这篇文章将为大家详细讲解有关使用Filter拦截器怎么实现请求跨域转发，小编觉得挺实用的，因此分享给大家做个参考，希望大家阅读完这篇文章后可以有所收获。
Filter拦截器实现请求跨域转发
因为公司项目需求，项目中前端请求需要通过一个类似中转的服务转发(请求在该服务中会重新包装一些通用参数)
在使用Filter实现转发后特做一次记录
package com.unicloud.cce.Filter;
import com.alibaba.fastjson.JSON;
import com.unicloud.cce.common.RestfulEntity;
import com.unicloud.cce.service.CloudosService;
import org.apache.commons.io.IOUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.*;
import org.springframework.stereotype.Component;
import org.springframework.util.AntPathMatcher;
import org.springframework.util.StringUtils;
import org.springframework.web.client.RestTemplate;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.*;
/**
* @author skyxt
* Created 2019-06-11 18:46
* Email skyxt.yang@gmail.com
*/
@WebFilter(filterName = "authFilter", urlPatterns = { "/*" })
@Component
public class RequestFilter implements Filter {
//该处配置需要转发的路径
public static final Set<String> FILTER_URL = Collections.unmodifiableSet(new HashSet<>(Arrays.asList(
"/config/*"
)));
@Autowired
private RestTemplate restTemplate;
@Autowired
private CloudosService cloudosService;
private final static Logger logger = LoggerFactory.getLogger(RequestFilter.class);
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
if (!(request instanceof HttpServletRequest) || !(response instanceof HttpServletResponse)) {
return;
}
HttpServletRequest req = (HttpServletRequest) request;
HttpServletResponse rsp = (HttpServletResponse) response;
AntPathMatcher matcher = new AntPathMatcher();
Optional<String> cloudIp = Optional.empty();
// for (String url : FILTER_URL) {
// if (matcher.match(url, req.getRequestURI().substring(req.getContextPath().length()))) {
// cloudIp = cloudosService.cloudosList("", "").stream().filter(cloudos ->
// cloudos.getId().equals(((HttpServletRequest) request).getHeader("cloudId"))
// ).map(Cloudos::getCloudIp).findFirst();
// }
// }
cloudIp = Optional.of("localhost");
if (cloudIp.isPresent()) {
switch (req.getMethod()) {
case "GET": {
request(req, rsp, HttpMethod.GET, cloudIp.get());
break;
}
case "POST": {
request(req, rsp, HttpMethod.POST, cloudIp.get());
break;
}
case "PUT": {
request(req, rsp, HttpMethod.PUT, cloudIp.get());
break;
}
case "PATCH": {
request(req, rsp, HttpMethod.PATCH, cloudIp.get());
break;
}
case "DELETE": {
request(req, rsp, HttpMethod.DELETE, cloudIp.get());
break;
}
default:{
logger.error("unknow request method:" + req.getMethod());
rsp.setCharacterEncoding("UTF-8");
try (PrintWriter out = rsp.getWriter()) {
out.write("请求方法未知");
} catch (Exception e1) {
logger.error(e1.getMessage() + e1);
}
}
}
} else {
chain.doFilter(request, response);
}
}
@Override
public void destroy() {
}
private void request(HttpServletRequest req, HttpServletResponse rsp, HttpMethod method, String cloudIp) throws IOException {
rsp.setCharacterEncoding("UTF-8");
String requestBody = IOUtils.toString(req.getInputStream(), "UTF-8");
Object body = null;
if (StringUtils.hasText(requestBody)) {
body = JSON.parse(requestBody);
}
HttpHeaders headers = new HttpHeaders();
Enumeration<String> headerNames = req.getHeaderNames();
while (headerNames.hasMoreElements()) {
String name = headerNames.nextElement();
headers.add(name, req.getHeader(name));
}
String url;
if (StringUtils.hasText(req.getQueryString())) {
url = String.format(
"http://%s:15120%s?%s",
cloudIp,
req.getRequestURI().substring(req.getContextPath().length()),
req.getQueryString()
);
} else {
url = String.format(
"http://%s:15120%s",
cloudIp,
req.getRequestURI().substring(req.getContextPath().length())
);
}
HttpEntity<Object> httpEntity = new HttpEntity<>(body, headers);
ResponseEntity<RestfulEntity> exchange = null;
try {
exchange = restTemplate.exchange(
url,
method,
httpEntity,
RestfulEntity.class
);
} catch (Exception e) {
logger.error(e.getMessage(), e);
try (PrintWriter out = rsp.getWriter()) {
out.write("请求异常");
} catch (Exception e1) {
logger.error(e1.getMessage() + e1);
}
}
if (exchange != null) {
exchange.getStatusCode();
rsp.setStatus(exchange.getStatusCodeValue());
exchange.getHeaders().entrySet().stream().forEach(entry -> {
String value = entry.getValue().toString();
rsp.addHeader(entry.getKey(), value.substring(1, value.length()-1));
});
try (PrintWriter out = rsp.getWriter()) {
out.write(JSON.toJSONString(exchange.getBody()));
} catch (Exception e) {
logger.error(e.getMessage(), e);
}
} else {
logger.info("error: URL:" + "http://" + cloudIp + ":15120" + req.getRequestURI().substring(req.getContextPath().length()));
try (PrintWriter out = rsp.getWriter()) {
out.write("请求异常");
} catch (Exception e1) {
logger.error(e1.getMessage() + e1);
}
}
}
}使用filter解决跨域
在web.xml配置拦截器
<filter>
<filter-name>servletFilterTest</filter-name>
<filter-class>cn.test.intercepter.ServletFilterTest</filter-class>
</filter>
<filter-mapping>
<filter-name>servletFilterTest</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
过滤器代码
import org.springframework.web.bind.annotation.RequestMethod;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class ServletFilterTest implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
HttpServletRequest httpServletRequest = (HttpServletRequest) servletRequest;
httpServletRequest.getSession();
HttpServletResponse httpResponse = (HttpServletResponse) servletResponse;
httpResponse.setHeader("Access-Control-Allow-Origin", "*");
httpResponse.setHeader("Access-Control-Allow-Methods", "*");
httpResponse.setHeader("Access-Control-Max-Age", "3600");
httpResponse.setHeader("Access-Control-Allow-Headers",
"Origin, X-Requested-With, Content-Type, Accept, Connection, User-Agent, Cookie");
httpResponse.setHeader("Access-Control-Allow-Credentials", "true");
httpResponse.setHeader("Content-type", "application/json");
httpResponse.setHeader("Cache-Control", "no-cache, must-revalidate");
if (httpServletRequest.getMethod().equals(RequestMethod.OPTIONS.name())) {
return ;
}
filterChain.doFilter(httpServletRequest, httpResponse);
}
@Override
public void destroy() {
}
}关于“使用Filter拦截器怎么实现请求跨域转发”这篇文章就分享到这里了，希望以上内容可以对大家有一定的帮助，使各位可以学到更多知识，如果觉得文章不错，请把它分享出去让更多的人看到。