//知识点：java 中如何将 "字符串数组" 合并成 "一个字符串" 例如String [] ss = new String [n] 字符串数组中有n个
	public static void main(String[] args) {
			String[] str = new String[3];
			str[0] = "first";
			str[1] = "second";
			str[2] = "third";			
			//方法1
			String allStr1 = new String();
			allStr1 = str[0].concat(str[1]).concat(str[2]); 
			//方法2
			String allStr2 = new String();
			allStr2 = str[0] + str[1] + str[2];
			//方法3
			StringBuffer sb = new StringBuffer();
			String allStr3 = sb.append(str[0]).append(str[1]).append(str[2]).toString();
			System.out.println(allStr1);
			System.out.println(allStr2);
			System.out.println(allStr3);
			//方法4
			StringBuffer sb1 = new StringBuffer();
			String allStr4="";
			for(int i=0;i<str.length;i++){
				allStr4=sb1.append(str[i]).toString();
			}
			System.out.println(allStr4);
	}

应用

/**
	 * 按消防栓主键查询出初始化数据，生成二维码
	 */
	@Override
	public Integer insertQRCode(String hydrantId) {
		//content= "http://www.zxhznkj.com/page/weizhi.html?fireplug=消防栓设备&number=消防栓编号&equipment=硬件01,触发器01;硬件02,触发器02;&hydrantId=1";
		HydrantQRCodeEntity hydrantQRCodeEntity=hydrantQRCodeMapper.queryByIdHydrantQRCode(hydrantId);
		String hydrantName=hydrantQRCodeEntity.getHydrantName();
		String hydrantNumber=hydrantQRCodeEntity.getHydrantNumber();
		List<HardwareQRCodeEntity> list=hardwareQRCodeMapper.queryByhydrantId(hydrantId);
		String [] equipment=new String [list.size()];//创建字符数组,存放所有硬件设备
		for(int i=0;i<list.size();i++){
			HardwareQRCodeEntity hqrce=list.get(i);
			String hardwareName=hqrce.getHardwareName();
			String hardwareType=hqrce.getHardwareType();
			String hardware=hardwareName+","+hardwareType+";";
			equipment[i]=hardware; //取出的多个硬件存到数组中			
		}
		//将字符串数组中的数据合并成一个字符串
		String equipmentstr="";
		StringBuffer sb = new StringBuffer(); 
		for(int i=0;i<equipment.length;i++){
			equipmentstr=sb.append(equipment[i]).toString();
		}
		String content="http://www.zxhznkj.com/page/weizhi.html?devicesName="+hydrantName+"&devicesNumber="+hydrantNumber+"&hydrantId="+hydrantId+"&equipment="+equipmentstr;
		//调用生成二维码的接口，生成二维码
		String imgPath="D:/upload/logo/logos.png"; //二维码logo
		String destPath ="D:/upload/zxing/"; //生成二维码的地方
		try {
			QRCodeUtil.encode(content,imgPath,destPath, true);
		} catch (Exception e) {
			e.printStackTrace();
		}
		//修改二维码相关数据
		hydrantQRCodeEntity.setQrCodeHost(content);
		hydrantQRCodeEntity.setQrCodePicture(destPath);
		hydrantQRCodeEntity.setQrCodeLogoimg(imgPath);
		hydrantQRCodeEntity.setQrCodeStatus("未使用");
		Integer iden=hydrantQRCodeMapper.updateHydrantQRCode(hydrantQRCodeEntity);
		return iden;
	}