(final String s) {
       String result = s;
       result = regexReplace(P_AMP, "&amp;", result);
       result = regexReplace(P_QUOTE, "&quot;", result);
       result = regexReplace(P_LEFT_ARROW, "&lt;", result);
       result = regexReplace(P_RIGHT_ARROW, "&gt;", result);
       return result;
   }
   //---------------------------------------------------------------
   /**
    * given a user submitted input String, filter out any invalid or restricted
    * html.
    *
    * @param input text (i.e. submitted by a user) than may contain html
    * @return "clean" version of input, with only valid, whitelisted html elements allowed
    */
   public String filter(final String input) {
       reset();
       String s = input;

debug("************************************************");
       debug("              INPUT: " + input);

s = escapeComments(s);
       debug("     escapeComments: " + s);

s = balanceHTML(s);
       debug("        balanceHTML: " + s);

s = checkTags(s);
       debug("          checkTags: " + s);

s = processRemoveBlanks(s);
       debug("processRemoveBlanks: " + s);

s = validateEntities(s);
       debug("    validateEntites: " + s);

debug("************************************************\n\n");
       return s;
   }
   public boolean isAlwaysMakeTags(){
       return alwaysMakeTags;
   }
   public boolean isStripComments(){
       return stripComment;
   }
   private String escapeComments(final String s) {
       final Matcher m = P_COMMENTS.matcher(s);
       final StringBuffer buf = new StringBuffer();
       if (m.find()) {
       /**(.*?)*/
           final String match = m.group(1);
           m.appendReplacement(buf, Matcher.quoteReplacement("<!--" + htmlSpecialChars(match) + "-->"));
       }
       m.appendTail(buf);
       return buf.toString();
   }
   private String balanceHTML(String s) {
       if (alwaysMakeTags) {
           //
           // try and form html
           //
           s = regexReplace(P_END_ARROW, "", s);
           s = regexReplace(P_BODY_TO_END, "<$1>", s);
           s = regexReplace(P_XML_CONTENT, "$1<$2", s);

} else {
           //
           // escape stray brackets
           //
           s = regexReplace(P_STRAY_LEFT_ARROW, "&lt;$1", s);
           s = regexReplace(P_STRAY_RIGHT_ARROW, "$1$2&gt;<", s);

//
           // the last regexp causes '<>' entities to appear
           // (we need to do a lookahead assertion so that the last bracket can
           // be used in the next pass of the regexp)
           //
           s = regexReplace(P_BOTH_ARROWS, "", s);
       }
       return s;
   }
   private String checkTags(String s) {
       Matcher m = P_TAGS.matcher(s);

final StringBuffer buf = new StringBuffer();
       while (m.find()) {
           String replaceStr = m.group(1);
           replaceStr = processTag(replaceStr);
           m.appendReplacement(buf, Matcher.quoteReplacement(replaceStr));
       }
       m.appendTail(buf);
       s = buf.toString();
       // these get tallied in processTag
       // (remember to reset before subsequent calls to filter method)
       for (String key : vTagCounts.keySet()) {
           for (int ii = 0; ii < vTagCounts.get(key); ii++) {
               s += "</" + key + ">";
           }
       }
       return s;
   }
   private String processRemoveBlanks(final String s) {
       String result = s;
       for (String tag : vRemoveBlanks) {
           if(!P_REMOVE_PAIR_BLANKS.containsKey(tag)){
               P_REMOVE_PAIR_BLANKS.putIfAbsent(tag, Pattern.compile("<" + tag + "(\\s[^>]*)?></" + tag + ">"));
           }
           result = regexReplace(P_REMOVE_PAIR_BLANKS.get(tag), "", result);
           if(!P_REMOVE_SELF_BLANKS.containsKey(tag)){
               P_REMOVE_SELF_BLANKS.putIfAbsent(tag, Pattern.compile("<" + tag + "(\\s[^>]*)?/>"));
           }
           result = regexReplace(P_REMOVE_SELF_BLANKS.get(tag), "", result);
       }
       return result;
   }
   private static String regexReplace(final Pattern regexPattern, final String replacement, final String s) {
       Matcher m = regexPattern.matcher(s);
       return m.replaceAll(replacement);
   }
   private String processTag(final String s) {
       // ending tags
       Matcher m = P_END_TAG.matcher(s);
       if (m.find()) {
           final String name = m.group(1).toLowerCase();
           if (allowed(name)) {
               if (!inArray(name, vSelfClosingTags)) {
                   if (vTagCounts.containsKey(name)) {
                       vTagCounts.put(name, vTagCounts.get(name) - 1);
                       return "</" + name + ">";
                   }
               }
           }
       }
       // starting tags
       m = P_START_TAG.matcher(s);
       if (m.find()) {
           final String name = m.group(1).toLowerCase();
           final String body = m.group(2);
           String ending = m.group(3);
           //debug( "in a starting tag, name='" + name + "'; body='" + body + "'; ending='" + ending + "'" );
           if (allowed(name)) {
               String params = "";
               final Matcher m2 = P_QUOTED_ATTRIBUTES.matcher(body);
               final Matcher m3 = P_UNQUOTED_ATTRIBUTES.matcher(body);
               final List<String> paramNames = new ArrayList<String>();
               final List<String> paramValues = new ArrayList<String>();
               while (m2.find()) {
               /**([a-z0-9]+)*/
                   paramNames.add(m2.group(1));
                   /**(.*?)*/
                   paramValues.add(m2.group(3));
               }
               while (m3.find()) {
               /**([a-z0-9]+)*/
                   paramNames.add(m3.group(1));
                   /**([^\"\\s']+)*/
                   paramValues.add(m3.group(3));
               }
               String paramName, paramValue;
               for (int ii = 0; ii < paramNames.size(); ii++) {
                   paramName = paramNames.get(ii).toLowerCase();
                   paramValue = paramValues.get(ii);
                   if (allowedAttribute(name, paramName)) {
                       if (inArray(paramName, vProtocolAtts)) {
                           paramValue = processParamProtocol(paramValue);
                       }
                       params += " " + paramName + "=\"" + paramValue + "\"";
                   }
               }
               if (inArray(name, vSelfClosingTags)) {
                   ending = " /";
               }
               if (inArray(name, vNeedClosingTags)) {
                   ending = "";
               }
               if (ending == null || ending.length() < 1) {
                   if (vTagCounts.containsKey(name)) {
                       vTagCounts.put(name, vTagCounts.get(name) + 1);
                   } else {
                       vTagCounts.put(name, 1);
                   }
               } else {
                   ending = " /";
               }
               return "<" + name + params + ending + ">";
           } else {
               return "";
           }
       }
       // comments
       m = P_COMMENT.matcher(s);
       if (!stripComment && m.find()) {
           return  "<" + m.group() + ">";
       }
       return "";
   }
   private String processParamProtocol(String s) {
       s = decodeEntities(s);
       final Matcher m = P_PROTOCOL.matcher(s);
       if (m.find()) {
           final String protocol = m.group(1);
           if (!inArray(protocol, vAllowedProtocols)) {
               // bad protocol, turn into local anchor link instead
               s = "#" + s.substring(protocol.length() + 1, s.length());
               if (s.startsWith(SS)) {
                   s = "#" + s.substring(3, s.length());
               }
           }
       }
       return s;
   }
   private String decodeEntities(String s) {
       StringBuffer buf = new StringBuffer();

Matcher m = P_ENTITY.matcher(s);
       while (m.find()) {
           final String match = m.group(1);
           final int decimal = Integer.decode(match).intValue();
           m.appendReplacement(buf, Matcher.quoteReplacement(chr(decimal)));
       }
       m.appendTail(buf);
       s = buf.toString();

buf = new StringBuffer();
       m = P_ENTITY_UNICODE.matcher(s);
       while (m.find()) {
           final String match = m.group(1);
           final int decimal = Integer.valueOf(match, 16).intValue();
           m.appendReplacement(buf, Matcher.quoteReplacement(chr(decimal)));
       }
       m.appendTail(buf);
       s = buf.toString();

buf = new StringBuffer();
       m = P_ENCODE.matcher(s);
       while (m.find()) {
           final String match = m.group(1);
           final int decimal = Integer.valueOf(match, 16).intValue();
           m.appendReplacement(buf, Matcher.quoteReplacement(chr(decimal)));
       }
       m.appendTail(buf);
       s = buf.toString();

s = validateEntities(s);
       return s;
   }
   private String validateEntities(final String s) {
       StringBuffer buf = new StringBuffer();

// validate entities throughout the string
       Matcher m = P_VALID_ENTITIES.matcher(s);
       while (m.find()) {
       /**([^&;]*)*/
           final String one = m.group(1);
           /**(?=(;|&|$))*/
           final String two = m.group(2);
           m.appendReplacement(buf, Matcher.quoteReplacement(checkEntity(one, two)));
       }
       m.appendTail(buf);
       return encodeQuotes(buf.toString());
   }
   private String encodeQuotes(final String s){
       if(encodeQuotes){
           StringBuffer buf = new StringBuffer();
           Matcher m = P_VALID_QUOTES.matcher(s);
           while (m.find()) {
           /**(>|^)*/
               final String one = m.group(1);
               /**([^<]+?)*/
               final String two = m.group(2);
               /**(<|$)*/
               final String three = m.group(3);
               m.appendReplacement(buf, Matcher.quoteReplacement(one + regexReplace(P_QUOTE, "&quot;", two) + three));
           }
           m.appendTail(buf);
           return buf.toString();
       }else{
           return s;
       }
   }
   private String checkEntity(final String preamble, final String term) {

return ";".equals(term) && isValidEntity(preamble)
               ? '&' + preamble
               : "&amp;" + preamble;
   }
   private boolean isValidEntity(final String entity) {
       return inArray(entity, vAllowedEntities);
   }
   private static boolean inArray(final String s, final String[] array) {
       for (String item : array) {
           if (item != null && item.equals(s)) {
               return true;
           }
       }
       return false;
   }
   private boolean allowed(final String name) {
       return (vAllowed.isEmpty() || vAllowed.containsKey(name)) && !inArray(name, vDisallowed);
   }
   private boolean allowedAttribute(final String name, final String paramName) {
       return allowed(name) && (vAllowed.isEmpty() || vAllowed.get(name).contains(paramName));
   }
}

敏感词过滤工具类

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Serializable;
import java.util.*;
import org.springframework.core.io.ClassPathResource;

/**
* Title:      SensitiveWordUtils
* @author:    gaodeqiang
* @date       2018年12月12日
* @version    V1.0
* Description: 敏感词过滤
*/
@SuppressWarnings("all")
public class SensitiveWordUtils implements Serializable {
private static final long serialVersionUID = 1L;
private SensitiveWordUtils() {
}

private static SensitiveWordUtils sensitiveWordUtils = null;

public synchronized static SensitiveWordUtils getSensitiveWordUtils() {
if (sensitiveWordUtils == null) {
sensitiveWordUtils = new SensitiveWordUtils();
}
return sensitiveWordUtils;
}
private static Set<String> sensitiveWordSet = null;
static {
try {
readResource("keywords.txt");
} catch (Exception e) {
e.printStackTrace();
}
// 初始化敏感词库
initSensitiveWordMap();
}
private static final int MinMatchTYpe = 1; // 最小匹配规则，如：敏感词库["中国","中国人"]，语句："我是中国人"，匹配结果：我是[中国]人
private static final int MaxMatchType = 2; // 最大匹配规则，如：敏感词库["中国","中国人"]，语句："我是中国人"，匹配结果：我是[中国人]
private static HashMap sensitiveWordMap = new HashMap<>();

/**
* @author gaodeqiang
* @Description 读取资源文件
* @date 2018年12月13日上午9:29:01
*/
private static void readResource(String name) throws Exception {
ClassPathResource resource = new ClassPathResource(name);
InputStream inputStream = resource.getInputStream();
InputStreamReader read = new InputStreamReader(inputStream, "utf-8");
// 初始化set集合
sensitiveWordSet = new HashSet<String>();
// 缓冲区读取流
BufferedReader bufferedReader = new BufferedReader(read);
// 循环读取文件中内容，每次读取一行内容
String txt = null;
while ((txt = bufferedReader.readLine()) != null) {
// 读取文件，将文件内容放入到set中
sensitiveWordSet.add(txt);
}
read.close();
}
/**
* @author gaodeqiang
* @Description 初始化敏感词库，构建DFA算法模型
* @date 2018年12月13日上午9:30:08
*/
private static void initSensitiveWordMap() {
// 初始化敏感词容器，减少扩容操作
sensitiveWordMap = new HashMap(sensitiveWordSet.size());
String key;
Map nowMap;
Map<String, String> newWorMap;
// 迭代sensitiveWordSet
Iterator<String> iterator = sensitiveWordSet.iterator();
while (iterator.hasNext()) {
// 关键字
key = iterator.next();
nowMap = sensitiveWordMap;
for (int i = 0; i < key.length(); i++) {
// 转换成char型
char keyChar = key.charAt(i);
// 库中获取关键字
Object wordMap = nowMap.get(keyChar);
// 如果存在该key，直接赋值，用于下一个循环获取
if (wordMap != null) {
nowMap = (Map) wordMap;
} else {
// 不存在则，则构建一个map，同时将isEnd设置为0，因为他不是最后一个
newWorMap = new HashMap<>();
// 不是最后一个
newWorMap.put("isEnd", "0");
nowMap.put(keyChar, newWorMap);
nowMap = newWorMap;
}

if (i == key.length() - 1) {
// 最后一个
nowMap.put("isEnd", "1");
}
}
}
}
/**
* @author gaodeqiang
* @Description 检查文字中是否包含敏感字符
* @date 2018年12月13日上午9:38:35
*/
private int checkSensitiveWord(String txt, int beginIndex, int matchType) {
// 敏感词结束标识位：用于敏感词只有1位的情况
boolean flag = false;
// 匹配标识数默认为0
int matchFlag = 0;
char word;
Map nowMap = sensitiveWordMap;
for (int i = beginIndex; i < txt.length(); i++) {
word = txt.charAt(i);
// 获取指定key
nowMap = (Map) nowMap.get(word);
if (nowMap != null) {// 存在，则判断是否为最后一个
// 找到相应key，匹配标识+1
matchFlag++;
// 如果为最后一个匹配规则,结束循环，返回匹配标识数
if ("1".equals(nowMap.get("isEnd"))) {
// 结束标志位为true
flag = true;
// 最小规则，直接返回,最大规则还需继续查找
if (MinMatchTYpe == matchType) {
break;
}
}
} else {// 不存在，直接返回
break;
}
}
if (matchFlag < 2 || !flag) {// 长度必须大于等于1，为词
matchFlag = 0;
}
return matchFlag;
}
/**
* @author gaodeqiang
* @Description 判断文字是否包含敏感字符 匹配规则 1：最小匹配规则，2：最大匹配规则
* @date 2018年12月13日上午9:34:23
*/
public boolean contains(String txt, int matchType) {
boolean flag = false;
for (int i = 0; i < txt.length(); i++) {
int matchFlag = checkSensitiveWord(txt, i, matchType); // 判断是否包含敏感字符
if (matchFlag > 0) { // 大于0存在，返回true
flag = true;
}
}
return flag;
}
/**
* @author gaodeqiang
* @Description 获取文字中的敏感词
* @date 2018年12月13日上午9:36:00
*/
public Set<String> getSensitiveWord(String txt, int matchType) {
Set<String> sensitiveWordList = new HashSet<>();

for (int i = 0; i < txt.length(); i++) {
// 判断是否包含敏感字符
int length = checkSensitiveWord(txt, i, matchType);
if (length > 0) {// 存在,加入list中
sensitiveWordList.add(txt.substring(i, i + length));
i = i + length - 1;// 减1的原因，是因为for会自增
}
}
return sensitiveWordList;
}
/**
* @author gaodeqiang
* @Description 替换敏感字字符
* @date 2018年12月13日上午9:36:34
*/
public String replaceSensitiveWord(String txt, char replaceChar, int matchType) {
String resultTxt = txt;
// 获取所有的敏感词
Set<String> set = getSensitiveWord(txt, matchType);
Iterator<String> iterator = set.iterator();
String word;
String replaceString;
while (iterator.hasNext()) {
word = iterator.next();
replaceString = getReplaceChars(replaceChar, word.length());
resultTxt = resultTxt.replaceAll(word, replaceString);
}
return resultTxt;
}

/**
* @author gaodeqiang
* @Description 获取替换字符串
* @date 2018年12月13日上午9:37:53
*/
private String getReplaceChars(char replaceChar, int length) {
String resultReplace = String.valueOf(replaceChar);
for (int i = 1; i < length; i++) {
resultReplace += replaceChar;
}
return resultReplace;
}
}

来源：https://blog.csdn.net/WoddenFish/article/details/84836824