Upgrade the jdbc driver to version 8.0.28 and connect to the pit record of MySQL

Problem description

Upgrade driver to  

mysql-connector-java 8.0.28

  after , Deploy and execute various error reports , But switch the connector to  

mysql-connector-java-5.1.48

  No problem , It's very confusing ！

Most of the information reported in error is that such information cannot be found 、 Unable to connect

It is mainly configured , There was no screenshot , Just pay attention to the differences from the old version

Official download address

Through all kinds of difficulties and dangers , Finally solved , Successfully connected , The solution is given below

Solution

The first is an example of a rookie , More comprehensive ; If you feel troublesome , The second option can be used

1. Full version

Here quote

Novice tutorial

Example

1. Database environment construction

--  Building a database  demo1
CREATE DATABASE IF NOT EXISTS demo1;

--  establish  websites  surface
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  ranking ',
 country char(10) NOT NULL DEFAULT '' COMMENT ' Country ',
 PRIMARY KEY (id)
) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8;

--  Write data
INSERT INTO websites
VALUES ('1', 'Google', 'https://www.google.cm/', '1', 'USA'), 
('2', ' TaoBao ', 'https://www.taobao.com/', '13', 'CN'), 
('3', ' Novice tutorial ', 'http://www.runoob.com', '5892', ''), 
('4', ' Microblogging ', 'http://weibo.com/', '20', 'CN'), 
('5', 'Facebook', 'https://www.facebook.com/', '3', 'USA');


2. Test class connection

The most important thing is here  MySQL  Version problem , The new version updates the name of the driver class to  

com.mysql.cj.jdbc.Driver

import java.sql.*;

public class JDBCTest {

 // MySQL 8.0  The following versions  - JDBC  Driver name and database  URL
 // static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";
 // static final String DB_URL = "jdbc:mysql://localhost:3306/RUNOOB";

 // MySQL 8.0  Above version  - 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/demo1?useSSL=false&allowPublicKeyRetrieval=true&serverTimezone=UTC&useServerPrepStmts=true";
 //  Pay attention to modifying the database name  

 //  User name and password of database , It needs to be based on your own settings
 static final String USER = "your db login name";
 static final String PASS = "your db password";

 public static void main(String[] args) {
 Connection conn = null;
 Statement stmt = null;
 try {
 //  register  JDBC  drive
 Class.forName(JDBC_DRIVER);

 //  Open the link
 System.out.println(" Connect to database ...");
 conn = DriverManager.getConnection(DB_URL, USER, PASS);

 //  Execute the query
 System.out.println("  Instantiation 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 fields
 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... When done
 rs.close();
 stmt.close();
 conn.close();
 } catch (SQLException se) {
 //  Handle  JDBC  error
 se.printStackTrace();
 } catch (Exception e) {
 //  Handle  Class.forName  error
 e.printStackTrace();
 } finally {
 //  close resource
 try {
 if (stmt != null) stmt.close();
 } catch (SQLException se2) {
 }//  Don't do anything?
 try {
 if (conn != null) conn.close();
 } catch (SQLException se) {
 se.printStackTrace();
 }
 }
 System.out.println("Goodbye!");
 }
}


Execution results , Successful connection

2. Lite version

The above example considers the overall , Use more exceptions , For ease of understanding , Let's simplify the amount of code

1. Database environment construction

--  Building a database  demo1
CREATE DATABASE IF NOT EXISTS demo1;

--  Create data tables  accounts
CREATE TABLE accounts (
 id int(3) NOT NULL PRIMARY KEY auto_increment,
 name varchar(5),
 money FLOAT(4,2)
 );

--  Write data
INSERT INTO accounts VALUES('1','jason','10000'),('2','you','99999');


2. Test class connection

Note that version 、 The order in which resources are released （ Call first , Final release , The release order is opposite to the call order ）

package com.jason.jdbc;

import java.sql.*;

public class JDBCDemo {
 public static void main(String[] args) throws Exception { //psvm  Quickly generate
 //1.  Registration drive
 Class.forName("com.mysql.cj.jdbc.Driver");
 //2.  Get the connection
 String url = "jdbc:mysql://localhost:3306/demo1?useSSL=false&allowPublicKeyRetrieval=true&serverTimezone=UTC&useServerPrepStmts=true";
 String username = "your db login name";
 String password = "your db password";
 Connection conn = DriverManager.getConnection(url, username, password);
 //3.  Definition sql
 String sql = "update accounts set money = 1000 where id = 2";
 //4.  Access to perform sql The object of  Statement
 Statement stmt = conn.createStatement();
 //5.  perform sql
 int count = stmt.executeUpdate(sql);// Rows affected
 //6.  Processing results
 System.out.println("Affected rows: "+count);
 //7.  Release resources  Statement  and  Connection  Pay attention to the release sequence
 stmt.close();
 conn.close();
 }
}


Execution results , Successful connection

summary

After all, it's an update , There will be some changes , We need to learn to see what's updated 、 Learn to go to the authorities to find solutions

For example, this error report can be from the latest  jar  Found in the package

stay  

5.x

  After the version , Registration driver code can be omitted without writing , This is the passage

//1.  Registration drive
//Class.forName("com.mysql.cj.jdbc.Driver");


as a result of ： drive  

jar

  It's a bag , Default  

META-INF services

  The corresponding driver class name is recorded in the directory , No need to write again

Maybe the version I use is too old , Can't keep up with the development of the times ~~