{"id":10008231,"date":"2023-09-05T20:17:04","date_gmt":"2023-09-05T12:17:04","guid":{"rendered":"https:\/\/blog.itmax.cn\/?p=10008231"},"modified":"2023-09-05T20:17:04","modified_gmt":"2023-09-05T12:17:04","slug":"spring-bean-%e5%88%ab%e5%90%8d%e5%a4%84%e7%90%86%e5%8e%9f%e7%90%86%e5%88%86%e6%9e%90","status":"publish","type":"post","link":"https:\/\/itmax.cn\/?p=10008231","title":{"rendered":"Spring Bean \u522b\u540d\u5904\u7406\u539f\u7406\u5206\u6790"},"content":{"rendered":"

\u4eca\u5929\u6765\u548c\u5c0f\u4f19\u4f34\u4eec\u804a\u4e00\u804a Spring \u4e2d\u5173\u4e8e Bean \u522b\u540d\u7684\u5904\u7406\u903b\u8f91\u3002<\/p>\n

1. Alias<\/h2>\n

\u522b\u540d\uff0c\u987e\u540d\u601d\u4e49\u5c31\u662f\u7ed9\u4e00\u4e2a Bean \u53bb\u4e24\u4e2a\u751a\u81f3\u591a\u4e2a\u540d\u5b57\u3002\u6574\u4f53\u4e0a\u6765\u8bf4\uff0c\u5728 Spring \u4e2d\uff0c\u6709\u4e24\u79cd\u4e0d\u540c\u7684\u522b\u540d\u5b9a\u4e49\u65b9\u5f0f\uff1a<\/p>\n

    \n
  1. \u5b9a\u4e49 Bean \u7684 name \u5c5e\u6027\uff0cname \u5c5e\u6027\u5728\u771f\u6b63\u7684\u5904\u7406\u8fc7\u7a0b\u4e2d\uff0c\u5b9e\u9645\u4e0a\u5c31\u662f\u6309\u7167\u522b\u540d\u6765\u5904\u7406\u7684\u3002<\/li>\n
  2. \u901a\u8fc7 alias \u6807\u7b7e\u5b9a\u4e49\u4e13\u95e8\u7684\u522b\u540d\uff0c\u901a\u8fc7 alias \u5b9a\u4e49\u51fa\u6765\u7684\u522b\u540d\u548c name \u5c5e\u6027\u5b9a\u4e49\u7684\u522b\u540d\u6700\u7ec8\u90fd\u662f\u5408\u5e76\u5728\u4e00\u8d77\u5904\u7406\u7684\uff0c\u6240\u4ee5\u8fd9\u4e24\u79cd\u5b9a\u4e49\u522b\u540d\u7684\u65b9\u5f0f\u6700\u7ec8\u662f\u6b8a\u9014\u540c\u5f52<\/strong>\u3002<\/li>\n<\/ol>\n

    \u90a3\u4e48\u5b9a\u4e49\u7684\u522b\u540d\u662f\u4fdd\u5b58\u5728\u54ea\u91cc\u5462\uff1f<\/p>\n

    \u5927\u5bb6\u77e5\u9053\uff0cBean \u89e3\u6790\u51fa\u6765\u4e4b\u540e\u88ab\u4fdd\u5b58\u5728\u5bb9\u5668\u4e2d\uff0c\u522b\u540d\u5176\u5b9e\u4e5f\u662f\u4e00\u6837\u7684\uff0c\u5bb9\u5668\u4e2d\u5b58\u5728\u4e00\u4e2a aliasMap \u4e13\u95e8\u7528\u6765\u4fdd\u5b58 Bean \u7684\u522b\u540d\uff0c\u4fdd\u5b58\u7684\u683c\u5f0f\u662f alias->name\uff0c\u4f8b\u5982\u6709\u4e00\u4e2a Bean \u7684\u540d\u5b57\u662f user\uff0c\u522b\u540d\u662f userAlias\uff0c\u90a3\u4e48\u4fdd\u5b58\u5728 aliasMap \u4e2d\u5c31\u662f userAlias->user\u3002<\/p>\n

    \u4e3e\u4e2a\u7b80\u5355\u4f8b\u5b50\uff1a<\/p>\n

    <bean class="org.javaboy.demo.User" id="user" name="user4,user5,user6"\/>\n<alias name="user" alias="user2"\/>\n<alias name="user2" alias="user3"\/><\/code><\/pre>\n
    \u5728\u4e0a\u9762\u8fd9\u6bb5\u5b9a\u4e49\u4e2d\uff0cuser2\u3001user3\u3001user4\u3001user5\u3001user6 \u90fd\u662f\u522b\u540d\u3002<\/p>\n
    2. AliasRegistry<\/h2>\n
    2.1 AliasRegistry<\/h3>\n
    Spring \u4e2d\u4e3a\u522b\u540d\u7684\u5904\u7406\u63d0\u4f9b\u4e86 AliasRegistry \u63a5\u53e3\uff0c\u8fd9\u4e2a\u63a5\u53e3\u4e2d\u63d0\u4f9b\u4e86\u522b\u540d\u5904\u7406\u7684\u4e3b\u8981\u65b9\u6cd5\uff1a<\/p>\n
    public interface AliasRegistry {\n    void registerAlias(String name, String alias);\n    void removeAlias(String alias);\n    boolean isAlias(String name);\n    String[] getAliases(String name);\n}<\/code><\/pre>\n
      \n
    • registerAlias\uff1a\u8fd9\u4e2a\u65b9\u6cd5\u7528\u6765\u6dfb\u52a0\u522b\u540d\uff0c\u6838\u5fc3\u903b\u8f91\u5c31\u662f\u5411 aliasMap \u4e2d\u6dfb\u52a0\u6570\u636e\u3002<\/li>\n
    • removeAlias\uff1a\u8fd9\u4e2a\u65b9\u6cd5\u7528\u6765\u4ece aliasMap \u4e2d\u79fb\u9664\u4e00\u4e2a\u522b\u540d\u3002<\/li>\n
    • isAlias\uff1a\u5224\u65ad\u7ed9\u5b9a\u7684 name \u662f\u5426\u662f\u4e00\u4e2a\u522b\u540d\u3002<\/li>\n
    • getAliases\uff1a\u6839\u636e\u7ed9\u5b9a\u7684\u540d\u5b57\u53bb\u83b7\u53d6\u6240\u6709\u7684\u522b\u540d\u3002<\/li>\n<\/ul>\n
      \u65b9\u6cd5\u5c31\u8fd9\u56db\u4e2a\uff0c\u770b\u4e00\u4e0b\u8fd9\u4e2a\u63a5\u53e3\u7684\u5b9e\u73b0\u7c7b\u6709\u54ea\u4e9b\u3002<\/p>\n
      \"\"<\/p>\n
      \u5927\u5bb6\u770b\u5230\uff0cAliasRegistry \u7684\u5b9e\u73b0\u7c7b\u5176\u5b9e\u8fd8\u662f\u86ee\u591a\u7684\uff0c\u4f46\u662f\u5927\u90e8\u5206\u90fd\u662f\u5bb9\u5668\uff0c\u771f\u6b63\u5b9e\u73b0\u4e86 AliasRegistry \u4e2d\u56db\u4e2a\u65b9\u6cd5\u7684\u53ea\u6709 SimpleAliasRegistry\uff0c\u5176\u4ed6\u7684\u5bb9\u5668\u5927\u90e8\u5206\u5176\u5b9e\u90fd\u662f\u4e3a\u4e86\u5177\u5907\u522b\u540d\u7ba1\u7406\u7684\u80fd\u529b\uff0c\u7ee7\u627f\u4e86 SimpleAliasRegistry\u3002<\/p>\n
      \u6240\u4ee5\u771f\u6b63\u7ed9\u6211\u4eec\u6574\u6d3b\u7684\u5176\u5b9e\u662f SimpleAliasRegistry\u3002<\/p>\n
      2.2 SimpleAliasRegistry<\/h3>\n
      SimpleAliasRegistry \u7c7b\u4e2d\u7684\u5185\u5bb9\u6bd4\u8f83\u591a\uff0c\u4e3a\u4e86\u8bb2\u89e3\u65b9\u4fbf\uff0c\u6211\u5c31\u6328\u4e2a\u8d34\u5c5e\u6027\u548c\u65b9\u6cd5\u51fa\u6765\uff0c\u8d34\u51fa\u6765\u540e\u548c\u5927\u5bb6\u5206\u4eab\u3002<\/p>\n
      private final Map<String, String> aliasMap = new ConcurrentHashMap<>(16);<\/code><\/pre>\n
      \u9996\u5148\uff0cSimpleAliasRegistry \u4e2d\u5b9a\u4e49\u4e86\u4e00\u4e2a aliasMap\uff0c\u8fd9\u4e2a\u5c31\u662f\u7528\u6765\u4fdd\u5b58\u522b\u540d\u7684\uff0c\u8fd9\u662f\u4e00\u4e2a Map \u96c6\u5408\uff0c\u63a5\u4e0b\u6765\u6240\u6709\u7684\u64cd\u4f5c\u90fd\u662f\u56f4\u7ed5\u8fd9\u4e2a\u96c6\u5408\u5c55\u5f00\u3002<\/p>\n
      @Override\npublic void removeAlias(String alias) {\n    synchronized (this.aliasMap) {\n        String name = this.aliasMap.remove(alias);\n        if (name == null) {\n            throw new IllegalStateException("No alias '" + alias + "' registered");\n        }\n    }\n}<\/code><\/pre>\n
      \u8fd9\u4e2a\u65b9\u6cd5\u7528\u6765\u79fb\u9664\u522b\u540d\uff0c\u79fb\u9664\u7684\u601d\u8def\u5f88\u7b80\u5355\uff0c\u5c31\u662f\u4ece aliasMap \u4e2d\u79fb\u9664\u6570\u636e\u5373\u53ef\uff0c\u5982\u679c remove \u65b9\u6cd5\u8fd4\u56de\u503c\u4e3a null \u90a3\u5c31\u8bf4\u660e\u8981\u79fb\u9664\u7684\u522b\u540d\u4e0d\u5b58\u5728\uff0c\u90a3\u4e48\u76f4\u63a5\u629b\u51fa\u5f02\u5e38\u3002<\/p>\n
      @Override\npublic boolean isAlias(String name) {\n    return this.aliasMap.containsKey(name);\n}<\/code><\/pre>\n
      \u8fd9\u4e2a\u662f\u5224\u65ad\u662f\u5426\u5305\u542b\u67d0\u4e00\u4e2a\u522b\u540d\uff0c\u8fd9\u4e2a\u5224\u65ad\u7b80\u5355\u3002\u6709\u4e00\u4e2a\u8ddf\u5b83\u5bb9\u6613\u4ea7\u751f\u6b67\u4e49\u7684\u65b9\u6cd5\uff0c\u5982\u4e0b\uff1a<\/p>\n
      public boolean hasAlias(String name, String alias) {\n    String registeredName = this.aliasMap.get(alias);\n    return ObjectUtils.nullSafeEquals(registeredName, name) ||\n            (registeredName != null && hasAlias(name, registeredName));\n}<\/code><\/pre>\n
      \u8fd9\u4e2a\u65b9\u6cd5\u662f\u5224\u65ad\u7ed9\u5b9a\u7684 name \u548c alias \u4e4b\u95f4\u662f\u5426\u5177\u5907\u5173\u8054\u5173\u7cfb\u3002\u5224\u65ad\u7684\u903b\u8f91\u5c31\u662f\u5148\u53bb aliasMap \u4e2d\uff0c\u6839\u636e alias \u67e5\u51fa\u6765\u8fd9\u4e2a alias \u6240\u5bf9\u5e94\u7684\u771f\u5b9e beanName\uff0c\u5373 registeredName\uff0c\u7136\u540e\u5224\u65ad registeredName \u548c name \u662f\u5426\u76f8\u7b49\uff0c\u5982\u679c\u76f8\u7b49\u5c31\u76f4\u63a5\u8fd4\u56de\uff0c\u5982\u679c\u4e0d\u76f8\u7b49\u5c31\u7ee7\u7eed\u9012\u5f52\u8c03\u7528\uff0c\u4e3a\u4ec0\u4e48\u8981\u9012\u5f52\u5462\uff1f\u56e0\u4e3a aliasMap \u4e2d\u5b58\u5728\u7684\u522b\u540d\u53ef\u80fd\u662f\u8fd9\u6837\u7684\uff1a<\/p>\n
        \n
      • a->b<\/li>\n
      • b->c<\/li>\n
      • c->d<\/li>\n<\/ul>\n
        \u5373 a \u662f b \u7684\u522b\u540d\uff0cb \u662f c \u7684\u522b\u540d\uff0cc \u662f d \u7684\u522b\u540d\uff0c\u73b0\u5728\u5982\u679c\u60f3\u8981\u5224\u65ad a \u548c d \u4e4b\u95f4\u7684\u5173\u7cfb\uff0c\u90a3\u4e48\u6839\u636e a \u67e5\u51fa\u6765\u7684 b \u663e\u7136\u4e0d\u7b49\u4e8e d\uff0c\u6240\u4ee5\u8981\u7ee7\u7eed\u9012\u5f52\uff0c\u518d\u6839\u636e b \u67e5 c\uff0c\u6839\u636e c \u67e5\u5230 d\uff0c\u8fd9\u6837\u5c31\u80fd\u786e\u5b9a a \u548c d \u662f\u5426\u6709\u5173\u7cfb\u4e86\u3002<\/p>\n
        @Override\npublic String[] getAliases(String name) {\n    List<String> result = new ArrayList<>();\n    synchronized (this.aliasMap) {\n        retrieveAliases(name, result);\n    }\n    return StringUtils.toStringArray(result);\n}\nprivate void retrieveAliases(String name, List<String> result) {\n    this.aliasMap.forEach((alias, registeredName) -> {\n        if (registeredName.equals(name)) {\n            result.add(alias);\n            retrieveAliases(alias, result);\n        }\n    });\n}<\/code><\/pre>\n
        getAliases \u65b9\u6cd5\u662f\u6839\u636e\u4f20\u5165\u7684 name \u627e\u5230\u5176\u5bf9\u5e94\u7684\u522b\u540d\uff0c\u4f46\u662f\u7531\u4e8e\u522b\u540d\u53ef\u80fd\u5b58\u5728\u591a\u4e2a\uff0c\u6240\u4ee5\u8c03\u7528 retrieveAliases \u65b9\u6cd5\u9012\u5f52\u53bb\u67e5\u627e\u6240\u6709\u7684\u522b\u540d\uff0c\u5c06\u627e\u5230\u7684\u522b\u540d\u90fd\u5b58\u5165\u5230\u4e00\u4e2a\u96c6\u5408\u4e2d\uff0c\u6700\u7ec8\u5c06\u96c6\u5408\u8f6c\u4e3a\u6570\u7ec4\u8fd4\u56de\u3002<\/p>\n
        protected void checkForAliasCircle(String name, String alias) {\n    if (hasAlias(alias, name)) {\n        throw new IllegalStateException("Cannot register alias '" + alias +\n                "' for name '" + name + "': Circular reference - '" +\n                name + "' is a direct or indirect alias for '" + alias + "' already");\n    }\n}<\/code><\/pre>\n
        \u8fd9\u4e2a\u65b9\u6cd5\u7528\u6765\u68c0\u67e5\u522b\u540d\u662f\u5426\u5b58\u5728\u6b7b\u7ed3\uff0c\u5373 a \u662f b \u7684\u522b\u540d\uff0cb \u662f a \u7684\u522b\u540d\u8fd9\u79cd\u60c5\u51b5\u3002\u68c0\u67e5\u7684\u65b9\u5f0f\u5f88\u7b80\u5355\uff0c\u5c31\u662f\u8c03\u7528 hasAlias \u65b9\u6cd5\uff0c\u4f46\u662f\u5c06\u4f20\u5165\u7684\u4e24\u4e2a\u53c2\u6570\u98a0\u5012\u8fc7\u6765\u5c31\u53ef\u4ee5\u4e86\u3002<\/p>\n
        public void resolveAliases(StringValueResolver valueResolver) {\n    synchronized (this.aliasMap) {\n        Map<String, String> aliasCopy = new HashMap<>(this.aliasMap);\n        aliasCopy.forEach((alias, registeredName) -> {\n            String resolvedAlias = valueResolver.resolveStringValue(alias);\n            String resolvedName = valueResolver.resolveStringValue(registeredName);\n            if (resolvedAlias == null || resolvedName == null || resolvedAlias.equals(resolvedName)) {\n                this.aliasMap.remove(alias);\n            }\n            else if (!resolvedAlias.equals(alias)) {\n                String existingName = this.aliasMap.get(resolvedAlias);\n                if (existingName != null) {\n                    if (existingName.equals(resolvedName)) {\n                        this.aliasMap.remove(alias);\n                        return;\n                    }\n                    throw new IllegalStateException(\n                            "Cannot register resolved alias '" + resolvedAlias + "' (original: '" + alias +\n                            "') for name '" + resolvedName + "': It is already registered for name '" +\n                            registeredName + "'.");\n                }\n                checkForAliasCircle(resolvedName, resolvedAlias);\n                this.aliasMap.remove(alias);\n                this.aliasMap.put(resolvedAlias, resolvedName);\n            }\n            else if (!registeredName.equals(resolvedName)) {\n                this.aliasMap.put(alias, resolvedName);\n            }\n        });\n    }\n}<\/code><\/pre>\n
        \u8fd9\u4e2a\u65b9\u6cd5\u662f\u5904\u7406\u522b\u540d\u662f\u5360\u4f4d\u7b26\u7684\u60c5\u51b5\uff0c\u4f8b\u5982\u5f53\u5f15\u5165\u4e86\u4e00\u4e2a .properties<\/code> \u6587\u4ef6\u4e4b\u540e\uff0c\u90a3\u4e48\u5728\u914d\u7f6e\u522b\u540d\u7684\u65f6\u5019\u5c31\u53ef\u4ee5\u5f15\u7528 .properties<\/code> \u4e2d\u7684\u53d8\u91cf\uff0c\u90a3\u4e48\u4e0a\u9762\u8fd9\u4e2a\u65b9\u6cd5\u5c31\u662f\u7528\u6765\u89e3\u6790\u53d8\u91cf\u7684\u3002<\/p>\n
        \u4f8b\u5982\u4e0b\u9762\u8fd9\u79cd\u60c5\u51b5\uff0c\u6211\u6709\u4e00\u4e2a alias.properties\uff0c\u5982\u4e0b\uff1a<\/p>\n
        name=user\nalias=javaboy<\/code><\/pre>\n
        \u7136\u540e\u5728 XML \u6587\u4ef6\u4e2d\u4f7f\u7528\u8fd9\u4e2a properties \u6587\u4ef6\uff0c\u5982\u4e0b\uff1a<\/p>\n
        <context:property-placeholder location="classpath:alias.properties"\/>\n<alias name="${name}" alias="${alias}"\/><\/code><\/pre>\n
        \u5bf9\u4e8e\u8fd9\u79cd\u60c5\u51b5\uff0c\u4e00\u5f00\u59cb\u5b58\u5165\u5230 aliasMap \u4e2d\u7684\u5c31\u662f\u5360\u4f4d\u7b26\u4e86\uff0cresolveAliases \u65b9\u6cd5\u5c31\u662f\u8981\u5c06\u8fd9\u4e9b\u5360\u4f4d\u7b26\u89e3\u6790\u4e3a\u5177\u4f53\u7684\u5b57\u7b26\u4e32\u3002<\/p>\n
        \u5927\u5bb6\u770b\u5230\uff0c\u9996\u5148\u8fd9\u91cc\u5c06 aliasMap \u590d\u5236\u4e00\u4efd\uff0c\u751f\u6210\u4e00\u4e2a aliasCopy\uff0c\u7136\u540e\u8fdb\u884c\u904d\u5386\u3002\u5728\u904d\u5386\u65f6\uff0c\u6839\u636e valueResolver \u5c06\u5f15\u7528\u4f7f\u7528\u7684\u5360\u4f4d\u7b26\u89e3\u6790\u4e3a\u771f\u6b63\u7684\u5b57\u7b26\uff0c\u5982\u679c\u89e3\u6790\u51fa\u6765\u7684\u3002\u5982\u679c\u89e3\u6790\u51fa\u6765\u7684 name \u548c\u522b\u540d\u662f\u76f8\u540c\u7684\uff0c\u90a3\u4e48\u663e\u7136\u662f\u6709\u95ee\u9898\u7684\uff0c\u5c31\u9700\u8981\u628a\u8fd9\u4e2a\u522b\u540d\u79fb\u9664\u6389\u3002<\/p>\n
        \u7ee7\u7eed\u5224\u65ad\uff0c\u5982\u679c\u89e3\u6790\u51fa\u6765\u7684\u522b\u540d\u548c\u539f\u672c\u7684\u522b\u540d\u4e0d\u76f8\u7b49\uff08\u8bf4\u660e\u522b\u540d\u4f7f\u7528\u4e86\u5360\u4f4d\u7b26\uff09\uff0c\u90a3\u4e48\u5c31\u53bb\u68c0\u67e5\u4e00\u4e0b\u8fd9\u4e2a\u522b\u540d\u5bf9\u5e94\u7684 name\uff0c\u5982\u679c\u8fd9\u4e2a name \u5df2\u7ecf\u5b58\u5728\uff0c\u4e14\u7b49\u4e8e\u5360\u4f4d\u7b26\u89e3\u6790\u51fa\u6765\u7684 name\uff0c\u8bf4\u660e\u8fd9\u4e2a\u522b\u540d\u5df2\u7ecf\u88ab\u5b9a\u4e49\u8fc7\u4e86\uff0c\u5373\u91cd\u590d\u5b9a\u4e49\uff0c\u90a3\u4e48\u5c31\u628a\u522b\u540d\u79fb\u9664\u6389\u5373\u53ef\u3002\u5982\u679c\u8fd9\u4e2a\u522b\u540d\u6307\u5411\u7684 name \u548c\u5360\u4f4d\u7b26\u89e3\u6790\u51fa\u6765\u7684 name \u4e0d\u76f8\u7b49\uff0c\u8bf4\u660e\u8bd5\u56fe\u8ba9\u4e00\u4e2a\u522b\u540d\u6307\u5411\u4e24\u4e2a bean\uff0c\u90a3\u4e48\u5c31\u76f4\u63a5\u629b\u51fa\u5f02\u5e38\u4e86\u3002<\/p>\n
        \u5982\u679c\u89e3\u6790\u51fa\u6765\u7684\u522b\u540d\u8fd8\u6ca1\u6709\u6307\u5411 name \u5c5e\u6027\u7684\u8bdd\uff0c\u90a3\u4e48\u5c31\u6b63\u5e38\u5904\u7406\uff0c\u68c0\u67e5\u662f\u5426\u5b58\u5728\u6b7b\u7ed3\u3001\u79fb\u9664\u5e26\u5360\u4f4d\u7b26\u7684\u522b\u540d\uff0c\u5b58\u5165\u89e3\u6790\u4e4b\u540e\u7684\u522b\u540d\u3002<\/p>\n
        \u6700\u540e\uff0c\u5982\u679c\u539f\u672c\u7684\u540d\u79f0\u548c\u89e3\u6790\u4e4b\u540e\u7684\u5c5e\u6027\u540d\u79f0\u4e0d\u76f8\u7b49\uff0c\u90a3\u4e48\u5c31\u76f4\u63a5\u4fdd\u5b58\u8fd9\u4e2a\u522b\u540d\u5373\u53ef\u3002<\/p>\n
        @Override\npublic void registerAlias(String name, String alias) {\n    synchronized (this.aliasMap) {\n        if (alias.equals(name)) {\n            this.aliasMap.remove(alias);\n        }\n        else {\n            String registeredName = this.aliasMap.get(alias);\n            if (registeredName != null) {\n                if (registeredName.equals(name)) {\n                    return;\n                }\n                if (!allowAliasOverriding()) {\n                    throw new IllegalStateException("Cannot define alias '" + alias + "' for name '" +\n                            name + "': It is already registered for name '" + registeredName + "'.");\n                }\n            }\n            checkForAliasCircle(name, alias);\n            this.aliasMap.put(alias, name);\n        }\n    }\n}<\/code><\/pre>\n
        \u8fd9\u4e2a\u5c31\u662f\u4f7f\u7528\u6700\u591a\u7684\u522b\u540d\u6ce8\u518c\u4e86\uff0c\u4f20\u5165\u7684\u53c2\u6570\u5206\u522b\u662f bean \u7684 name \u548c alias\uff0c\u5982\u679c alias \u8ddf name \u76f8\u7b49\uff0c\u4e8c\u8bdd\u4e0d\u8bf4\u76f4\u63a5\u79fb\u9664\uff0c\u8fd9\u4e2a alias \u6709\u95ee\u9898\u3002<\/p>\n
        \u5426\u5219\u5c31\u53bb\u67e5\u8be2\u8fd9\u4e2a alias\uff0c\u68c0\u67e5\u8fd9\u4e2a alias \u662f\u5426\u5df2\u7ecf\u6709\u5bf9\u5e94\u7684 name \u4e86\uff0c\u5982\u679c\u6709\uff0c\u4e14\u7b49\u4e8e\u4f20\u5165\u7684 name\uff0c\u90a3\u4e48\u76f4\u63a5\u8fd4\u56de\u5c31\u884c\u4e86\uff0c\u4e0d\u7528\u6ce8\u518c\uff0c\u56e0\u4e3a\u5df2\u7ecf\u6ce8\u518c\u8fc7\u4e86\uff1b\u5982\u679c\u6709\u4e14\u4e0d\u7b49\u4e8e\u4f20\u5165\u7684 name\uff0c\u90a3\u4e48\u5c31\u629b\u51fa\u5f02\u5e38\uff0c\u56e0\u4e3a\u4e00\u4e2a alias \u4e0d\u80fd\u6307\u5411\u4e24\u4e2a name\u3002\u6700\u540e\u5c31\u662f\u68c0\u67e5\u548c\u4fdd\u5b58\u4e86\u3002<\/p>\n
        public String canonicalName(String name) {\n    String canonicalName = name;\n    String resolvedName;\n    do {\n        resolvedName = this.aliasMap.get(canonicalName);\n        if (resolvedName != null) {\n            canonicalName = resolvedName;\n        }\n    }\n    while (resolvedName != null);\n    return canonicalName;\n}<\/code><\/pre>\n
        \u8fd9\u4e2a\u65b9\u6cd5\u7528\u6765\u89e3\u6790\u51fa\u6765\u522b\u540d\u91cc\u8fb9\u9876\u683c\u7684\u540d\u5b57\uff0c\u4f8b\u5982\u6709\u4e00\u4e2a bean \u6709\u5f88\u591a\u522b\u540d\uff0ca->b,b->c,c->d\uff0c\u90a3\u4e48\u8fd9\u4e2a\u65b9\u6cd5\u7684\u76ee\u7684\u5c31\u662f\u4f20\u5165 a\u3001b\u3001c \u4e2d\u4efb\u610f\u4e00\u4e2a\uff0c\u8fd4\u56de d \u5373\u53ef\u3002\u56e0\u4e3a Spring \u5bb9\u5668\u5728\u5904\u7406\u7684\u65f6\u5019\uff0c\u5e76\u4e0d\u7528\u7ba1\u8fd9\u4e48\u591a\u522b\u540d\u95ee\u9898\uff0c\u5bb9\u5668\u53ea\u9700\u8981\u4e13\u6ce8\u4e00\u4e2a\u540d\u5b57\u5373\u53ef\uff0c\u56e0\u4e3a\u6700\u540e\u4e00\u4e2a\u522b\u540d\u5b9e\u9645\u4e0a\u5c31\u662f\u6307\u5411\u771f\u5b9e\u7684 beanId \u4e86\uff0c\u6240\u4ee5\u6700\u7ec8\u62ff\u5230\u7684 bean \u540d\u79f0\u5176\u5b9e\u76f8\u5f53\u4e8e bean \u7684 ID \u4e86\u3002<\/p>\n
        \u522b\u540d\u7684\u5904\u7406\u4e3b\u8981\u5c31\u662f\u8fd9\u4e9b\u65b9\u6cd5\u3002<\/p>\n
        3. \u539f\u7406\u5206\u6790<\/h2>\n
        \u524d\u9762\u6211\u4eec\u8bf4\u4e86\uff0c\u522b\u540d\u7684\u6765\u6e90\u4e3b\u8981\u662f\u4e24\u4e2a\u5730\u65b9\uff1aname \u5c5e\u6027\u548c alias \u6807\u7b7e\uff0c\u6211\u4eec\u5206\u522b\u6765\u770b\u3002<\/p>\n
        3.1 name \u5904\u7406<\/h3>\n
        \u5bf9\u4e8e name \u5c5e\u6027\u7684\u5904\u7406\uff0c\u6709\u4e24\u4e2a\u5730\u65b9\uff0c\u4e00\u4e2a\u662f\u5728 bean \u5b9a\u4e49\u89e3\u6790\u7684\u65f6\u5019\uff0c\u5c06 name \u5c5e\u6027\u89e3\u6790\u4e3a alias\uff0c\u5177\u4f53\u5728 BeanDefinitionParserDelegate#parseBeanDefinitionElement \u65b9\u6cd5\u4e2d\uff08\u8fd9\u4e2a\u65b9\u6cd5\u5728\u4e4b\u524d\u8ddf\u5927\u5bb6\u8bb2 bean \u7684\u9ed8\u8ba4\u540d\u79f0\u751f\u6210\u7b56\u7565\u7684\u65f6\u5019\uff0c\u89c1\u8fc7\uff09\uff1a<\/p>\n
        @Nullable\npublic BeanDefinitionHolder parseBeanDefinitionElement(Element ele, @Nullable BeanDefinition containingBean) {\n    String id = ele.getAttribute(ID_ATTRIBUTE);\n    String nameAttr = ele.getAttribute(NAME_ATTRIBUTE);\n    List<String> aliases = new ArrayList<>();\n    if (StringUtils.hasLength(nameAttr)) {\n        String[] nameArr = StringUtils.tokenizeToStringArray(nameAttr, MULTI_VALUE_ATTRIBUTE_DELIMITERS);\n        aliases.addAll(Arrays.asList(nameArr));\n    }\n    \/\/\u7701\u7565\u5176\u4ed6\n}<\/code><\/pre>\n
        \u53ef\u4ee5\u770b\u5230\uff0c\u8fd9\u91cc\u5c31\u4ece XML \u8282\u70b9\u4e2d\u63d0\u53d6\u51fa\u6765 name \u5c5e\u6027\uff0c\u7136\u540e\u5207\u5206\u4e3a\u4e00\u4e2a\u6570\u7ec4\uff0c\u5e76\u5c06\u4e4b\u5b58\u5165\u5230 aliases \u5c5e\u6027\u4e2d\u3002\u63a5\u4e0b\u6765\u5728\u540e\u7eed\u7684 BeanDefinitionReaderUtils#registerBeanDefinition \u65b9\u6cd5\u4e2d\uff0c\u518d\u628a aliases \u4e2d\u7684\u503c\u6ce8\u518c\u4e00\u4e0b\uff0c\u5982\u4e0b\uff1a<\/p>\n
        public static void registerBeanDefinition(\n        BeanDefinitionHolder definitionHolder, BeanDefinitionRegistry registry)\n        throws BeanDefinitionStoreException {\n    String beanName = definitionHolder.getBeanName();\n    registry.registerBeanDefinition(beanName, definitionHolder.getBeanDefinition());\n    String[] aliases = definitionHolder.getAliases();\n    if (aliases != null) {\n        for (String alias : aliases) {\n            registry.registerAlias(beanName, alias);\n        }\n    }\n}<\/code><\/pre>\n
        \u8fd9\u5c31\u662f XML \u4e2d\u7684 name \u5c5e\u6027\u662f\u5982\u4f55\u53d8\u4e3a\u522b\u540d\u7684\u3002<\/p>\n
        3.2 \u522b\u540d\u6807\u7b7e\u5904\u7406<\/h3>\n
        \u522b\u540d\u7684\u53e6\u4e00\u4e2a\u6765\u6e90\u662f\u522b\u540d\u6807\u7b7e\uff0c\u5728 Spring \u89e3\u6790 XML \u6807\u7b7e\u7684\u65f6\u5019\uff0c\u6709\u9488\u5bf9\u522b\u540d\u6807\u7b7e\u7684\u4e13\u95e8\u5904\u7406\uff0c\u5177\u4f53\u4f4d\u7f6e\u662f\u5728 DefaultBeanDefinitionDocumentReader#parseDefaultElement \u65b9\u6cd5\u4e2d\uff1a<\/p>\n
        private void parseDefaultElement(Element ele, BeanDefinitionParserDelegate delegate) {\n    if (delegate.nodeNameEquals(ele, IMPORT_ELEMENT)) {\n        importBeanDefinitionResource(ele);\n    }\n    else if (delegate.nodeNameEquals(ele, ALIAS_ELEMENT)) {\n        processAliasRegistration(ele);\n    }\n    else if (delegate.nodeNameEquals(ele, BEAN_ELEMENT)) {\n        processBeanDefinition(ele, delegate);\n    }\n    else if (delegate.nodeNameEquals(ele, NESTED_BEANS_ELEMENT)) {\n        \/\/ recurse\n        doRegisterBeanDefinitions(ele);\n    }\n}<\/code><\/pre>\n
        \u8fd9\u91cc\u4f1a\u53bb\u5224\u65ad\u6807\u7b7e\u7684\u7c7b\u578b\uff0c\u5982\u679c\u662f\u522b\u540d\uff0c\u5c31\u8c03\u7528 processAliasRegistration \u65b9\u6cd5\u8fdb\u884c\u5904\u7406\uff1a<\/p>\n
        protected void processAliasRegistration(Element ele) {\n    String name = ele.getAttribute(NAME_ATTRIBUTE);\n    String alias = ele.getAttribute(ALIAS_ATTRIBUTE);\n    boolean valid = true;\n    if (!StringUtils.hasText(name)) {\n        getReaderContext().error("Name must not be empty", ele);\n        valid = false;\n    }\n    if (!StringUtils.hasText(alias)) {\n        getReaderContext().error("Alias must not be empty", ele);\n        valid = false;\n    }\n    if (valid) {\n        try {\n            getReaderContext().getRegistry().registerAlias(name, alias);\n        }\n        catch (Exception ex) {\n            getReaderContext().error("Failed to register alias '" + alias +\n                    "' for bean with name '" + name + "'", ele, ex);\n        }\n        getReaderContext().fireAliasRegistered(name, alias, extractSource(ele));\n    }\n}<\/code><\/pre>\n
        \u53ef\u4ee5\u770b\u5230\uff0c\u8fd9\u91cc\u4e5f\u662f\u4ece XML \u6587\u4ef6\u4e2d\u7684\u522b\u540d\u6807\u7b7e\u4e0a\uff0c\u63d0\u53d6\u51fa\u6765 name \u548c alias \u5c5e\u6027\u503c\uff0c\u6700\u540e\u8c03\u7528 registerAlias \u65b9\u6cd5\u8fdb\u884c\u6ce8\u518c\u3002<\/p>\n
        \u597d\u5566\uff0c\u8fd9\u5c31\u662f Spring \u4e2d\u5173\u4e8e\u522b\u540d\u7684\u5904\u7406\u6d41\u7a0b\u5566\uff5e<\/p>\n
        https:\/\/segmentfault.com\/a\/1190000044182220<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"
        \u4eca\u5929\u6765\u548c\u5c0f\u4f19\u4f34\u4eec\u804a\u4e00\u804a Spring \u4e2d\u5173\u4e8e Bean \u522b\u540d\u7684\u5904\u7406\u903b\u8f91\u3002 1. Alias \u522b\u540d\uff0c\u987e\u540d\u601d\u4e49\u5c31\u662f […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[4],"tags":[],"class_list":["post-10008231","post","type-post","status-publish","format-standard","hentry","category-share"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10008231","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=10008231"}],"version-history":[{"count":0,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10008231\/revisions"}],"wp:attachment":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=10008231"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=10008231"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=10008231"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}