Spring之IOC容器的加载过程

1 ClassPathResource classPathResource=new ClassPathResource("spring-mvc.xml");
2         DefaultListableBeanFactory factory=new DefaultListableBeanFactory();
3         XmlBeanDefinitionReader reader=new XmlBeanDefinitionReader(factory);
4         reader.loadBeanDefinitions(classPathResource);

  1 //IOC 容器加载的核心方法
  2 public int loadBeanDefinitions(EncodedResource encodedResource) throws BeanDefinitionStoreException {
  3                  try {
  4                 InputStream inputStream = encodedResource.getResource().getInputStream();
  5                 try {
  6                     //一：读取xml文件
  7                     InputSource inputSource = new InputSource(inputStream);
  8                     if (encodedResource.getEncoding() != null) {
  9                         inputSource.setEncoding(encodedResource.getEncoding());
 10                     }
 11                      //二：加载 beanefinition
 12                     var5 = this.doLoadBeanDefinitions(inputSource, encodedResource.getResource());
 13                 } finally {
 14                     inputStream.close();
 15                 }
 16             } 
 17 
 18             return var5;
 19         }
 20     }
 21 
 22 
 23 protected int doLoadBeanDefinitions(InputSource inputSource, Resource resource) throws BeanDefinitionStoreException {
 24         try {
 25              //一 1） 将xml文件转换为document
 26             Document doc = this.doLoadDocument(inputSource, resource);
 27             return this.registerBeanDefinitions(doc, resource);
 28 }
 29 }
 30 
 31            //一 2） 开始执行
 32   public void registerBeanDefinitions(Document doc, XmlReaderContext readerContext) {
 33         this.readerContext = readerContext;
 34         this.logger.debug("Loading bean definitions");
 35         Element root = doc.getDocumentElement();
 36         this.doRegisterBeanDefinitions(root);
 37     }
 38 
 39  protected void doRegisterBeanDefinitions(Element root) {
 40        
 41         this.preProcessXml(root);
 42       //三 解析Element 获取xml内容
 43         this.parseBeanDefinitions(root, this.delegate);
 44         this.postProcessXml(root);
 45         this.delegate = parent;
 46     }
 47     //解析Element 得到node 判断node内容
 48  protected void parseBeanDefinitions(Element root, BeanDefinitionParserDelegate delegate) {
 49         if (delegate.isDefaultNamespace(root)) {
 50             NodeList nl = root.getChildNodes(); 
 52             for(int i = 0; i < nl.getLength(); ++i) {
 53                 Node node = nl.item(i);
 54                 if (node instanceof Element) {
 55                     Element ele = (Element)node;
 56                     if (delegate.isDefaultNamespace(ele)) {
 57                       //读取document的内容
 58                         this.parseDefaultElement(ele, delegate);
 59                     } else {
 60                         delegate.parseCustomElement(ele);
 61                     }
 62                 }
 63             }
 64         } else {
 65             delegate.parseCustomElement(root);
 66         }
 67 
 68     }
 69 
 70       //四 判断xml中（document中节点的类型）
 71 private void parseDefaultElement(Element ele, BeanDefinitionParserDelegate delegate) {
 72         if (delegate.nodeNameEquals(ele, "import")) {
 73             this.importBeanDefinitionResource(ele);
 74         } else if (delegate.nodeNameEquals(ele, "alias")) {
 75             this.processAliasRegistration(ele);
 76         } else if (delegate.nodeNameEquals(ele, "bean")) {
                //五 载入beanDefinition
 77             this.processBeanDefinition(ele, delegate);
 78         } else if (delegate.nodeNameEquals(ele, "beans")) {
 79             this.doRegisterBeanDefinitions(ele);
 80         }
 81 
 82     }
 83 protected void processBeanDefinition(Element ele, BeanDefinitionParserDelegate delegate) {
 84         BeanDefinitionHolder bdHolder = delegate.parseBeanDefinitionElement(ele);
 85         if (bdHolder != null) {
 86             bdHolder = delegate.decorateBeanDefinitionIfRequired(ele, bdHolder);
 87 
 88             try {
 89                 BeanDefinitionReaderUtils.registerBeanDefinition(bdHolder, this.getReaderContext().getRegistry());
 90             } catch (BeanDefinitionStoreException var5) {
 91                 this.getReaderContext().error("Failed to register bean definition with name ‘" + bdHolder.getBeanName() + "‘", ele, var5);
 92             }
 93 
 94             this.getReaderContext().fireComponentRegistered(new BeanComponentDefinition(bdHolder));
 95         }
 96 
 97     }
 98 //六 注册 BeanDefinitionReaderUtils
 99  public static void registerBeanDefinition(BeanDefinitionHolder definitionHolder, BeanDefinitionRegistry registry) throws BeanDefinitionStoreException {
100      //获取bean的名称   
101      String beanName = definitionHolder.getBeanName();
102      // 注册bean 并将bean放入到ioc容器里面
103         registry.registerBeanDefinition(beanName, definitionHolder.getBeanDefinition());
104         String[] aliases = definitionHolder.getAliases();
105         if (aliases != null) {
106             String[] var4 = aliases;
107             int var5 = aliases.length;
108 
109             for(int var6 = 0; var6 < var5; ++var6) {
110                 String alias = var4[var6];
111                //七 加载其他信息 如：是否是单例，是否允许重载 是否是abstract 类等
112                 registry.registerAlias(beanName, alias);
113             }
114         }
115 
116     }
117 //DefaultListableBeanFactory
118 public void registerBeanDefinition(String beanName, BeanDefinition beanDefinition) throws BeanDefinitionStoreException {
119         Assert.hasText(beanName, "Bean name must not be empty");
120         Assert.notNull(beanDefinition, "BeanDefinition must not be null");
121         if (beanDefinition instanceof AbstractBeanDefinition) {
122             try {
123                 ((AbstractBeanDefinition)beanDefinition).validate();
124             } catch (BeanDefinitionValidationException var9) {
125                 throw new BeanDefinitionStoreException(beanDefinition.getResourceDescription(), beanName, "Validation of bean definition failed", var9);
126             }
127         }
128               //bean 已经存在
129         BeanDefinition existingDefinition = (BeanDefinition)this.beanDefinitionMap.get(beanName);
130         if (existingDefinition != null) {
131            //不允许覆盖 报异常
132             if (!this.isAllowBeanDefinitionOverriding()) {
133                 throw new BeanDefinitionStoreException(beanDefinition.getResourceDescription(), beanName, "Cannot register bean definition [" + beanDefinition + "] for bean ‘" + beanName + "‘: There is already [" + existingDefinition + "] bound.");
134             }     
137             this.beanDefinitionMap.put(beanName, beanDefinition);
138         } else {
139             if (this.hasBeanCreationStarted()) {
140                 Map var4 = this.beanDefinitionMap;
141                 synchronized(this.beanDefinitionMap) {
142                    //将bean放入容器
143                     this.beanDefinitionMap.put(beanName, beanDefinition);
144                     List<String> updatedDefinitions = new ArrayList(this.beanDefinitionNames.size() + 1);
145                     updatedDefinitions.addAll(this.beanDefinitionNames);
146                     updatedDefinitions.add(beanName);
147                     this.beanDefinitionNames = updatedDefinitions;
148                     if (this.manualSingletonNames.contains(beanName)) {
149                         Set<String> updatedSingletons = new LinkedHashSet(this.manualSingletonNames);
150                         updatedSingletons.remove(beanName);
151                         this.manualSingletonNames = updatedSingletons;
152                     }
153                 }
154             } else {
155                 this.beanDefinitionMap.put(beanName, beanDefinition);
156                 this.beanDefinitionNames.add(beanName);
157                 this.manualSingletonNames.remove(beanName);
158             }
159 
160             this.frozenBeanDefinitionNames = null;
161         }
162         
163         if (existingDefinition != null || this.containsSingleton(beanName)) {
164             this.resetBeanDefinition(beanName);
165         }
166 
167     }