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;
    }
}

以上为个人经验，希望能给大家一个参考，也希望大家多多支持服务器之家。

原文链接：https://blog.csdn.net/WoddenFish/article/details/84836824