TimeMeasureUtil：做單次時間測量。

1、為了能確保 startTime 和 endTime 都正確設置，因而采用實例對象來實現。每次測量是都能判斷對象是否處在正確狀態。

2、該類為工具類，即使測試時產生許多對象實例也對軟件無任何影響。

public class TimeMeasureUtil {private long startTime = 0;private long endTime = 0;private TimeMeasureUtil(){}public static TimeMeasureUtil newInstance(){return new TimeMeasureUtil();}public void start(){startTime = System.currentTimeMillis();}public void end(){endTime = System.currentTimeMillis();}public long measure(){// Invalid: Before yif( startTime == 0 ){throw new IllegalStateException( "Must call metod start() first, when call method measure()." );}if( endTime == 0 ){throw new IllegalStateException( "Must call metod end() first, when call method measure()." );}if( startTime > endTime ){throw new IllegalStateException( "Must call metod start() first, when call method end()." );}return endTime - startTime;}}

使用示例：

@Testpublic void testMeasure_ok() {TimeMeasureUtil timeUtil = TimeMeasureUtil.newInstance();timeUtil.start();// 下面這段代碼用實際待測方法代替try {Thread.sleep( 1000 );} catch (InterruptedException e) {e.printStackTrace();}timeUtil.end();assertEquals( 1000, timeUtil.measure() );}

由于單次測量可能的偏差太大，沒有統計意義，如下類測量平均時間！
TimeMeasureProxy：

1、默認運行20次得平均

2、給定運行次數的平均

缺陷：

1、由于是用反射實現，參數是通過 Object[ ] 來傳遞。有原始類型（如：byte，int，char...）參數的方法不能測試！只能用 TimeMeasureUtil 來實現測試。?

2、如果第一次執行方法后改變了某屬性，而該屬性改變后又會影響下一次方法的執行（可能會有不同的時間），這樣的方法不能測試。可能的改進方式：先“克隆” count 個該對象，然后用這樣相同屬性的對象來執行方法（每個對象執行一次方法）。因為這樣要求，被測試類提供“克隆”方法，“因測試而影響邏輯”不可取，所以沒有實現。

import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method;public class TimeMeasureProxy {// default measure countprivate int count = 20;private TimeMeasureProxy(){}private TimeMeasureProxy( int count ){this.count = count;}public static TimeMeasureProxy newInstance(){return new TimeMeasureProxy();}public static TimeMeasureProxy newInstance( int count ){return new TimeMeasureProxy( count );}public long avgTime( Object owner, String methodName, Object[] args ){// valid parameters.if( owner == null ){throw new IllegalStateException("owner can't be null.");}if( methodName == null ){throw new IllegalStateException("methodName can't be null.");}Class<?> ownerClass = owner.getClass();Class<?>[] argsClass = null;if( args != null ){argsClass = new Class[ args.length ];for( int i=0 ; i<args.length ; i++ ){argsClass[i] = args[i].getClass();}}Method method;try {method = ownerClass.getMethod( methodName, argsClass );} catch (SecurityException e) {throw new RuntimeException( e );} catch (NoSuchMethodException e) {throw new RuntimeException( e );}return totalTime( owner, method, args)/count;}long totalTime( Object owner, Method method, Object[] args ){long totalTime = 0;try {for( int i=0; i<count ; i++ ){TimeMeasureUtil timeUtil = TimeMeasureUtil.newInstance();timeUtil.start();method.invoke( owner, args );timeUtil.end();totalTime += timeUtil.measure();}} catch (IllegalArgumentException e) {throw new RuntimeException( e );} catch (IllegalAccessException e) {throw new RuntimeException( e );} catch (InvocationTargetException e) {throw new RuntimeException( e );}return totalTime;}}

使用示例：

1、待測試的類

class ForMeasureAvgTime{public void justForTest(){try {Thread.sleep( 335 );} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}}public void justForTestWithParams( Integer age, String name ){try {Thread.sleep( 558 );} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}} }

2、通過TimeMeasureProxy 來測試

@Test//測量無參數方法&默認次數（20）public void testAvgTime_defaultCount() {ForMeasureAvgTime forMeasure = new ForMeasureAvgTime();TimeMeasureProxy proxy = TimeMeasureProxy.newInstance();long avgTime = proxy.avgTime( forMeasure, "justForTest", null );System.out.println( "avgTime=" + avgTime );assertTrue( (avgTime - 335) < 5 || (335 - avgTime) < 5);}@Test//測量有參數方法&給定次數（10）public void testAvgTime_giveCount() {ForMeasureAvgTime forMeasure = new ForMeasureAvgTime();TimeMeasureProxy proxy = TimeMeasureProxy.newInstance( 10 );long avgTime = proxy.avgTime( forMeasure, "justForTestWithParams", new Object[]{24, "GongQiang"} );System.out.println( "avgTime=" + avgTime );assertTrue( (avgTime - 558) < 5 || (558 - avgTime) < 5);}

總結

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