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代码：/**
 * 该类为网上书店操作数据库的公用类
 * 用于数据库连接、查询和更新等操作 
 */
package bean;

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

public class DBClass
{
private String driver; 
private String url;
private String username;
private String password;
private Connection connection;
private Statement statement;
private String message="";

public DBClass(){
driver="sun.jdbc.odbc.JdbcOdbcDriver";
url="jdbc:odbc:softtest";
username="";
password="";
connection=null;
statement=null;
message="";
}

public DBClass(String driver,String url,String username,String password){
this.driver=driver;
this.url=url;
this.username=username;
this.password=password;
this.connection=null;
this.statement=null;
this.message="";
}

public String getDriver(){
return driver;
}

public void setDriver(String driver){
this.driver=driver;
}

public String getUrl(){
return url;
}

public void setUrl(String url){
this.url=url;
}

public String getUsername(){
return username;
}

public void setUsername(String username){
this.username=username;
}

public String getPassword(){
return password;
}

public void setPassword(String password){
this.password=password;
}

public Connection getConnection(){
return connection;
}

public void setConnection(Connection connection){
this.connection=connection;
}

public Statement getStatement(){
return statement;
}

public void setStatement(Statement statement){
this.statement=statement;
}


public String getMessage(){
return message;
}

public void setMessage(String message){
this.message=message;
}

/* 连接数据库 */
public void connect(){
try{

Class.forName(driver);
  connection=DriverManager.getConnection(url,username,password);
  statement=connection.createStatement();
 

   
}catch(ClassNotFoundException cnfe){
message="connection:"+cnfe;
}catch(SQLException sqle){
message="executeQuery:"+sqle;
}
}

/* 执行SQL查询并返回结果 */
public ResultSet executeQuery(String query){
ResultSet resultset=null;
try{
  resultset=statement.executeQuery(query);
}catch(SQLException sqle){
message="executeQuery:"+sqle;
}
return resultset;
}

/* 执行数据库更新操作 */
public void executeUpdate(String command){
try{

statement.executeUpdate(command);
}catch(SQLException sqle){
message="executeUpdate:"+sqle;
}
}

/* 关闭数据库连接 */
public void closeConnection(){
try{
connection.close();
}catch(SQLException sqle){
message="closeConnection:"+sqle;
}
}

public static void main(String args[]){
DBClass db=new DBClass();
String str="insert into user values('a','a','a','a','a','a','a','a','a')";
db.connect();
db.executeUpdate(str);
db.closeConnection();

}


}
执行错误：
java中关于键盘代替按钮的一些有关问题（是代替）~