常用工具类
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1.HtmlUtil
向页面输入String,会自动转为json格式:

package com.zys.training.util; import com.fasterxml.jackson.databind.ObjectMapper; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.PrintWriter; import java.util.HashMap; import java.util.Iterator; import java.util.Map; /** * 向页面输出String * @author yushizhong */ public class HtmlUtil { /** * 输出string * @param response * @param jsonStr */ public static void writerJson(HttpServletResponse response, String jsonStr) { writer(response, jsonStr); } public static void writerJson(HttpServletResponse response, Object object) throws Exception { ObjectMapper mapper = new ObjectMapper(); String jsonString = mapper.writeValueAsString(object) ; writer(response, jsonString); } private static void writer(HttpServletResponse response, String str) { try { // 设置页面不缓存 response.setHeader("Pragma", "No-cache"); response.setHeader("Cache-Control", "no-cache"); response.setHeader("Access-Control-Allow-Origin","*"); response.setCharacterEncoding("UTF-8"); PrintWriter out = null; out = response.getWriter(); out.print(str); out.flush(); out.close(); } catch ( Exception ex){ ex.printStackTrace(); } } public static Map<String, String> getParameterMap(HttpServletRequest request) { // 参数Map Map properties = request.getParameterMap(); // 返回值Map Map<String, String> returnMap = new HashMap<String, String>(); Iterator entries = properties.entrySet().iterator(); Map.Entry entry; String name = ""; String value = ""; while (entries.hasNext()) { entry = (Map.Entry) entries.next(); name = (String) entry.getKey(); Object valueObj = entry.getValue(); if (null == valueObj) { value = ""; } else if (valueObj instanceof String[]) { String[] values = (String[]) valueObj; for (int i = 0; i < values.length; i++) { value = values[i] + ","; } value = value.substring(0, value.length() - 1); } else { value = valueObj.toString(); } returnMap.put(name, value); } return returnMap; } }
调用方式:
@RequestMapping("/get") public void get(HttpServletResponse response){ response.setContentType("application/json"); HtmlUtil.writerJson(response, "hello"); }
2.Md5Utils
md5加密

package com.example.springsecurity.util; import java.math.BigInteger; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; public class Md5Utils { public static String md5(String plainText) { byte[] secretBytes = null; try { secretBytes = MessageDigest.getInstance("md5").digest( plainText.getBytes()); } catch (NoSuchAlgorithmException e) { throw new RuntimeException("没有md5这个算法!"); } String md5code = new BigInteger(1, secretBytes).toString(16);// 16进制数字 // 如果生成数字未满32位,需要前面补0 for (int i = 0; i < 32 - md5code.length(); i++) { md5code = "0" + md5code; } return md5code; } }
调用方式:
Md5Utils.md5("123")
3.ImageUtil
图片验证码,将验证码内容保存session中

package com.gh.util; import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.image.BufferedImage; import java.io.BufferedReader; import java.io.FileInputStream; import java.io.FileReader; import java.io.IOException; import java.io.InputStreamReader; import java.util.ArrayList; import java.util.List; import java.util.Random; import javax.imageio.ImageIO; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class ImageUtil{ public static void createImage(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // 禁止缓存 // response.setHeader("Cache-Control", "no-cache"); // response.setHeader("Pragma", "no-cache"); // response.setDateHeader("Expires", -1); int width = 120; int height = 25; // 步骤一 绘制一张内存中图片 BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); // 步骤二 图片绘制背景颜色 ---通过绘图对象 Graphics graphics = bufferedImage.getGraphics();// 得到画图对象 --- 画笔 // 绘制任何图形之前 都必须指定一个颜色 graphics.setColor(getRandColor(200, 250)); graphics.fillRect(0, 0, width, height); // 步骤三 绘制边框 graphics.setColor(Color.WHITE); graphics.drawRect(0, 0, width - 1, height - 1); // 步骤四 四个随机数字 Graphics2D graphics2d = (Graphics2D) graphics; // 设置输出字体 graphics2d.setFont(new Font("宋体", Font.BOLD, 18)); Random random = new Random();// 生成随机数 String words = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"; // 定义x坐标 int x = 10; String word = ""; for (int i = 0; i < 4; i++) { int index = random.nextInt(words.length()); // 随机颜色 graphics2d .setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110))); // 旋转 -30 --- 30度 int jiaodu = random.nextInt(60) - 30; // 换算弧度 double theta = jiaodu * Math.PI / 180; // 获得字母数字 char c = words.charAt(index); word += c; // 将c 输出到图片 graphics2d.rotate(theta, x, 20); graphics2d.drawString(String.valueOf(c), x, 20); graphics2d.rotate(-theta, x, 20); x += 30; } System.out.println(word); // 将验证码内容保存session request.getSession().setAttribute("checkcode_session", word); // 步骤五 绘制干扰线 graphics.setColor(getRandColor(160, 200)); int x1; int x2; int y1; int y2; for (int i = 0; i < 30; i++) { x1 = random.nextInt(width); x2 = random.nextInt(12); y1 = random.nextInt(height); y2 = random.nextInt(12); graphics.drawLine(x1, y1, x1 + x2, x2 + y2); } // 将上面图片输出到浏览器 ImageIO graphics.dispose();// 释放资源 ImageIO.write(bufferedImage, "jpg", response.getOutputStream()); } /** * 取其某一范围的color * * @param fc * int 范围参数1 * @param bc * int 范围参数2 * @return Color */ private static Color getRandColor(int fc, int bc) { // 取其随机颜色 Random random = new Random(); if (fc > 255) { fc = 255; } if (bc > 255) { bc = 255; } int r = fc + random.nextInt(bc - fc); int g = fc + random.nextInt(bc - fc); int b = fc + random.nextInt(bc - fc); return new Color(r, g, b); } }
调用方式:
@GetMapping("/getImageCode") public void getImageCode(HttpServletRequest request, HttpServletResponse response) throws Exception { imageUtil.createImage(request, response); }
4.SmsService
短信验证码,用于验证短信

package com.zys.springboottestexample.service; import com.aliyuncs.CommonRequest; import com.aliyuncs.CommonResponse; import com.aliyuncs.DefaultAcsClient; import com.aliyuncs.IAcsClient; import com.aliyuncs.exceptions.ClientException; import com.aliyuncs.exceptions.ServerException; import com.aliyuncs.http.MethodType; import com.aliyuncs.profile.DefaultProfile; import lombok.extern.slf4j.Slf4j; import org.springframework.beans.factory.annotation.Value; import org.springframework.stereotype.Component; /* pom.xml <dependency> <groupId>com.aliyun</groupId> <artifactId>aliyun-java-sdk-core</artifactId> <version>4.0.3</version> </dependency> */ /** * 发送短信 */ @Slf4j @Component public class SmsService { //域名 private static String domain = "dysmsapi.aliyuncs.com"; //执行动作 private static String action = "SendSms"; //版本号,api发布的为准 private static String version = "2017-05-25"; //地区编码 private static String regionId = "cn-hangzhou"; //签名名称 private static String signName = "生活网站后台管理系统"; //模版CODE,默认的 private static String defaultTemplateCode = "SMS_181855626"; @Value("${sms.accessKeyId}") private String accessKeyId; @Value("${sms.secret}") private String secret; public void sendMsgCode(String phone, String code) { this.sendCode(phone, code, defaultTemplateCode); } private void sendCode(String phone, String code, String templateCode) { try { DefaultProfile profile = DefaultProfile.getProfile(regionId, accessKeyId, secret); IAcsClient client = new DefaultAcsClient(profile); CommonRequest request = new CommonRequest(); request.setMethod(MethodType.POST); request.setDomain(domain); request.setAction(action); request.setVersion(version); request.putQueryParameter("RegionId", regionId); request.putQueryParameter("PhoneNumbers", phone); request.putQueryParameter("SignName", signName); request.putQueryParameter("TemplateCode", templateCode); request.putQueryParameter("TemplateParam", "{\"code\":\"" + code + "\"}"); CommonResponse response = client.getCommonResponse(request); log.info("发送短信结果:" + response.getData()); } catch (Exception e) { e.printStackTrace(); log.error("短信发送异常:" + e.getMessage()); } } }
具体用法:将代码中的依赖添加到项目的依赖中,在配置文件中配置keyId和秘钥
sms: accessKeyId: 4545484518888 secret: 2151584552
然后注入并调用这个方法,传入验证码和手机号即可。对应验证和上面的图片验证码类型,存入redis。
调用方式:
@Autowired private SmsService smsService; ..... smsService.sendMsg("17012122353","123456")
5.CodeUtil
生成指定位数的字符串,包含数组和字母。

package com.example.springsecurity.util; import java.util.Random; public class CodeUtil { public static String getCode(int len){ String content = "qwertyuiopasdfghjklzxcvbnm1234567890ZXCVBNMQWERTYUIOPASDFGHJKL"; Random random = new Random(); String result = ""; for(int i =0 ;i<len;i++){ int index = random.nextInt(content.length()); char c = content.charAt(index); result+=c; } return result; } }
调用方式:
CodeUtil.getCode(6)
6.DeleteFileUtil
删除文件及文件夹。

package com.zys.training.util; import java.io.File; /** * @Author: yushizhong * @Date: 2020/2/21 12:07 * @Title: 文件及文件夹的删除 */ public class DeleteFileUtil { //文件的删除 public static boolean deleteFile(String pathname) { boolean result = false; File file = new File(pathname); if (file.exists()) { file.delete(); result = true; } return result; } //文件夹的删除(强制删除) public static void deleteAllFilesOfDir(File path) { if (null != path) { if (!path.exists()) return; if (path.isFile()) { boolean result = path.delete(); int tryCount = 0; while (!result && tryCount++ < 10) { System.gc(); // 回收资源 result = path.delete(); } } File[] files = path.listFiles(); if (null != files) { for (int i = 0; i < files.length; i++) { deleteAllFilesOfDir(files[i]); } } path.delete(); } } }
调用方式:
DeleteFileUtil.deleteFile(文件路径)
DeleteFileUtil.deleteAllFilesOfDir(文件夹路径)
7.ExcelResolveUtil
解析excel内容,返回一个JOSNArray。

package com.example.uploaddemo.util; import net.sf.json.JSONArray; import net.sf.json.JSONObject; import org.apache.poi.hssf.usermodel.HSSFDateUtil; import org.apache.poi.hssf.usermodel.HSSFWorkbook; import org.apache.poi.openxml4j.exceptions.InvalidFormatException; import org.apache.poi.poifs.filesystem.POIFSFileSystem; import org.apache.poi.ss.usermodel.Cell; import org.apache.poi.ss.usermodel.Row; import org.apache.poi.ss.usermodel.Sheet; import org.apache.poi.ss.usermodel.Workbook; import org.apache.poi.xssf.usermodel.XSSFWorkbook; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.text.DateFormat; import java.text.DecimalFormat; import java.text.SimpleDateFormat; import java.util.Date; import java.util.HashMap; import java.util.Map; /** * @Author: yushizhong * @Date: 2020/2/22 12:07 * @Title: 解析excel内容 */ public class ExcelResolveUtil { public final static String XLSX = ".xlsx"; public final static String XLS = ".xls"; /** * 获取Excel文件(.xls和.xlsx都支持) * * @param file 文件对象 * @return 解析excle后的Json数据 */ public static JSONArray readExcel(File file ) throws Exception { int res = checkFile(file); if (res == 0) { System.out.println("File not found"); } else if (res == 1) { return readXLSX(file ); } else if (res == 2) { return readXLS(file ); } JSONArray array = new JSONArray(); return array; } /** * 判断File文件的类型 * * @param file 传入的文件 * @return 0-文件为空,1-XLSX文件,2-XLS文件,3-其他文件 */ public static int checkFile(File file) { if (file == null) { return 0; } String fileName = file.getName(); if (fileName.endsWith(XLSX)) { return 1; } if (fileName.endsWith(XLS)) { return 2; } return 3; } /** * 读取XLSX文件 * * @param file * @return * @throws IOException * @throws InvalidFormatException */ public static JSONArray readXLSX(File file ) throws InvalidFormatException, IOException, InvalidFormatException { Workbook book = new XSSFWorkbook(file); Sheet sheet = book.getSheetAt(0); return read(sheet, book ); } /** * 读取XLS文件 * * @param file 文件对象 * @throws IOException * @throws FileNotFoundException */ public static JSONArray readXLS(File file ) throws FileNotFoundException, IOException { POIFSFileSystem poifsFileSystem = new POIFSFileSystem(new FileInputStream(file)); Workbook book = new HSSFWorkbook(poifsFileSystem); Sheet sheet = book.getSheetAt(0); return read(sheet, book ); } /** * 解析数据 * * @param sheet 表格sheet对象 * @param book 用于流关闭 * @return * @throws IOException */ public static JSONArray read(Sheet sheet, Workbook book ) throws IOException { int rowStart = sheet.getFirstRowNum(); // 首行下标 int rowEnd = sheet.getLastRowNum(); // 尾行下标 // 如果首行与尾行相同,表明只有一行,直接返回空数组 if (rowStart == rowEnd) { book.close(); return new JSONArray(); } // 获取第一行JSON对象键 Row firstRow = sheet.getRow(rowStart); int cellStart = firstRow.getFirstCellNum(); int cellEnd = firstRow.getLastCellNum(); Map<Integer, String> keyMap = new HashMap<Integer, String>(); for (int j = cellStart; j < cellEnd; j++) { keyMap.put(j, getValue(firstRow.getCell(j), rowStart, j, book, true)); } // 获取每行JSON对象的值 JSONArray array = new JSONArray(); for (int i = rowStart + 1; i <= rowEnd; i++) { Row eachRow = sheet.getRow(i); JSONObject obj = new JSONObject(); StringBuffer sb = new StringBuffer(); for (int k = cellStart; k < cellEnd; k++) { if (eachRow != null) { String val = getValue(eachRow.getCell(k), i, k, book, false); sb.append(val); // 所有数据添加到里面,用于判断该行是否为空 obj.put(keyMap.get(k), val); } } if (sb.toString().length() > 0) { array.add(obj); } } book.close(); return array; } /** * 获取每个单元格的数据 * * @param cell 单元格对象 * @param rowNum 第几行 * @param index 该行第几个 * @param book 主要用于关闭流 * @param isKey 是否为键:true-是,false-不是。 如果解析Json键,值为空时报错;如果不是Json键,值为空不报错 * @return * @throws IOException */ public static String getValue(Cell cell, int rowNum, int index, Workbook book, boolean isKey) throws IOException { // 空白或空 if (cell == null || cell.getCellType() == Cell.CELL_TYPE_BLANK) { if (isKey) { book.close(); throw new NullPointerException(String.format("the key on row %s index %s is null ", ++rowNum, ++index)); } else { return ""; } } // 0. 数字 类型 if (cell.getCellType() == Cell.CELL_TYPE_NUMERIC) { if (HSSFDateUtil.isCellDateFormatted(cell)) { Date date = cell.getDateCellValue(); DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); return df.format(date); } //防止当作数字而导致最后的0丢失 DecimalFormat df = new DecimalFormat("0"); String val = df.format(cell.getNumericCellValue()); val = val.toUpperCase(); if (val.contains("E")) { val = val.split("E")[0].replace(".", ""); } return val; } // 1. String类型 if (cell.getCellType() == Cell.CELL_TYPE_STRING) { String val = cell.getStringCellValue(); if (val == null || val.trim().length() == 0) { if (book != null) { book.close(); } return ""; } return val.trim(); } // 2. 公式 CELL_TYPE_FORMULA if (cell.getCellType() == Cell.CELL_TYPE_FORMULA) { return cell.getStringCellValue(); } // 4. 布尔值 CELL_TYPE_BOOLEAN if (cell.getCellType() == Cell.CELL_TYPE_BOOLEAN) { return cell.getBooleanCellValue() + ""; } // 5. 错误 CELL_TYPE_ERROR return ""; } }
依赖jar:

<!-- POI,excel解析相关 --> <dependency> <groupId>org.apache.poi</groupId> <artifactId>poi</artifactId> <version>3.17</version> </dependency> <!-- https://mvnrepository.com/artifact/org.apache.poi/poi-ooxml --> <dependency> <groupId>org.apache.poi</groupId> <artifactId>poi-ooxml</artifactId> <version>3.17</version> </dependency> <dependency> <groupId>net.sf.json-lib</groupId> <artifactId>json-lib</artifactId> <version>2.4</version> <classifier>jdk15</classifier> </dependency>
调用方式:
JSONArray jsonArray = ExcelResolveUtil.readExcel(new File("D:\\files\\文件导入\\成绩.xls"));
8.DiskFreeUtils
获取磁盘使用信息。

package com.zys.training.util; import java.io.File; import java.text.DecimalFormat; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; public class DiskFreeUtils { private static DecimalFormat DECIMALFORMAT = new DecimalFormat("#.##"); /** * 获取磁盘使用信息 * @return */ public static List<Map<String, String>> getInfo() { List<Map<String, String>> list = new ArrayList<Map<String, String>>(); File[] roots = File.listRoots();// 获取磁盘分区列表 for (File file : roots) { Map<String, String> map = new HashMap<String, String>(); long freeSpace=file.getFreeSpace(); long totalSpace=file.getTotalSpace(); long usableSpace=totalSpace-freeSpace; map.put("path", file.getPath().split(":")[0]); map.put("freeSpace", freeSpace / 1024 / 1024 / 1024 + "G");// 空闲空间 map.put("usableSpace", usableSpace / 1024 / 1024 / 1024 + "G");// 可用空间 map.put("totalSpace",totalSpace / 1024 / 1024 / 1024 + "G");// 总空间 map.put("percent", DECIMALFORMAT.format(((double)usableSpace/(double)totalSpace)*100)+"%");// 总空间 list.add(map); } return list; } }
调用方式:
List<Map<String, String>> map=DiskFreeUtils.getInfo();
9.PropertiesUtil
读取.properties配置文件的内容至Map中。

package com.zys.training.util; import java.io.IOException; import java.io.InputStream; import java.util.Enumeration; import java.util.HashMap; import java.util.Map; import java.util.Properties; /** * 读取.properties配置文件的内容至Map中 */ public class PropertiesUtil { /** * 读取.properties配置文件的内容至Map * * @param propertiesFile * @return * @throws IOException */ public static Map read(String propertiesFile) throws Exception { try { if (!(propertiesFile.indexOf("properties") > 0)) { propertiesFile = propertiesFile + ".properties"; } InputStream inStream = Thread.currentThread().getContextClassLoader().getResourceAsStream(propertiesFile); Properties p = new Properties(); p.load(inStream); Map<Object, Object> map = properties2map(p); return map; } catch (IOException e) { throw new Exception(e); } } /** * 将属性文件转为map * * @param prop * @return */ public static Map properties2map(Properties prop) { Map<Object, Object> map = new HashMap<Object, Object>(); Enumeration enu = prop.keys(); while (enu.hasMoreElements()) { Object obj = enu.nextElement(); Object objv = prop.get(obj); map.put(obj, objv); } return map; } }
调用方式:
Map read = PropertiesUtil.read("application.properties");
10.HttpClient
使用java发送get/post请求
导入坐标

<dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpclient</artifactId> <version>4.5.3</version> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>1.2.58</version> </dependency>
添加工具类

package com.example.task.test; import com.alibaba.fastjson.JSON; import com.alibaba.fastjson.JSONObject; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.client.ResponseHandler; import org.apache.http.client.methods.HttpPost; import org.apache.http.client.methods.HttpUriRequest; import org.apache.http.client.methods.RequestBuilder; import org.apache.http.config.ConnectionConfig; import org.apache.http.entity.StringEntity; import org.apache.http.impl.client.CloseableHttpClient; import org.apache.http.impl.client.HttpClients; import org.apache.http.util.EntityUtils; import org.springframework.stereotype.Component; import java.io.IOException; /** * @author zhongyushi * @date 2020/7/21 0021 * @dec 使用apache的http协议发送请求 */ @Component public class HttpClient { private ConnectionConfig connectionConfig = ConnectionConfig.custom().setBufferSize(4128).build(); private CloseableHttpClient httpClient = HttpClients.custom().setDefaultConnectionConfig(connectionConfig).build(); /** * get请求,返回JSONObject */ public JSONObject get(String url) { try { RequestBuilder builder = RequestBuilder.get(url); HttpUriRequest request = builder.build(); return httpClient.execute(request, getResponseHandler()); } catch (Exception e) { e.printStackTrace(); JSONObject error = new JSONObject(); error.put("msg", e.getMessage()); return error; } } /** * post请求-返回JSONObject */ public JSONObject post(String url, String json) { try { HttpPost httpPost = new HttpPost(url); //设置请求体 if (json != null && json != "") { //解决中文乱码问题 StringEntity entity = new StringEntity(json, "utf-8"); entity.setContentEncoding("UTF-8"); entity.setContentType("application/json"); httpPost.setEntity(entity); } return httpClient.execute(httpPost, getResponseHandler()); } catch (Exception e) { JSONObject error = new JSONObject(); error.put("msg", e.getMessage()); e.printStackTrace(); return error; } } /** * 指定响应返回类型=JSONObject */ private ResponseHandler<JSONObject> getResponseHandler() { ResponseHandler<JSONObject> handler = new ResponseHandler<JSONObject>() { public JSONObject handleResponse(HttpResponse response) throws IOException { HttpEntity entity = response.getEntity(); if (entity != null) { String json = EntityUtils.toString(entity, "UTF-8"); return JSON.parseObject(json); } return null; } }; return handler; } }
调用方式:
private String url="https://autumnfish.cn/api"; //注入写的方法 @Autowired private HttpClient httpClient; @GetMapping("/get") public JSONObject get(){ JSONObject jsonObject = httpClient.get(url + "/joke/list?num=" + 10); return jsonObject; } @PostMapping("/post") public JSONObject post(){ Map<String,Object> map=new HashMap<>(); map.put("username","张三111"); JSONObject jsonObject = httpClient.post(url + "/user/reg", JSON.toJSONString(map)); return jsonObject; }
11.dateFormat
格式化日期,根据指定的格式进行格式化。
//格式化日期函数,YYYY-mm-dd HH:MM:SS或yyyy-mm-dd HH:MM:ss function dateFormat(fmt, date) { if (fmt == null) { fmt = 'YYYY-mm-dd HH:MM:SS' } if (date != '') { let ret const opt = { "Y+": date.getFullYear().toString(), // 年 "y+": date.getFullYear().toString(), // 年 "m+": (date.getMonth() + 1).toString(), // 月 "d+": date.getDate().toString(), // 日 "H+": date.getHours().toString(), // 时 "M+": date.getMinutes().toString(), // 分 "S+": date.getSeconds().toString(), // 秒 "s+": date.getSeconds().toString() // 秒 // 有其他格式化字符需求可以继续添加,必须转化成字符串 } for (let k in opt) { ret = new RegExp("(" + k + ")").exec(fmt) if (ret) { fmt = fmt.replace(ret[1], (ret[1].length == 1) ? (opt[k]) : (opt[k].padStart(ret[1].length, "0"))) } } } else { fmt = 'date不能为空' } return fmt }
调用方式
dateFormat('YYYY-mm-dd HH:MM:SS',new Date()) //或 dateFormat('yyyy-mm-dd HH:MM:ss',new Date())
12.preDate
计算当前时间的前几天时间。
function preDate(flag, day) { let fotmat = null if (flag == null) { fotmat = 'YYYY-mm-dd' } else if (flag == 0) { fotmat = 'YYYY-mm-dd HH:MM' } //传入参数不合法,就设置默认是30天 if (!Number.isInteger(day)) { day = 30 } const date = new Date(new Date().getTime() - 3600 * 1000 * 24 * day) return date }
调用方式
preDate(null,30)
如果需要再进行时间的格式化,再调用上面的日期格式化函数即可。
13.获取文件头,判断文件格式
枚举类,列举所有文件头格式
package com.zxh.bootdemo0705.util; /** * 文件头 */ public enum FileHeaderEnum { PNG("89504E47"), JPEG_JPG("FFD8FF"), DOC("D0CF11E0"), DOCX("504B0304"); //文件头标识 private String headerIdent; FileHeaderEnum(String headerIdent) { this.headerIdent = headerIdent; } public String getHeaderIdent() { return headerIdent; } }
工具类获取文件头,进行判断
package com.zxh.bootdemo0705.util; import java.io.*; public class FileUtil { /** * 检查是否是png文件 * * @param file * @return */ public static Boolean checkFileByPng(File file) { return checkFile(FileHeaderEnum.PNG, file); } /** * 检查是否是jpg/jpeg文件 * * @param file * @return */ public static Boolean checkFileByJpgOrJpeg(File file) { return checkFile(FileHeaderEnum.JPEG_JPG, file); } /** * 检查是否是doc文件 * * @param file * @return */ public static Boolean checkFileByDoc(File file) { return checkFile(FileHeaderEnum.DOC, file); } /** * 检查是否是docx文件 * * @param file * @return */ public static Boolean checkFileByDocx(File file) { return checkFile(FileHeaderEnum.DOCX, file); } /** * 检查是否是doc/docx文件 * * @param file * @return */ public static Boolean checkFileByDocOrDocx(File file) { return checkFileByDoc(file) || checkFileByDocx(file); } private static Boolean checkFile(FileHeaderEnum fileHeaderEnum, File file) { Boolean isLegal = false; InputStream is = null; try { is = new FileInputStream(file); byte[] b = new byte[4]; is.read(b, 0, b.length); isLegal = fileHeaderEnum.getHeaderIdent().equals(bytesToHexString(b)); } catch (Exception e) { e.printStackTrace(); } finally { if (null != is) { try { is.close(); } catch (IOException e) { e.printStackTrace(); } } } return isLegal; } private static String bytesToHexString(byte[] src) { StringBuilder builder = new StringBuilder(); if (src == null || src.length <= 0) { return null; } String hv; for (byte b : src) { hv = Integer.toHexString(b & 0xFF).toUpperCase(); if (hv.length() < 2) { builder.append(0); } builder.append(hv); } return builder.toString(); } }
直接调用工具类即可。
就是这么简单,你学废了吗?感觉有用的话,给笔者点个赞吧 !
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