Spring源码分析非懒加载的单例Bean初始化过程(下篇)

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doCreateBean方法

上文【Spring源码分析】非懒加载的单例Bean初始化过程(上篇),分析了单例的Bean初始化流程,并跟踪代码进入了主流程,看到了Bean是如何被实例化出来的。先贴一下AbstractAutowireCapableBeanFactory的doCreateBean方法代码:

 1 protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final Object[] args) {
 2     // Instantiate the bean.
 3     BeanWrapper instanceWrapper = null;
 4     if (mbd.isSingleton()) {
 5         instanceWrapper = this.factoryBeanInstanceCache.remove(beanName);
 6     }
 7     if (instanceWrapper == null) {
 8         instanceWrapper = createBeanInstance(beanName, mbd, args);
 9     }
10     final Object bean = (instanceWrapper != null ? instanceWrapper.getWrappedInstance() : null);
11     Class beanType = (instanceWrapper != null ? instanceWrapper.getWrappedClass() : null);
12 
13     // Allow post-processors to modify the merged bean definition.
14     synchronized (mbd.postProcessingLock) {
15         if (!mbd.postProcessed) {
16             applyMergedBeanDefinitionPostProcessors(mbd, beanType, beanName);
17             mbd.postProcessed = true;
18         }
19     }
20 
21     // Eagerly cache singletons to be able to resolve circular references
22     // even when triggered by lifecycle interfaces like BeanFactoryAware.
23     boolean earlySingletonExposure = (mbd.isSingleton() && this.allowCircularReferences &&
24             isSingletonCurrentlyInCreation(beanName));
25     if (earlySingletonExposure) {
26         if (logger.isDebugEnabled()) {
27             logger.debug("Eagerly caching bean '" + beanName +
28                     "' to allow for resolving potential circular references");
29         }
30         addSingletonFactory(beanName, new ObjectFactory() {
31             public Object getObject() throws BeansException {
32                 return getEarlyBeanReference(beanName, mbd, bean);
33             }
34         });
35     }
36 
37     // Initialize the bean instance.
38     Object exposedObject = bean;
39     try {
40         populateBean(beanName, mbd, instanceWrapper);
41         if (exposedObject != null) {
42             exposedObject = initializeBean(beanName, exposedObject, mbd);
43         }
44     }
45     catch (Throwable ex) {
46         if (ex instanceof BeanCreationException && beanName.equals(((BeanCreationException) ex).getBeanName())) {
47             throw (BeanCreationException) ex;
48         }
49         else {
50             throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Initialization of bean failed", ex);
51         }
52     }
53 
54     if (earlySingletonExposure) {
55         Object earlySingletonReference = getSingleton(beanName, false);
56         if (earlySingletonReference != null) {
57             if (exposedObject == bean) {
58                 exposedObject = earlySingletonReference;
59             }
60             else if (!this.allowRawInjectionDespiteWrapping && hasDependentBean(beanName)) {
61                 String[] dependentBeans = getDependentBeans(beanName);
62                 Set<String> actualDependentBeans = new LinkedHashSet<String>(dependentBeans.length);
63                 for (String dependentBean : dependentBeans) {
64                     if (!removeSingletonIfCreatedForTypeCheckOnly(dependentBean)) {
65                         actualDependentBeans.add(dependentBean);
66                     }
67                 }
68                 if (!actualDependentBeans.isEmpty()) {
69                     throw new BeanCurrentlyInCreationException(beanName,
70                             "Bean with name '" + beanName + "' has been injected into other beans [" +
71                             StringUtils.collectionToCommaDelimitedString(actualDependentBeans) +
72                             "] in its raw version as part of a circular reference, but has eventually been " +
73                             "wrapped. This means that said other beans do not use the final version of the " +
74                             "bean. This is often the result of over-eager type matching - consider using " +
75                             "'getBeanNamesOfType' with the 'allowEagerInit' flag turned off, for example.");
76                 }
77             }
78         }
79     }
80 
81     // Register bean as disposable.
82     try {
83         registerDisposableBeanIfNecessary(beanName, bean, mbd);
84     }
85     catch (BeanDefinitionValidationException ex) {
86         throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Invalid destruction signature", ex);
87     }
88 
89     return exposedObject;
90 }

下面继续分析初始化一个Bean的流程,不太重要的流程就跳过了。

 

属性注入

属性注入的代码比较好找,可以看一下40行,取名为populateBean,即填充Bean的意思,看一下代码实现:

 1 protected void populateBean(String beanName, AbstractBeanDefinition mbd, BeanWrapper bw) {
 2     PropertyValues pvs = mbd.getPropertyValues();
 3 
 4     if (bw == null) {
 5         if (!pvs.isEmpty()) {
 6             throw new BeanCreationException(
 7                     mbd.getResourceDescription(), beanName, "Cannot apply property values to null instance");
 8         }
 9         else {
10             // Skip property population phase for null instance.
11             return;
12         }
13     }
14 
15     // Give any InstantiationAwareBeanPostProcessors the opportunity to modify the
16     // state of the bean before properties are set. This can be used, for example,
17     // to support styles of field injection.
18     boolean continueWithPropertyPopulation = true;
19 
20     if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {
21         for (BeanPostProcessor bp : getBeanPostProcessors()) {
22             if (bp instanceof InstantiationAwareBeanPostProcessor) {
23                 InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
24                 if (!ibp.postProcessAfterInstantiation(bw.getWrappedInstance(), beanName)) {
25                     continueWithPropertyPopulation = false;
26                     break;
27                 }
28             }
29         }
30     }
31 
32     if (!continueWithPropertyPopulation) {
33         return;
34     }
35 
36     if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_NAME ||
37             mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_TYPE) {
38         MutablePropertyValues newPvs = new MutablePropertyValues(pvs);
39 
40         // Add property values based on autowire by name if applicable.
41         if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_NAME) {
42             autowireByName(beanName, mbd, bw, newPvs);
43         }
44 
45         // Add property values based on autowire by type if applicable.
46         if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_TYPE) {
47             autowireByType(beanName, mbd, bw, newPvs);
48         }
49 
50         pvs = newPvs;
51     }
52 
53     boolean hasInstAwareBpps = hasInstantiationAwareBeanPostProcessors();
54     boolean needsDepCheck = (mbd.getDependencyCheck() != RootBeanDefinition.DEPENDENCY_CHECK_NONE);
55 
56     if (hasInstAwareBpps || needsDepCheck) {
57         PropertyDescriptor[] filteredPds = filterPropertyDescriptorsForDependencyCheck(bw);
58         if (hasInstAwareBpps) {
59             for (BeanPostProcessor bp : getBeanPostProcessors()) {
60                 if (bp instanceof InstantiationAwareBeanPostProcessor) {
61                     InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
62                     pvs = ibp.postProcessPropertyValues(pvs, filteredPds, bw.getWrappedInstance(), beanName);
63                     if (pvs == null) {
64                         return;
65                     }
66                 }
67             }
68         }
69         if (needsDepCheck) {
70             checkDependencies(beanName, mbd, filteredPds, pvs);
71         }
72     }
73 
74     applyPropertyValues(beanName, mbd, bw, pvs);
75 }

这段代码层次有点深,跟一下74行的applyPropertyValues方法,最后那个pvs的实现类为MutablePropertyValues,里面持有一个List<PropertyValue>,每一个PropertyValue包含了此Bean属性的属性名与属性值。74行的代码实现为:

 1 protected void applyPropertyValues(String beanName, BeanDefinition mbd, BeanWrapper bw, PropertyValues pvs) {
 2     if (pvs == null || pvs.isEmpty()) {
 3         return;
 4     }
 5 
 6     MutablePropertyValues mpvs = null;
 7     List<PropertyValue> original;
 8         
 9     if (System.getSecurityManager()!= null) {
10         if (bw instanceof BeanWrapperImpl) {
11             ((BeanWrapperImpl) bw).setSecurityContext(getAccessControlContext());
12         }
13     }
14 
15     if (pvs instanceof MutablePropertyValues) {
16         mpvs = (MutablePropertyValues) pvs;
17         if (mpvs.isConverted()) {
18             // Shortcut: use the pre-converted values as-is.
19             try {
20                 bw.setPropertyValues(mpvs);
21                 return;
22             }
23             catch (BeansException ex) {
24                 throw new BeanCreationException(
25                         mbd.getResourceDescription(), beanName, "Error setting property values", ex);
26             }
27         }
28         original = mpvs.getPropertyValueList();
29     }
30     else {
31         original = Arrays.asList(pvs.getPropertyValues());
32     }
33 
34     TypeConverter converter = getCustomTypeConverter();
35     if (converter == null) {
36         converter = bw;
37     }
38     BeanDefinitionValueResolver valueResolver = new BeanDefinitionValueResolver(this, beanName, mbd, converter);
39 
40     // Create a deep copy, resolving any references for values.
41     List<PropertyValue> deepCopy = new ArrayList<PropertyValue>(original.size());
42     boolean resolveNecessary = false;
43     for (PropertyValue pv : original) {
44         if (pv.isConverted()) {
45             deepCopy.add(pv);
46         }
47         else {
48             String propertyName = pv.getName();
49             Object originalValue = pv.getValue();
50             Object resolvedValue = valueResolver.resolveValueIfNecessary(pv, originalValue);
51             Object convertedValue = resolvedValue;
52             boolean convertible = bw.isWritableProperty(propertyName) &&
53                         !PropertyAccessorUtils.isNestedOrIndexedProperty(propertyName);
54             if (convertible) {
55                 convertedValue = convertForProperty(resolvedValue, propertyName, bw, converter);
56             }
57             // Possibly store converted value in merged bean definition,
58             // in order to avoid re-conversion for every created bean instance.
59             if (resolvedValue == originalValue) {
60                 if (convertible) {
61                     pv.setConvertedValue(convertedValue);
62                 }
63                 deepCopy.add(pv);
64             }
65             else if (convertible && originalValue instanceof TypedStringValue &&
66                     !((TypedStringValue) originalValue).isDynamic() &&
67                     !(convertedValue instanceof Collection || ObjectUtils.isArray(convertedValue))) {
68                 pv.setConvertedValue(convertedValue);
69                 deepCopy.add(pv);
70             }
71             else {
72                 resolveNecessary = true;
73                 deepCopy.add(new PropertyValue(pv, convertedValue));
74             }
75         }
76     }
77     if (mpvs != null && !resolveNecessary) {
78         mpvs.setConverted();
79     }
80 
81     // Set our (possibly massaged) deep copy.
82     try {
83         bw.setPropertyValues(new MutablePropertyValues(deepCopy));
84     }
85     catch (BeansException ex) {
86         throw new BeanCreationException(
87                 mbd.getResourceDescription(), beanName, "Error setting property values", ex);
88     }
89 }

之后在第41行~第76行做了一次深拷贝(只是名字叫做深拷贝而已,其实就是遍历PropertyValue然后一个一个赋值到一个新的List而不是Java语义上的Clone,这里使用深拷贝是为了解析Values值中的所有引用),将PropertyValue一个一个赋值到一个新的List里面去,起名为deepCopy。最后执行83行进行复制,bw即BeanWrapper,持有Bean实例的一个Bean包装类,看一下代码实现:

 1 public void setPropertyValues(PropertyValues pvs, boolean ignoreUnknown, boolean ignoreInvalid)
 2         throws BeansException {
 3 
 4     List<PropertyAccessException> propertyAccessExceptions = null;
 5     List<PropertyValue> propertyValues = (pvs instanceof MutablePropertyValues ?
 6             ((MutablePropertyValues) pvs).getPropertyValueList() : Arrays.asList(pvs.getPropertyValues()));
 7     for (PropertyValue pv : propertyValues) {
 8         try {
 9             // This method may throw any BeansException, which won't be caught
10             // here, if there is a critical failure such as no matching field.
11             // We can attempt to deal only with less serious exceptions.
12             setPropertyValue(pv);
13         }
14         catch (NotWritablePropertyException ex) {
15             if (!ignoreUnknown) {
16                 throw ex;
17             }
18             // Otherwise, just ignore it and continue...
19         }
20         catch (NullValueInNestedPathException ex) {
21             if (!ignoreInvalid) {
22                 throw ex;
23             }
24             // Otherwise, just ignore it and continue...
25         }
26         catch (PropertyAccessException ex) {
27             if (propertyAccessExceptions == null) {
28                 propertyAccessExceptions = new LinkedList<PropertyAccessException>();
29             }
30             propertyAccessExceptions.add(ex);
31         }
32     }
33 
34     // If we encountered individual exceptions, throw the composite exception.
35     if (propertyAccessExceptions != null) {
36         PropertyAccessException[] paeArray =
37                 propertyAccessExceptions.toArray(new PropertyAccessException[propertyAccessExceptions.size()]);
38         throw new PropertyBatchUpdateException(paeArray);
39     }
40 }

这段代码没什么特别的,遍历前面的deepCopy,拿每一个PropertyValue,执行第12行的setPropertyValue:

 1 public void setPropertyValue(PropertyValue pv) throws BeansException {
 2     PropertyTokenHolder tokens = (PropertyTokenHolder) pv.resolvedTokens;
 3     if (tokens == null) {
 4         String propertyName = pv.getName();
 5         BeanWrapperImpl nestedBw;
 6         try {
 7             nestedBw = getBeanWrapperForPropertyPath(propertyName);
 8         }
 9         catch (NotReadablePropertyException ex) {
10             throw new NotWritablePropertyException(getRootClass(), this.nestedPath + propertyName,
11                     "Nested property in path '" + propertyName + "' does not exist", ex);
12         }
13         tokens = getPropertyNameTokens(getFinalPath(nestedBw, propertyName));
14         if (nestedBw == this) {
15             pv.getOriginalPropertyValue().resolvedTokens = tokens;
16         }
17         nestedBw.setPropertyValue(tokens, pv);
18     }
19     else {
20         setPropertyValue(tokens, pv);
21     }
22 }

找一个合适的BeanWrapper,这里就是自身,然后执行17行的setPropertyValue方法进入最后一步,方法非常长,截取核心的一段:

 1 final Method writeMethod = (pd instanceof GenericTypeAwarePropertyDescriptor ?
 2     ((GenericTypeAwarePropertyDescriptor) pd).getWriteMethodForActualAccess() :
 3     pd.getWriteMethod());
 4     if (!Modifier.isPublic(writeMethod.getDeclaringClass().getModifiers()) && !writeMethod.isAccessible()) {
 5     if (System.getSecurityManager()!= null) {
 6         AccessController.doPrivileged(new PrivilegedAction<Object>() {
 7                 public Object run() {
 8                     writeMethod.setAccessible(true);
 9                     return null;
10                 }
11             });
12         }
13         else {
14             writeMethod.setAccessible(true);
15         }
16     }
17     final Object value = valueToApply;
18     if (System.getSecurityManager() != null) {
19     try {
20         AccessController.doPrivileged(new PrivilegedExceptionAction<Object>() {
21             public Object run() throws Exception {
22                 writeMethod.invoke(object, value);
23                 return null;
24             }
25         }, acc);
26     }
27     catch (PrivilegedActionException ex) {
28         throw ex.getException();
29     }
30 }
31 else {
32     writeMethod.invoke(this.object, value);
33 }

大致流程就是两步:

(1)拿到写方法并将方法的可见性设置为true

(2)拿到Value值,对Bean通过反射调用写方法

这样完成了对于Bean属性值的设置。

 

Aware注入

接下来是Aware注入。在使用Spring的时候我们将自己的Bean实现BeanNameAware接口、BeanFactoryAware接口等,依赖容器帮我们注入当前Bean的名称或者Bean工厂,其代码实现先追溯到上面doCreateBean方法的42行initializeBean方法:

 1 protected Object initializeBean(final String beanName, final Object bean, RootBeanDefinition mbd) {
 2     if (System.getSecurityManager() != null) {
 3         AccessController.doPrivileged(new PrivilegedAction<Object>() {
 4             public Object run() {
 5                 invokeAwareMethods(beanName, bean);
 6                 return null;
 7             }
 8         }, getAccessControlContext());
 9     }
10     else {
11         invokeAwareMethods(beanName, bean);
12     }
13         
14     Object wrappedBean = bean;
15     if (mbd == null || !mbd.isSynthetic()) {
16         wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);
17     }
18 
19     try {
20         invokeInitMethods(beanName, wrappedBean, mbd);
21     }
22     catch (Throwable ex) {
23         throw new BeanCreationException(
24                 (mbd != null ? mbd.getResourceDescription() : null),
25                 beanName, "Invocation of init method failed", ex);
26     }
27 
28     if (mbd == null || !mbd.isSynthetic()) {
29         wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
30     }
31     return wrappedBean;
32 }

看一下上面第5行的实现:

 1 private void invokeAwareMethods(final String beanName, final Object bean) {
 2     if (bean instanceof BeanNameAware) {
 3         ((BeanNameAware) bean).setBeanName(beanName);
 4     }
 5     if (bean instanceof BeanClassLoaderAware) {
 6         ((BeanClassLoaderAware) bean).setBeanClassLoader(getBeanClassLoader());
 7     }
 8     if (bean instanceof BeanFactoryAware) {
 9         ((BeanFactoryAware) bean).setBeanFactory(AbstractAutowireCapableBeanFactory.this);
10     }
11 }

看到这里判断,如果bean是BeanNameAware接口的实现类会调用setBeanName方法、如果bean是BeanClassLoaderAware接口的实现类会调用setBeanClassLoader方法、如果是BeanFactoryAware接口的实现类会调用setBeanFactory方法,注入对应的属性值。

 

调用BeanPostProcessor的postProcessBeforeInitialization方法

上面initializeBean方法再看16行其实现:

 1 public Object applyBeanPostProcessorsBeforeInitialization(Object existingBean, String beanName)
 2         throws BeansException {
 3 
 4     Object result = existingBean;
 5     for (BeanPostProcessor beanProcessor : getBeanPostProcessors()) {
 6         result = beanProcessor.postProcessBeforeInitialization(result, beanName);
 7         if (result == null) {
 8             return result;
 9         }
10     }
11     return result;
12 }

遍历每个BeanPostProcessor接口实现,调用postProcessBeforeInitialization方法,这个接口的调用时机之后会总结,这里就代码先简单提一下。

 

调用初始化方法

initializeBean方法的20行,调用Bean的初始化方法,看一下实现:

 1 protected void invokeInitMethods(String beanName, final Object bean, RootBeanDefinition mbd)
 2         throws Throwable {
 3 
 4     boolean isInitializingBean = (bean instanceof InitializingBean);
 5     if (isInitializingBean && (mbd == null || !mbd.isExternallyManagedInitMethod("afterPropertiesSet"))) {
 6         if (logger.isDebugEnabled()) {
 7             logger.debug("Invoking afterPropertiesSet() on bean with name '" + beanName + "'");
 8         }
 9         if (System.getSecurityManager() != null) {
10             try {
11                 AccessController.doPrivileged(new PrivilegedExceptionAction<Object>() {
12                     public Object run() throws Exception {
13                         ((InitializingBean) bean).afterPropertiesSet();
14                         return null;
15                     }
16                 }, getAccessControlContext());
17             }
18             catch (PrivilegedActionException pae) {
19                 throw pae.getException();
20             }
21         }                
22         else {
23             ((InitializingBean) bean).afterPropertiesSet();
24         }
25     }
26 
27     if (mbd != null) {
28         String initMethodName = mbd.getInitMethodName();
29         if (initMethodName != null && !(isInitializingBean && "afterPropertiesSet".equals(initMethodName)) &&
30                     !mbd.isExternallyManagedInitMethod(initMethodName)) {
31             invokeCustomInitMethod(beanName, bean, mbd);
32         }
33     }
34 }

看到,代码做了两件事情:

1、先判断Bean是否InitializingBean的实现类,是的话,将Bean强转为InitializingBean,直接调用afterPropertiesSet()方法

2、尝试去拿init-method,假如有的话,通过反射,调用initMethod

因此,两种方法各有优劣:使用实现InitializingBean接口的方式效率更高一点,因为init-method方法是通过反射进行调用的;从另外一个角度讲,使用init-method方法之后和Spring的耦合度会更低一点。具体使用哪种方式调用初始化方法,看个人喜好。

 

调用BeanPostProcessor的postProcessAfterInitialization方法

最后一步,initializeBean方法的29行:

 1 public Object applyBeanPostProcessorsAfterInitialization(Object existingBean, String beanName)
 2         throws BeansException {
 3 
 4     Object result = existingBean;
 5     for (BeanPostProcessor beanProcessor : getBeanPostProcessors()) {
 6         result = beanProcessor.postProcessAfterInitialization(result, beanName);
 7         if (result == null) {
 8             return result;
 9         }
10     }
11     return result;
12 }

同样遍历BeanPostProcessor,调用postProcessAfterInitialization方法。因此对于BeanPostProcessor方法总结一下:

1、在初始化每一个Bean的时候都会调用每一个配置的BeanPostProcessor的方法

2、在Bean属性设置、Aware设置后调用postProcessBeforeInitialization方法

3、在初始化方法调用后调用postProcessAfterInitialization方法

 

注册需要执行销毁方法的Bean

接下来看一下最上面doCreateBean方法的第83行registerDisposableBeanIfNecessary(beanName, bean, mbd)这一句,完成了创建Bean的最后一件事情:注册需要执行销毁方法的Bean。

看一下方法的实现:

 1 protected void registerDisposableBeanIfNecessary(String beanName, Object bean, RootBeanDefinition mbd) {
 2     AccessControlContext acc = (System.getSecurityManager() != null ? getAccessControlContext() : null);
 3     if (!mbd.isPrototype() && requiresDestruction(bean, mbd)) {
 4         if (mbd.isSingleton()) {
 5             // Register a DisposableBean implementation that performs all destruction
 6             // work for the given bean: DestructionAwareBeanPostProcessors,
 7             // DisposableBean interface, custom destroy method.
 8             registerDisposableBean(beanName,
 9                     new DisposableBeanAdapter(bean, beanName, mbd, getBeanPostProcessors(), acc));
10         }
11         else {
12             // A bean with a custom scope...
13             Scope scope = this.scopes.get(mbd.getScope());
14             if (scope == null) {
15                 throw new IllegalStateException("No Scope registered for scope '" + mbd.getScope() + "'");
16             }
17             scope.registerDestructionCallback(beanName,
18                     new DisposableBeanAdapter(bean, beanName, mbd, getBeanPostProcessors(), acc));
19         }
20     }
21 }

其中第3行第一个判断为必须不是prototype(原型)的,第二个判断requiresDestruction方法的实现为:

1 protected boolean requiresDestruction(Object bean, RootBeanDefinition mbd) {
2     return (bean != null &&
3             (bean instanceof DisposableBean || mbd.getDestroyMethodName() != null ||
4                     hasDestructionAwareBeanPostProcessors()));
5 }

要注册销毁方法,Bean需要至少满足以下三个条件之一:

(1)Bean是DisposableBean的实现类,此时执行DisposableBean的接口方法destroy()

(2)Bean标签中有配置destroy-method属性,此时执行destroy-method配置指定的方法

(3)当前Bean对应的BeanFactory中持有DestructionAwareBeanPostProcessor接口的实现类,此时执行DestructionAwareBeanPostProcessor的接口方法postProcessBeforeDestruction

在满足上面三个条件之一的情况下,容器便会注册销毁该Bean,注册Bean的方法很简单,见registerDisposableBean方法实现:

1 public void registerDisposableBean(String beanName, DisposableBean bean) {
2     synchronized (this.disposableBeans) {
3         this.disposableBeans.put(beanName, bean);
4     }
5 }

容器销毁的时候,会遍历disposableBeans,逐一执行销毁方法。

 

流程总结

本文和上篇文章分析了Spring Bean初始化的步骤,最后用一幅图总结一下Spring Bean初始化的流程:

801753-20170204111521089-1301937796

图只是起梳理流程作用,抛砖引玉,具体代码实现还需要网友朋友们照着代码自己去一步一步分析。

==================================================================================我不能保证写的每个地方都是对的,但是至少能保证不复制、不黏贴,保证每一句话、每一行代码都经过了认真的推敲、仔细的斟酌。每一篇文章的背后,希望都能看到自己对于技术、对于生活的态度。

我相信乔布斯说的,只有那些疯狂到认为自己可以改变世界的人才能真正地改变世界。面对压力,我可以挑灯夜战、不眠不休;面对困难,我愿意迎难而上、永不退缩。

其实我想说的是,我只是一个程序员,这就是我现在纯粹人生的全部。==================================================================================

来源: http://www.cnblogs.com/xrq730/p/6363055.html


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