项目上有个小需求，要限制访问者的IP，屏蔽未授权的请求。该场景使用过滤器来做再合适不过了。
SecurityFilter.java：
public class SecurityFilter implements Filter {
private Log log = LogFactory.getLog(SecurityFilter.class);
private List<String> whitelist = new ArrayList<String>();
private List<String> regexlist = new ArrayList<String>();
private static final String _JSON_CONTENT = "application/json; charset=UTF-8";
private static final String _HTML_CONTENT = "text/html; charset=UTF-8";
private static final String _403_JSON = "{'code': '403', 'msg': '访问被拒绝，客户端未授权！'}";
private static final String _403_HTML = "<html><body><div style='text-align:center'><h1 style='margin-top: 10px;'>403 Forbidden!</h1><hr><span>@lichmama</span></div></body></html>";
@Override
public void destroy() {
}
@Override
public void doFilter(ServletRequest servletrequest, ServletResponse servletresponse, FilterChain filterchain)
throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) servletrequest;
HttpServletResponse response = (HttpServletResponse) servletresponse;
if (isSecurityRequest(request)) {
filterchain.doFilter(request, response);
} else {
log.info("拒绝来自[" + request.getRemoteAddr() + "]的访问请求：" + request.getRequestURI());
response.setStatus(403);
if (isAjaxRequest(request)) {
response.setContentType(_JSON_CONTENT);
response.getWriter().print(_403_JSON);
} else {
response.setContentType(_HTML_CONTENT);
response.getWriter().print(_403_HTML);
}
}
}
@Override
public void init(FilterConfig filterconfig) throws ServletException {
String allowedIP = filterconfig.getInitParameter("allowedIP");
if (allowedIP != null && allowedIP.length() > 0) {
for (String item : allowedIP.split(",\\s*")) {
// 支持通配符*
if (item.contains("*")) {
String regex = item.replace(".", "\\.").replace("*", "\\d{1,3}");
regexlist.add(regex);
} else {
whitelist.add(item);
}
}
}
}
/**
* 判断当前请求是否来自可信任的地址
*
* @param request
* @return
*/
private boolean isSecurityRequest(HttpServletRequest request) {
String ip = request.getRemoteAddr();
for (String item : whitelist) {
if (ip.equals(item))
return true;
}
for (String item : regexlist) {
if (ip.matches(item))
return true;
}
return false;
}
/**
* 判断请求是否是AJAX请求
* @param request
* @return
*/
private boolean isAjaxRequest(HttpServletRequest request) {
String header = request.getHeader("X-Requested-With");
if (header != null && header.length() > 0) {
if ("XMLHttpRequest".equalsIgnoreCase(header))
return true;
}
return false;
}
}
web.xml增加配置：
<filter>
<filter-name>securityFilter</filter-name>
<filter-class>com.lichmama.webdemo.filter.SecurityFilter</filter-class>
<init-param>
<param-name>allowedIP</param-name>
<param-value>192.168.5.*</param-value>
</init-param>
</filter> <filter-mapping>
<filter-name>securityFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
尝试访问，结果如下：
*如何在Filter中获取Response的内容？这个问题之前还真没思考过，搜索了下得知如下方法可行：
1.实现一个PrintWriterWrapper，用于替换ServletResponse中的Writer
package com.lichmama.webdemo; import java.io.PrintWriter;
import java.io.Writer; public class PrintWriterWrapper extends PrintWriter { private StringBuilder buff; public PrintWriterWrapper(Writer writer) {
super(writer);
buff = new StringBuilder();
} @Override
public void write(int i) {
super.write(i);
buff.append(i);
} @Override
public void write(char[] ac, int i, int j) {
super.write(ac, i, j);
buff.append(ac, i, j);
} @Override
public void write(char[] ac) {
super.write(ac);
buff.append(ac);
} @Override
public void write(String s, int i, int j) {
super.write(s, i, j);
buff.append(s, i, j);
} @Override
public void write(String s) {
super.write(s);
buff.append(s);
} @Override
public void flush() {
super.flush();
buff.delete(0, buff.length());
} public String getContent() {
return buff.toString();
}
}
2.实现一个ResponseWrapper，用于替换过滤链（FilterChain）中的ServletResponse：
package com.lichmama.webdemo; import java.io.IOException;
import java.io.PrintWriter; import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper; public class ResponseWrapper extends HttpServletResponseWrapper { private PrintWriterWrapper writer; public ResponseWrapper(HttpServletResponse response) {
super(response);
} @Override
public PrintWriter getWriter() throws IOException {
if (writer == null)
writer = new PrintWriterWrapper(super.getWriter());
return writer;
} }
3.编写Filter实现获取Response的内容捕获：
package com.lichmama.webdemo.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.HttpServletResponse; import com.lichmama.webdemo.PrintWriterWrapper;
import com.lichmama.webdemo.ResponseWrapper; public class TestFilter implements Filter { @Override
public void init(FilterConfig filterconfig) throws ServletException {
} @Override
public void doFilter(ServletRequest servletrequest, ServletResponse servletresponse, FilterChain filterchain)
throws IOException, ServletException {
ResponseWrapper responsewrapper = new ResponseWrapper((HttpServletResponse) servletresponse);
filterchain.doFilter(servletrequest, responsewrapper);
PrintWriterWrapper writerWrapper = (PrintWriterWrapper) responsewrapper.getWriter();
// TODO retrieve content from PrintWriterWrapper
String content = writerWrapper.getContent();
} @Override
public void destroy() {
} }
that's it~