测试代码

package org.simonme.srcstudy.spring3.demo.stub;
import static org.junit.Assert.assertNotNull;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.simonme.srcstudy.spring3.demo.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
/**
* <一句话功能简述>
* <功能详细描述>
*
* @author  //www.cnblogs.com/simoncook
* @version  [版本号, 2017年11月4日]

* @see  [相关类/方法]
* @since  [产品/模块版本]
*/
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations={"/applicationContext.xml"})
public class UserServiceAssemblyByJUnit
{
private UserService userService;
@Test
public void test()
{
assertNotNull(userService);
}
public UserService getUserService()
{

return userService;
}
@Autowired
public void setUserService(UserService userService)
{
this.userService = userService;
}

　　分析方式

　　this.userService = userService; 这一行直接断点

　　堆栈信息

org.simonme.srcstudy.spring3.demo.stub.UserServiceAssemblyByJUnit.setUserService(org.simonme.srcstudy.spring3.demo.service.UserService) line: 50
sun.reflect.NativeMethodAccessorImpl.invoke0(java.lang.reflect.Method, java.lang.Object, java.lang.Object[]) line: not available [native method]
sun.reflect.NativeMethodAccessorImpl.invoke(java.lang.Object, java.lang.Object[]) line: 39
sun.reflect.DelegatingMethodAccessorImpl.invoke(java.lang.Object, java.lang.Object[]) line: 25
java.lang.reflect.Method.invoke(java.lang.Object, java.lang.Object...) line: 597
org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredMethodElement.inject(java.lang.Object, java.lang.String, org.springframework.beans.PropertyValues) line: 582
org.springframework.beans.factory.annotation.InjectionMetadata.inject(java.lang.Object, java.lang.String, org.springframework.beans.PropertyValues) line: 84
org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(org.springframework.beans.PropertyValues, java.beans.PropertyDescriptor[], java.lang.Object, java.lang.String) line: 282
org.springframework.beans.factory.support.DefaultListableBeanFactory(org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory).populateBean(java.lang.String, org.springframework.beans.factory.support.AbstractBeanDefinition, org.springframework.beans.BeanWrapper) line: 1074
org.springframework.beans.factory.support.DefaultListableBeanFactory(org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory).autowireBeanProperties(java.lang.Object, int, boolean) line: 374
org.springframework.test.context.support.DependencyInjectionTestExecution

Listener.injectDependencies(org.springframework.test.context.TestContext) line: 110
org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(org.springframework.test.context.TestContext) line: 75
org.springframework.test.context.TestContextManager.prepareTestInstance(java.lang.Object) line: 321
org.springframework.test.context.junit4.SpringJUnit4ClassRunner.createTest() line: 220
org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1.runReflectiveCall() line: 301
org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1(org.junit.internal.runners.model.ReflectiveCallable).run() line: 12
org.springframework.test.context.junit4.SpringJUnit4ClassRunner.methodBlock(org.junit.runners.model.FrameworkMethod) line: 303
org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(org.junit.runners.model.FrameworkMethod, org.junit.runner.notification.RunNotifier) line: 240
org.springframework.test.context.junit4.SpringJUnit4ClassRunner(org.junit.runners.BlockJUnit4ClassRunner).runChild(java.lang.Object, org.junit.runner.notification.RunNotifier) line: 50
org.junit.runners.ParentRunner$3.run() line: 238
org.junit.runners.ParentRunner$1.schedule(java.lang.Runnable) line: 63
org.springframework.test.context.junit4.SpringJUnit4ClassRunner(org.junit.runners.ParentRunner<T>).runChildren(org.junit.runner.notification.RunNoti

fier) line: 236
org.junit.runners.ParentRunner<T>.access$000(org.junit.runners.ParentRunner, org.junit.runner.notification.RunNotifier) line: 53
org.junit.runners.ParentRunner$2.evaluate() line: 229

　　看junit的运作方式

　　从main方法到runner

　　翻看官方guide 很容易发现JUnitCore是main方法所在类

　　JUnitCore是如何到runner的呢？ 看下面分析

org.junit.runner.JUnitCore.main(String...)
// 一些listener构造之类，然后通过AllDefaultPossibilitiesBuilder 构建runner
org.junit.internal.builders.AllDefaultPossibilitiesBuilder.runnerForClass(Class<?>)
List<RunnerBuilder> builders = Arrays.asList(
ignoredBuilder(),
annotatedBuilder(),
suiteMethodBuilder(),
junit3Builder(),
junit4Builder());
for (RunnerBuilder each : builders) {
Runner runner = each.safeRunnerForClass(testClass);
if (runner != null) {
return runner;
}
}

　　找到一个就直接返回

　　ignoredBuilder 可以用过Ignore注解忽略你的test case

　　annotatedBuilder 是找 RunWith注解定义的自定义runner

　　junit3Builder 如果test case 继承自TestCase类 则用junit3的runner

　　junit4Builder 直接对接 BlockJUnit4ClassRunner

　　spring的SpringJUnit4ClassRunner也是继承自BlockJUnit4ClassRunner

　　回头去看上面的堆栈信息 一目了然

　　关键点在于重写 org.junit.runners.BlockJUnit4ClassRunner.createTest() 这个方法

protected Object createTest() throws Exception {
return getTestClass().getOnlyConstructor().newInstance();
}
/**
* Delegates to the parent implementation for creating the test instance and
* then allows the {@link #getTestContextManager() TestContextManager} to
* prepare the test instance before returning it.
*
* @see TestContextManager#prepareTestInstance(Object)
*/
@Override
protected Object createTest() throws Exception {
Object testInstance = super.createTest();
getTestContextManager().prepareTestInstance(testInstance);
return testInstance;
}

　　也就是把JUnit原生的创建test case的instance的过程接用spring容器装配的方式接管过来就可以了。

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