datastore.java

个人数字平台（可以很方便的管理个人数据） 纯java编写

package bit.jeffy.db;

import java.sql.*;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/*
 * 创建日期 2005-4-7
 *
 * TODO 要更改此生成的文件的模板，请转至
 * 窗口 － 首选项 － Java － 代码样式 － 代码模板
 */

/**
 * @author jeffy522
 * 
 * TODO 要更改此生成的类型注释的模板，请转至 窗口 － 首选项 － Java － 代码样式 － 代码模板
 */
public class DataStore {

	private static DataStore db = null;

	private static Connection conn = null;

	private Statement stmt = null;
	
	private boolean hadErrors = false;

	private DataStore() throws Exception {
		if (conn == null) {
			Class.forName("com.mysql.jdbc.Driver");
			conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydatabase", "root",
					"1");
			stmt = conn.createStatement();
		}
	}
	
	public void beginTransaction() throws SQLException
    {
		conn.setAutoCommit(false);
    }
	
	public void commitTransaction() throws SQLException
    {
        if( !hadErrors ){
            conn.commit();
        }
        else{
        	conn.rollback();
        	hadErrors = false;
        }       

        hadErrors = false;
        conn.setAutoCommit(true);
    }

	public void ErrorOccur( ){
		hadErrors = true;
	}
	
	public static DataStore getInstance() {
		if (db == null) {
			try {
				db = new DataStore();
			} catch (Exception e) {
				conn = null;
				Log log = LogFactory.getLog("mylog");
				log.error("数据库连接出错-DataStore.java");
				return null;
			}
		}
		return db;

	}

	synchronized public void execute(String sql){
		try{
			if (stmt != null)
				stmt.executeUpdate(sql);
			else {
				Log log = LogFactory.getLog("mylog");
				log.error("数据库插入数据出错");
			}
		}catch(SQLException e){
			
		}
	}

	synchronized public ResultSet read(String sql){
		ResultSet tmp = null;
		
		try{
			if (stmt != null) {
				tmp = stmt.executeQuery(sql);
				return tmp;
			} else {
				return null;
			}
		}catch(SQLException e){
			return null;
		}
	}
	
	synchronized public int readCount( String sql ){
		int nCount = 0;
		
		try {
			if( stmt != null ) {
				ResultSet tmp = null;
				tmp = stmt.executeQuery(sql);
				if( tmp!=null && tmp.next() ) {
					nCount = tmp.getInt(1);
				}else {
					nCount = 0;
				}
			}else {
				nCount = 0;
			}
		}catch(SQLException e) {
			nCount = 0;
		}
		
		return nCount;
	}

	synchronized public void stop() {
		try {
			if (conn != null) {
				conn.close();
				stmt.close();
			}
		} catch (Exception e) {
			/* 记录到日志 */
			Log log = LogFactory.getLog("mylog");
			log.error("数据库关闭出错-DataStore.java");
		} finally {
			conn = null;
		}
	}
}