最简单的字符串相加    性能最好
slf4j MessageFormatter 使用 indexOf 解析占位符 然后拼接参数  性能较好
jdk String.format  功能强大 使用正则解析占位符 性能最差

3种方式的耗时
151 289 1975
61 464 776
15 196 743
16 101 714
16 101 707
16 101 723
16 100 737
16 101 725
17 110 733
16 107 812
17 103 731
16 102 724
17 104 727



测试代码

import java.time.LocalDateTime;

import org.slf4j.helpers.MessageFormatter;

public class StringFormatPerfTest {

    private static final int COUNT = 1000000;

    private static final String JDK_FORMAT = "now time is %s";
    private static final String SLF4J_FORMAT = "now time is {}";

    public static void main(String[] args) throws Exception {
        while (true) {
            run();
        }
    }

    private static String format(String format, Object... args) {
        return MessageFormatter.arrayFormat(format, args).getMessage();
    }

    private static void run() {
        String now = LocalDateTime.now().toString();
        long start = System.currentTimeMillis();
        for (int i = 0; i < COUNT; i++) {
            format(SLF4J_FORMAT, now);
        }
        long end = System.currentTimeMillis();
        long slf4jTime = end - start;

        start = System.currentTimeMillis();
        for (int i = 0; i < COUNT; i++) {
            String.format(JDK_FORMAT, now);
        }
        end = System.currentTimeMillis();
        long jdkTime = end - start;

        start = System.currentTimeMillis();
        for (int i = 0; i < COUNT; i++) {
            String str = "now time is " + now;
        }
        end = System.currentTimeMillis();
        long time = end - start;

        System.out.println(time + " " + slf4jTime + " " + jdkTime);
    }
}

完整代码
https://gitee.com/dyyx/springboothello/blob/master/src/main/java/log/StringFormatPerfTest.java


 string format几种方式