0
# Additional Utilities
1

2
Specialized utilities for validation, random generation, reflection, system operations, and various other common programming tasks.
3

4
## Import
5

6
```java
7
import cn.hutool.core.util.*;
8
import cn.hutool.core.lang.Validator;
9
import cn.hutool.system.SystemUtil;
10
import cn.hutool.extra.qr.QrCodeUtil;
11
import cn.hutool.captcha.CaptchaUtil;
12
```
13

14
## Validation Utilities
15

16
### Data Format Validation
17

18
```java { .api }
19
// Email validation
20
public static boolean isEmail(CharSequence email);
21

22
// Phone number validation
23
public static boolean isPhone(CharSequence mobile);
24
public static boolean isMobile(CharSequence mobile);
25

26
// ID card validation
27
public static boolean isCitizenId(CharSequence citizenId);
28
public static boolean isValidCard(CharSequence cardNumber);
29

30
// URL validation
31
public static boolean isUrl(CharSequence url);
32
public static boolean isIpv4(CharSequence ipv4);
33
public static boolean isIpv6(CharSequence ipv6);
34
```
35

36
### Number and String Validation
37

38
```java { .api }
39
// Number validation
40
public static boolean isNumber(CharSequence str);
41
public static boolean isInteger(CharSequence str);
42
public static boolean isDouble(CharSequence str);
43

44
// String format validation
45
public static boolean isLetter(CharSequence value);
46
public static boolean isLetterUpper(CharSequence value);
47
public static boolean isLetterLower(CharSequence value);
48
public static boolean isChinese(CharSequence str);
49
public static boolean isWord(CharSequence value);
50
```
51

52
**Usage Examples:**
53

54
```java
55
// Validate user input
56
String email = "user@example.com";
57
boolean validEmail = Validator.isEmail(email);  // true
58

59
String phone = "13812345678";
60
boolean validPhone = Validator.isMobile(phone);  // true
61

62
String idCard = "110101199003077890";
63
boolean validId = Validator.isCitizenId(idCard);  // depends on checksum
64

65
// Validate numeric input
66
String numberStr = "123.45";
67
boolean isNum = Validator.isNumber(numberStr);  // true
68
boolean isInt = Validator.isInteger(numberStr);  // false
69
```
70

71
## Random Generation Utilities
72

73
### Random Data Generation
74

75
```java { .api }
76
// Random strings
77
public static String randomString(int length);
78
public static String randomString(String baseString, int length);
79
public static String randomStringUpper(int length);
80
public static String randomNumbers(int length);
81

82
// Random numbers
83
public static int randomInt();
84
public static int randomInt(int min, int max);
85
public static long randomLong();
86
public static long randomLong(long min, long max);
87
public static double randomDouble();
88
public static double randomDouble(double min, double max);
89

90
// Random selection
91
public static <T> T randomEle(T[] array);
92
public static <T> T randomEle(List<T> list);
93
public static <T> List<T> randomEles(List<T> list, int count);
94
```
95

96
### UUID and ID Generation
97

98
```java { .api }
99
// UUID generation
100
public static String randomUUID();
101
public static String simpleUUID();
102
public static String fastUUID();
103
public static String fastSimpleUUID();
104

105
// Snowflake ID (distributed unique ID)
106
public static long getSnowflakeNextId();
107
public static String getSnowflakeNextIdStr();
108

109
// Object ID (MongoDB style)
110
public static String objectId();
111
```
112

113
**Usage Examples:**
114

115
```java
116
// Generate random data
117
String sessionId = RandomUtil.randomString(32);
118
String captcha = RandomUtil.randomNumbers(6);
119
int randomPort = RandomUtil.randomInt(8000, 9000);
120

121
// Generate unique IDs
122
String uuid = IdUtil.randomUUID();
123
String simpleId = IdUtil.simpleUUID();  // No dashes
124
long snowflakeId = IdUtil.getSnowflakeNextId();
125
String objectId = IdUtil.objectId();
126

127
// Random selection
128
List<String> colors = Arrays.asList("red", "green", "blue", "yellow");
129
String randomColor = RandomUtil.randomEle(colors);
130
List<String> twoColors = RandomUtil.randomEles(colors, 2);
131
```
132

133
## Reflection Utilities
134

135
### Class Operations
136

137
```java { .api }
138
// Class loading and inspection
139
public static Class<?> loadClass(String name);
140
public static boolean isPresent(String className);
141
public static <T> T newInstance(Class<T> clazz, Object... params);
142

143
// Method operations
144
public static Method getMethod(Class<?> clazz, String methodName, Class<?>... paramTypes);
145
public static Object invoke(Object obj, String methodName, Object... args);
146
public static Object invokeStatic(Class<?> clazz, String methodName, Object... args);
147

148
// Field operations
149
public static Field getField(Class<?> clazz, String fieldName);
150
public static Object getFieldValue(Object obj, String fieldName);
151
public static void setFieldValue(Object obj, String fieldName, Object value);
152
```
153

154
### Type Utilities
155

156
```java { .api }
157
// Type checking
158
public static boolean isBasicType(Class<?> clazz);
159
public static boolean isWrapClass(Class<?> clazz);
160
public static boolean isPrimitiveWrapper(Class<?> clazz);
161

162
// Generic type operations
163
public static Type getTypeArgument(Type type);
164
public static Type getTypeArgument(Type type, int index);
165
public static Class<?> getClass(Type type);
166
```
167

168
**Usage Examples:**
169

170
```java
171
// Dynamic object creation
172
Class<?> userClass = ReflectUtil.loadClass("com.example.User");
173
Object user = ReflectUtil.newInstance(userClass, "John", 30);
174

175
// Dynamic method invocation
176
Object result = ReflectUtil.invoke(user, "getName");
177
ReflectUtil.invoke(user, "setAge", 31);
178

179
// Dynamic field access
180
String name = (String) ReflectUtil.getFieldValue(user, "name");
181
ReflectUtil.setFieldValue(user, "active", true);
182

183
// Check if class exists
184
boolean hasClass = ReflectUtil.isPresent("com.mysql.cj.jdbc.Driver");
185
```
186

187
## System Information Utilities
188

189
### JVM and Runtime Information
190

191
```java { .api }
192
// JVM information
193
public static JavaInfo getJavaInfo();
194
public static JvmInfo getJvmInfo();
195
public static RuntimeInfo getRuntimeInfo();
196

197
// Host information
198
public static HostInfo getHostInfo();
199
public static OsInfo getOsInfo();
200
public static UserInfo getUserInfo();
201

202
// Memory information
203
public static long getTotalMemory();
204
public static long getFreeMemory();
205
public static long getUsedMemory();
206
public static long getMaxMemory();
207
```
208

209
### System Properties
210

211
```java { .api }
212
// Get system properties
213
public static String get(String key);
214
public static String get(String key, String defaultValue);
215
public static void set(String key, String value);
216

217
// Common properties
218
public static String getJavaHome();
219
public static String getUserHome();
220
public static String getUserDir();
221
public static String getTmpDir();
222
public static String getFileSeparator();
223
public static String getPathSeparator();
224
public static String getLineSeparator();
225
```
226

227
**Usage Examples:**
228

229
```java
230
// System information
231
JavaInfo javaInfo = SystemUtil.getJavaInfo();
232
System.out.println("Java Version: " + javaInfo.getVersion());
233

234
OsInfo osInfo = SystemUtil.getOsInfo();
235
System.out.println("OS: " + osInfo.getName() + " " + osInfo.getVersion());
236

237
// Memory monitoring
238
long usedMemory = SystemUtil.getUsedMemory();
239
long totalMemory = SystemUtil.getTotalMemory();
240
double memoryUsage = (double) usedMemory / totalMemory * 100;
241
System.out.println("Memory usage: " + memoryUsage + "%");
242

243
// System properties
244
String javaHome = SystemUtil.getJavaHome();
245
String userHome = SystemUtil.getUserHome();
246
String tmpDir = SystemUtil.getTmpDir();
247
```
248

249
## QR Code and Captcha Utilities
250

251
### QR Code Generation
252

253
```java { .api }
254
// Generate QR codes
255
public static BufferedImage generate(String content, int width, int height);
256
public static void generate(String content, int width, int height, File file);
257
public static String generateAsBase64(String content, int width, int height);
258

259
// Decode QR codes
260
public static String decode(File qrCodeFile);
261
public static String decode(BufferedImage qrCodeImage);
262
```
263

264
### Captcha Generation
265

266
```java { .api }
267
// Create different types of captchas
268
public static LineCaptcha createLineCaptcha(int width, int height);
269
public static CircleCaptcha createCircleCaptcha(int width, int height);
270
public static ShearCaptcha createShearCaptcha(int width, int height);
271
public static GifCaptcha createGifCaptcha(int width, int height);
272
```
273

274
**Usage Examples:**
275

276
```java
277
// Generate QR code
278
String url = "https://hutool.cn";
279
QrCodeUtil.generate(url, 200, 200, new File("qrcode.png"));
280

281
// Generate captcha
282
LineCaptcha captcha = CaptchaUtil.createLineCaptcha(200, 100);
283
String code = captcha.getCode();  // Get the answer
284
captcha.write(new File("captcha.png"));  // Save image
285

286
// Verify captcha
287
boolean verified = captcha.verify(userInputCode);
288
```
289

290
## Coordinate and Geographic Utilities
291

292
### Coordinate Conversions
293

294
```java { .api }
295
// Coordinate system conversions
296
public static double[] wgs84ToGcj02(double lng, double lat);
297
public static double[] gcj02ToWgs84(double lng, double lat);
298
public static double[] gcj02ToBd09(double lng, double lat);
299
public static double[] bd09ToGcj02(double lng, double lat);
300

301
// Distance calculations
302
public static double distance(double lng1, double lat1, double lng2, double lat2);
303
```
304

305
## Number and Math Utilities
306

307
### Number Operations
308

309
```java { .api }
310
// Number parsing and formatting
311
public static Number parseNumber(String numberStr);
312
public static int parseInt(String numberStr);
313
public static long parseLong(String numberStr);
314
public static double parseDouble(String numberStr);
315

316
// Number validation
317
public static boolean isNumber(String str);
318
public static boolean isInteger(String str);
319
public static boolean isDouble(String str);
320

321
// Number comparison
322
public static boolean equals(Number num1, Number num2);
323
public static int compare(Number num1, Number num2);
324

325
// Number formatting
326
public static String decimalFormat(String format, Object value);
327
public static String formatPercent(double number, int decimalPlaces);
328
```
329

330
### Mathematical Operations
331

332
```java { .api }
333
// Basic math operations
334
public static double add(Number... numbers);
335
public static double subtract(Number num1, Number num2);
336
public static double multiply(Number... numbers);
337
public static double divide(Number num1, Number num2);
338

339
// Rounding operations
340
public static double roundUp(double value, int scale);
341
public static double roundDown(double value, int scale);
342
public static double round(double value, int scale);
343

344
// Range operations
345
public static boolean isIn(Number value, Number min, Number max);
346
public static Number max(Number... numbers);
347
public static Number min(Number... numbers);
348
```
349

350
**Usage Examples:**
351

352
```java
353
// Safe number parsing
354
String userInput = "123.45";
355
double value = NumberUtil.parseDouble(userInput);  // Handles null and invalid formats
356

357
// Precise calculations (avoids floating point errors)
358
double result = NumberUtil.add(0.1, 0.2);  // Returns exactly 0.3
359
double percentage = NumberUtil.formatPercent(0.1234, 2);  // "12.34%"
360

361
// Number validation and comparison
362
boolean isNum = NumberUtil.isNumber("123.45");
363
boolean equal = NumberUtil.equals(123.0, 123);  // true
364

365
// Geographic calculations
366
// Convert GPS coordinates between different systems
367
double[] wgs84 = {116.3974, 39.9093};  // Beijing in WGS84
368
double[] gcj02 = CoordinateUtil.wgs84ToGcj02(wgs84[0], wgs84[1]);
369

370
// Calculate distance between two points
371
double distance = CoordinateUtil.distance(116.3974, 39.9093, 121.4737, 31.2304);  // Beijing to Shanghai
372
```
373

374
All utility classes provide null-safe operations and handle edge cases gracefully. They follow consistent naming conventions and provide both basic and advanced functionality for common programming tasks.