//HashMap的主干数组，可以看到就是一个Entry数组，初始值为空数组{}，主干数组的长度一定是2的次幂，至于为什么这么做，后面会有详细分析。
transient Entry<K,V>[] table = (Entry<K,V>[]) EMPTY_TABLE;

static class Entry<K,V> implements Map.Entry<K,V> {
  final K key;
  V value;
  Entry<K,V> next;//存储指向下一个Entry的引用，单链表结构
  int hash;//对key的hashcode值进行hash运算后得到的值，存储在Entry，避免重复计算

  /**
         * Creates new entry.
         */
  Entry(int h, K k, V v, Entry<K,V> n) {
    value = v;
    next = n;
    key = k;
    hash = h;
  } 

//实际存储的key-value键值对的个数
transient int size;
//阈值，当table == {}时，该值为初始容量（初始容量默认为16）；当table被填充了，也就是为table分配内存空间后，threshold一般为 capacity*loadFactory。HashMap在进行扩容时需要参考threshold，后面会详细谈到
int threshold;
//负载因子，代表了table的填充度有多少，默认是0.75
final float loadFactor;
//用于快速失败，由于HashMap非线程安全，在对HashMap进行迭代时，如果期间其他线程的参与导致HashMap的结构发生变化了（比如put，remove等操作），需要抛出异常ConcurrentModificationException
transient int modCount;

public HashMap(int initialCapacity, float loadFactor) {
　　　　　//此处对传入的初始容量进行校验，最大不能超过MAXIMUM_CAPACITY = 1<<30(230)
        if (initialCapacity < 0)
            throw new IllegalArgumentException("Illegal initial capacity: " +
                                               initialCapacity);
        if (initialCapacity > MAXIMUM_CAPACITY)
            initialCapacity = MAXIMUM_CAPACITY;
        if (loadFactor <= 0 || Float.isNaN(loadFactor))
            throw new IllegalArgumentException("Illegal load factor: " +
                                               loadFactor);

        this.loadFactor = loadFactor;
        threshold = initialCapacity;
　　　　　
        init();//init方法在HashMap中没有实际实现，不过在其子类如 linkedHashMap中就会有对应实现
    }

    public V put(K key, V value) {
        //如果table数组为空数组{}，进行数组填充（为table分配实际内存空间），入参为threshold，此时threshold为initialCapacity 默认是1<<4(24=16)
        if (table == EMPTY_TABLE) {
            inflateTable(threshold);
        }
       //如果key为null，存储位置为table[0]或table[0]的冲突链上
        if (key == null)
            return putForNullKey(value);
        int hash = hash(key);//对key的hashcode进一步计算，确保散列均匀
        int i = indexFor(hash, table.length);//获取在table中的实际位置
        for (Entry<K,V> e = table[i]; e != null; e = e.next) {
        //如果该对应数据已存在，执行覆盖操作。用新value替换旧value，并返回旧value
            Object k;
            if (e.hash == hash && ((k = e.key) == key || key.equals(k))) {
                V oldValue = e.value;
                e.value = value;
                e.recordAccess(this);
                return oldValue;
            }
        }
        modCount++;//保证并发访问时，若HashMap内部结构发生变化，快速响应失败
        addEntry(hash, key, value, i);//新增一个entry
        return null;
    }    

private void inflateTable(int toSize) {
        int capacity = roundUpToPowerOf2(toSize);//capacity一定是2的次幂
        threshold = (int) Math.min(capacity * loadFactor, MAXIMUM_CAPACITY + 1);//此处为threshold赋值，取capacity*loadFactor和MAXIMUM_CAPACITY+1的最小值，capaticy一定不会超过MAXIMUM_CAPACITY，除非loadFactor大于1
        table = new Entry[capacity];
        initHashSeedAsNeeded(capacity);
    }

 private static int roundUpToPowerOf2(int number) {
        // assert number >= 0 : "number must be non-negative";
        return number >= MAXIMUM_CAPACITY
                ? MAXIMUM_CAPACITY
                : (number > 1) ? Integer.highestOneBit((number - 1) << 1) : 1;
    }

//这是一个神奇的函数，用了很多的异或，移位等运算，对key的hashcode进一步进行计算以及二进制位的调整等来保证最终获取的存储位置尽量分布均匀
final int hash(Object k) {
        int h = hashSeed;
        if (0 != h && k instanceof String) {
            return sun.misc.Hashing.stringHash32((String) k);
        }

        h ^= k.hashCode();

        h ^= (h >>> 20) ^ (h >>> 12);
        return h ^ (h >>> 7) ^ (h >>> 4);
    }

/**
     * 返回数组下标
     */
static int indexFor(int h, int length) {
  return h & (length-1);
}

void addEntry(int hash, K key, V value, int bucketIndex) {
        if ((size >= threshold) && (null != table[bucketIndex])) {
            resize(2 * table.length);//当size超过临界阈值threshold，并且即将发生哈希冲突时进行扩容
            hash = (null != key) ? hash(key) : 0;
            bucketIndex = indexFor(hash, table.length);
        }

        createEntry(hash, key, value, bucketIndex);
    }

 void resize(int newCapacity) {
        Entry[] oldTable = table;
        int oldCapacity = oldTable.length;
        if (oldCapacity == MAXIMUM_CAPACITY) {
            threshold = Integer.MAX_VALUE;
            return;
        }

        Entry[] newTable = new Entry[newCapacity];
        transfer(newTable, initHashSeedAsNeeded(newCapacity));
        table = newTable;
        threshold = (int)Math.min(newCapacity * loadFactor, MAXIMUM_CAPACITY + 1);
    }

void transfer(Entry[] newTable, boolean rehash) {
        int newCapacity = newTable.length;
　　　　　//for循环中的代码，逐个遍历链表，重新计算索引位置，将老数组数据复制到新数组中去（数组不存储实际数据，所以仅仅是拷贝引用而已）
        for (Entry<K,V> e : table) {
            while(null != e) {
                Entry<K,V> next = e.next;
                if (rehash) {
                    e.hash = null == e.key ? 0 : hash(e.key);
                }
                int i = indexFor(e.hash, newCapacity);
　　　　　　　　　 //将当前entry的next链指向新的索引位置,newTable[i]有可能为空，有可能也是个entry链，如果是entry链，直接在链表头部插入。
                e.next = newTable[i];
                newTable[i] = e;
                e = next;
            }
        }
    }

 public V get(Object key) {
　　　　 //如果key为null,则直接去table[0]处去检索即可。
        if (key == null)
            return getForNullKey();
        Entry<K,V> entry = getEntry(key);
        return null == entry ? null : entry.getValue();
 }

final Entry<K,V> getEntry(Object key) {
            
        if (size == 0) {
            return null;
        }
        //通过key的hashcode值计算hash值
        int hash = (key == null) ? 0 : hash(key);
        //indexFor (hash&length-1) 获取最终数组索引，然后遍历链表，通过equals方法比对找出对应记录
        for (Entry<K,V> e = table[indexFor(hash, table.length)];
             e != null;
             e = e.next) {
            Object k;
            if (e.hash == hash && 
                ((k = e.key) == key || (key != null && key.equals(k))))
                return e;
        }
        return null;
    }    

/**
 * Created by chengxiao on 2016/11/15.
 */
public class MyTest {
    private static class Person{
        int idCard;
        String name;

        public Person(int idCard, String name) {
            this.idCard = idCard;
            this.name = name;
        }
        @Override
        public boolean equals(Object o) {
            if (this == o) {
                return true;
            }
            if (o == null || getClass() != o.getClass()){
                return false;
            }
            Person person = (Person) o;
            //两个对象是否等值，通过idCard来确定
            return this.idCard == person.idCard;
        }

    }
    public static void main(String []args){
        HashMap<Person,String> map = new HashMap<Person, String>();
        Person person = new Person(1234,"乔峰");
        //put到hashmap中去
        map.put(person,"天龙八部");
        //get取出，从逻辑上讲应该能输出“天龙八部”
        System.out.println("结果:"+map.get(new Person(1234,"萧峰")));
    }
}

 final Segment<K,V>[] segments;

 transient volatile HashEntry<K,V>[] table;

 static final class HashEntry<K,V> {
        final int hash;
        final K key;
        volatile V value;
        volatile HashEntry<K,V> next;
        //其他省略
}    

Segment(float lf, int threshold, HashEntry<K,V>[] tab) {
            this.loadFactor = lf;//负载因子
            this.threshold = threshold;//阈值
            this.table = tab;//主干数组即HashEntry数组
        }

public ConcurrentHashMap(int initialCapacity,
                               float loadFactor, int concurrencyLevel) {
          if (!(loadFactor > 0) || initialCapacity < 0 || concurrencyLevel <= 0)
              throw new IllegalArgumentException();
          //MAX_SEGMENTS 为1<<16=65536，也就是最大并发数为65536
          if (concurrencyLevel > MAX_SEGMENTS)
              concurrencyLevel = MAX_SEGMENTS;
          //2的sshif次方等于ssize，例:ssize=16,sshift=4;ssize=32,sshif=5
         int sshift = 0;
         //ssize 为segments数组长度，根据concurrentLevel计算得出
         int ssize = 1;
         while (ssize < concurrencyLevel) {
             ++sshift;
             ssize <<= 1;
         }
         //segmentShift和segmentMask这两个变量在定位segment时会用到，后面会详细讲
         this.segmentShift = 32 - sshift;
         this.segmentMask = ssize - 1;
         if (initialCapacity > MAXIMUM_CAPACITY)
             initialCapacity = MAXIMUM_CAPACITY;
         //计算cap的大小，即Segment中HashEntry的数组长度，cap也一定为2的n次方.
         int c = initialCapacity / ssize;
         if (c * ssize < initialCapacity)
             ++c;
         int cap = MIN_SEGMENT_TABLE_CAPACITY;
         while (cap < c)
             cap <<= 1;
         //创建segments数组并初始化第一个Segment，其余的Segment延迟初始化
         Segment<K,V> s0 =
             new Segment<K,V>(loadFactor, (int)(cap * loadFactor),
                              (HashEntry<K,V>[])new HashEntry[cap]);
         Segment<K,V>[] ss = (Segment<K,V>[])new Segment[ssize];
         UNSAFE.putOrderedObject(ss, SBASE, s0);
         this.segments = ss;
     }

 public V put(K key, V value) {
        Segment<K,V> s;
        //concurrentHashMap不允许key/value为空
        if (value == null)
            throw new NullPointerException();
        //hash函数对key的hashCode重新散列，避免差劲的不合理的hashcode，保证散列均匀
        int hash = hash(key);
        //返回的hash值无符号右移segmentShift位与段掩码进行位运算，定位segment
        int j = (hash >>> segmentShift) & segmentMask;
        if ((s = (Segment<K,V>)UNSAFE.getObject          // nonvolatile; recheck
             (segments, (j << SSHIFT) + SBASE)) == null) //  in ensureSegment
            s = ensureSegment(j);
        return s.put(key, hash, value, false);
    }

 public V get(Object key) {
        Segment<K,V> s;
        HashEntry<K,V>[] tab;
        int h = hash(key);
        long u = (((h >>> segmentShift) & segmentMask) << SSHIFT) + SBASE;
        //先定位Segment，再定位HashEntry
        if ((s = (Segment<K,V>)UNSAFE.getObjectVolatile(segments, u)) != null &&
            (tab = s.table) != null) {
            for (HashEntry<K,V> e = (HashEntry<K,V>) UNSAFE.getObjectVolatile
                     (tab, ((long)(((tab.length - 1) & h)) << TSHIFT) + TBASE);
                 e != null; e = e.next) {
                K k;
                if ((k = e.key) == key || (e.hash == h && key.equals(k)))
                    return e.value;
            }
        }
        return null;
    }

final V put(K key, int hash, V value, boolean onlyIfAbsent) {
            HashEntry<K,V> node = tryLock() ? null :
                scanAndLockForPut(key, hash, value);//tryLock不成功时会遍历定位到的HashEnry位置的链表（遍历主要是为了使CPU缓存链表），若找不到，则创建HashEntry。tryLock一定次数后（MAX_SCAN_RETRIES变量决定），则lock。若遍历过程中，由于其他线程的操作导致链表头结点变化，则需要重新遍历。
            V oldValue;
            try {
                HashEntry<K,V>[] tab = table;
                int index = (tab.length - 1) & hash;//定位HashEntry，可以看到，这个hash值在定位Segment时和在Segment中定位HashEntry都会用到，只不过定位Segment时只用到高几位。
                HashEntry<K,V> first = entryAt(tab, index);
                for (HashEntry<K,V> e = first;;) {
                    if (e != null) {
                        K k;
                        if ((k = e.key) == key ||
                            (e.hash == hash && key.equals(k))) {
                            oldValue = e.value;
                            if (!onlyIfAbsent) {
                                e.value = value;
                                ++modCount;
                            }
                            break;
                        }
                        e = e.next;
                    }
                    else {
                        if (node != null)
                            node.setNext(first);
                        else
                            node = new HashEntry<K,V>(hash, key, value, first);
                        int c = count + 1;
　　　　　　　　　　　　　　//若c超出阈值threshold，需要扩容并rehash。扩容后的容量是当前容量的2倍。这样可以最大程度避免之前散列好的entry重新散列，具体在另一篇文章中有详细分析，不赘述。扩容并rehash的这个过程是比较消耗资源的。
                        if (c > threshold && tab.length < MAXIMUM_CAPACITY)
                            rehash(node);
                        else
                            setEntryAt(tab, index, node);
                        ++modCount;
                        count = c;
                        oldValue = null;
                        break;
                    }
                }
            } finally {
                unlock();
            }
            return oldValue;
        }

package com.test.spring;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
/**
 * bean后置处理器
 * @author zss
 *
 */
public class PostProcessor implements BeanPostProcessor {

    @Override
    public Object postProcessBeforeInitialization(Object bean,
            String beanName) throws BeansException {
        if ("narCodeService".equals(beanName)) {//过滤掉bean实例ID为narCodeService
            return bean;
        }
        System.out.println("后置处理器处理bean=【"+beanName+"】开始");
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return bean;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean,
            String beanName) throws BeansException {
        if ("narCodeService".equals(beanName)) {
            return bean;
        }
        System.out.println("后置处理器处理bean=【"+beanName+"】完毕!");
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return bean;
    }

}

//注意:接口中两个方法不能返回null，如果返回null那么在后续初始化方法将报空指针异常或者通过getBean()方法获取不到bena实例对象
//因为后置处理器从Spring IoC容器中取出bean实例对象没有再次放回IoC容器中

public interface BeanPostProcessor {  
  
    /** 
     * Apply this BeanPostProcessor to the given new bean instance <i>before</i> any bean 
     * initialization callbacks (like InitializingBean's {@code afterPropertiesSet} 
     * or a custom init-method). The bean will already be populated with property values.    
     */  
    //实例化、依赖注入完毕，在调用显示的初始化之前完成一些定制的初始化任务  
    Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException;  
  
      
    /** 
     * Apply this BeanPostProcessor to the given new bean instance <i>after</i> any bean 
     * initialization callbacks (like InitializingBean's {@code afterPropertiesSet}   
     * or a custom init-method). The bean will already be populated with property values.       
     */  
    //实例化、依赖注入、初始化完毕时执行  
    Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException;  
  
}

    /**  
     * Add a new BeanPostProcessor that will get applied to beans created  
     * by this factory. To be invoked during factory configuration.  
     * <p>Note: Post-processors submitted here will be applied in the order of  
     * registration; any ordering semantics expressed through implementing the  
     * {@link org.springframework.core.Ordered} interface will be ignored. Note  
     * that autodetected post-processors (e.g. as beans in an ApplicationContext)  
     * will always be applied after programmatically registered ones.  
     * @param beanPostProcessor the post-processor to register  
     */    
    void addBeanPostProcessor(BeanPostProcessor beanPostProcessor);   

package com.test.spring;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
/**
 * bean后置处理器
 * @author zss
 *
 */
public class PostProcessor implements BeanPostProcessor {

    @Override
    public Object postProcessBeforeInitialization(Object bean,
            String beanName) throws BeansException {
        System.out.println("后置处理器处理bean=【"+beanName+"】开始");
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return bean;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean,
            String beanName) throws BeansException {
        System.out.println("后置处理器处理bean=【"+beanName+"】完毕!");
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return bean;
    }
}
----------------------------------------------------------------------------------------------------------------------------------------
package com.test.spring;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;

public class PostProcessorB implements BeanPostProcessor {

    @Override
    public Object postProcessBeforeInitialization(Object bean,
            String beanName) throws BeansException {
        System.out.println("后置处理器开始调用了");
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return bean;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean,
            String beanName) throws BeansException {
        System.out.println("后置处理器调用结束了");
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return bean;
    }
}

package com.test.spring;

import org.junit.Before;
import org.junit.Test;
import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class T {
    AbstractApplicationContext applicationcontext=null;
    @Before
    public void before() {
        System.out.println("》》》Spring ApplicationContext容器开始初始化了......");
        applicationcontext= new ClassPathXmlApplicationContext(new String[]{"test1-service.xml"});
        System.out.println("》》》Spring ApplicationContext容器初始化完毕了......");
    }
    @Test
    public void  test() {
        applicationcontext.registerShutdownHook();   
    }
}

package com.test.spring;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.core.Ordered;
/**
 * bean后置处理器
 * @author zss
 *
 */
public class PostProcessor implements BeanPostProcessor,Ordered{

    @Override
    public Object postProcessBeforeInitialization(Object bean,
            String beanName) throws BeansException {
        System.out.println("后置处理器处理bean=【"+beanName+"】开始");
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return bean;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean,
            String beanName) throws BeansException {
        System.out.println("后置处理器处理bean=【"+beanName+"】完毕!");
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return bean;
    }

    @Override
    public int getOrder() {
        return 1;
    }
}
----------------------------------------------------------------------------
package com.test.spring;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.core.Ordered;

public class PostProcessorB implements BeanPostProcessor,Ordered {

    @Override
    public Object postProcessBeforeInitialization(Object bean,
            String beanName) throws BeansException {
        System.out.println("后置处理器开始调用了");
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return bean;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean,
            String beanName) throws BeansException {
        System.out.println("后置处理器调用结束了");
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return bean;
    }

    @Override
    public int getOrder() {
        return 0;
    }
}

public interface BeanNameAware extends Aware {
      void setBeanName(String name);
}

package com.github.jettyrun.springinterface.demo.aware.beannameaware;

import org.springframework.beans.factory.BeanNameAware;

/**
 * Created by jetty on 18/1/31.
 */
public class User implements BeanNameAware{

    private String id;

    private String name;

    private String address;

    public void setBeanName(String beanName) {
        //ID保存BeanName的值
        id=beanName;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "User{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", address='" + address + '\'' +
                '}';
    }
}

package com.github.jettyrun.springinterface.demo.aware.beannameaware;

import org.springframework.beans.factory.BeanNameAware;

/**
 * Created by jetty on 18/1/31.
 */
public class User2 {

    private String id;

    private String name;

    private String address;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "User{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", address='" + address + '\'' +
                '}';
    }
}

 public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("classpath:application-beanaware.xml");

        User user=context.getBean(User.class);
        System.out.println(String.format("实现了BeanNameAware接口的信息BeanId=%s,所有信息=%s",user.getId(),user.toString()));

        User2 user2=context.getBean(User2.class);
        System.out.println(String.format("未实现BeanNameAware接口的信息BeanId=%s,所有信息=%s",user2.getId(),user2.toString()));
    }

package com.dpb.processor;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
/**
 * 自定义BeanPostProcessor实现类
 * BeanPostProcessor接口的作用是：
 *      我们可以通过该接口中的方法在bean实例化、配置以及其他初始化方法前后添加一些我们自己的逻辑
 * @author dengp
 *
 */
public class MyBeanPostProcessor implements BeanPostProcessor{

    /**
     * 实例化、依赖注入完毕，在调用显示的初始化之前完成一些定制的初始化任务
     * 注意：方法返回值不能为null
     * 如果返回null那么在后续初始化方法将报空指针异常或者通过getBean()方法获取不到bena实例对象
     * 因为后置处理器从Spring IoC容器中取出bean实例对象没有再次放回IoC容器中
     */
    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("初始化 before--实例化的bean对象:"+bean+"\t"+beanName);
        // 可以根据beanName不同执行不同的处理操作
        return bean;
    }

    /**
     * 实例化、依赖注入、初始化完毕时执行 
     * 注意：方法返回值不能为null
     * 如果返回null那么在后续初始化方法将报空指针异常或者通过getBean()方法获取不到bena实例对象
     * 因为后置处理器从Spring IoC容器中取出bean实例对象没有再次放回IoC容器中
     */
    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("初始化 after...实例化的bean对象:"+bean+"\t"+beanName);
        // 可以根据beanName不同执行不同的处理操作
        return bean;
    }

}

@PostConstruct
private void init(){
  doSomething...
}

public class MyServiceImpl implements InitializingBean {

    @Override
    public void afterPropertiesSet() throws Exception {
        System.out.println("AfterPropertiesSet method: myServiceImpl");
    }
}