SpringMvc 系统启动时加载数据到内存中

 

 在项目启动时加载数据到内存中(我这里是数据字典)，以后再代码中就不用每次从​​数据库​​去查询了

  Dictionary 数据字典实体

SysInitBean  要初始化的Bean，要实现  ServletContextAware 接口

package com.wonders.framework.base;

import java.util.Properties;

import javax.servlet.ServletContext;

import net.sf.json.JSONObject;

import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.web.context.ServletContextAware;

import com.wonders.framework.dictionary.service.DictionaryService;
import com.wonders.framework.util.FileUtil;

//实现ServletContextAware，可以获得servletcontext
//@Component注解了，直接在xml里配置这个bean就行了，系统自动调用
@Component
public class SysInitBean implements  ServletContextAware {
  @Autowired
  private DictionaryService dictionaryService;
  
  @Override
  public void setServletContext(ServletContext sc) {
    // 把项目名称放到application中
    String ctxPath=sc.getContextPath();
    sc.setAttribute("ctxPath",ctxPath);
    
    //初始化数据字典到application中
    dictionaryService.init(sc);
  }
}

DictionaryServiceImpl 

     用来查询数据字典

package com.wonders.framework.dictionary.service.impl;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;

import javax.servlet.ServletContext;

import net.sf.json.JSONObject;

import org.apache.log4j.Logger;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import com.wonders.framework.dictionary.dao.DictionaryDao;
import com.wonders.framework.dictionary.entity.po.Dictionary;
import com.wonders.framework.dictionary.service.DictionaryService;
import com.wonders.framework.util.FileUtil;

@Component("dictionaryServiceImpl")
public class DictionaryServiceImpl implements DictionaryService {
  private static Logger logger = Logger.getLogger(DictionaryServiceImpl.class
      .getName());

  // private static Map<String, Map<String, String>> localDics = new
  // HashMap<String, Map<String, String>>();
  @Autowired
  private DictionaryDao dictionaryDao;
  private ServletContext sc;

  // @PostConstruct
  public void init(ServletContext sc) {
    this.sc = sc;
    List<Dictionary> list = null;
    try {
      list = dictionaryDao.findAll();
    } catch (Exception e) {
      logger.error("数据字典数据查找失败!");
    }
    if (null == list) {
      return;
    }
    Map<String, Map<String, String>> localDics = new HashMap<String, Map<String, String>>();
    Map<String, String> map = null;
    for (Dictionary dic : list) {
      String type = dic.getType();
      if (localDics.containsKey(type)) {
        map = localDics.get(type);
        map.put(dic.getKey(), dic.getValue());
      } else {
        map = new HashMap<String, String>();
        map.put(dic.getKey(), dic.getValue());
        localDics.put(type, map);
      }
    }
    Properties prop = FileUtil
        .getProperties("/config/dictionary.properties");
    for (Object key : prop.keySet()) {
      Object value = prop.get(key);
      sc.setAttribute((String) key,
          JSONObject.fromObject(localDics.get(value)));
    }
  }

  public String getValue(String type, String key) {
    JSONObject jsonObject = (JSONObject) sc.getAttribute(type);
    return (String) jsonObject.get(key);
  }

  public boolean isDic(String type) {
    JSONObject jsonObject = (JSONObject) sc.getAttribute(type);
    return jsonObject == null ? false : true;
  }

  public String getKey(String type, String value) {
    JSONObject jsonObject = (JSONObject) sc.getAttribute(type);
    for (Object key : jsonObject.keySet()) {
      String sValue = (String) jsonObject.get(key);
      if (sValue.equals(value)) {
        return (String) key;
      }
    }
    return null;
  }

  // @PreDestroy
  // public void destroy() {
  // localDics = null;
  // }

  @SuppressWarnings("unchecked")
  public Map<String, String> findDictionary(String type) {
    JSONObject jsonObject = (JSONObject) sc.getAttribute(type);
    return jsonObject;
  }
}