当jsp请求servlet地址时放回的中文为乱码，首先我数据库中的编码格式为utf-8，包括jsp，myeclipse，servlet，都设置了这个编码，菜鸟小编最终百度到解决办法，直接上代码。

package application.admin.servlet.cate;

import java.io.*;
import javax.servlet.*;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.*;

import org.json.JSONArray;

import application.admin.cate.Cate;
import common.api.CommonApi;


@WebServlet("/CateListServlet")
public class CateListServlet extends HttpServlet {
   private String json_data;

   public void init() throws ServletException
   {

   }

   public void doGet(HttpServletRequest request,
                     HttpServletResponse response)
             throws ServletException, IOException
   {
        request.setCharacterEncoding("UTF-8");
        response.setCharacterEncoding("UTF-8");
        response.setContentType("text/html; charset=utf-8");
        response.setHeader("Content-Type", "text/html; charset=utf-8");
        JSONArray book_cate_list;
        String user_id = request.getParameter("user_id");
        String state = request.getParameter("state");
        Cate cate = new Cate();
        try {
            book_cate_list = cate.book_cate_list();//获取所有图书分类
            int count_cate = cate.count_cate();//统计图书分类个数
            json_data = CommonApi.return_json(book_cate_list,count_cate);//拼装返回数据
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        response.getOutputStream().write(json_data.getBytes("utf-8")); 
   }

   public void destroy()
   {
       // 什么也不做
   }
}

package application.admin.servlet.cate;

import java.io.*;
import javax.servlet.*;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.*;

import org.json.JSONArray;

import application.admin.cate.Cate;
import common.api.CommonApi;


@WebServlet("/CateListServlet")
public class CateListServlet extends HttpServlet {
   private String json_data;

   public void init() throws ServletException
   {

   }

   public void doGet(HttpServletRequest request,
                     HttpServletResponse response)
             throws ServletException, IOException
   {
        request.setCharacterEncoding("UTF-8");
        response.setCharacterEncoding("UTF-8");
        response.setContentType("text/html; charset=utf-8");
        response.setHeader("Content-Type", "text/html; charset=utf-8");
        JSONArray book_cate_list;
        String user_id = request.getParameter("user_id");
        String state = request.getParameter("state");
        Cate cate = new Cate();
        try {
            book_cate_list = cate.book_cate_list();//获取所有图书分类
            int count_cate = cate.count_cate();//统计图书分类个数
            json_data = CommonApi.return_json(book_cate_list,count_cate);//拼装返回数据
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        response.getOutputStream().write(json_data.getBytes("utf-8")); 
   }

   public void destroy()
   {
       // 什么也不做
   }
}