easyui-datagrid通过action从数据库获取数据的关键代码

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实际上是结合struts2来从数据获取json格式的数据。
 
关键代码:
GetUserAction.java代码
 
package com.log.control;
import java.io.IOException;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.http.HttpServletRequest;
import org.apache.struts2.ServletActionContext;
import org.codehaus.jackson.JsonFactory;
import org.codehaus.jackson.JsonGenerator;
import org.codehaus.jackson.map.ObjectMapper;
import com.log.entity.User4;
import com.opensymphony.xwork2.ActionSupport;
 
/**
 * 用于从数据库获取数据
 * @author Wei
 * @time  2016年9月19日 上午12:45:39
 */
public class GetUserAction extends ActionSupport {
      private User4 user;
      /**
       *
       */
      private static final long serialVersionUID = 1L;
      /**
       * 获取json格式字符串
       * @param obj
       * @return
       */
      public String getJsonString(Object obj) {
            ObjectMapper om = new ObjectMapper();
            StringWriter sw = new StringWriter();
            try {
                  JsonGenerator jg = new JsonFactory().createJsonGenerator(sw);
                  om.writeValue(jg, obj);
                  jg.close();
            } catch (IOException e) {
                  // TODO Auto-generated catch block
                  e.printStackTrace();
            }
            return sw.toString();
      }
      /**
       * 把从数据库获取到的数据 List<User4> list 写到页面上
       * @param obj
       */
      public void writeJson(Object obj) {
            String json = getJsonString(obj);
            try {
                  ServletActionContext.getResponse().setContentType("text/html;charset=utf-8");
                  ServletActionContext.getResponse().getWriter().write(json);
            } catch (IOException e) {
                  // TODO Auto-generated catch block
                  e.printStackTrace();
            }
      }
      /**
       *
       */
      @Override
      public String execute() throws Exception {
            // easyui-datagrid表格 点击下一页的时候 的参数 page=2&rows=11&sort=email&order=DESC
            HttpServletRequest req = ServletActionContext.getRequest();
            //System.out.println("---11111---page:"+req.getParameter("page"));
            //System.out.println("GetUserAction.java----------"+req.getQueryString());
            UserDao dao = new UserDao();
            //开启hibernate的transaction等
            dao.init();
            List<User4> list = new ArrayList<User4>();
            for(int i=1;i<20;i++){
                  //通过hibernate从数据库获取数据,放到list中
                  list.add((User4) dao.session.get(User4.class, i));
            }
            //销毁hibernate相关的资源
            dao.destroy();
            //写到页面上
            writeJson(list);
            return null;
      }
}
 
UserDao.java代码
package com.log.control;
import java.sql.Date;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
public class UserDao {
//    private SessionFactory sessionFactory;
//    private Session session;
//    private Transaction transaction;
      
      public SessionFactory sessionFactory;
      public Session session;
      public Transaction transaction;
//    @Before
      public void init() {
            Configuration configuration = new Configuration().configure();
            ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties())
                        .buildServiceRegistry();
            sessionFactory = configuration.buildSessionFactory(serviceRegistry);
            session = sessionFactory.openSession();
            transaction = session.beginTransaction();
      }
//    @After
      public void destroy() {
            transaction.commit();
            session.close();
            sessionFactory.close();
      }
//    @Test
      public void testInsert() {
            UserDao dao = new UserDao();
            dao.init();
            for (int i = 43; i < 64; i++) {
                  dao.session
                              .save(new User4(55, "xiaohong" + i, "qq" + i + "@163.com", new Date(System.currentTimeMillis())));
            }
            dao.destroy();
      }
}
 
 具体页面展示:
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获取到的json数据:
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