package org.com.gather;

import java.util.*;
import java.sql.*;
import org.com.gather.exception.*;

//切換了類,原版本事DBImpl,考慮到功能上的限制
//開發了另一個版本,DBImpl2,直接利用框架來切換類

public class DBImpl2 implements DB{
	private Properties pro = null;
	private Log log = null;
	private BackUp back = null;

	private static String key = "key";
	private static DBImpl2 instance = null;

	
	//屬性由Spring注入
	private DBImpl2(Properties pro){
		this.pro = pro;
	}

	//私有的構造器,為了獲取實例,要提供一個靜態方法,
	//通過該方法獲取實例
	public static DBImpl2 getInstance(Properties pro){
		if(instance == null){
			synchronized(key){
				if(instance == null){
					instance = new DBImpl2(pro);
				}
			}
		}
		return instance;
	}

	//有可能多個線程會同時保存數據,也就是說這個方法
	//將會出現并發問題,為了防止多個線程同時對做入庫
	//操作,在這加一個同步鎖.
	public synchronized void storeToDB(Collection col)throws SQLException,ClassNotFoundException,DBException{

		log.writeInfo("應該入庫數量大下---"+col.size());

		if(!col.isEmpty()){
			long start = System.currentTimeMillis();
			Connection con = null;
	
			con = this.getConnection();

			log.writeDebug("成功獲取連接,程序繼續執行!");
			long end = System.currentTimeMillis();
			long time = (end - start)/1000;
			log.writeInfo("獲取連接時長為 --->"+time);
			
			//構建一塊緩存
			Collection coll = new ArrayList();
			
			//取出batchSize,每次入庫量大小
			String s_size = pro.getProperty("batchSize");
			int size = new Integer(s_size).intValue();
			
			int c_size = col.size();
		
			//對入庫集合進行遍歷
			Iterator iter = col.iterator();
			//為了測試,這里只插入一個字段
			String sql = "insert into dt values(?)";
			PreparedStatement pstmt = null;
			try{
				pstmt = con.prepareStatement(sql);
			}catch(SQLException e){
				e.printStackTrace();
				log.writeError("解析sql語句出異常!");
				back.storeForEmpty(col);
				log.writeInfo("成功把入庫數據備份!");
				System.exit(0);
			}

			while(iter.hasNext()){
				//把集合的數據存放到緩存,等到數量到了
				//batch-size指定的數量后再一次入庫;
				coll.add(iter.next());

				//如果集合數據存放到緩存,則可把集合的數據
				//刪除;
				iter.remove();
				
				if(coll.size() == size){
					try{
						con.setAutoCommit(false);

						Iterator it = coll.iterator();
						while(it.hasNext()){
							BIDR bidr = (BIDR)it.next();
							pstmt.setString(1,bidr.getLoginName());
							pstmt.addBatch();
						}
						pstmt.executeBatch();
						con.commit();
					}catch(SQLException e){
						log.writeError(e.getMessage());
						//把剩下沒入庫的數據,一并保存;
						col.addAll(coll);
						back.storeForEmpty(col);
						log.writeInfo("入庫過程重出異常,成功把數據備份到文件;");
						
						try{
							con.rollback();
							log.writeInfo("入庫異常,回滾!");
						}catch(SQLException ee){
							ee.printStackTrace();
							log.writeError("數據庫異常,數據回滾!");
							throw new DBException(ee);
						}
						throw new DBException(e);
					}
					//把緩存清空,重新載入數據;
					coll.clear();
				}
			}


		//把剩余的數據,繼續入庫;
			Iterator itr = coll.iterator();
			try{
				con.setAutoCommit(false);
		 
				while(itr.hasNext()){
					BIDR br = (BIDR)itr.next();
					pstmt.setString(1,br.getLoginName());
					pstmt.addBatch();
				}
				pstmt.executeBatch();
				con.commit();
			}catch(SQLException e){
				e.printStackTrace();
				back.storeForEmpty(coll);
				log.writeInfo("成功把剩余數據備份!");
				try{
					con.rollback();
				}catch(SQLException ee){
					ee.printStackTrace();
					log.writeError("入庫異常,剩余數據回滾!");
					throw new DBException(e);
				}
			}
			//清空緩存;
			coll.clear();
			//把剩余的集合數據清空; 
			col.clear();
			log.writeDebug("成功將數據插入數據庫!");
		}else{
			System.out.println("入庫數據量為零!");
		}
	}

	//這里每次都是拿到物理連接,可以考慮用連接池.
	public Connection getConnection()throws SQLException,ClassNotFoundException{
		Class.forName(pro.getProperty("driver"));
		Connection con = DriverManager.getConnection(pro.getProperty("url"),pro.getProperty("username"),pro.getProperty("password"));
		return con;
	}

	public void setLog(Log log){
		this.log = log;
	}

	public void setBackUpServer(BackUp back){
		this.back = back;
	}

}