Sentinel 错误页优化，自定义返回数据

sentinel 1.8之前的版本，实现 UrlBlockHandler 接口;

sentinel 1.8之后的版本，改成了 BlockExceptionHandler 接口

import com.alibaba.csp.sentinel.adapter.spring.webmvc.callback.BlockExceptionHandler;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.alibaba.csp.sentinel.slots.block.authority.AuthorityException;
import com.alibaba.csp.sentinel.slots.block.degrade.DegradeException;
import com.alibaba.csp.sentinel.slots.block.flow.FlowException;
import com.alibaba.csp.sentinel.slots.block.flow.param.ParamFlowException;
import com.alibaba.csp.sentinel.slots.system.SystemBlockException;

import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.Builder;
import lombok.Data;
import org.springframework.stereotype.Component;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * 错误页优化，自定义返回数据
 */
@Component
public class MyUrlBlockHandler implements BlockExceptionHandler {
    @Override
    public void handle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, BlockException e) throws Exception {
        JsonResult error = null;
        if (e instanceof FlowException) {
            // 限流异常
            error = JsonResult.builder()
                    .status(-1)
                    .msg("被限流了")
                    .build();
        } else if (e instanceof DegradeException) {
            error = JsonResult.builder()
                    .status(-1)
                    .msg("降级")
                    .build();
        } else if (e instanceof ParamFlowException) {
            error = JsonResult.builder()
                    .status(-1)
                    .msg("热点参数限流")
                    .build();
        } else if (e instanceof SystemBlockException) {
            error = JsonResult.builder()
                    .status(-1)
                    .msg("系统规则不通过")
                    .build();
        } else if (e instanceof AuthorityException) {
            error = JsonResult.builder()
                    .status(-1)
                    .msg("授权规则不通过")
                    .build();
        }
        httpServletResponse.setStatus(500);
        httpServletResponse.setCharacterEncoding("utf-8");
        httpServletResponse.setHeader("Content-type", "application/json;charset=utf-8");
        httpServletResponse.setContentType("application/json;charset=utf-8");
        new ObjectMapper().writeValue(httpServletResponse.getWriter(), error);
    }
}

@Builder
@Data
class JsonResult {
    private Integer status;
    private String msg;
}