方法一：全局配置（推荐这个）

/**
 * @author qushen
 * @date 2021/2/14 13:12
 */
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 org.springframework.stereotype.Component;

/**
 * 处理跨域问题
 * @author wuzhou
 *
 */
@Component
public class OriginFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest req, ServletResponse res,
                         FilterChain chain) throws IOException, ServletException {
        HttpServletResponse response = (HttpServletResponse) res;
        response.setHeader("Access-Control-Allow-Origin", "*");
        response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE,PUT");
        response.setHeader("Access-Control-Max-Age", "3600");
        response.setHeader("Access-Control-Allow-Headers", "x-requested-with");
        chain.doFilter(req, res);
    }

    @Override
    public void destroy() {
        // TODO Auto-generated method stub

    }

}

方法二： 单类配置

    @RequestMapping(value = "/hello")
    @CrossOrigin(origins = "*")
    public String hello() {
        return "hello";
    }

 方法三：全局配置

@Configuration
public class WebMvcConfig extends WebMvcConfigurerAdapter {

    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/**")
                .allowedOrigins("*")
                .allowedMethods("POST", "GET", "PUT", "OPTIONS", "DELETE")
                .maxAge(3600)
                .allowCredentials(true);
    }
}

////////////////////////////////////////////////////////

@Configuration
public class WebMvcConfig implements WebMvcConfigurer {

    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/**")
                .allowedOrigins("*")
                .allowedMethods("POST", "GET", "PUT", "OPTIONS", "DELETE")
                .maxAge(3600)
                .allowCredentials(true);
    }
}