Bootstrap每天必学之级联下拉菜单_javascript技巧

package com.honzh.spring.controller;

import java.util.ArrayList;
import java.util.List;

import javax.servlet.http.HttpServletResponse;

import org.apache.log4j.Logger;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;

import com.honzh.biz.database.entity.City;
import com.honzh.biz.database.entity.Option;
import com.honzh.biz.database.entity.Provincial;
import com.honzh.common.util.JsonUtil;
import com.honzh.spring.service.CityService;
import com.honzh.spring.service.ProvincialService;

@Controller
@RequestMapping(value = "/procity")
public class ProcityController extends BaseController {
  private static Logger logger = Logger.getLogger(ProcityController.class);

  /**
   * 当传递city_code，则表明下拉框要被选中，否则不选中
   */
  @RequestMapping("")
  public void index(@RequestParam(value = "city_code", required = false) String city_code,
      @RequestParam(value = "pro_code", required = false) String pro_code, HttpServletResponse response) {
    try {
      logger.debug("获取所在地区" + city_code + ", 省" + pro_code);

      // 如果pro_code为””，则表明要获取城市菜单，否则获取市级菜单
      if (!pro_code.equals("")) {
        Integer pro_id = ProvincialService.getInstance().getByProvincialcode(pro_code).getId();
        List citys = CityService.getInstance().getCitysByProvincialId(pro_id);
        List coptions = new ArrayList(citys.size());

        for (City city : citys) {
          Option coption = new Option();
          coption.setId(city.getId());
          coption.setName(city.getCname());
          coption.setValue(city.getCode());

          // 市级菜单被选中
          if (city_code != null && !city_code.equals("")) {
            if (city.getCode().equals(city_code)) {
              coption.setSelected("selected");
            }
          }
          coptions.add(coption);
        }
        renderJson(response, coptions);
      } else {
        List provincials = ProvincialService.getInstance().getProvincials();

        // 转换成标准的option属性（name,value,selected）
        List options = new ArrayList(provincials.size());

        // 被选中的省市
        // 则说明是展示页面，此时需要为省级菜单和市级菜单设置选择项
        if (city_code != null && !city_code.equals("")) {
          Provincial selected_provincial = ProvincialService.getInstance().getProvincialByCitycode(city_code);

          pro_code = selected_provincial.getProcode();
        } else {
          pro_code = provincials.get(0) == null ? "" : provincials.get(0).getProcode();
        }

        for (Provincial provincial : provincials) {
          Option option = new Option();
          option.setId(provincial.getId());
          option.setName(provincial.getProname());
          option.setValue(provincial.getProcode());

          if (!pro_code.equals("") && provincial.getProcode().equals(pro_code)) {
            option.setSelected("selected");
          }

          options.add(option);
        }

        renderJson(response, JsonUtil.toJson(options));
      }

    } catch (Exception e) {
      logger.error(e.getMessage());
      logger.error(e.getMessage(), e);

      renderJson(response, null);
    }
  }

}

package com.honzh.spring.service;

import java.util.ArrayList;
import java.util.List;

import com.honzh.biz.database.entity.City;
import com.honzh.biz.database.entity.Provincial;
import com.honzh.biz.database.mapper.ProvincialMapper;
import com.honzh.common.spring.SpringContextHolder;

public class ProvincialService {

  private static Object lock = new Object();
  private static ProvincialService config = null;

  private ProvincialService() {
    provincials = new ArrayList();

    ProvincialMapper mapper = SpringContextHolder.getBean(ProvincialMapper.class);
    provincials.addAll(mapper.getProvincials());
  }

  public static ProvincialService getInstance() {
    synchronized (lock) {
      if (null == config) {
        config = new ProvincialService();
      }
    }
    return (config);
  }

  public Provincial getByProvincialcode(String provincial_code) {
    for (Provincial provincial : provincials) {
      if (provincial.getProcode().equals(provincial_code)) {
        return provincial;
      }
    }
    return null;
  }

  private List provincials = null;

  public List getProvincials() {
    return provincials;
  }

  public Provincial getProvincialByCitycode(String city_code) {
    City city = CityService.getInstance().getCityByCode(city_code);

    for (Provincial provincial : provincials) {
      if (provincial.getId().intValue() == city.getProid().intValue()) {
        return provincial;
      }
    }
    return null;
  }

  public Provincial getProvincialByCode(String province_code) {
    for (Provincial provincial : provincials) {
      if (provincial.getProcode().equals(province_code)) {
        return provincial;
      }
    }
    return null;
  }

}

  /**
   * 如果出错的话，response直接返回404
   */
  protected void renderJson(HttpServletResponse response, Object responseObject) {
    PrintWriter out = null;
    try {
      if (responseObject == null) {
        response.sendError(404);
        return;
      }
      // 将实体对象转换为JSON Object转换
      String responseStr = JsonUtil.toJson(responseObject);
      response.setCharacterEncoding("UTF-8");
      response.setContentType("application/json; charset=utf-8");

      out = response.getWriter();
      out.append(responseStr);

      logger.debug("返回是：" + responseStr);
    } catch (IOException e) {
      logger.error(e.getMessage());
      logger.error(e.getMessage(), e);
    } finally {
      if (out != null) {
        out.close();
      }
    }
  }