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Java Model
There is a newer version: 1.1.5
package com.litongjava.map;
import java.util.HashMap;
import java.util.Map;
import java.util.function.BiFunction;
import java.util.function.Function;

/**
 * SyncWriteMap 同步写 HashMap
 * 创建原因是 HashMap扩容时，遇到并发修改可能造成 100% CPU 占用
 * 
 * SyncWriteMap 拥有 HashMap 的性能，但不保障并发访问的线程安全
 * 只用于读多写少且不用保障线程安全的场景
 * 
 * 例如 MethodKit 中用于缓存 MethodInfo 的 cache，被写入的数据
 * 不用保障是单例，读取之后会做 null 值判断
 * 
 * ActionMapping 中的 HashMap 是系统启动时在独立线程内初始化的，
 * 不存在并发写，只存在并发读的情况，所以仍然可以使用 HashMap
 */
public class SyncWriteMap extends HashMap {
	
	private static final long serialVersionUID = -7287230891751869148L;
	
	public SyncWriteMap() {
	}
	
	public SyncWriteMap(int initialCapacity) {
		super(initialCapacity);
	}
	
	public SyncWriteMap(int initialCapacity, float loadFactor) {
		super(initialCapacity, loadFactor);
	}
	
	public SyncWriteMap(Map m) {
		super(m);
	}
	
	@Override
	public V put(K key, V value) {
		synchronized (this) {
			return super.put(key, value);
		}
	}
	
	@Override
	public V putIfAbsent(K key, V value) {
		synchronized (this) {
			return super.putIfAbsent(key, value);
		}
	}
	
	@Override
	public void putAll(Map m) {
		synchronized (this) {
			super.putAll(m);
		}
	}
	
	@Override
	public V remove(Object key) {
		synchronized (this) {
			return super.remove(key);
		}
	}
	
	@Override
	public void clear() {
		synchronized (this) {
			super.clear();
		}
	}
	
	@Override
    public V computeIfAbsent(K key, Function mappingFunction) {
        synchronized (this) {
            return super.computeIfAbsent(key, mappingFunction);
        }
    }
    
    @Override
    public V computeIfPresent(K key, BiFunction remappingFunction) {
        synchronized (this) {
            return super.computeIfPresent(key, remappingFunction);
        }
    }
    
    @Override
    public V compute(K key, BiFunction remappingFunction) {
        synchronized (this) {
            return super.compute(key, remappingFunction);
        }
    }
    
    @Override
    public boolean replace(K key, V oldValue, V newValue) {
        synchronized (this) {
            return super.replace(key, oldValue, newValue);
        }
    }
    
    @Override
    public V replace(K key, V value) {
        synchronized (this) {
            return super.replace(key, value);
        }
    }
    
    @Override
    public void replaceAll(BiFunction function) {
        synchronized (this) {
            super.replaceAll(function);
        }
    }
    
    @Override
    public V merge(K key, V value, BiFunction remappingFunction) {
        synchronized (this) {
            return super.merge(key, value, remappingFunction);
        }
    }
}