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;

    }

}