java连接数据库步骤(mysql):
加载驱动,获取连接,创建处理命令,执行sql命令,处理结果,关闭资源.
public class JDBCCrud {
/**
* 向表中添加数据
*/
public void insert(String username,String password){
Connection conn = null;
Statement stmt = null;
try {
//加载驱动
Class.forName("com.mysql.jdbc.Driver");
//获取连接
conn = DriverManager.getConnection(
"jdbc:mysql://127.0.0.1:3306/mydb?user=root&password=9527");
//创建处理命令
stmt = conn.createStatement();
//执行sql命令
int i = stmt.executeUpdate(
"insert into user(username,password) values('"+username+"','"+password+"')");
//处理结果
if(i>0){
System.out.println("操作成功,影响数据行数:"+i);
}
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}finally{
try {
//alt+shift+z
if(stmt != null)stmt.close();
if(conn != null)conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
public void login(String username,String password){
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/mydb?user=root&password=9527");
stmt = conn.createStatement();
//执行查询操作获取结果集
rs = stmt.executeQuery("select * from user where username='"+username+"' and password='"+password+"'");
//取出结果集中的数据
if(rs.next()){
//根据数据表中的列名称以及类型从结果集中取出指定的列数据
int id = rs.getInt("id");
String uname = rs.getString("username");
String pword = rs.getString("password");
System.out.println(id+"--"+uname+"--"+pword);
}
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}finally{
try {
if(rs != null)rs.close();
if(stmt != null)stmt.close();
if(conn != null)conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
/**
*查询所有操作
*
*/
public void queryAll(){
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/mydb?user=root&password=9527");
stmt = conn.createStatement();
//执行查询操作获取结果集
rs = stmt.executeQuery("select id,username,password from user");
//取出结果集中的数据
while(rs.next()){
//根据数据表中的列名称以及类型从结果集中取出指定的列数据
int id = rs.getInt("id");
String uname = rs.getString("username");
String pword = rs.getString("password");
System.out.println(id+"--"+uname+"--"+pword);
}
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}finally{
try {
if(rs != null)rs.close();
if(stmt != null)stmt.close();
if(conn != null)conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
/**
* 删除数据操作
*/
public void delete(int id){
Connection conn = null;
Statement stmt = null;
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/mydb?user=root&password=9527");
stmt = conn.createStatement();
int i = stmt.executeUpdate("delete from user where id="+id+"");
if(i > 0){
System.out.println("操作成功,影响数据行数:"+i);
System.out.println("删除"+id+"号用户成功!");
}
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}finally{
try {
if(stmt != null)stmt.close();
if(conn != null)conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
/**
* 更新数据操作
*/
public void updete(int id,String username,String password){
Connection conn = null;
Statement stmt = null;
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/mydb?user=root&password=9527");
stmt = conn.createStatement();
int i = stmt.executeUpdate(
"update user set username='"+username+"',password='"+password+"' where id="+id+"");
if(i>0){
System.out.println("操作成功,影响数据行数:"+i);
System.out.println("修改成功!");
}
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}finally{
try {
if(stmt != null)stmt.close();
if(conn != null)conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
public static void main(String[] args) {
int id = 1;
String username = "rose";
String password = "654321";
JDBCCrud jdbc = new JDBCCrud();
//jdbc.insert(username,password);
//jdbc.queryAll();
//jdbc.updete(id, username, password);
//jdbc.delete(id);
jdbc.login(username,password);
}
}
