Hutool 39

If you meant version 3.9 specifically (not 4.x or 5.x), this post highlights the features that made that release line so popular.

Category 6: Encryption & Hashing (4 methods)

24. SecureUtil.md5(inputString) Returns MD5 hash as a hex string. Great for checksums.

25. SecureUtil.sha256(inputString) Safer hashing for passwords (though use SecureUtil.bcrypt for production).

26. SecureUtil.aes(key).encrypt(plainText) Symmetric encryption made dead simple. hutool 39

27. DigestUtil.bcrypt(password) Industry-standard password hashing with auto-salt and work factor.

Conclusion

Hutool 3.9 is a "just works" utility library. It does not chase trends but solves real Java frustrations with concise, well-tested code. If you are maintaining a Java 8 codebase and need a Swiss army knife for common tasks, Hutool 3.9 delivers without bloat.

If you are looking for "Hutool 39," you are likely looking for the modern, active version of the library (specifically versions like 5.8.11+ which require JDK 1.8+). Hutool is a popular Java utility library that simplifies JDK standard operations. If you meant version 3

Here is a comprehensive development guide for using modern Hutool (v5.8.x+).

2. HttpUtil: No More Http Client Boilerplate

Making a GET or POST request in native Java is verbose. Hutool makes it a one-liner.

// Simple GET request
String response = HttpUtil.get("https://api.example.com/data");
// POST with parameters
HashMap<String, Object> paramMap = new HashMap<>();
paramMap.put("username", "hutool");
paramMap.put("password", "123456");
String result = HttpUtil.post("https://api.example.com/login", paramMap);
 Category 6: Encryption & Hashing (4 methods) 
  24

5. Examples (Common Tasks)

Layer 2: IO & File Handling (FileUtil, IoUtil)

Working with files in raw Java requires FileInputStream, BufferedReader, and manual resource closing. Hutool reduces 10 lines of code to 1.