Tools:
eclipse, MySQL, MySQL connection driver: mysql-connector-java-5.1.45.jar
1, Create a new java project and then create a new folder - libs (used to store various external packages)
2. Add a connection to the mysql database in the package The package
is mysql-connector-java-5.1.45-bin.jar, then copy and paste it under the libs folder of our java project (note that it is in the physical address); at this time, in In eclipse—right-click the libs folder—Refresh, and put the downloaded JDBC into the folder, as shown in the following figure:
##3, Jar package on the build path
a. Click on the project - select Properties
4. Connect the mysql database in the java project
Create two new Class class files in the java project package, which I named DBHelper and Demo
package sqldemo1; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.SQLException; public class DBHelper { public static final String url = "jdbc:mysql://127.0.0.1/student"; public static final String name = "com.mysql.jdbc.Driver"; public static final String user = "root"; public static final String password = ""; public Connection conn = null; public PreparedStatement pst = null; public DBHelper(String sql) { try { Class.forName(name);//指定连接类型 conn = DriverManager.getConnection(url,user,password);//获取连接 pst = conn.prepareStatement(sql);//准备执行语句 } catch (Exception e) { e.printStackTrace(); } } public void close() { try { this.conn.close(); this.pst.close(); } catch (SQLException e) { e.printStackTrace(); } } }Write another Demo.java to execute related queries OperationThe code is as follows:
package sqldemo1; import java.sql.ResultSet; import java.sql.SQLException; public class Demo { static String sql = null; static DBHelper db1 = null; static ResultSet ret = null; public static void main(String[] args) { sql = "select *from stuinfo";//SQL语句 db1 = new DBHelper(sql);//创建DBHelper对象 try { ret = db1.pst.executeQuery();//执行语句,得到结果集 while (ret.next()) { String uid = ret.getString(1); String ufname = ret.getString(2); String ulname = ret.getString(3); String udate = ret.getString(4); System.out.println(uid + "\t" + ufname + "\t" + ulname + "\t" + udate ); }//显示数据 ret.close(); db1.close();//关闭连接 } catch (SQLException e) { e.printStackTrace(); } } }
5. Analysis of the reasons for failure to connect to the mysql database
a. Is the database service open?b. Whether the corresponding database has been created; c. Whether the jar package has been added; d. Whether the driver has been loaded; e. Connection string, Are the login name and password correct? Recommended tutorial:The above is the detailed content of Steps to connect java to database. For more information, please follow other related articles on the PHP Chinese website!