【JAVA】-常用代码速查

1-日期相关

1-1 将时间字符串转化Long时间戳

 public static String dateToStamp(String s) throws ParseException{        
    String res;
	SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
	Date date = simpleDateFormat.parse(s);
	long ts = date.getTime();
	res = String.valueOf(ts);
	return res;
}

1-2 将Long时间戳转换为时间字符串

public static String stampToDate(String s){        String res;
	SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
	long lt = new Long(s);
	Date date = new Date(lt);
	res = simpleDateFormat.format(date);
	return res;
}

1-3 将日期格式化

  Date date = new SimpleDateFormat("yyyy-MM-dd").parse("2005-06-09");
  String now = new SimpleDateFormat("yyyy年MM月dd日").format(date);

2-Fastjson

2-1.对象转JSON字符串

String s = JSON.toJSONString(data);

2-2.字符串转JSON对象

JSONObject jsonObject = JSON.parseObject(string);

2-3.JSON对象遍历

JSONObject jsonInfo = new JSONObject();        
Iterator iter = jsonInfo.entrySet().iterator();
while (iter.hasNext()) {
	Map.Entry entry = (Map.Entry) iter.next();
	System.out.println(entry.getKey().toString());
	System.out.println(entry.getValue().toString());
}

3-BigDecimal

3-1 转化

BigDecimal bigDecimal= (BigDecimal)objects[0];
Integer id=Integer.parseInt(bigDecimal.toString());

4-List

4-1 转化

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public String listToString(List list, char separator) {
	StringBuilder sb = new StringBuilder();
	for (int i = 0; i < list.size(); i++) {
		sb.append(list.get(i)).append(separator);
	}
	return sb.toString().substring(0, sb.toString().length() - 1);
}

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public String listToString(List list, char separator) {
	StringBuilder sb = new StringBuilder();
	for (int i = 0; i < list.size(); i++) {
		if (i == list.size() - 1) {
			sb.append(list.get(i));
		} else {
			sb.append(list.get(i));
			sb.append(separator);
		}
	}
	return sb.toString();
}

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public String listToString(List list, char separator) {
	StringBuilder sb = new StringBuilder();
	for (int i = 0; i < list.size(); i++) {
		sb.append(list.get(i));
		if (i < list.size() - 1) {
			sb.append(separator);
		}
	}
	return sb.toString();
}

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public String listToString(List<String> list, Separator separator) {
	StringBuilder sb = new StringBuilder();
	for (String s : list) {
		if (s != null && !"".equals(s)) {
			sb.append(separator.get()).append(s);
		}
	}
	return sb.toString();
}

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public String listToString(List list, char separator) {
	return org.apache.commons.lang.StringUtils.join(list.toArray(), separator);
}

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5-Jackson

5-1 转化

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写对象为字符串
ObjectMapper mapper = new ObjectMapper();
String mapJakcson = mapper.writeValueAsString(dto);
转化字符串为对象
ObjectMapper m = new ObjectMapper();
ProfessionalPBCReportDTO test1 = m.readValue(mapJakcson, Class.class);
JaskSon 设置日期格式
SimpleDateFormat fmt = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
mapper.setDateFormat(fmt);

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