初學SpringBoot 易踩雷區與拆彈指南

踩雷地圖持續更新中

Photo by Tamanna Rumee on Unsplash

Maven installation

• Homebrew: Your CLT does not support macOS 11.0
• Maven Installation On Mac | How To Install Maven On Mac | Maven Tutorial For Beginners | Simplilearn

MySQL No permission

MySQL Error: : ‘Access denied for user ‘root’@’localhost’

-> Find my.cnf and revise it (/usr/local/etc/my.cnf)

find /usr/local/ -iname "mysql"

Spring Data JPA （超級大雷）

• 如何解决idea报java.sql.SQLException: Access denied for user ‘’@’localhost’ (using password: NO)
• Spring boot starter parent 2.0.0 not found dependency
• springboot启动报错Error creating bean with name requestMappingHandlerMapping defined in class path resou

出現Bean 相關error 的話可以檢查的地方（之後有遇到不一樣的會再新增上來）：
  1. Controller 名稱是否重複
  2. 有些Class 的註解是否忘了加（例如Service 之類的）
  3. 若是Repository 無法Autowired 的話，則要確認執行的Class 跟Repository    是否在同一個package 下

版本問題

Thymeleaf

• Cannot resolve org.thymeleaf:thymeleaf-spring5:3.0.2.RELEASE_蓝墨の学习笔记-CSDN博客
• springboot与thymeleaf版本问题冲突_suxintang_time的博客-CSDN博客

@NotBlank

• why isn’t @NotBlank not showing up as an import

函式新舊寫法

Spring Data JPA — Select

// Old 
public Book findOne(long id) {
	return bookRepository.findOne(id);
}
// New 
public Book findOne(long id) {
	return bookRepository.findById(id).orElse(null);
}

Spring Data JPA — Delete

// Old
public void delete(long id) {
	bookRepository.delete(id);
}
// New
public void delete(long id) {
	bookRepository.deleteById(id);
}

Sort

public Page<Book> findAllByPage() {
        // Sort sort = new Sort(Sort.Direction.DESC, "id"); OLD
        Sort sort = Sort.by(Sort.Direction.DESC, "id");
        // Pageable pageable = new PageRequest(1, 5); OLD
        Pageable pageable = PageRequest.of(1, 5, sort);
        return bookRepository.findAll(pageable);
}
        //Sort sort = new Sort(Sort.Direction.DESC, "id");
        Sort sort = Sort.by(Sort.Direction.DESC, "id");
        //Pageable pageable = new PageRequest(1, 5);
        Pageable pageable = PageRequest.of(1, 5, sort);
        return bookRepository.findAll(pageable);
}