l JDBC
Brief introduction
- JDBC
（
Java DataBase Connectivity,java
Database Connectivity) is a method for performing
SQL
Statement
Java API
It can provide uniform access to a variety of relational databases, which consists of a group with
Java
Written in language classes and interfaces.
JDBC
It provides a benchmark that allow you to build more advanced tools and interfaces that enable database developers to write database applications
- Java
It has a sturdy, safe, easy to use, easy to understand and can be automatically downloaded from the Internet and other characteristics, is to write database applications outstanding language. Need is
Java
Applications and various methods of dialogue between different databases.
- JDBC
It can be used on a variety of platforms
Java
,Such as
Windows
，
Mac OS
And various versions of the
UNIX
。
- JDBC
Library includes commonly used with databases mentioned below each of the tasks related to the
API
。
l JDBC
Login code verification realize ideas
*
Keyboard to enter a user name and password, the user comparison information in the database to determine whether the login is successful
* 1
,Connect to the database
* MyJDBCUtils.getConnection()
* 2
To get the request object
stmt
* conn.createStmtement()
* 3
Create keyboard objects, obtain a user name and password
* 3.1
Create a keyboard input objects
* 3.2
Prompt the user to enter
* 3.3
Get user input
* 4
,write
SQL
Statement, the user name and password into the
SQL
Statement
* 5
Execute the query
,
Obtaining query results
* stmt.executeQuery(sql);
* 6
Judgment based on the result of the query is successful login
* 7
, Close the connection
l Java
Tools
in
java
Development process
，
Often use some code
Scanner
、
Random
The same class
，
They are the keyboard input
，
Generating a random number based
，
Like as a tool
，
in
java
It is referred to as tools
。
When we write your own code
，
Some functions and codes
java
Similar tools
Such as database connections, authenticated login will be used to get long, every time writing too much trouble, we can try to write your own tools, when used directly to guide each packet call on the line, can improve our development efficiency.
l
Package
JDBC
Tools
n
Incorporation database connection object
n
Method of adding connection release
code show as below
：
Tools Code
：
package com.qianfeng.util;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
/**
* JDBC
Tools
*
The method of obtaining connection with a
* @author dushine
*/
public class JDBCUtil {
/**
*
Method for obtaining a database connection
* @return Connection conn
* @throws SQLException
*/
public static Connection getConnection() throws SQLException {
String url = "jdbc:mysql://localhost:3306/class?useSSL=false";
String user = "root";
String password = "root";
Connection conn = DriverManager.getConnection(url,user,password);
return conn;
}
/**
*
Connection release method
* @param conn
* @throws SQLException
*/
public static void releaseSourse(Connection conn) throws SQLException {
if (conn != null) {
conn.close();
}
}
/**
*
Connection release method
* @param conn
Database connection object
* @param stmt
carried out
SQL
Object statement
* @throws SQLException
*/
public static void releaseSourse(Connection conn,Statement stmt) throws SQLException {
if (stmt != null) {
stmt.close();
}
if (conn != null) {
conn.close();
}
}
/**
*
Connection release method
* @param conn
Database connection object
* @param stmt
carried out
SQL
Object statement
* @param resultSet
carried out
SQL
Statement returns the result set
* @throws SQLException
*/
public static void releaseSourse(Connection conn,Statement stmt,ResultSet resultSet) throws SQLException {
if (resultSet != null) {
resultSet.close();
}
if (stmt != null) {
stmt.close();
}
if (conn != null) {
conn.close();
}
}
}
Test Class Code
：
package com.qianfeng.demos;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.Scanner;
import com.qianfeng.util.JDBCUtil;
public class Demo04 {
public static void main(String[] args) throws Exception {
/**
*
log in Register
*
Get user input
*
As a condition of the contents of the input query the database
*/
Scanner sc = new Scanner(System.in);
System.out.println("
please enter user name
:");
String name = sc.nextLine();
System.out.println("
Please enter your password
:");
String pwd = sc.nextLine();
//
Registration drive
Class.forName("com.mysql.jdbc.Driver");
/*
String url = "jdbc:mysql://localhost:3306/class?useSSL=false";
String user = "root";
String password = "root";
//
Acquisition and database connection
Connection conn = DriverManager.getConnection(url, user, password);*/
Connection conn = JDBCUtil.getConnection();
//
Using a connection object gets executed
sql
Object
Statement stmt = conn.createStatement();
//
write
SQL
Statement
String sql = "select * from userinfo where username='"+name+"' and password='"+pwd+"'";
System.out.println(sql);
//
carried out
SQL
Statement returns the result to obtain
ResultSet resultSet = stmt.executeQuery(sql);
if (resultSet.next()) {
System.out.println("
Landed successfully!
");
} else {
System.out.println("
wrong user name or password!
");
}
JDBCUtil.releaseSourse(conn, stmt, resultSet);
sc.close();
}
}