Java之ByteBuffer的flip,clear及rewind区别

  public final Buffer clear() {  
    position = 0;     //设置为0
    limit = capacity;    //极限和容量相同
    mark = -1;   //取消标记
    return this;  
} 

public final Buffer rewind() {  
    position = 0;  
    mark = -1;  
    return this;  
} 

public final Buffer flip() {  
     limit = position;   
     position = 0;  
     mark = -1;  
     return this;  
 }