java数据库封装

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 Datebase{

public Connection conn=null

public Statement stmt=null

public ResultSet rs=null

public PreparedStatement preparedstmt=null

private static String dbDriver="com.mysql.jdbc.Driver"

private static String dbUrl="jdbc:mysql://localhost/graduatedmanager?useUnicode=true&characterEncoding=gb2312"

private static String dbUser="root"

private static String dbPwd="root"

//打开数据库连接

public Datebase(){}

public static Connection getConnection()

{

java.sql.Connection conn=null

try

{

Class.forName(dbDriver)

conn=DriverManager.getConnection(dbUrl,dbUser,dbPwd)

}

catch(Exception e)

{

e.printStackTrace()

}

if(conn==null)

{

System.err.println("警告：数据库连接失败！")

}

return conn

}

//读取结果集

public ResultSet doQuery(String sql)

{

try

{

conn=Datebase.getConnection()

stmt=((java.sql.Connection) conn).createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY)

rs=stmt.executeQuery(sql)

}

catch(SQLException e)

{

e.printStackTrace()

}

return rs

}

//更新数据

public int Prepared_doUpdate(String sql,String parameters[])

{

int result=0

try

{

conn=Datebase.getConnection()

preparedstmt=conn.prepareStatement(sql)

/* for(int i=0i<parameters.lengthi++)

{

System.out.println(parameters[i])

}*/

if(parameters!=null)

{

for(int i=0i<parameters.lengthi++)

{

preparedstmt.setString(i+1,parameters[i])

}

}

result=preparedstmt.executeUpdate()

}

catch(SQLException e)

{

e.printStackTrace()

System.out.println(" *** 作失败")

result=0

}

return result

}

//更新数据

public int doUpdate(String sql)

{

int result=0

try

{

conn=Datebase.getConnection()

stmt=((java.sql.Connection) conn).createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY)

result=stmt.executeUpdate(sql)

}

catch(SQLException e)

{

result=0

}

return result

}

//关闭数据库连接

public void closeConnection()

{

try

{

if(rs!=null)

rs.close()

}

catch(Exception e)

{

e.printStackTrace()

}

try

{

if(conn!=null)

((Statement) conn).close()

}

catch(Exception e)

{

e.printStackTrace()

}

}

}

class.forName(driver)

}

catch (ClassNotFoundException e)

{

e.printStackTrace()

}

错了，应该写在方法里面。。。

public Connection getConnection()

{

try{

class.forName(driver)

connection = DriverManager.getConnection(URL,username,password)

}

catch (SQLException e1)

{

e1.printStackTrace()

}

catch (ClassNotFoundException e)

{

e.printStackTrace()

}

return connection

}

或者把他放在构造方法里。

当然是：

Exception in thread "main" java.lang.Error: Unresolved compilation problems:

编译肯定不对。