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在mybatis的interceptor获取MapperMethod.ParamMap这种参数类型时，常常会多出param1，param2，collection，list，array这些参数，这些不是接口本人定义的，而是ParamNameResolver主动增加的
ParamNameResolver
org/apache/ibatis/reflection/ParamNameResolver.java
public class ParamNameResolver { public static final String GENERIC_NAME_PREFIX = "param"; /** * <p> * A single non-special parameter is returned without a name. * Multiple parameters are named using the naming rule. * In addition to the default names, this method also adds the generic names (param1, param2, * ...). * </p> * * @param args * the args * @return the named params */ public Object getNamedParams(Object[] args) { final int paramCount = names.size(); if (args == null || paramCount == 0) { return null; } else if (!hasParamAnnotation && paramCount == 1) { Object value = args[names.firstKey()]; return wrapToMapIfCollection(value, useActualParamName ? names.get(0) : null); } else { final Map<String, Object> param = new ParamMap<>(); int i = 0; for (Map.Entry<Integer, String> entry : names.entrySet()) { param.put(entry.getValue(), args[entry.getKey()]); // add generic param names (param1, param2, ...) final String genericParamName = GENERIC_NAME_PREFIX + (i + 1); // ensure not to overwrite parameter named with @Param if (!names.containsValue(genericParamName)) { param.put(genericParamName, args[entry.getKey()]); } i++; } return param; } } //......}getNamedParams办法针对单个参数没有加@Param的场景会调用wrapToMapIfCollection，其余的则应用param1,param2这种，这里用了contains，也就是如果自身命名就有蕴含param1,param2这种则不会增加
wrapToMapIfCollection
org/apache/ibatis/reflection/ParamNameResolver.java
/** * Wrap to a {@link ParamMap} if object is {@link Collection} or array. * * @param object a parameter object * @param actualParamName an actual parameter name * (If specify a name, set an object to {@link ParamMap} with specified name) * @return a {@link ParamMap} * @since 3.5.5 */ public static Object wrapToMapIfCollection(Object object, String actualParamName) { if (object instanceof Collection) { ParamMap<Object> map = new ParamMap<>(); map.put("collection", object); if (object instanceof List) { map.put("list", object); } Optional.ofNullable(actualParamName).ifPresent(name -> map.put(name, object)); return map; } else if (object != null && object.getClass().isArray()) { ParamMap<Object> map = new ParamMap<>(); map.put("array", object); Optional.ofNullable(actualParamName).ifPresent(name -> map.put(name, object)); return map; } return object; }wrapToMapIfCollection对于collection类型增加collection，对于list类型还会增加list参数，如果是array类型则会增加array参数，不过这里应用了ifPresent，也就是如果自身参数名蕴含了则不会增加
小结
mybatis的ParamNameResolver针对单个参数没有加@Param的场景会调用wrapToMapIfCollection，最多会增加collection、list、array这些参数；其余的则多增加param1,param2这类参数。