//使用连接池的数据源
public class PooledDataSource implements DataSource {

  private static final Log log = LogFactory.getLog(PooledDataSource.class);

  private final PoolState state = new PoolState(this);

  //真正用于创建连接的数据源
  private final UnpooledDataSource dataSource;

  // OPTIONAL CONFIGURATION FIELDS
  //最大活跃连接数
  protected int poolMaximumActiveConnections = 10;
  //最大闲置连接数
  protected int poolMaximumIdleConnections = 5;
  //最大checkout时长（最长使用时间）
  protected int poolMaximumCheckoutTime = 20000;
  //无法取得连接是最大的等待时间
  protected int poolTimeToWait = 20000;
  //最多允许几次无效连接
  protected int poolMaximumLocalBadConnectionTolerance = 3;
  //测试连接是否有效的sql语句
  protected String poolPingQuery = "NO PING QUERY SET";
  //是否允许测试连接
  protected boolean poolPingEnabled;
  //配置一段时间，当连接在这段时间内没有被使用，才允许测试连接是否有效
  protected int poolPingConnectionsNotUsedFor;
  //根据数据库url、用户名、密码生成一个hash值，唯一标识一个连接池，由这个连接池生成的连接都会带上这个值
  private int expectedConnectionTypeCode;

  public PooledDataSource() {
    dataSource = new UnpooledDataSource();
  }

  public PooledDataSource(UnpooledDataSource dataSource) {
    this.dataSource = dataSource;
  }
}

private PooledConnection popConnection(String username, String password) throws SQLException {
    boolean countedWait = false;
    PooledConnection conn = null;
    long t = System.currentTimeMillis();//记录尝试获取连接的起始时间戳
    int localBadConnectionCount = 0;//初始化获取到无效连接的次数

    while (conn == null) {
      synchronized (state) {//获取连接必须是同步的
        if (!state.idleConnections.isEmpty()) {//检测是否有空闲连接
          // Pool has available connection
          //有空闲连接直接使用
          conn = state.idleConnections.remove(0);
          if (log.isDebugEnabled()) {
            log.debug("Checked out connection " + conn.getRealHashCode() + " from pool.");
          }
        } else {// 没有空闲连接
          if (state.activeConnections.size() < poolMaximumActiveConnections) {//判断活跃连接池中的数量是否大于最大连接数
            // 没有则可创建新的连接
            conn = new PooledConnection(dataSource.getConnection(), this);
            if (log.isDebugEnabled()) {
              log.debug("Created connection " + conn.getRealHashCode() + ".");
            }
          } else {// 如果已经等于最大连接数，则不能创建新连接
            //获取最早创建的连接
            PooledConnection oldestActiveConnection = state.activeConnections.get(0);
            long longestCheckoutTime = oldestActiveConnection.getCheckoutTime();
            if (longestCheckoutTime > poolMaximumCheckoutTime) {//检测是否已经以及超过最长使用时间
              // 如果超时，对超时连接的信息进行统计
              state.claimedOverdueConnectionCount++;//超时连接次数+1
              state.accumulatedCheckoutTimeOfOverdueConnections += longestCheckoutTime;//累计超时时间增加
              state.accumulatedCheckoutTime += longestCheckoutTime;//累计的使用连接的时间增加
              state.activeConnections.remove(oldestActiveConnection);//从活跃队列中删除
              if (!oldestActiveConnection.getRealConnection().getAutoCommit()) {//如果超时连接未提交，则手动回滚
                try {
                  oldestActiveConnection.getRealConnection().rollback();
                } catch (SQLException e) {//发生异常仅仅记录日志
                  /*
                     Just log a message for debug and continue to execute the following
                     statement like nothing happend.
                     Wrap the bad connection with a new PooledConnection, this will help
                     to not intterupt current executing thread and give current thread a
                     chance to join the next competion for another valid/good database
                     connection. At the end of this loop, bad {@link @conn} will be set as null.
                   */
                  log.debug("Bad connection. Could not roll back");
                }  
              }
              //在连接池中创建新的连接，注意对于数据库来说，并没有创建新连接；
              conn = new PooledConnection(oldestActiveConnection.getRealConnection(), this);
              conn.setCreatedTimestamp(oldestActiveConnection.getCreatedTimestamp());
              conn.setLastUsedTimestamp(oldestActiveConnection.getLastUsedTimestamp());
              //让老连接失效
              oldestActiveConnection.invalidate();
              if (log.isDebugEnabled()) {
                log.debug("Claimed overdue connection " + conn.getRealHashCode() + ".");
              }
            } else {
              // 无空闲连接，最早创建的连接没有失效，无法创建新连接，只能阻塞
              try {
                if (!countedWait) {
                  state.hadToWaitCount++;//连接池累计等待次数加1
                  countedWait = true;
                }
                if (log.isDebugEnabled()) {
                  log.debug("Waiting as long as " + poolTimeToWait + " milliseconds for connection.");
                }
                long wt = System.currentTimeMillis();
                state.wait(poolTimeToWait);//阻塞等待指定时间
                state.accumulatedWaitTime += System.currentTimeMillis() - wt;//累计等待时间增加
              } catch (InterruptedException e) {
                break;
              }
            }
          }
        }
        if (conn != null) {//获取连接成功的，要测试连接是否有效，同时更新统计数据
          // ping to server and check the connection is valid or not
          if (conn.isValid()) {//检测连接是否有效
            if (!conn.getRealConnection().getAutoCommit()) {
              conn.getRealConnection().rollback();//如果遗留历史的事务，回滚
            }
            //连接池相关统计信息更新
            conn.setConnectionTypeCode(assembleConnectionTypeCode(dataSource.getUrl(), username, password));
            conn.setCheckoutTimestamp(System.currentTimeMillis());
            conn.setLastUsedTimestamp(System.currentTimeMillis());
            state.activeConnections.add(conn);
            state.requestCount++;
            state.accumulatedRequestTime += System.currentTimeMillis() - t;
          } else {//如果连接无效
            if (log.isDebugEnabled()) {
              log.debug("A bad connection (" + conn.getRealHashCode() + ") was returned from the pool, getting another connection.");
            }
            state.badConnectionCount++;//累计的获取无效连接次数+1
            localBadConnectionCount++;//当前获取无效连接次数+1
            conn = null;
            //拿到无效连接，但如果没有超过重试的次数，允许再次尝试获取连接，否则抛出异常
            if (localBadConnectionCount > (poolMaximumIdleConnections + poolMaximumLocalBadConnectionTolerance)) {
              if (log.isDebugEnabled()) {
                log.debug("PooledDataSource: Could not get a good connection to the database.");
              }
              throw new SQLException("PooledDataSource: Could not get a good connection to the database.");
            }
          }
        }
      }

    }

    if (conn == null) {
      if (log.isDebugEnabled()) {
        log.debug("PooledDataSource: Unknown severe error condition.  The connection pool returned a null connection.");
      }
      throw new SQLException("PooledDataSource: Unknown severe error condition.  The connection pool returned a null connection.");
    }

    return conn;
  }

//回收连接资源
  protected void pushConnection(PooledConnection conn) throws SQLException {

    synchronized (state) {//回收连接必须是同步的
      state.activeConnections.remove(conn);//从活跃连接池中删除此连接
      if (conn.isValid()) {
          //判断闲置连接池资源是否已经达到上限
        if (state.idleConnections.size() < poolMaximumIdleConnections && conn.getConnectionTypeCode() == expectedConnectionTypeCode) {
            //没有达到上限，进行回收
          state.accumulatedCheckoutTime += conn.getCheckoutTime();
          if (!conn.getRealConnection().getAutoCommit()) {
            conn.getRealConnection().rollback();//如果还有事务没有提交，进行回滚操作
          }
          //基于该连接，创建一个新的连接资源，并刷新连接状态
          PooledConnection newConn = new PooledConnection(conn.getRealConnection(), this);
          state.idleConnections.add(newConn);
          newConn.setCreatedTimestamp(conn.getCreatedTimestamp());
          newConn.setLastUsedTimestamp(conn.getLastUsedTimestamp());
          //老连接失效
          conn.invalidate();
          if (log.isDebugEnabled()) {
            log.debug("Returned connection " + newConn.getRealHashCode() + " to pool.");
          }
          //唤醒其他被阻塞的线程，因为获取连接过程中，有些线程是阻塞的
          state.notifyAll();
        } else {//如果闲置连接池已经达到上限了，将连接真实关闭
          state.accumulatedCheckoutTime += conn.getCheckoutTime();
          if (!conn.getRealConnection().getAutoCommit()) {
            conn.getRealConnection().rollback();
          }
          //关闭真的数据库连接
          conn.getRealConnection().close();
          if (log.isDebugEnabled()) {
            log.debug("Closed connection " + conn.getRealHashCode() + ".");
          }
          //将连接对象设置为无效
          conn.invalidate();
        }
      } else {
        if (log.isDebugEnabled()) {
          log.debug("A bad connection (" + conn.getRealHashCode() + ") attempted to return to the pool, discarding connection.");
        }
        state.badConnectionCount++;
      }
    }
  }

/**
 * PoolState：用于管理PooledConnection对象状态的组件，通过两个list分别
 * 管理空闲状态的连接资源和活跃状态的连接资源
 * 
 * @author Clinton Begin
 */
public class PoolState {

  protected PooledDataSource dataSource;
  //空闲的连接池资源集合
  protected final List<PooledConnection> idleConnections = new ArrayList<>();
  //活跃的连接池资源集合
  protected final List<PooledConnection> activeConnections = new ArrayList<>();
  //请求的次数
  protected long requestCount = 0;
  //累计的获得连接的时间
  protected long accumulatedRequestTime = 0;
  //累计的使用连接的时间。从连接取出到归还，算一次使用的时间；
  protected long accumulatedCheckoutTime = 0;
  //使用连接超时的次数
  protected long claimedOverdueConnectionCount = 0;
  //累计超时时间
  protected long accumulatedCheckoutTimeOfOverdueConnections = 0;
  //累计等待时间
  protected long accumulatedWaitTime = 0;
  //等待次数 
  protected long hadToWaitCount = 0;
  //无效的连接次数 
  protected long badConnectionCount = 0;

  public PoolState(PooledDataSource dataSource) {
    this.dataSource = dataSource;
  }
}

BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(new FileInputStream("c://a.txt")));

public interface Cache {

  String getId();//缓存实现类的id

  void putObject(Object key, Object value);//往缓存中添加数据，key一般是CacheKey对象

  Object getObject(Object key);//根据指定的key从缓存获取数据

  Object removeObject(Object key);//根据指定的key从缓存删除数据

  void clear();//清空缓存

  int getSize();//获取缓存的个数
  
  ReadWriteLock getReadWriteLock();//获取读写锁

}

public class PerpetualCache implements Cache {

  private final String id;

  private Map<Object, Object> cache = new HashMap<>();

  public PerpetualCache(String id) {
    this.id = id;
  }

  @Override
  public String getId() {
    return id;
  }

  @Override
  public int getSize() {
    return cache.size();
  }

  @Override
  public void putObject(Object key, Object value) {
    cache.put(key, value);
  }

  @Override
  public Object getObject(Object key) {
    return cache.get(key);
  }

  @Override
  public Object removeObject(Object key) {
    return cache.remove(key);
  }

  @Override
  public void clear() {
    cache.clear();
  }

  @Override
  public ReadWriteLock getReadWriteLock() {
    return null;
  }

  @Override
  public boolean equals(Object o) {
    if (getId() == null) {
      throw new CacheException("Cache instances require an ID.");
    }
    if (this == o) {
      return true;
    }
    if (!(o instanceof Cache)) {
      return false;
    }

    Cache otherCache = (Cache) o;
    return getId().equals(otherCache.getId());
  }

  @Override
  public int hashCode() {
    if (getId() == null) {
      throw new CacheException("Cache instances require an ID.");
    }
    return getId().hashCode();
  }

}

public class BlockingCache implements Cache {

  //阻塞的超时时长
  private long timeout;
  //被装饰的底层对象，一般是PerpetualCache
  private final Cache delegate;
  //锁对象集，粒度到key值
  private final ConcurrentHashMap<Object, ReentrantLock> locks;

  public BlockingCache(Cache delegate) {
    this.delegate = delegate;
    this.locks = new ConcurrentHashMap<>();
  }

  @Override
  public String getId() {
    return delegate.getId();
  }

  @Override
  public int getSize() {
    return delegate.getSize();
  }

  @Override
  public void putObject(Object key, Object value) {
    try {
      delegate.putObject(key, value);
    } finally {
      releaseLock(key);
    }
  }

  @Override
  public Object getObject(Object key) {
    acquireLock(key);//根据key获得锁对象，获取锁成功加锁，获取锁失败阻塞一段时间重试
    Object value = delegate.getObject(key);
    if (value != null) {//获取数据成功的，要释放锁
      releaseLock(key);
    }        
    return value;
  }

  @Override
  public Object removeObject(Object key) {
    // despite of its name, this method is called only to release locks
    releaseLock(key);
    return null;
  }

  @Override
  public void clear() {
    delegate.clear();
  }

  @Override
  public ReadWriteLock getReadWriteLock() {
    return null;
  }
  
  private ReentrantLock getLockForKey(Object key) {
    ReentrantLock lock = new ReentrantLock();//创建锁
    ReentrantLock previous = locks.putIfAbsent(key, lock);//把新锁添加到locks集合中，如果添加成功使用新锁，如果添加失败则使用locks集合中的锁
    return previous == null ? lock : previous;
  }
  
//根据key获得锁对象，获取锁成功加锁，获取锁失败阻塞一段时间重试
  private void acquireLock(Object key) {
    //获得锁对象
    Lock lock = getLockForKey(key);
    if (timeout > 0) {//使用带超时时间的锁
      try {
        boolean acquired = lock.tryLock(timeout, TimeUnit.MILLISECONDS);
        if (!acquired) {//如果超时抛出异常
          throw new CacheException("Couldn‘t get a lock in " + timeout + " for the key " +  key + " at the cache " + delegate.getId());  
        }
      } catch (InterruptedException e) {
        throw new CacheException("Got interrupted while trying to acquire lock for key " + key, e);
      }
    } else {//使用不带超时时间的锁
      lock.lock();
    }
  }
  
  private void releaseLock(Object key) {
    ReentrantLock lock = locks.get(key);
    if (lock.isHeldByCurrentThread()) {
      lock.unlock();
    }
  }

  public long getTimeout() {
    return timeout;
  }

  public void setTimeout(long timeout) {
    this.timeout = timeout;
  }  
}

public class CacheKey implements Cloneable, Serializable {

  private static final long serialVersionUID = 1146682552656046210L;

  public static final CacheKey NULL_CACHE_KEY = new NullCacheKey();

  private static final int DEFAULT_MULTIPLYER = 37;
  private static final int DEFAULT_HASHCODE = 17;

  private final int multiplier;//参与hash计算的乘数
  private int hashcode;//CacheKey的hash值，在update函数中实时运算出来的
  private long checksum;//校验和，hash值的和
  private int count;//updateList的中元素个数
  // 8/21/2017 - Sonarlint flags this as needing to be marked transient.  While true if content is not serializable, this is not always true and thus should not be marked transient.
  //该集合中的元素觉得两个CacheKey是否相等
  private List<Object> updateList;

  public CacheKey() {
    this.hashcode = DEFAULT_HASHCODE;
    this.multiplier = DEFAULT_MULTIPLYER;
    this.count = 0;
    this.updateList = new ArrayList<>();
  }

  public CacheKey(Object[] objects) {
    this();
    updateAll(objects);
  }

  public void update(Object object) {
    //获取object的hash值
    int baseHashCode = object == null ? 1 : ArrayUtil.hashCode(object); 
    //更新count、checksum以及hashcode的值
    count++;
    checksum += baseHashCode;
    baseHashCode *= count;
    hashcode = multiplier * hashcode + baseHashCode;
    //将对象添加到updateList中
    updateList.add(object);
  }

  public void updateAll(Object[] objects) {
    for (Object o : objects) {
      update(o);
    }
  }

  @Override
  public boolean equals(Object object) {
    if (this == object) {//比较是不是同一个对象
      return true;
    }
    if (!(object instanceof CacheKey)) {//是否类型相同
      return false;
    }

    final CacheKey cacheKey = (CacheKey) object;

    if (hashcode != cacheKey.hashcode) {//hashcode是否相同
      return false;
    }
    if (checksum != cacheKey.checksum) {//checksum是否相同
      return false;
    }
    if (count != cacheKey.count) {//count是否相同
      return false;
    }

    //以上都不相同，才按顺序比较updateList中元素的hash值是否一致
    for (int i = 0; i < updateList.size(); i++) {
      Object thisObject = updateList.get(i);
      Object thatObject = cacheKey.updateList.get(i);
      if (!ArrayUtil.equals(thisObject, thatObject)) {
        return false;
      }
    }
    return true;
  }

  @Override
  public int hashCode() {
    return hashcode;
  }
}

public interface ObjectFactory {

  void setProperties(Properties properties);

  <T> T create(Class<T> type);

  <T> T create(Class<T> type, List<Class<?>> constructorArgTypes, List<Object> constructorArgs);
 
  <T> boolean isCollection(Class<T> type);

}

public class DefaultObjectFactory implements ObjectFactory, Serializable {

  private static final long serialVersionUID = -8855120656740914948L;

  @Override
  public <T> T create(Class<T> type) {
    return create(type, null, null);
  }

  @SuppressWarnings("unchecked")
  @Override
  public <T> T create(Class<T> type, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
    //判断类是不是集合类，如果是集合类指定具体的实现类
    Class<?> classToCreate = resolveInterface(type);
    // we know types are assignable
    return (T) instantiateClass(classToCreate, constructorArgTypes, constructorArgs);
  }

  @Override
  public void setProperties(Properties properties) {
    // no props for default
  }

  private  <T> T instantiateClass(Class<T> type, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
    try {
      Constructor<T> constructor;
      //通过无参构造函数创建对象
      if (constructorArgTypes == null || constructorArgs == null) {
        constructor = type.getDeclaredConstructor();
　　　　　//如果不是public修饰的，转为public修饰
        if (!constructor.isAccessible()) {
          constructor.setAccessible(true);
        }
        return constructor.newInstance();
      }
      //根据指定的参数列表查找构造函数，并实例化对象
      constructor = type.getDeclaredConstructor(constructorArgTypes.toArray(new Class[constructorArgTypes.size()]));
      if (!constructor.isAccessible()) {
        constructor.setAccessible(true);
      }
      return constructor.newInstance(constructorArgs.toArray(new Object[constructorArgs.size()]));
    } catch (Exception e) {
      StringBuilder argTypes = new StringBuilder();
      if (constructorArgTypes != null && !constructorArgTypes.isEmpty()) {
        for (Class<?> argType : constructorArgTypes) {
          argTypes.append(argType.getSimpleName());
          argTypes.append(",");
        }
        argTypes.deleteCharAt(argTypes.length() - 1); // remove trailing ,
      }
      StringBuilder argValues = new StringBuilder();
      if (constructorArgs != null && !constructorArgs.isEmpty()) {
        for (Object argValue : constructorArgs) {
          argValues.append(String.valueOf(argValue));
          argValues.append(",");
        }
        argValues.deleteCharAt(argValues.length() - 1); // remove trailing ,
      }
      throw new ReflectionException("Error instantiating " + type + " with invalid types (" + argTypes + ") or values (" + argValues + "). Cause: " + e, e);
    }
  }

  protected Class<?> resolveInterface(Class<?> type) {
    Class<?> classToCreate;
    if (type == List.class || type == Collection.class || type == Iterable.class) {
      classToCreate = ArrayList.class;
    } else if (type == Map.class) {
      classToCreate = HashMap.class;
    } else if (type == SortedSet.class) { // issue #510 Collections Support
      classToCreate = TreeSet.class;
    } else if (type == Set.class) {
      classToCreate = HashSet.class;
    } else {
      classToCreate = type;
    }
    return classToCreate;
  }

  @Override
  public <T> boolean isCollection(Class<T> type) {
    return Collection.class.isAssignableFrom(type);
  }

}

public interface ReflectorFactory {

  boolean isClassCacheEnabled();

  void setClassCacheEnabled(boolean classCacheEnabled);

  Reflector findForClass(Class<?> type);
}

public class DefaultReflectorFactory implements ReflectorFactory {
  private boolean classCacheEnabled = true;
  private final ConcurrentMap<Class<?>, Reflector> reflectorMap = new ConcurrentHashMap<>();

  public DefaultReflectorFactory() {
  }

  @Override
  public boolean isClassCacheEnabled() {
    return classCacheEnabled;
  }

  @Override
  public void setClassCacheEnabled(boolean classCacheEnabled) {
    this.classCacheEnabled = classCacheEnabled;
  }

  @Override
  public Reflector findForClass(Class<?> type) {
    if (classCacheEnabled) {
            // synchronized (type) removed see issue #461
      return reflectorMap.computeIfAbsent(type, Reflector::new);
    } else {
      return new Reflector(type);
    }
  }

}

public class Reflector {

  private final Class<?> type;//对应的class
  private final String[] readablePropertyNames;//可读属性的名称集合，存在get方法即可读
  private final String[] writeablePropertyNames;//可写属性的名称集合，存在set方法即可写
  private final Map<String, Invoker> setMethods = new HashMap<>();//保存属性相关的set方法
  private final Map<String, Invoker> getMethods = new HashMap<>();//保存属性相关的get方法
  private final Map<String, Class<?>> setTypes = new HashMap<>();//保存属性相关的set方法入参类型
  private final Map<String, Class<?>> getTypes = new HashMap<>();//保存属性相关的get方法返回类型
  private Constructor<?> defaultConstructor;//class默认的构造函数

  //记录所有属性的名称集合
  private Map<String, String> caseInsensitivePropertyMap = new HashMap<>();

  public Reflector(Class<?> clazz) {
    type = clazz;
    addDefaultConstructor(clazz);//获取clazz的默认构造函数
    addGetMethods(clazz);//处理clazz中的get方法信息，填充getMethods、getTypes
    addSetMethods(clazz);//处理clazz中的set方法信息，填充setMethods、setTypes
    addFields(clazz);//处理没有get、set方法的属性
    //根据get、set方法初始化可读属性集合和可写属性集合
    readablePropertyNames = getMethods.keySet().toArray(new String[getMethods.keySet().size()]);
    writeablePropertyNames = setMethods.keySet().toArray(new String[setMethods.keySet().size()]);
    //初始化caseInsensitivePropertyMap
    for (String propName : readablePropertyNames) {
      caseInsensitivePropertyMap.put(propName.toUpperCase(Locale.ENGLISH), propName);
    }
    for (String propName : writeablePropertyNames) {
      caseInsensitivePropertyMap.put(propName.toUpperCase(Locale.ENGLISH), propName);
    }
  }
}

public interface ObjectWrapper {

  //获取对象指定属性的值
  Object get(PropertyTokenizer prop);

  //设置对象指定属性的值
  void set(PropertyTokenizer prop, Object value);

  String findProperty(String name, boolean useCamelCaseMapping);

  String[] getGetterNames();

  String[] getSetterNames();

  Class<?> getSetterType(String name);

  Class<?> getGetterType(String name);

  boolean hasSetter(String name);

  boolean hasGetter(String name);

  MetaObject instantiatePropertyValue(String name, PropertyTokenizer prop, ObjectFactory objectFactory);
  //判断当前对象是否为集合
  boolean isCollection();
  
  //当前集合添加一个元素
  void add(Object element);
  
  //当前集合添加另外一个集合
  <E> void addAll(List<E> element);

}

public interface ObjectWrapperFactory {

  boolean hasWrapperFor(Object object);

  ObjectWrapper getWrapperFor(MetaObject metaObject, Object object);

}

//----------------源码分析之反射工具类的实例---------------------
    @Test
    public void reflectionTest(){
        //反射工具类初始化
        ObjectFactory objectFactory = new DefaultObjectFactory();
        //通过ObjectFactory创建TUser对象
        TUser user = objectFactory.create(TUser.class);
        ObjectWrapperFactory objectWrapperFactory = new DefaultObjectWrapperFactory();
        ReflectorFactory reflectorFactory = new DefaultReflectorFactory();
        MetaObject metaObject = MetaObject.forObject(user, objectFactory, objectWrapperFactory, reflectorFactory);

        //模拟数据库行数据转化成对象
        //1.模拟从数据库读取数据
        Map<String, Object> dbResult = new HashMap<>();
        dbResult.put("id", 1);
        dbResult.put("user_name", "lison");
        dbResult.put("real_name", "李晓宇");
        TPosition tp = new TPosition();
        tp.setId(1);
        dbResult.put("position_id", tp);
        //2.模拟映射关系
        Map<String, String> mapper = new HashMap<String, String>();
        mapper.put("id", "id");
        mapper.put("userName", "user_name");
        mapper.put("realName", "real_name");
        mapper.put("position", "position_id");
        
        //3.使用反射工具类将行数据转换成pojo
        BeanWrapper objectWrapper = (BeanWrapper) metaObject.getObjectWrapper();
        
        Set<Entry<String, String>> entrySet = mapper.entrySet();
        for (Entry<String, String> colInfo : entrySet) {
            String propName = colInfo.getKey();
            Object propValue = dbResult.get(colInfo.getValue());
            PropertyTokenizer proTokenizer = new PropertyTokenizer(propName);
            objectWrapper.set(proTokenizer, propValue);
        }
        System.out.println(metaObject.getOriginalObject());
        
}