dbconnection.java

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package com.jblack.tool;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class DBConnection {
	static private String strDriver = "com.mysql.jdbc.Driver";
	static private String strUrl = "jdbc:mysql://localhost:3306/test";
	static private String strUser = "root";
	static private String strPwd = "123";
	private Connection conn = null;
	private Statement stmt = null;
	private ResultSet rs = null;

	static {
		try {
			Class.forName(strDriver);
		} catch (ClassNotFoundException ex) {
			System.out.println("Error load" + strDriver);
		}
	}

	public DBConnection() {
	}

	public ResultSet executeQuery(String sql) {
		try {
			rs = getStatement().executeQuery(sql);
		} catch (SQLException ex) {
			System.out.println("query error:" + ex.getMessage());
		}
		return rs;
	}

	public ResultSet executePreQuery(String sql, Object[] args) {
		try {
			PreparedStatement preStmt = getConnection().prepareStatement(sql);
			for (int i = 0; i < args.length; i++) {
				preStmt.setObject(i + 1, args[i]);
			}
			rs = preStmt.executeQuery();
		} catch (SQLException ex) {
			System.err.println("query error:" + ex.getMessage());
		}
		return rs;
	}

	public int executeUpdate(String sql) {
		int resultNum = 0;
		try {
			resultNum = getStatement().executeUpdate(sql);
		} catch (SQLException ex) {
			System.err.println("update error:" + ex.getMessage());
		} finally {
		}
		return resultNum;
	}
	 public int insertAndGetPKKey(String sql) {
	        int resultNum = 0;
	        try {
	           getStatement().executeUpdate(sql,Statement.RETURN_GENERATED_KEYS);
	           ResultSet rs = getStatement().getGeneratedKeys();
	           if (rs != null && rs.next()) 
	        	   resultNum = rs.getInt(1);//���ز�������id
	        } catch (SQLException ex) {
	            System.err.println("update error:" + ex.getMessage());
	        }
	        return resultNum;
	    }
	    

	public void close() {
		try {
			if (rs != null) {
				rs.close();
				rs = null;
			}
			if (stmt != null) {
				stmt.close();
				stmt = null;
			}
			if (conn != null) {
				conn.close();
				conn = null;
			}
		} catch (Exception ex) {
			System.err.println("close error:" + ex.getMessage());
		}
	}

	private Connection getConnection() {
		try {
			if (conn == null || conn.isClosed())
				conn = DriverManager.getConnection(strUrl, strUser, strPwd);
		} catch (Exception ex) {
			ex.printStackTrace();
			return null;
		}
		return conn;
	}

	private Statement getStatement() {
		try {
			if (stmt == null)
				stmt = getConnection().createStatement();
		} catch (Exception ex) {
			ex.printStackTrace();
			return null;
		}
		return stmt;
	}
}