New file |
| | |
| | | import java.sql.Connection; |
| | | import java.sql.DriverManager; |
| | | import java.sql.SQLException; |
| | | import java.text.DecimalFormat; |
| | | |
| | | public class DatabaseConnectionTest { |
| | | public static void main(String[] args) { |
| | | /*String url = "jdbc:mysql://localhost:3306/canlian?useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=true&serverTimezone=GMT%2B8"; |
| | | String username = "root"; |
| | | String password = "123456"; |
| | | |
| | | try (Connection connection = DriverManager.getConnection(url, username, password)) { |
| | | System.out.println("数据库连接成功!"); |
| | | } catch (SQLException e) { |
| | | System.out.println("数据库连接失败:" + e.getMessage()); |
| | | }*/ |
| | | String s = calcRate(5, 4); |
| | | System.out.println(s); |
| | | } |
| | | public static String calcRate(Integer currentValue, Integer previousValue) { |
| | | //去年的数据为0的情况 |
| | | if (previousValue == 0){ |
| | | return currentValue == 0 ? "同比持平" : "无同比数据"; |
| | | } |
| | | // 计算变化率 |
| | | double changeRate = (currentValue - previousValue) * 100.0 / previousValue; |
| | | // 格式化输出(保留两位小数,带正负号) |
| | | DecimalFormat df = new DecimalFormat("0.00"); |
| | | String absoluteValue = df.format(Math.abs(changeRate)); |
| | | if (changeRate > 0) { |
| | | return "同比增加" + absoluteValue + "%"; |
| | | } else if (changeRate < 0) { |
| | | return "同比减少" + absoluteValue + "%"; |
| | | } else { |
| | | return "同比持平"; |
| | | } |
| | | |
| | | } |
| | | } |