java解决请求跨域的两种方法

java解决请求跨域问题，有以下两种写法

1.使用拦截器，实现javax.servlet.Filter接口

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.annotation.WebFilter;
import javax.servlet.http.HttpServletResponse;

@WebFilter(filterName="CorsFilter" , urlPatterns="*.do")
public class CorsFilter implements Filter{

 @Override
 public void destroy() {
 }

 @Override
 public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain)
 throws IOException, ServletException {
 HttpServletResponse response = (HttpServletResponse) resp;
 response.setHeader("Access-Control-Allow-Origin", "*"); //解决跨域访问报错
  response.setHeader("Access-Control-Allow-Methods", "POST, PUT, GET, OPTIONS, DELETE");
  response.setHeader("Access-Control-Max-Age", "3600"); //设置过期时间
  response.setHeader("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept, client_id, uuid, Authorization");
  response.setHeader("Cache-Control", "no-cache, no-store, must-revalidate"); // 支持HTTP 1.1.
  response.setHeader("Pragma", "no-cache"); // 支持HTTP 1.0. response.setHeader("Expires", "0");
  chain.doFilter(req, resp); 

 }

 @Override
 public void init(FilterConfig arg0) throws ServletException {
 }
}

如果想用xml的形式配置拦截器，可以删除@WebFilter(filterName="CorsFilter" , urlPatterns="*.do")，然后在web.xml中添加下面的配置

<filter>
 <filter-name>CorsFilter</filter-name>
 <filter-class>com.huaming.filter.CorsFilter</filter-class>
</filter>
<filter-mapping>
 <filter-name>CorsFilter</filter-name>
 <url-pattern>*.do</url-pattern>
</filter-mapping>

2.使用注解的形式，配置org.springframework.web.filter.CorsFilter，通常springboot项目多数使用这种方式

import org.springframework.web.filter.CorsFilter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.cors.CorsConfiguration;
import org.springframework.web.cors.UrlBasedCorsConfigurationSource;

/**
 * 解决跨域问题springboot所需配置
 */
@Configuration
public class CORSConfiguration {

 @Bean
 public CorsFilter corsFilter() {
 //1.添加CORS配置信息
 CorsConfiguration config = new CorsConfiguration();
 //1) 允许的域,不要写*，否则cookie就无法使用了
 config.addAllowedOrigin("*");
 config.addAllowedHeader("*"); // 允许任何头
 config.addAllowedMethod("*"); // 允许任何方法（post、get等）
 //2) 是否发送Cookie信息
 config.setAllowCredentials(true);
 //3) 允许的请求方式
 config.addAllowedMethod("OPTIONS");
 config.addAllowedMethod("HEAD");
 config.addAllowedMethod("GET");
 config.addAllowedMethod("PUT");
 config.addAllowedMethod("POST");
 config.addAllowedMethod("DELETE");
 config.addAllowedMethod("PATCH");
 // 4）允许的头信息
 config.addAllowedHeader("*");

 // 5)配置有效时长
 config.setMaxAge(3600*24L);

 //2.添加映射路径，我们拦截一切请求
 UrlBasedCorsConfigurationSource configSource = new UrlBasedCorsConfigurationSource();
 configSource.registerCorsConfiguration("/**", config);

 //3.返回新的CorsFilter.
 return new CorsFilter(configSource);
 }
}

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