spring源碼分析（一）

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一、首先分析AliasRegistry介面。

　　1、Alias別名，Registry註冊表，AliasRegistry別名註冊表介面。

　　2、共有四個方法，註冊別名，判斷是否別名，擷取別名數組，移除別名。

　　3、我自己試著寫了一個這個介面的實作類別：

package com.lzh.spring.test;import java.util.ArrayList;import java.util.Hashtable;import java.util.Iterator;import java.util.List;import java.util.Map;import java.util.Map.Entry;import org.springframework.core.AliasRegistry;/** * 別名註冊表介面的實現 * @author LiaoZhengHan * @date 2018年8月29日 */public class MyAliasRegistry implements AliasRegistry{        private Map<String, String> aliasMap = new Hashtable<>();    @Override    public void registerAlias(String name, String alias) {                if (isAlias(alias)) {            throw new IllegalStateException();        }                aliasMap.put(alias, name);    }    @Override    public void removeAlias(String alias) {        aliasMap.remove(alias);    }    @Override    public boolean isAlias(String name) {        return aliasMap.containsKey(name);    }    @Override    public String[] getAliases(String name) {                List<String> aliases = new ArrayList<>();        Iterator<Entry<String, String>> it = aliasMap.entrySet().iterator();        Entry<String, String> entry = null;        while (it.hasNext()) {            entry = it.next();            if (entry.getValue().equals(name)) {                aliases.add(entry.getKey());            }        }        String[] array = new String[aliases.size()];        return aliases.toArray(array);    }}

 

/* * Copyright 2002-2012 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * *      http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package org.springframework.core;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import java.util.concurrent.ConcurrentHashMap;import org.springframework.util.Assert;import org.springframework.util.StringUtils;import org.springframework.util.StringValueResolver;/** * Simple implementation of the {@link AliasRegistry} interface. * Serves as base class for * {@link org.springframework.beans.factory.support.BeanDefinitionRegistry} * implementations. * * @author Juergen Hoeller * @since 2.5.2 */public class SimpleAliasRegistry implements AliasRegistry {    /** Map from alias to canonical name */    private final Map<String, String> aliasMap = new ConcurrentHashMap<String, String>(16);    @Override    public void registerAlias(String name, String alias) {        Assert.hasText(name, "‘name‘ must not be empty");        Assert.hasText(alias, "‘alias‘ must not be empty");        if (alias.equals(name)) {            this.aliasMap.remove(alias);        }        else {            if (!allowAliasOverriding()) {                String registeredName = this.aliasMap.get(alias);                if (registeredName != null && !registeredName.equals(name)) {                    throw new IllegalStateException("Cannot register alias ‘" + alias + "‘ for name ‘" +                            name + "‘: It is already registered for name ‘" + registeredName + "‘.");                }            }            checkForAliasCircle(name, alias);            this.aliasMap.put(alias, name);        }    }    /**     * Return whether alias overriding is allowed.     * Default is {@code true}.     */    protected boolean allowAliasOverriding() {        return true;    }    @Override    public void removeAlias(String alias) {        String name = this.aliasMap.remove(alias);        if (name == null) {            throw new IllegalStateException("No alias ‘" + alias + "‘ registered");        }    }    @Override    public boolean isAlias(String name) {        return this.aliasMap.containsKey(name);    }    @Override    public String[] getAliases(String name) {        List<String> result = new ArrayList<String>();        synchronized (this.aliasMap) {            retrieveAliases(name, result);        }        return StringUtils.toStringArray(result);    }    /**     * Transitively retrieve all aliases for the given name.     * @param name the target name to find aliases for     * @param result the resulting aliases list     */    private void retrieveAliases(String name, List<String> result) {        for (Map.Entry<String, String> entry : this.aliasMap.entrySet()) {            String registeredName = entry.getValue();            if (registeredName.equals(name)) {                String alias = entry.getKey();                result.add(alias);                retrieveAliases(alias, result);            }        }    }    /**     * Resolve all alias target names and aliases registered in this     * factory, applying the given StringValueResolver to them.     * <p>The value resolver may for example resolve placeholders     * in target bean names and even in alias names.     * @param valueResolver the StringValueResolver to apply     */    public void resolveAliases(StringValueResolver valueResolver) {        Assert.notNull(valueResolver, "StringValueResolver must not be null");        synchronized (this.aliasMap) {            Map<String, String> aliasCopy = new HashMap<String, String>(this.aliasMap);            for (String alias : aliasCopy.keySet()) {                String registeredName = aliasCopy.get(alias);                String resolvedAlias = valueResolver.resolveStringValue(alias);                String resolvedName = valueResolver.resolveStringValue(registeredName);                if (resolvedAlias.equals(resolvedName)) {                    this.aliasMap.remove(alias);                }                else if (!resolvedAlias.equals(alias)) {                    String existingName = this.aliasMap.get(resolvedAlias);                    if (existingName != null && !existingName.equals(resolvedName)) {                        throw new IllegalStateException(                                "Cannot register resolved alias ‘" + resolvedAlias + "‘ (original: ‘" + alias +                                "‘) for name ‘" + resolvedName + "‘: It is already registered for name ‘" +                                registeredName + "‘.");                    }                    checkForAliasCircle(resolvedName, resolvedAlias);                    this.aliasMap.remove(alias);                    this.aliasMap.put(resolvedAlias, resolvedName);                }                else if (!registeredName.equals(resolvedName)) {                    this.aliasMap.put(alias, resolvedName);                }            }        }    }    /**     * Determine the raw name, resolving aliases to canonical names.     * @param name the user-specified name     * @return the transformed name     */    public String canonicalName(String name) {        String canonicalName = name;        // Handle aliasing...        String resolvedName;        do {            resolvedName = this.aliasMap.get(canonicalName);            if (resolvedName != null) {                canonicalName = resolvedName;            }        }        while (resolvedName != null);        return canonicalName;    }    /**     * Check whether the given name points back to given alias as an alias     * in the other direction, catching a circular reference upfront and     * throwing a corresponding IllegalStateException.     * @param name the candidate name     * @param alias the candidate alias     * @see #registerAlias     */    protected void checkForAliasCircle(String name, String alias) {        if (alias.equals(canonicalName(name))) {            throw new IllegalStateException("Cannot register alias ‘" + alias +                    "‘ for name ‘" + name + "‘: Circular reference - ‘" +                    name + "‘ is a direct or indirect alias for ‘" + alias + "‘ already");        }    }}

 

 

spring源碼分析（一）