Java MySQL Connection

In this chapter, we will introduce how Java uses JDBC to connect to a MySQL database.

Java requires a driver package to connect to MySQL. The latest version download address is:http://dev.mysql.com/downloads/connector/j/After decompressing, you get the jar library file, then import it into your corresponding project.

You can download the jar package provided by this site:mysql-connector-java-5.1.39-bin.jar

This example uses Eclipse to import the jar package:

Database connection for MySQL 8.0 and above is different:

  • 1. Driver package version for MySQL 8.0 and abovemysql-connector-java-8.0.16.jar。

  • 2、com.mysql.jdbc.Driverchanged tocom.mysql.cj.jdbc.Driver。

  • MySQL 8.0 and above does not require establishing an SSL connection; you need to explicitly disable it.

  • allowPublicKeyRetrieval=true allows the client to retrieve the public key from the server.

  • Finally, you also need to set CST.

The way to load the driver and connect to the database is as follows:

Class.forName("com.mysql.cj.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test_demo?useSSL=false&allowPublicKeyRetrieval=true&serverTimezone=UTC","root","password");

Create Test Data

Next, we will create the EXAMPLE database in MySQL, and create a websites data table. The table structure is as follows:

CREATE TABLE `websites` ( `id` int(11) NOT NULL AUTO_INCREMENT, `name` char(20) NOT NULL DEFAULT '' COMMENT 'Site Name', `url` varchar(255) NOT NULL DEFAULT '', `alexa` int(11) NOT NULL DEFAULT '0' COMMENT 'Alexa Rank', `country` char(10) NOT NULL DEFAULT '' COMMENT 'Country', PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8;

Insert some data:

INSERT INTO `websites` VALUES ('1', 'Google', 'https://www.google.cm/', '1', 'USA'), ('2', 'Taobao', 'https://www.taobao.com/', '13', 'CN'), ('3', 'Example', 'http://www.example.com', '5892', ''), ('4', 'Weibo', 'http://weibo.com/', '20', 'CN'), ('5', 'Facebook', 'https://www.facebook.com/', '3', 'USA');

The data table is displayed as follows:

Connect to Database

The following example uses JDBC to connect to a MySQL database. Note that some data such as username and password need to be configured according to your development environment:

MySQLDemo.java file code:

package com.example.test; import java.sql.*; public class MySQLDemo { //MySQL versions below 8.0 - JDBC driver name and database URL static final String JDBC_DRIVER = "com.mysql.jdbc.Driver"; static final String DB_URL = "jdbc:mysql://localhost:3306/EXAMPLE"; //MySQL 8.0 and above - JDBC driver name and database URL //static final String JDBC_DRIVER = "com.mysql.cj.jdbc.Driver"; //static final String DB_URL = "jdbc:mysql://localhost:3306/EXAMPLE?useSSL=false&allowPublicKeyRetrieval=true&serverTimezone=UTC"; //The database username and password need to be set according to your own settings static final String USER = "root"; static final String PASS = "123456"; public static void main(String[] args) { Connection conn = null; Statement stmt = null; try{ //Register JDBC driver Class.forName(JDBC_DRIVER); //Open connection System.out.println("Connecting to database..."); conn = DriverManager.getConnection(DB_URL,USER,PASS); //Execute query System.out.println("Instantiate Statement object..."); stmt = conn.createStatement(); String sql; sql = "SELECT id, name, url FROM websites"; ResultSet rs = stmt.executeQuery(sql); //Expand the result set database while(rs.next()){ //Retrieve by field int id = rs.getInt("id"); String name = rs.getString("name"); String url = rs.getString("url"); //Output data System.out.print("ID: " + id); System.out.print(", site name:" + name); System.out.print(", site URL:" + url); System.out.print("\n"); } //Close after completion rs.close(); stmt.close(); conn.close(); }catch(SQLException se){ //Handle JDBC errors se.printStackTrace(); }catch(Exception e){ //Handle Class.forName errors e.printStackTrace(); }finally{ //Close resources try{ if(stmt!=null) stmt.close(); }catch(SQLException se2){ }//Do nothing try{ if(conn!=null) conn.close(); }catch(SQLException se){ se.printStackTrace(); } } System.out.println("Goodbye!"); } }

The output of the above example is as follows:

Other extensions