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