计算Java中任意一个方法的执行时间的工具类
如何获取一个方法的执行时间，不论是静态方法还是静态方法，不论是私有方法还是共有方法，如果该对象不能
被实例化，使用该对象的class对象也可以，例如Arrays.class也可以作为bean传入方法中
只有当方法是static，使用bean和bean.class都可以，但如果不是static，你使用bean.class 会报错
该方法主要用来计算一个方法的执行时间和是否打印方法的执行时间和输出结果，我制作这个方法主要用来比较排序算法的时间复杂度
下面是工具类的代码：
1 package algorithm.study.utils; 2 3 import java.lang.reflect.Method; 4 5 /** 6 * This class is getting a method execute time and provide some other functions. 7 * 8 * @author ygh 2017年2月24日 9 */ 10 public class MethodExecuteTimeUtils { 11 12 /** 13 * Get a method execute time using millisecond and cancel method's print return result and 14 * execute time. 15 * 16 * @param bean The method is in this bean 17 * @param params The parameter the method execute need 18 * @param methodName The name of the method 19 * @param types The parameter type of the method 20 * @return The execute time of this method 21 * @throws Exception If <code>getMethod</code> or <code>invoke</code> fail. 22 */ 23 public static long getMethodExecuteTime(Object bean, Object[] params, String methodName, Class<?>[] types) 24 throws Exception { 25 return getMethodExecuteTime(bean, params, methodName, types, false, false); 26 } 27 28 /** 29 * Get a method execute time using millisecond and cancel print method's return result. 30 * 31 * @param bean The method is in this bean 32 * @param params The parameter the method execute need 33 * @param methodName The name of the method 34 * @param types The parameter type of the method 35 * @param isPrintExecutetime Whether print the execute time in console, true is print false not 36 * @param isViewMehtodResult Whether print the return result in console, true is print false not 37 * @return The execute time of this method 38 * @throws Exception If <code>getMethod</code> or <code>invoke</code> fail. 39 */ 40 public static long getMethodExecuteTime(Object bean, Object[] params, String methodName, 41 Class<?>[] types, boolean isPrintExecutetime) throws Exception { 42 return getMethodExecuteTime(bean, params, methodName, types, isPrintExecutetime, false); 43 } 44 45 /** 46 * Get a method execute time using millisecond and add some other service. 47 * 48 * @param bean The method is in this bean 49 * @param params The parameter the method execute need 50 * @param methodName The name of the method 51 * @param types The parameter type of the method 52 * @param isPrintExecutetime Whether print the execute time in console, true is print false not 53 * @param isViewMehtodResult Whether print the return result in console, true is print false not 54 * @return The execute time of this method 55 * @throws Exception If <code>getMethod</code> or <code>invoke</code> fail. 56 */ 57 public static long getMethodExecuteTime(Object bean, Object[] params, String methodName, 58 Class<?>[] types, boolean isPrintExecutetime, boolean isViewMehtodResult) throws Exception { 59 Class<?> clazz; 60 long executeTime = -1L; 61 boolean isAccessiable = false; 62 Method method = null; 63 if (bean instanceof Class<?>) { 64 clazz = (Class<?>) bean; 65 } else { 66 clazz = bean.getClass(); 67 } 68 try { 69 if (types == null) { 70 method = clazz.getDeclaredMethod(methodName); 71 } else { 72 method = clazz.getDeclaredMethod(methodName, types); 73 } 74 isAccessiable = method.isAccessible(); 75 if (!isAccessiable) { 76 method.setAccessible(true); 77 } 78 79 if (isViewMehtodResult) { 80 executeTime = getReturnMethodExecuteTime(bean, params, method); 81 } else { 82 executeTime = getMethodExecuteTime(bean, params, method); 83 } 84 method.setAccessible(isAccessiable); 85 if (isPrintExecutetime) { 86 printExecute(clazz, methodName, executeTime); 87 } 88 } catch (Exception e) { 89 throw new Exception("excute method fail"); 90 } 91 return executeTime; 92 } 93 94 /** 95 * Get a method execute time, use millisecond. We don't think the method whether has a return 96 * result 97 * 98 * @param bean The method is in this bean 99 * @param params The parameters the method execute need 100 * @param method The Method entity 101 * @return The millisecond the method execute spend 102 * @throws Exception If the method invoke fail 103 */ 104 private static long getMethodExecuteTime(Object bean, Object[] params, Method method) throws Exception { 105 long startTime = System.currentTimeMillis(); 106 method.invoke(bean, params); 107 long endTime = System.currentTimeMillis(); 108 return endTime - startTime; 109 } 110 111 /** 112 * Get a method execute time, use millisecond. The method must has a return result will input 113 * the return result in console ,If the method has not return result, please call 114 * <code>getMethodExecuteTime</code> method. 115 * 116 * @param bean The method is in this bean 117 * @param params The parameters the method execute need 118 * @param method The Method entity 119 * @return The millisecond the method execute spend 120 * @throws Exception If the method invoke fail 121 */ 122 private static long getReturnMethodExecuteTime(Object bean, Object[] params, Method method) 123 throws Exception { 124 long startTime = System.currentTimeMillis(); 125 Object result = (Object) method.invoke(bean, params); 126 long endTime = System.currentTimeMillis(); 127 if (result != null) { 128 System.out.println("result input：" + result.toString()); 129 } else { 130 System.out.println("Warning:" + bean.getClass().getName() + "." + method.getName() 131 + "has not return " + "result,please setting the isViewMehtodResult as false"); 132 } 133 return endTime - startTime; 134 } 135 136 /** 137 * Print the execute time of method 138 * 139 * @param methodName The name of the method 140 * @param time The execute of the method 141 */ 142 public static void printExecute(Class<?> clazz, String methodName, long time) { 143 System.out.println(clazz.getName() + "." + methodName + " execute time: " + time); 144 } 145 }
Person类，用于测试：
1 package javareflect.demo; 2 /** 3 * This a person domain used test java.reflect 4 * @author ygh 5 * 2017年2月26日 6 */ 7 public class Person { 8 9 private String name; 10 11 private Integer age; 12 13 private static String gender; 14 15 public static String getGender(){ 16 return gender; 17 } 18 19 public static void setGender(String gender){ 20 System.out.println("性别："+gender); 21 } 22 23 public String getName() { 24 return name; 25 } 26 27 public void setName(String name) { 28 this.name = name; 29 } 30 31 public Integer getAge() { 32 return age; 33 } 34 35 public void setAge(Integer age) { 36 this.age = age; 37 } 38 39 public static void fun1(){ 40 System.out.println("this is fun1"); 41 } 42 43 private void fun2(){ 44 System.out.println("this is private method"); 45 } 46 47 48 }
下面是测试代码：测试执行Person类里面的各种Method，静态的，私有的，共有的
1 public class ReflectTest { 2 @Test 3 public void fun1() throws Exception { 4 Person person = new Person(); 5 Object[] params = null; 6 Class<?>[] types = null; 7 MethodExecuteTimeUtils.getMethodExecuteTime(person, params, "fun2", types, true, true); 8 } 9 @Test 10 public void fun2() throws Exception { 11 Person person = new Person(); 12 Object[] params = null; 13 Class<?>[] types = null; 14 MethodExecuteTimeUtils.getMethodExecuteTime(person, params, "fun1", types, true, true); 15 } 16 @Test 17 public void fun3() throws Exception { 18 Person person = new Person(); 19 Object[] params = {12}; 20 Class<?>[] types = {Integer.class}; 21 MethodExecuteTimeUtils.getMethodExecuteTime(person, params, "setAge", types, true, true); 22 System.out.println(person.getAge()); 23 } 24 }
下面是测试代码，比较Java自带的排序方法和归并排序哪个时间复杂度更高。
1 package algorithm.study.demo2; 2 3 4 import java.util.Arrays; 5 6 import org.junit.Test; 7 8 import algorithm.study.utils.MethodExecuteTimeUtils; 9 10 /** 11 * This class implement MergeSort 12 * @author ygh 13 * 2017年2月23日 14 */ 15 public class MergeSort { 16 17 /** 18 * Arithmetic thoughts: 19 * If we want to sort a array elements,we can sort their left,then 20 * sort their right. In the left array, we can use same thought 21 * separate the left array to halt then sort them..... 22 * At last,it will change into tow number compare,then merge 23 * 24 * @param arr The array need to sort 25 * @param A temporary array to store elements that have sorted,its length is right-left 26 * 27 * @param left The left index of elements you want to sort in this array 28 * @param right The right index of elements you want to sort in this array 29 */ 30 public void mergeSort(int[] sortedArr,int[] tmpArr,int left,int right){ 31 if(left<right){ 32 int mid = (left+right) / 2; 33 mergeSort(sortedArr,tmpArr, left, mid); 34 mergeSort(sortedArr,tmpArr, mid+1, right); 35 merge(sortedArr, tmpArr,left,mid,right); 36 copy(sortedArr, tmpArr,left,right); 37 } 38 } 39 40 /** 41 * Copy elements from temporary array to sorted array. The index range is from left to rigth 42 * @param haltSortedArr The array need to sort 43 * @param tmpArr The temporary array 44 * @param left The left index 45 * @param right The right index 46 */ 47 private void copy(int[] haltSortedArr, int[] tmpArr, int left, int right) { 48 for(int i=left;i<=right;i++){ 49 haltSortedArr[i]=tmpArr[i]; 50 } 51 } 52 53 /** 54 * This method is to merge elements from haltSortedArr.now the haltSortedArr 55 * has became sorted half by half.The elements' index from left to mid is sorted,and the 56 * elements' index from mid to right is sorted.So we just need to merge it to get all order 57 * array 58 * @param haltSortedArr The array has became sorted half by half 59 * @param tmpArr A temporary array to store elements order. 60 * @param left The left index of elements you want to sort in this array 61 * @param mid The order element separator index 62 * @param right The right index of elements you want to sort in this array 63 */ 64 private void merge(int[] haltSortedArr, int[] tmpArr, int left, int mid, int right) { 65 int i=left; 66 int j=mid+1; 67 int d = left; 68 while (i <= mid && j <= right) { 69 if (haltSortedArr[i] <= haltSortedArr[j]) { 70 tmpArr[d++]=haltSortedArr[i++]; 71 }else{ 72 tmpArr[d++]=haltSortedArr[j++]; 73 } 74 } 75 76 if(i>mid){//If i more mid,indicate some elements have not be put in temporary array in array right 77 while(j<=right){ 78 tmpArr[d++]=haltSortedArr[j++]; 79 } 80 }else{//If i less mid,indicate some elements have not be put in temporary array in array left 81 while(i<=mid){ 82 tmpArr[d++]=haltSortedArr[i++]; 83 } 84 } 85 } 86 87 88 /** 89 * Get a random array by size and max value 90 * @param size The size the new array you want to create 91 * @param maxValue The max value in the array; 92 * @return A randow array 93 */ 94 private int[] getRandomArray(int size,int maxValue){ 95 int []arr = new int[size]; 96 for(int i=0;i<size;i++){ 97 arr[i]=getIntRandomValue(maxValue); 98 } 99 return arr; 100 } 101 102 /** 103 * Get a random that less than max value 104 * @param maxValue The max value you get the random number 105 * @return A random number less than max value 106 */ 107 private int getIntRandomValue(int maxValue){ 108 return (int) (Math.random()*maxValue); 109 } 110 111 112 /** 113 * This is a method to test how long time the mergeSort spend on 114 * @param arr The array need to sort 115 * @throws Exception 116 */ 117 public void testMergeSort(int[] arr) throws Exception{ 118 MergeSort m = new MergeSort(); 119 Class<?>[] types = {int[].class,int[].class,int.class,int.class}; 120 String methodName = "mergeSort"; 121 int size = arr.length-1; 122 int[] tmp = new int[size]; 123 mergeSort(arr, tmp, 0, size-1); 124 Object[] params={arr,tmp,0,size-1}; 125 MethodExecuteTimeUtils.getMethodExecuteTime(m, params,methodName,types,true); 126 } 127 128 /** 129 * This is a method to test how long time the javaself sort method spend on 130 * @param arr The array need to sort 131 * @throws Exception 132 */ 133 public void testJavaSort(int[] arr) throws Exception{ 134 Class<?>[] types = {int[].class}; 135 String methodName = "sort"; 136 Object[] params = {arr}; 137 //although Arrays can be instance,you use Arrays.class also available,and static method also available 138 MethodExecuteTimeUtils.getMethodExecuteTime(Arrays.class, params, methodName, types,true); 139 } 140 141 /** 142 * print array into console 143 * @param arr The array need to print console 144 */ 145 public void printArray(int[] arr){ 146 System.out.println(Arrays.toString(arr)); 147 } 148 149 /** 150 * This is just a test method 151 * @throws Exception 152 */ 153 @Test 154 public void fun3() throws Exception{ 155 int size = 922000; 156 int maxValue = 9999999; 157 //construct random array 158 int[] arr1 = getRandomArray(size, maxValue); 159 int[] arr2 = Arrays.copyOf(arr1, size); 160 testMergeSort(arr2); 161 testJavaSort(arr1); 162 } 163 164 165 166 167 }
