public HttpConnection header(String header, String value, boolean isOverride) {
		if (null != this.conn) {
			if (isOverride) {
				this.conn.setRequestProperty(header, value);
			} else {
				this.conn.addRequestProperty(header, value);
			}
		}

		return this;
	}
public HttpConnection header ( String header , String value , boolean isOverride ) { if ( null != this . conn ) { if ( isOverride ) { this . conn . setRequestProperty ( header , value ) ; } else { this . conn . addRequestProperty ( header , value ) ; } } return this ; }
设置请求头<br>
当请求头存在时，覆盖之

@param header 头名
@param value 头值
@param isOverride 是否覆盖旧值
@return HttpConnection