databaseutil.java

一个用JSP写的网络购物系统

package cn.edu.dlnu.frame.utils;

import java.util.*;
import java.sql.*;

public class DataBaseUtil {
	private static String url, driver, user, password;
	private Connection connection = null;
	static {
		ResourceBundle bundle = ResourceBundle.getBundle("jdbc");
		try {
			url = bundle.getString("jdbc.url");
			driver = bundle.getString("jdbc.driverClassName");
			user = bundle.getString("jdbc.username");
			password = bundle.getString("jdbc.password");
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	public DataBaseUtil() {
		try {
			Class.forName(driver);
			connection = DriverManager.getConnection(url, user, password);
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		} catch (SQLException e) {
			e.printStackTrace();
		}

	}

	protected void finalize() throws Throwable {
		try {
			if (connection != null) {
				connection.close();
			}
		} catch (SQLException e) {
			e.printStackTrace();

		}
		super.finalize();
	}
	public void beginTransaction(){
		try{
			connection.setAutoCommit(false);
		}catch(SQLException e){
			e.printStackTrace();
		}
	}
	public void commit(){
		try{
			connection.commit();
			connection.setAutoCommit(true);
		}catch(SQLException e){
			e.printStackTrace();
		}
	}
	public void rollback(){
		try{
			connection.rollback();
			connection.setAutoCommit(true);
		}catch(SQLException e){
			e.printStackTrace();
		}
	}

	public List<Map<String, Object>> queryForList(String sql, Object[] params) {
		PreparedStatement stmt = null;
		ResultSet rs = null;
		List<Map<String, Object>> result = new ArrayList<Map<String, Object>>();
		;
		try {
			stmt = connection.prepareStatement(sql);
			if (params != null) {
				for (int i = 0; i < params.length; i++) {
					stmt.setObject(i + 1, params[i]);
				}
			}
			rs = stmt.executeQuery();
			ResultSetMetaData rsmd = rs.getMetaData();
			int count = rsmd.getColumnCount();

			while (rs.next()) {
				Map<String, Object> row = new HashMap<String, Object>();
				for (int i = 0; i < count; i++) {
					row.put(rsmd.getColumnName(i + 1), rs.getObject(i + 1));
				}
				result.add(row);
			}

		} catch (SQLException e) {
			e.printStackTrace();

		}
		return result;
	}

	public Map<?, ?> queryForMap(String sql, Object[] params) throws Exception {
		List<?> result = queryForList(sql, params);
		if (result.size() == 1) {
			return (Map<?, ?>) result.get(0);
		} else {
			throw new Exception("except 1 row actually return " + result.size() + "rows");
		}

	}

	public boolean executeUpdate(String sql, Object[] params) {

		PreparedStatement stmt = null;
		int result = -1;
		try {
			stmt = connection.prepareStatement(sql);
			for (int i = 0; i < params.length; i++) {
				stmt.setObject(i + 1, params[i]);
				System.out.print(params[i]);
			}
			result = stmt.executeUpdate();
		} catch (SQLException e) {
			e.printStackTrace();

		}
		if (result > 0) {
			return true;
		} else {
			return false;
		}
	}

}