如何使用Java进行数据库高性能优化？

HikariConfig config = new HikariConfig();
config.setJdbcUrl("jdbc:mysql://localhost:3306/mydb");
config.setUsername("user");
config.setPassword("password");
HikariDataSource dataSource = new HikariDataSource(config);

Connection connection = dataSource.getConnection();
// 使用连接进行数据库操作

connection.close(); // 关闭连接，将连接放回连接池

String sql = "SELECT * FROM users WHERE username = ?";
PreparedStatement statement = connection.prepareStatement(sql);
statement.setString(1, "john");

ResultSet rs = statement.executeQuery();
// 处理查询结果

rs.close();
statement.close();

CREATE INDEX idx_username ON users(username);

String sql = "INSERT INTO users(username) VALUES(?)";
PreparedStatement statement = connection.prepareStatement(sql);

for (int i = 0; i < 100; i++) {
    statement.setString(1, "user" + i);
    statement.addBatch();
}

int[] results = statement.executeBatch();
statement.close();

String sql = "SELECT * FROM users LIMIT 10 OFFSET 20";
Statement statement = connection.createStatement();

ResultSet rs = statement.executeQuery(sql);
// 处理查询结果

rs.close();
statement.close();