5 ways java connects to a database

package com.hsp.edu; import com.mysql.cj.jdbc.Driver; import java.lang.reflect.Constructor; import java.lang.reflect.InvocationTargetException; import java.sql.Connection; import java.sql.SQLException; import java.util.Properties; // 5 ways java can obtain a connection public class JdbcConnect {public static void main(String[] args) throws SQLException, ClassNotFoundException, InstantiationException, IllegalAccessException, NoSuchMethodException, InvocationTargetException { connect01(); connect02(); } // Method 1: Import the third-party library Driver class public static void connect01() throws SQLException {// Obtain the driver Driver driver = new Driver(); / / get connection String url = "JDBC: mysql: / / localhost: 3306 / JDBC? serverTimezone=UTC&useSSL=false&useSer" + "verPrepStmts=true&characterEncoding=utf-8&useSSL=false"; // Put the user name and password into the Properities object. Properties properties = new Properties(); properties.setProperty("user","root"); setProperty("password","888888"); // user properties.setProperty("password","888888"); final Connection connect = driver.connect(url, properties); // password Final connection connect = driver.connect(URL, properties); System.out.println(connect); // Method 2: Use reflection to load the Driver: Dynamic loading, more flexible, Reduce dependencies public static void connect02() throws ClassNotFoundException, InstantiationException, IllegalAccessException, SQLException, NoSuchMethodException InvocationTargetException {/ / get Driver Class bytecode file object final Class <? > clazz = Class.forName("com.mysql.cj.jdbc.Driver"); // Note: When a bytecode file object is used to obtain a Driver object, the direct newInstance is prompted by the idea that final Constructor<? > Constructor = clazz.getDeclaredConstructor(); final Driver driver = (Driver)Constructor.newInstance(); String url = "jdbc:mysql://localhost:3306/jdbc? serverTimezone=UTC&useSSL=false&useSer" + "verPrepStmts=true&characterEncoding=utf-8&useSSL=false"; // Put the user name and password into the Properities object. Properties properties = new Properties(); properties.setProperty("user","root"); setProperty("password","888888"); // user properties.setProperty("password","888888"); final Connection connect = driver.connect(url, properties); // password Final connection connect = driver.connect(URL, properties); System.out.println(connect); }}

// Method 3: Use the DriverManager replacement Driver public static void connect03 () throws SQLException, InvocationTargetException, InstantiationException, IllegalAccessException, NoSuchMethodException, ClassNotFoundException {// The DriverManager Class supports a better way to get connections by taking the user and password directly as parameters instead of storing them in Properities final Class<? > clazz = Class.forName("com.mysql.cj.jdbc.Driver"); final Constructor<? > constructor = clazz.getDeclaredConstructor(); final Driver driver =(Driver)constructor.newInstance(); / / create the url and user and password String url = "JDBC: mysql: / / localhost: 3306 / JDBC? serverTimezone=UTC&useSSL=false&useSer" + "verPrepStmts=true&characterEncoding=utf-8&useSSL=false"; String user = "root"; final String password = "888888"; DriverManager.registerDriver(driver); / / registered Driver to drive the final Connection Connection = DriverManager. GetConnection (url, user, password); System.out.println(connection); }

// Method 4: Automatic registration is done when the Driver is loaded (this method is used most often, Recommended:) public static void connect04() throws ClassNotFoundException, SQLException {// The Driver class is loaded using reflection. Class.forName("com.mysql.cj.jdbc.Driver") is registered. String url = "jdbc:mysql://localhost:3306/jdbc? serverTimezone=UTC&useSSL=false&useSer" + "verPrepStmts=true&characterEncoding=utf-8&useSSL=false"; String user = "root"; String password="888888"; final Connection connection = DriverManager.getConnection(url, user, password); System.out.println(connection); }

// Method 5: Further optimization, Writes information to the configuration file public static void connect05() throws IOException, ClassNotFoundException, SQLException {// Obtain configuration file information from the Properties object. properties = new Properties(); properties.load(new FileInputStream("src\\mysql.properties")); // The information about the configuration file is read into properties. // Obtain related information. final String user = properties.getProperty("user"); // User final String password = properties.getProperty("password"); // User final string password = properties.getproperty ("password"); // password final String url = properties.getProperty("url"); //url final String driver = properties.getProperty("driver"); Class.forName(driver); / / registered to drive the final Connection Connection = DriverManager. GetConnection (url, user, password); // Get the connection System.out.println(connection); }

package com.hsp; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; import java.sql.Statement; import java.util.Properties; /* Refer to the teacher's code and use Method 5 to complete 1. Create news Table 2. Add 5 records using jdbc 3. Change the content of record id=1 to a new record */ public class Jdbc02 {public static void main(String[] args) throws IOException, ClassNotFoundException, SQLException {// Preposition: Get the information in the configuration file. Properties properties = new Properties(); properties.load(new FileInputStream("src\\mysql1.properties")); // Read information to the collection final String driver = properties.getProperty("driver"); // Get the full class name final String url = properties.getProperty("url"); // Get url final String user = properties.getProperty("user"); // Obtain the user name final String password = properties.getProperty("password"); // Get the password System.out.println(properties); //1. Register the driver Class.forName(driver); / / 2. Get connect final Connection Connection = DriverManager. GetConnection (url, user, password); Run the SQL statement //String sql1 = "CREATE TABLE news(id INT,content VARCHAR(32))"; //3. String sql2="INSERT INTO news VALUES (1,' resident health '),(2,' commodity health '),(3,' giant panda ')"; String sql3="UPDATE news SET content=' Hubei 'WHERE id=1;" ; final Statement statement = connection.createStatement(); //final int row1 = statement.executeUpdate(sql1); final int row2 = statement.executeUpdate(sql2); // Return the number of affected rows. Final int row2 = statement.executeUpdate(SQL2); final int row3 = statement.executeUpdate(sql3); // Return the number of affected rows. Final int row3 = statement.executeUpdate(sql3); // : Check whether the command is executed successfully. /*if(row1! =0){System.out.println(" Executed successfully "); }else {System.out.println(" Execution failed "); }*/ if (row2! =0){System.out.println(" Executed successfully "); }else {System.out.println(" Execution failed "); } if(row3! =0){System.out.println(" Executed successfully "); }else {System.out.println(" Execution failed "); } //4. close the resource statement.close(); connection.close(); }}