dbaccess.java

用途： 自动查询所有数据库的所有表

import java.sql.*;

public class DBAccess {

	final public static String strDriver="com.microsoft.jdbc.sqlserver.SQLServerDriver";
	
	final public static String strURL="jdbc:microsoft:sqlserver://localhost:1433;databasename=";
	
	final public static String strUser="sa";
	
	final public static String strPwd="sa";
	
	private static DBAccess db=null;
	
	private Connection con=null;
	
	private Statement stmt=null;
	
	private ResultSet rst=null;
	
	public static boolean onlyOneMode=false;//单例模式默认为假
	
	
	public static boolean isOnlyOneMode() {
		return onlyOneMode;
	}

	public static void setOnlyOneMode(boolean onlyOne) {
		onlyOneMode = onlyOne;
	}

	private DBAccess(String strURL_database){
		try {
			Class.forName(DBAccess.strDriver);
			con=DriverManager.getConnection(DBAccess.strURL+strURL_database,DBAccess.strUser,DBAccess.strPwd );
			stmt=con.createStatement();
		} catch (Exception e) {
			// TODO 自动生成 catch 块
			e.printStackTrace();
		}
	}
	
	private DBAccess(){
		try {
			Class.forName(DBAccess.strDriver);
			con=DriverManager.getConnection(DBAccess.strURL+"wh",DBAccess.strUser,DBAccess.strPwd );
			stmt=con.createStatement();
		} catch (Exception e) {
			// TODO 自动生成 catch 块
			e.printStackTrace();
		}
	}
	
	public static DBAccess getDBAccess(){
		//单例模式
		if((db==null && onlyOneMode==true)||onlyOneMode==false){
			db=new DBAccess();
		}	
	
		return db;
	}
	
	public static DBAccess getDBAccess(String strURL_database){
		//单例模式
		if((db==null && onlyOneMode==true)||onlyOneMode==false){
			db=new DBAccess(strURL_database);
		}
		
		return db;
	}
	
	public Connection getConnection(){
		return con;
	}
	
	public ResultSet query(String sql){
		try {
			rst=stmt.executeQuery(sql);
		} catch (SQLException e) {
			// TODO 自动生成 catch 块
			e.printStackTrace();
		}
		return rst;
	}
	
	public int update(String sql){
		int flag=0;
		try {
			flag=stmt.executeUpdate(sql);
		} catch (SQLException e) {
			// TODO 自动生成 catch 块
			e.printStackTrace();
		}
		return flag;
	}
	
	public void closeDB() {
		//单例模式则返回
		if(onlyOneMode){
			return;
		}
		
		try {
			if (rst != null) {
				rst.close();
				rst = null;
			}

			if (stmt != null) {
				stmt.close();
				stmt = null;
			}

			if (con != null) {
				con.close();
				con = null;
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}

}