How can I bulk update database data using Java?

To bulk modify database data, you can use JDBC in Java to connect to the database and execute SQL statements. First, you need to import the JDBC driver. Depending on the database you are using, you can find the corresponding driver on the official website or Maven repository. Then, you need to establish a database connection. You can use the `java.sql.Connection` interface to connect to the database, as shown below:

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public class Main {
    public static void main(String[] args) {
        String url = "jdbc:mysql://localhost:3306/mydatabase";
        String username = "root";
        String password = "password";
        try {
            Connection conn = DriverManager.getConnection(url, username, password);
            // 执行SQL语句
            conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

In the DriverManager.getConnection method, you need to provide the database URL, username, and password. Next, you can execute SQL statements to modify data in the database. You can use the executeUpdate method of the java.sql.Statement interface to execute SQL statements, as shown below:

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
public class Main {
    public static void main(String[] args) {
        String url = "jdbc:mysql://localhost:3306/mydatabase";
        String username = "root";
        String password = "password";
        try {
            Connection conn = DriverManager.getConnection(url, username, password);
            Statement stmt = conn.createStatement();
            String sql = "UPDATE mytable SET column1 = 'new value' WHERE column2 = 'condition'";
            int rowsAffected = stmt.executeUpdate(sql);
            System.out.println("Rows affected: " + rowsAffected);
            stmt.close();
            conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

In the above example, we executed an `UPDATE` statement to modify the values in the column1 of the rows in mytable table that meet the condition. You can batch modify database data by iterating through the data and executing the appropriate SQL statements.