Java计算代码段执行时间的详细过程

package org.feng.calc;
/**
 * 运行的方法内容：使用Lambda
 *
 * @version V1.0
 */
@FunctionalInterface
public interface MethodBody {
    void run();
}

package org.feng.calc;
import lombok.Data;
import java.util.ArrayList;
import java.util.List;
/**
 * 计算执行时间的结果保存
 *
 * @version V1.0
 */
@Data
public class CalcExecuteTimeResult {
    /**
     * 执行代码花费的时间
     */
    private List<Long> costTime;
    public CalcExecuteTimeResult(int size) {
        costTime = new ArrayList<>(size);
    }
}

package org.feng.calc;
import lombok.Getter;
import java.util.ArrayList;
import java.util.List;
import java.util.Set;
import java.util.concurrent.TimeUnit;
/**
 * 执行模板
 *
 * @version V1.0
 */
public class ExecuteTemplate {
    private final List<MethodBody> methodBodyList;
    @Getter
    private CalcExecuteTimeResult calcExecuteTimeResult;
    public ExecuteTemplate() {
        this.methodBodyList = new ArrayList<>();
    }
    public void addMethod(MethodBody methodBody) {
        methodBodyList.add(methodBody);
    }
    /**
     * 执行
     *
     * @param timeUnit  时间单位
     * @param frequency 频次-单个方法{@link MethodBody}实例执行的次数
     */
    void process(TimeUnit timeUnit, long frequency) {
        this.calcExecuteTimeResult = new CalcExecuteTimeResult(methodBodyList.size());
        List<Long> costTime = calcExecuteTimeResult.getCostTime();
        for (MethodBody methodBody : methodBodyList) {
            long startTime = getTime(timeUnit);
            for (int i = 0; i < frequency; i++) {
                methodBody.run();
            }
            long endTime = getTime(timeUnit);
            costTime.add(endTime - startTime);
        }
    }
    private long getTime(TimeUnit timeUnit) {
        if (!SUPPORTED_TIME_UNIT.contains(timeUnit)) {
            throw new UnsupportedOperationException("不支持的时间单位：" + timeUnit);
        }
        if (TimeUnit.NANOSECONDS.equals(timeUnit)) {
            return System.nanoTime();
        }
        return System.currentTimeMillis();
    }
    /**
     * 当前支持的时间单位
     */
    private static final Set<TimeUnit> SUPPORTED_TIME_UNIT = Set.of(TimeUnit.MILLISECONDS, TimeUnit.NANOSECONDS);
}

package org.feng.calc;
import lombok.Setter;
import lombok.experimental.Accessors;
import java.util.concurrent.TimeUnit;
/**
 * 计算执行时间-上下文
 *
 * @version V1.0
 */
@Setter
@Accessors(chain = true)
public class CalcExecuteTimeContext {
    private TimeUnit timeUnit;
    private Long frequency;
    private ExecuteTemplate executeTemplate;
    public CalcExecuteTimeResult run() {
        executeTemplate.process(timeUnit, frequency);
        return executeTemplate.getCalcExecuteTimeResult();
    }
    public void addMethod(MethodBody methodBody){
        executeTemplate.addMethod(methodBody);
    }
}

package org.feng.calc;
import java.util.concurrent.TimeUnit;
/**
 * 测试运行
 *
 * @version v1.0
 */
public class Client {
    public static void main(String[] args) {
        // 初始化上下文：设置每个方法执行的次数，以及计算时间时使用的时间单位，执行模板
        CalcExecuteTimeContext context = new CalcExecuteTimeContext()
                .setFrequency(2L)
                .setTimeUnit(TimeUnit.MILLISECONDS)
                .setExecuteTemplate(new ExecuteTemplate());
        context.addMethod(() -> {
            System.out.println(111);
            System.out.println(111);
            System.out.println(111);
            System.out.println(111);
            System.out.println(111);
        });
        context.addMethod(() -> {
            System.out.println(222);
            System.out.println(222);
            System.out.println(222);
            System.out.println(222);
            System.out.println(222);
        });
        // 计算得到方法运行的结果
        CalcExecuteTimeResult executeTimeResult = context.run();
        System.out.println(executeTimeResult);
    }
}