jdbc连接数据库及对数据库实现增删改查

public class JdbcDemo {
//MySql
public static final String DRIVER = "com.mysql.jdbc.Driver";
public static final String URL = "jdbc:mysql://localhost:port/databse";
//Oracle
//public static final String DRIVER = "oracle.jdbc.driver.OracleDriver";
//public static final String URL = "jdbc:oracle:thin:@host:port:databse";

//SQL Server
//public static final String DRIVER = "com.microsoft.sqlserver.jdbc.SQLServerDriver ";
//public static final String URL = "jdbc:sqlserver://host:port;database","user","password";

public static final String DBNAME = "root";
public static final String DBPASS = "123456";

//连接数据库
public static Connection getConn()
{
Connection conn=null;
try{
Class.forName(DRIVER);//必须把驱动类导入到项目来，才能完成加载
conn=DriverManager.getConnection(URL,DBNAME,DBPASS);
}catch(Exception e){
System.err.println("警告：数据库连接失败！");
}
return conn;
}

//关闭数据库
public static void close(Connection conn)
{
if(conn!=null)
try{
conn.close();
}catch(SQLException e){
e.printStackTrace();
}
}
}

<pre name="code" class="java">//以对用户表为例子，其中user表包含number,nickname和password三个字段，进行演示
public class DBOperation{
//添加用户----->增
public void addUser(User user) throws Exception {
Connection conn = JdbcDemo.getConn();//获取连接
PreparedStatement prep = conn.prepareStatement("insert into user values(?,?,?)");
prep.setString(1, user.getNumber());//设置第一个参数
prep.setString(2, user.getNickName());//设置第二个参数
prep.setString(3, user.getPassword());//设置第三个参数
prep.executeUpdate();//执行语句
JdbcDemo.close();//关闭连接
}
//删除用户----->删
public void deleteUser(String number) throws Exception{
Connection conn = JdbcDemo.getConn();//获取连接
PreparedStatement prep = conn.prepareStatement("delete from user where number = ?");
prep.setString(1, number);//设置第一个参数
prep.executeUpdate();//执行语句
JdbcDemo.close();//关闭连接
}
//修改用户信息---------->改
public void updateUser(User user) throws Exception {
Connection conn = JdbcDemo.getConn();//获取连接
PreparedStatement prep = conn.prepareStatement("update user set nickname=?,password=? where number=?");
prep.setString(1, user.getNickName());
prep.setString(2, user.getPassword());
prep.setString(3,user.getNumber());
prep.executeUpdate();
JdbcDemo.close();//关闭连接
}
//查询所有用户------------->查
public List<User> findAllUser() throws Exception {
Connection conn = JdbcDemo.getConn();//获取连接
PreparedStatement prep = conn.prepareStatement("select * from user");
ResultSet rst = prep.executeQuery();//执行查询语句，把查询结果保存到结果集rst中
ArrayList<User>list = new ArrayList<User>();
while(rst.next()){
User user = new  User();
user.setNumber(rst.getString("number"));
user.setNickName(rst.getString("nickname"));
user.setPassword(rst.getString("password"));
list.add(user);
}
return list;
}
}