人手必备的java工具类，中间件
<!-- Maps,Sets,Preconditions -->
<dependency>
<groupId>com.google.guava</groupId>
<artifactId>guava</artifactId>
<version>28.1-jre</version>
</dependency>
<!-- CollectionUtils -->
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-collections4</artifactId>
<version>4.4</version>
</dependency>
<!-- StringUtils -->
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
</dependency>
<!-- JSON专用工具包 -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.62</version>
</dependency>Json工具类
ServerResponse - 通用Json响应对象
ResponseCode是封装code和desc的枚举类
package com.mmall.common;
import org.codehaus.jackson.annotate.JsonIgnore;
import org.codehaus.jackson.map.annotate.JsonSerialize;
import java.io.Serializable;
/**
* 代表响应里要封装的数据对象
* @param <T>
*/
// 设置返回的json对象没有null，保证序列化json的时候，如果是null的对象，key也会消失
//@JsonSerialize(include = JsonSerialize.Inclusion.NON_NULL)
@JsonInclude(JsonInclude.Include.NON_NULL)//jackson 实体转json 为NULL的字段不参加序列化（即不显示）
public class ServerResponse<T> implements Serializable {
/**
* 状态码
*
*/
private int status;
/**
* 响应的相关信息（例如用户名不存，密码错误等）
*/
private String msg;
/**
* 封装的数据对象信息
*/
private T data;
// 构建私有构造器，封装public方法时更加优雅
private ServerResponse(int status){
this.status = status;
}
private ServerResponse(int status,String msg){
this.status = status;
this.msg = msg;
}
private ServerResponse(int status,String msg,T data){
this.status = status;
this.msg = msg;
this.data = data;
}
private ServerResponse(int status,T data){
this.status = status;
this.data = data;
}
// 在序列化json对象过程中忽视该结果
@JsonIgnore
public boolean isSuccess(){
return this.status == ResponseCode.SUCCESS.getCode();
}
public int getStatus() {
return status;
}
public String getMsg() {
return msg;
}
public T getData() {
return data;
}
/**
* 成功响应，静态方法对外开放
*/
public static <T> ServerResponse<T> createBySuccess(){
return new ServerResponse<T>(ResponseCode.SUCCESS.getCode());
}
// 只响应成功信息
public static <T> ServerResponse<T> createBySuccessMessage(String msg){
return new ServerResponse<T>(ResponseCode.SUCCESS.getCode(),msg);
}
public static <T> ServerResponse<T> createBySuccess(T data){
return new ServerResponse<T>(ResponseCode.SUCCESS.getCode(),data);
}
// 创建一个成功的服务器响应，把响应信息和对象data填充进去
public static <T> ServerResponse<T> createBySuccess(String msg,T data){
return new ServerResponse<T>(ResponseCode.SUCCESS.getCode(),msg, data);
}
/**
* 失败响应
*/
public static <T> ServerResponse<T> createByError(){
return new ServerResponse<T>(ResponseCode.ERROR.getCode(),ResponseCode.ERROR.getDesc());
}
// 只响应失败信息
public static <T> ServerResponse<T> createByErrorMessage(String errorMessage){
return new ServerResponse<T>(ResponseCode.ERROR.getCode(),errorMessage);
}
/**
* 暴露一个参数端错误的响应
*/
public static <T> ServerResponse<T> createByErrorCodeMessage(int errorCode,String errorMessage){
return new ServerResponse<T>(errorCode,errorMessage);
}
}
JackSonUtils - Json与pojo对象相互转化工具类
import java.io.IOException;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;
/**
* @Title JsonUtils.java
* @Package com.aust.utils
* @Description 定义响应的Json对象格式，以及如何转换为Json对象
* Copyright:Copyright (c) 2019
* Company:anhui.aust.imooc
*
* @author austwuhong
* @date 2019/10/31 19:11 PM
* @version v1.0
*/
public class JackSonUtils {
private static final ObjectMapper MAPPER = new ObjectMapper();
/**
* 将对象转为Json格式的字符串
* @param data
* @return
*/
public static Object objectToJson(Object data) {
try {
String string = MAPPER.writeValueAsString(data);
return string;
} catch (JsonProcessingException e) {
e.printStackTrace();
}
return null;
}
/**
* 将Json结果集转为对象
* @param <T>
* @param jsonData Json数据
* @param beanType 对象Object类型
* @return
*/
public static <T> T jsonToPojo(String jsonData,Class<T> beanType) {
try {
T t = MAPPER.readValue(jsonData, beanType);
return t;
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (JsonProcessingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
}GSONUtil - google的JSON工具类gson将普通的json串转为pojo对象
import java.lang.reflect.Type;
import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
class User {
private String username;
private int userId;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public int getUserId() {
return userId;
}
public void setUserId(byte userId) {
this.userId = userId;
}
@Override
public String toString() {
return "User [username=" + username + ", userId=" + userId + "]";
}
}
/**
* google的JSON工具类gson将普通的json串转为pojo对象
* @author Administrator
*
*/
public class GSONUtil {
/**
* @param jsonData JSON格式的字符串
* @return JavaBean对象
*/
public <T> T getJSON(String jsonData) {
Gson gson = new Gson();
Type typeOfT = new TypeToken<T>(){}.getType();
T t = gson.fromJson(jsonData, typeOfT);
return t;
}
// 基础测试
public static void main(String[] args) {
String jsonData = "[{\"username\":\"arthinking\",\"userId\":001},{\"username\":\"Jason\",\"userId\":002}]";
jsonData = "{" +
" \"code\":200," +
" \"message\":\"success\"," +
" \"data\":\"{\"username\":\"arthinking\",\"userId\":001}\"" +
" }";
jsonData = "{\"username\":\"rachel\",\"userId\":123456}";
Gson gson = new Gson();
Type typeOfT = new TypeToken<User>(){}.getType();
User users = gson.fromJson(jsonData, typeOfT);
System.out.println("解析JSON数据");
// for (Iterator<User> iterator = users.iterator(); iterator.hasNext();) {
// User user = iterator.next();
// System.out.print(user.getUsername() + " | ");
// System.out.println(user.getUserId());
// }
System.out.println(users);
}
}CloneUtils - 对象克隆工具类
通过序列化和内存流对象流实现对象深拷贝
其实Spring也有一个用于复制bean的工具类
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
/**
* 通过序列化和内存流对象流实现对象深拷贝
* @author Administrator
*
*/
public class CloneUtils {
// 禁止实例化
private CloneUtils() {
throw new AssertionError();
}
@SuppressWarnings("unchecked")
public static <T> T clone(T obj) throws Exception {
ByteArrayOutputStream bout = new ByteArrayOutputStream();
ObjectOutputStream oos = new ObjectOutputStream(bout);
oos.writeObject(obj);
// 输入流必须确定源
ByteArrayInputStream bis = new ByteArrayInputStream(bout.toByteArray());
ObjectInputStream ois = new ObjectInputStream(bis);
// NOTICE 强制从Object转为泛型T,如果传入的对象类型不是T可能会出错
return (T) ois.readObject();
}
}UploadUtil - 文件上传工具类
可用于SSM框架中文件的上传
import java.io.File;
import java.io.IOException;
import org.springframework.web.multipart.MultipartFile;
public class UploadUtil {
private static String basePath = "D:\\Repositories\\uploadFiles\\";// 文件上传保存路径
/**
* 管理上传文件的保存
* @param file
* @return 如果保存上传文件成功，则返回新文件名，否则返回空""
*/
public static String saveFile(MultipartFile file) {
try {
// 为防止文件名重复，需要使用随机文件名+文件扩展名，但保存到数据库时应使用原文件名(不可用时间戳，因为在多线程的情况下有可能取到同一个时间戳)
// 不使用UUID，UUID入库性能并不好
String extName = file.getOriginalFilename();
int index = extName.lastIndexOf(".");
if(index > -1) {
extName = extName.substring(index);// 这里substring中参数不能为-1否则报异常
} else {
extName = "";
}
// 随机名+后缀命名并保存到basePath路径下
String newFileName = Math.random() + extName;
File newFilePath = new File(basePath + newFileName);
while(newFilePath.exists()) {
newFileName = Math.random() + extName;
newFilePath = new File(basePath + newFileName);
}
file.transferTo(newFilePath);
return newFileName;
} catch (IllegalStateException | IOException e) {
e.printStackTrace();
}
return "";
}
}DBUtil - JDBC连接专用工具类
节省jdbc连接代码量
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
/**
* SELF 自定义工具类
* 标准的数据库工具类
* @author Shiniad
*/
public class DBUtil {
public static String username = "root";
public static String password = "root";
public static String driver = "com.mysql.jdbc.Driver";
public static String url = "jdbc:mysql://127.0.0.1:3306/mywork?useUnicode=true&characterEncoding=utf8";
static String sql = "insert into sys_user(uname,upassword) values ('测试',325) ";
public static Connection conn = null;
public static Statement st = null;
public static ResultSet rs = null;
// 增删改
public static int update() {
int count = 0;
try {
Class.forName(driver);// 加载驱动
conn = DriverManager.getConnection(url,username,password);// 创建连接
st = conn.createStatement();// 执行SQL语句
count = st.executeUpdate(sql);
} catch(ClassNotFoundException e) {
e.printStackTrace();
return 0;
} catch(SQLException e) {
e.printStackTrace();
return 0;
}
return count;
}
// 查询
public static ResultSet query() {
try {
Class.forName(driver);// 加载驱动
conn = DriverManager.getConnection(url,username,password);// 创建连接
st = conn.createStatement();// 执行SQL语句
rs = st.executeQuery(sql);
} catch (ClassNotFoundException e) {
e.printStackTrace();
return null;
} catch (SQLException e) {
e.printStackTrace();
return null;
}
return rs;
}
// 关闭内部资源
public static void closeSource() {
if(rs!=null) {
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(st!=null) {
try {
st.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(conn!=null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
// 关闭外部资源
public static void closeSource(ResultSet rs, Statement st, Connection conn) {
if(rs!=null) {
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(st!=null) {
try {
st.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(conn!=null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
/*
public static void main(String[] args) throws SQLException, ClassNotFoundException {
DBUtil.sql = "select * from sys_user";
ResultSet rSet = DBUtil.query();
while(rSet.next()) {
System.out.println(rSet.getInt(1) + "\t" + rSet.getString(2));
}
// 数据库的插入操作
// DBUtil.sql = "insert into sys_user(uname,upassword) values ('测试2',325) ";
// if(DBUtil.update()>0) {
// System.out.println("添加成功");
// } else {
// System.out.println("添加失败");
// }
// 关闭连接（关闭内部连接）
DBUtil.closeSource();
System.out.println(DBUtil.conn.isClosed());
}
*/
}加密工具类
DES - DES加密工具类
import java.security.SecureRandom;
import java.util.Base64;
import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
/**
*
* SELF 自定义工具类
* 经典DES加密
* @author 宏
*/
public class DES {
// 加密
public static String encrypt(String content, String password) {
byte[] contentByte = content.getBytes();
byte[] passwordByte = password.getBytes();
SecureRandom random = new SecureRandom();
try {
// 生成秘文证书
DESKeySpec key = new DESKeySpec(passwordByte);
SecretKeyFactory factory = SecretKeyFactory.getInstance("DES");
SecretKey secretKey = factory.generateSecret(key);
// 使用证书加密
Cipher cipher = Cipher.getInstance("DES");
cipher.init(Cipher.ENCRYPT_MODE, secretKey, random);// 配置参数
byte[] result = cipher.doFinal(contentByte);
// Base64加密,将二进制文件转成字符串格式
String contentResult = Base64.getEncoder().encodeToString(result);
return contentResult;
} catch(Exception e) {
e.printStackTrace();
return null;
}
}
// 解密
public static byte[] decrypt(String password, byte[] result) {
byte[] passwordByte = password.getBytes();
SecureRandom random = new SecureRandom();
try {
// 生成秘文证书
DESKeySpec key = new DESKeySpec(passwordByte);
SecretKeyFactory factory = SecretKeyFactory.getInstance("DES");
SecretKey secretKey = factory.generateSecret(key);
// 解密
Cipher decipher = Cipher.getInstance("DES");
decipher.init(Cipher.DECRYPT_MODE, secretKey, random);
byte[] de_result = decipher.doFinal(result);
return de_result;
} catch(Exception e) {
e.printStackTrace();
return null;
}
}
// 解密2
public static byte[] decrypt(String password, String contentResult) {
byte[] passwordByte = password.getBytes();
byte[] result = Base64.getDecoder().decode(contentResult);
SecureRandom random = new SecureRandom();
try {
// 生成秘文证书
DESKeySpec key = new DESKeySpec(passwordByte);
SecretKeyFactory factory = SecretKeyFactory.getInstance("DES");
SecretKey secretKey = factory.generateSecret(key);
// 解密
Cipher decipher = Cipher.getInstance("DES");
decipher.init(Cipher.DECRYPT_MODE, secretKey, random);
byte[] de_result = decipher.doFinal(result);
return de_result;
} catch(Exception e) {
e.printStackTrace();
return null;
}
}
public static void main(String[] args) throws Exception {
String content = "123456";
String password = "UnkonwnSecret";// 明文密码
String contentResult = encrypt(content, password);
System.out.println("加密后的文本：" + contentResult);
if(contentResult!=null) {
byte[] myByte = decrypt(password, contentResult);
System.out.println("解密后的文本：" + new String(myByte));
}
// // 生成秘文证书
// DESKeySpec key = new DESKeySpec(password.getBytes());
// SecretKeyFactory factory = SecretKeyFactory.getInstance("DES");
// SecretKey secretKey = factory.generateSecret(key);// 将明文密码转为秘钥证书
// // 使用证书加密
// Cipher cipher = Cipher.getInstance("DES");
// cipher.init(Cipher.ENCRYPT_MODE, secretKey);
// byte[] result = cipher.doFinal(content.getBytes());
// // Base64转码
// String base64Result = Base64.getEncoder().encodeToString(result);
}
}MD5 - MD5加密工具类
SHA1同理，将MD5换成SHA1即可
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
/**
* SELF 自定义类
* 加密算法 MD5/SHA1
* @author Shiniad
*
*/
public class MD5 {
public static String contentResult;
public static String salt;
public static void encrypt(String password) {
MD5.contentResult = null;
MD5.salt = null;
SecureRandom random = new SecureRandom();
String salt = String.valueOf(random.nextDouble());// 随机盐
String contentResult = null;
try {
MessageDigest md = MessageDigest.getInstance("MD5");
byte[] result = md.digest((password).getBytes());
contentResult = ByteArrayUtil.bytesToHex(result);
if(contentResult!=null && salt!=null) {
MD5.contentResult = contentResult;
MD5.salt = salt;
}
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
}
}
public static boolean verification(String salt,String secretKey) {
System.out.print("请输入密码验证：");
java.util.Scanner in = new java.util.Scanner(System.in);
String password = in.nextLine();
try {
MessageDigest md = MessageDigest.getInstance("SHA1");
byte[] result = md.digest((password+salt).getBytes());
String contentResult = ByteArrayUtil.bytesToHex(result);
if(contentResult.equals(secretKey)) {
System.out.println("您输入的密码正确。");
in.close();
return true;
}
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
}
System.out.println("您输入的密码错误！");
in.close();
return false;
}
// 基础测试
public static void main(String[] args) throws Exception {
String password = "123456";
encrypt(password);
System.out.println("盐值为：" + MD5.salt + ", 密钥为：" + MD5.contentResult);
while( !MD5.verification(MD5.salt, MD5.contentResult) ) {
MD5.verification(MD5.salt, MD5.contentResult);
}
// MD5的核心API
// MessageDigest md = MessageDigest.getInstance("MD5");
// byte[] result = md.digest(password.getBytes());
}
}ByteArrayUtil - 字节转换工具类，将字节/字节数组转为16进制数(字符串格式)
/**
* SELF 自定义工具类
* 字节转换工具，将字节/字节数组转为16进制数(字符串格式)
* @author 宏
*/
public class ByteArrayUtil {
public static String byteToHex(byte b) {
String hex = Integer.toHexString(b & 0xFF);// 将b与常数(1111 1111)sub2进行与运算，将头三个字节的随机位的值定为0
if(hex.length() < 2) {
hex = "0" + hex;// 标记个位整数为16进制数
}
return hex;
}
public static String bytesToHex(byte[] b) {
StringBuffer sb = new StringBuffer();
String str = "";
for (byte c : b) {
str = byteToHex(c);
sb.append(str);
}
return new String(sb);
}
}File2MultipartFileUtil - File转MultipartFile工具类
public class File2MultipartFileUtil{
public static MultipartFile getMultipartFile(String filePath) {
File file = new File(filePath);
FileItemFactory factory = new DiskFileItemFactory(16, null);
FileItem item = factory.createItem(file.getName(), "text/plain", true, file.getName());
int bytesRead = 0;
byte[] buffer = new byte[4096];
try(FileInputStream fis = new FileInputStream(file);
OutputStream os = item.getOutputStream()) {
while((bytesRead=fis.read(buffer, 0, 4096)) != -1) {
os.write(buffer, 0, bytesRead);
}
} catch (Exception e) {
throw new RuntimeException("getMultipartFile error:" + e.getMessage());
}
MultipartFile cFilePath = new CommonsMultipartFile(item);
return cFilePath;
}
}SendMailUtil - java发送邮件的工具包
package com.mydemo.project.utils;
import java.io.UnsupportedEncodingException;
import java.security.Security;
import java.util.Date;
import java.util.Properties;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class SendMailUtil {
private static final Logger logger = LoggerFactory.getLogger(SendMailUtil.class);
/**
*
* @param subject 邮件主题
* @param content 邮件内容(可以是html)
* @param toEmailAddres 收件人
* @param log
* @throws MessagingException
*/
@SuppressWarnings("restriction")
public static void sendMail(String subject,String content,String toEmailAddres) throws MessagingException {
String host = "smtp.163.com"; //邮箱服务器地址
String port = "465"; //发送邮件的端口 25/587
String auth = "true"; //是否需要进行身份验证,视调用的邮箱而定，比方说QQ邮箱就需要，否则就会发送失败
String protocol = "smtp"; //传输协议
String mailFrom = "1*5@163.com"; //发件人邮箱
String personalName = "1*5"; //发件人邮箱别名
String username = "1*5@163.com"; //发件人邮箱用户名
String password = "***"; //发件人邮箱密码，163邮箱使用授权码
String mailDebug = "false"; //是否开启debug
String contentType = null; //邮件正文类型
Security.addProvider(new com.sun.net.ssl.internal.ssl.Provider()); // ssl认证
final String SSL_FACTORY = "javax.net.ssl.SSLSocketFactory";
Properties props = new Properties();
props.put("mail.smtp.host", host);
props.put("mail.smtp.auth", auth == null ? "true" : auth);
props.put("mail.transport.protocol", protocol == null ? "smtp" : protocol);
props.put("mail.smtp.port", port == null ? "25" : port);
props.put("mail.debug", mailDebug == null ? "false" : mailDebug);
props.setProperty("mail.smtp.socketFactory.class", SSL_FACTORY);
Session mailSession = Session.getInstance(props);
// 设置session,和邮件服务器进行通讯。
MimeMessage message = new MimeMessage(mailSession);
// 设置邮件主题
message.setSubject(subject);
// 设置邮件正文
message.setContent(content, contentType == null ? "text/html;charset=UTF-8" : contentType);
// 设置邮件发送日期
message.setSentDate(new Date());
InternetAddress address = null;
try {
address = new InternetAddress(mailFrom, personalName);
} catch (UnsupportedEncodingException e) {
logger.info("ip地址编码异常：{}",e.getMessage());
e.printStackTrace();
}
// 设置邮件发送者的地址
message.setFrom(address);
// 设置邮件接收方的地址
message.setRecipients(Message.RecipientType.TO, toEmailAddres);
Transport transport = null;
transport = mailSession.getTransport();
message.saveChanges();
transport.connect(host, username, password);
transport.sendMessage(message, message.getAllRecipients());
transport.close();
}
public static void main(String[] args) {
String subject = "from java";
String content = "<h1>hello world!</h1>";
String toEmailAddres = "7*@qq.com";
try {
sendMail(subject, content, toEmailAddres);
System.out.println("邮件发送成功");
} catch (MessagingException e) {
logger.info("邮件发送失败：{}",e.getMessage());
e.printStackTrace();
}
}
}
其它参考网址
https://www.jianshu.com/p/d36...
常用guava工具包
比较常用的有Preconditions前置校验/Lists/Maps工具类
https://www.baidu.com/link?ur...
https://blog.csdn.net/Munger6...
commons-io工具包
FileUtils-非常强大的文件转字节数组工具包
java
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