dsProject/ds-gw/src/main/java/com/dsideal/gw/Handler/RouterHandler.java

package com.dsideal.gw.Handler;

import cn.hutool.json.JSONObject;
import com.dsideal.gw.GwApplication;
import com.jfinal.handler.Handler;
import okhttp3.*;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;


public class RouterHandler extends Handler {
    /**
     * 功能：输出JSON文本串
     *
     * @param res
     * @param jo
     */
    public void renderJson(HttpServletResponse res, JSONObject jo) {
        res.setHeader("Access-Control-Allow-Origin", "*");
        res.setHeader("Cache-Control", "no-cache");
        res.setCharacterEncoding("UTF-8");
        res.setContentType("application/json");
        try {
            res.getWriter().println(jo);
            res.getWriter().flush();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    public void renderJson(HttpServletResponse res, String msg) {
        renderJson(res, new JSONObject().put("msg", msg));
    }

    //OkHttp的实例，单例模式
    private static final OkHttpClient OK_HTTP_CLIENT = new OkHttpClient();

    //OkHttp的回调函数，同步执行
    private void executeRequest(Request request, HttpServletResponse res) throws IOException {
        Response response = OK_HTTP_CLIENT.newCall(request).execute();
        if (response.isSuccessful()) {
            String responseBody = response.body().string();
            renderJson(res, responseBody);
        } else {
            renderJson(res, "请求失败！");
        }
    }

    @Override
    public void handle(String target, HttpServletRequest req, HttpServletResponse res, boolean[] isHandled) {

        //可以正确获取到URL的完整路径
        String servletPath = req.getServletPath();
        String queryString = req.getQueryString();

        //路由到哪个微服务
        int firstSlashIndex = servletPath.indexOf('/'); // 找到第一个 '/' 的索引
        int secondSlashIndex = servletPath.indexOf('/', firstSlashIndex + 1); // 从第一个 '/' 之后开始找第二个 '/' 的索引

        if (firstSlashIndex != -1 && secondSlashIndex != -1) {
            String prefix = servletPath.substring(firstSlashIndex + 1, secondSlashIndex); // 截取两个 '/' 之间的内容
            if (!GwApplication.routeDict.containsKey(prefix)) {
                renderJson(res, prefix + "前缀没有找到合适的路由表，请检查是否请求正确！");
            } else {
                //路由到哪个微服务
                String FORWARD_URL = GwApplication.routeDict.get(prefix);
                //处理GET请求
                if (req.getMethod().equals("GET")) {
                    //参数:queryString
                    Request request;
                    if (queryString != null) {
                        request = new Request.Builder().url(FORWARD_URL + "?" + queryString).get().build();
                    } else {
                        request = new Request.Builder().url(FORWARD_URL).get().build();
                    }
                    try {
                        executeRequest(request, res);
                    } catch (IOException e) {
                        renderJson(res, "请求失败！"+ e);
                    }
                }//处理POST请求
                else if (req.getMethod().equals("POST")) {
                    // RequestBody body = RequestBody.create(jsonBody, MediaType.parse("application/json; charset=utf-8"));
                    // Request request = new Request.Builder().url(FORWARD_URL).post(body).build();
                } else {
                    // MinIO - 服务端签名直传（前端 + 后端 + 效果演示）
                    //https://blog.csdn.net/CYK_byte/article/details/140254412
                    renderJson(res, "系统只支持GET,POST，其它的OPTIONS不支持！文件上传请使用S3协议进行直传，不通过JAVA处理，JAVA只处理授权！");
                }
            }
        } else {
            renderJson(res, "输入的字符串格式不正确，没有找到两个 '/'。");
        }
        //停止filter
        isHandled[0] = true;
    }
}