循环依赖检测方法 spring源码方法
场景：checkForAliasCircle(name,alias);
this.aliasMap.put(alias,name);
A,B
B,C
当准备存入C,A时，执行checkForAliasCircle检验是否构成key-value循环
代码实现检测方式：
publicclassSimpleAliasRegistryimplementsAliasRegistry{
/**Mapfromaliastocanonicalname*/
privatefinalMap<String,String>aliasMap=newConcurrentHashMap<String,String>(16);
/**
*Determinetherawname,resolvingaliasestocanonicalnames.
*@paramnametheuser-specifiedname
*@returnthetransformedname
*/
publicStringcanonicalName(Stringname){
StringcanonicalName=name;
//Handlealiasing...
StringresolvedName;
do{
resolvedName=this.aliasMap.get(canonicalName);
if(resolvedName!=null){
canonicalName=resolvedName;
}
}
while(resolvedName!=null);
returncanonicalName;
}
/**
*Checkwhetherthegivennamepointsbacktogivenaliasasanalias
*intheotherdirection,catchingacircularreferenceupfrontand
*throwingacorrespondingIllegalStateException.
*@paramnamethecandidatename
*@paramaliasthecandidatealias
*@see#registerAlias
*/
protectedvoidcheckForAliasCircle(Stringname,Stringalias){
if(alias.equals(canonicalName(name))){
thrownewIllegalStateException("Cannotregisteralias'"+alias+
"'forname'"+name+"':Circularreference-'"+
name+"'isadirectorindirectaliasfor'"+alias+"'already");
}
}