java连接数据库的代码

Question

如题所述

Answer 1

package mysql;
import java.sql.*;

/**

* @author xys
*/
public class ConnectMysql {
public static Connection getConnection() throws ClassNotFoundException, SQLException {
String url = "jdbc:mysql://localhost:3306/databaseName";
String user = "mysqluser";
String password = "password";
String driverClass = "com.mysql.cj.jdbc.Driver";
Connection connection = null;
Class.forName(driverClass);
try {
connection = DriverManager.getConnection(url, user, password);
} catch (SQLException e) {
e.printStackTrace();
}
if (connection != null) {
System.out.println("数据库连接成功");
} else {
System.out.println("数据库连接失败");
connection.close();
}
return connection;
}

public void getResult() throws ClassNotFoundException, SQLException {
// 实例化 Statement 对象
Statement statement = getConnection().createStatement();
// 要执行的 Mysql 数据库操作语句（增、删、改、查）
String sql = "";
// 展开结果集数据库
ResultSet resultSet = statement.executeQuery(sql);
while (resultSet.next()) {
// 通过字段检索
int id = resultSet.getInt("id");
String name = resultSet.getString("name");

// 输出数据
System.out.println("ID : " +id);
System.out.println("name :" + name);
}
// 完成后需要依次关闭
resultSet.close();
statement.close();
getConnection().close();
}
}

Answer 2

用这个类吧.好的话,给我加加分.
import java.sql.*;
/**
* @功能: 一个JDBC的本地化API连接类,封装了数据操作方法,只用传一个SQL语句即可
* @作者: 李开欢
* @日期: 2007/
*/
public class ConnectionDemo {
/*
* 这里可以将常量全部放入另一个类中,以方便修改
*/
private static Connection conn;
private static Statement ps;
private static ResultSet rs;
private static final String DRIVER = "com.microsoft.jdbc.sqlserver.SQLServerDriver";
private static final String URL = "jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=mydb";
private static final String USER ="sa";
private static final String PASS = "sa";
public ConnectionDemo() {
// TODO Auto-generated constructor stub
ConnectionDemo.getConnection();
}
public static Connection getConnection(){
System.out.println("连接中...");
try {
Class.forName(ConnectionDemo.DRIVER);
conn = DriverManager.getConnection(ConnectionDemo.URL, ConnectionDemo.USER, ConnectionDemo.PASS);
System.out.println("成功连接");
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return conn;
}
public static Statement getStatement(String sql){
System.out.println("执行SQL语句中...");
try {
ps = conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE);
if(sql.substring(0, 6).equals("select")){
rs = ps.executeQuery(sql);
System.out.println("执行完查询操作,结果已返回ResultSet集合");
}else if(sql.substring(0, 6).equals("delete")){
ps.executeUpdate(sql);
System.out.println("已执行完毕删除操作");
}else if(sql.substring(0, 6).equals("insert")){
ps.executeUpdate(sql);
System.out.println("已执行完毕增加操作");
}else{
ps.executeUpdate(sql);
System.out.println("已执行完毕更新操作");
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return ps;
}
public static ResultSet getResultSet(){
System.out.println("查询结果为:");
return rs;
}
public static void closeConnection(){
System.out.println("关闭连接中...");
try {
if (rs != null) {
rs.close();
System.out.println("已关闭ResultSet");
}
if (ps != null) {
ps.close();
System.out.println("已关闭Statement");
}
if (conn != null) {
conn.close();
System.out.println("已关闭Connection");
}
} catch (Exception e) {
// TODO: handle exception
}
}
public static void main(String[] args) {
// TODO Auto-generated method stub
ConnectionDemo.getConnection();
String sql = "delete from type where id = 1";
ConnectionDemo.getStatement(sql);
String sql2 = "insert into type values(1,'教学设备')";
ConnectionDemo.getStatement(sql2);
String sql1 = "select * from type";
ConnectionDemo.getStatement(sql1);
ResultSet rs = ConnectionDemo.getResultSet();
System.out.println("编号 "+"类 型");
try {
while(rs.next()){
System.out.print(" "+rs.getInt(1)+" ");
System.out.println(rs.getString(2));
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
ConnectionDemo.closeConnection();
}
}