package com.tgb.hibernate;import java.lang.reflect.Method;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;import org.jdom.Document;
import org.jdom.Element;
import org.jdom.input.SAXBuilder;
import org.jdom.xpath.XPath;import com.tgb.hibernate.model.User;public class Session {//表名String tableName = "user";  //存放数据库连接配置private Map<String, String> conConfig = new HashMap<String, String>();//存放实体属性private Map<String ,String > columns = new HashMap<String ,String >();  //实体的get方法集合
    String methodNames[];  public Session () {  //初始化实体，这里就不用读取配置文件的方式了，有点麻烦。 columns.put("id", "id");  columns.put("name", "name");  columns.put("password", "password");  methodNames = new String[columns.size()];  }  /*** 创建数据库连接* @return* @throws Exception*/public Connection createConnection() throws Exception {//解析xml文件，读取数据库连接配置      SAXBuilder sb = new SAXBuilder();  Document doc = sb.build(this.getClass().getClassLoader().getResourceAsStream("hibernate.cfg.xml"));  Element root = doc.getRootElement();  List list = XPath.selectNodes(root, "/hibernate-configuration/property");  for (int i = 0; i < list.size(); i++) {              Element property = (Element) list.get(i);  String name = property.getAttributeValue("name");  String value = property.getText();           conConfig.put(name, value);           }  //根据配置文件获得数据库连接Class.forName(conConfig.get("driver"));  Connection con = DriverManager.getConnection(conConfig.get("url"),conConfig.get("username"),conConfig.get("password"));  return con;}/*** save方法，持久化对象* @param user*/public void save(User user) {  String sql = createSql();  System.out.println(sql);  try {  Connection con = createConnection();  PreparedStatement state =  (PreparedStatement) con.prepareStatement(sql);  for(int i=0;i<methodNames.length;i++) {  //得到每一个方法的对象  Method method = user.getClass().getMethod(methodNames[i]);  //得到他的返回类型  Class cla = method.getReturnType();  //根据返回类型来设置插入数据库中的每个属性值。  if(cla.getName().equals("java.lang.String")) {  String returnValue = (String)method.invoke(user);  state.setString(i+1, returnValue);  }  else if(cla.getName().equals("int")) {  Integer returnValue = (Integer) method.invoke(user);  state.setInt(i+1, returnValue);  }                        }  state.executeUpdate();  state.close();  con.close();  } catch (ClassNotFoundException e) {      e.printStackTrace();  } catch (SQLException e) {  e.printStackTrace();  } catch (Exception e) {  e.printStackTrace();  }   }  /** * 得到sql语句 * @return 返回sql语句 */  private String createSql() {  //strColumn代表数据库中表中的属性列。并将其连接起来。  String strColumn = "";  int index=0;  for(String key :columns.keySet())  {  strColumn +=key+",";  String v = columns.get(key);  //获得属性的get方法，需要将属性第一个字母大写如：getId()v = "get" + Character.toUpperCase(v.charAt(0)) + v.substring(1);  methodNames[index] = v; index++;  }  strColumn  = strColumn.substring(0, strColumn.length()-1);  //拼接参数占位符，即：(?, ?, ?)String strValue = "";  for(int i=0;i<columns.size();i++)  strValue +="?,";  strValue = strValue.substring(0,strValue.length()-1);  String sql = "insert into " + tableName +"(" + strColumn + ")" + " values (" + strValue + ")";   return sql;  }
}