BaseServlet

package com.czy.web.servlet;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

/**
 * 每个servlet被访问都会执行其上层HttpServlet的service方法
 * 故重写service方法实现抽取
 */
public class BaseServlet extends HttpServlet {
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String uri = req.getRequestURI();  // /travel/user/add
        String methodName = uri.substring(uri.lastIndexOf('/')+1);

        //调用方法：子类会调用父类的service方法那么此时this就是该子类
        try {
            Method method = this.getClass().getMethod(methodName,HttpServletRequest.class,HttpServletResponse.class);
            //暴力反射
            //method.setAccessible(true);
            method.invoke(this,req,resp);
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        }
    }

    /**
     * 将传入的对象序列化，并返回给客户端
     * @param obj
     */
    public void writeValue(Object obj,HttpServletResponse response) throws IOException {
        ObjectMapper mapper = new ObjectMapper();
        response.setContentType("application/json;charset=utf-8");
        mapper.writeValue(response.getWriter(),obj);
    }

    /**
     * 将传入的对象序列化为json，返回
     * @param obj
     * @return
     */
    public String writeValueAsString(Object obj) throws JsonProcessingException {
        ObjectMapper mapper = new ObjectMapper();
        return mapper.writeValueAsString(obj);
    }
}