02. 学习SpringBoot4+JPA基本的增删改查接口

<dependency>
    <groupId>cn.hutool</groupId>
    <artifactId>hutool-all</artifactId>
    <version>5.8.25</version>
</dependency>

  # 配置 jap方言
  jpa:
    database-platform: org.hibernate.dialect.MySQLDialect
    hibernate:
      ddl-auto: none  # 手动创建数据库
    show-sql: true
    properties:
      hibernate:
        # 核心配置：格式化 SQL
        format_sql: true
        # 高级配置：显示 SQL 里的参数（把 ? 换成实际的值）
        use_sql_comments: true

/**
 * 新增或者更新数据
 */
@Operation(summary = "新增管理员", description = "新增管理员对象，提供JSON对象数据")
@PostMapping("/save")
public Result save(@RequestBody Admin admin) {
    adminService.save(admin);
    return Result.success();
}

public void save(Admin admin) {
    if (admin.getId() == null) {  // 新增  数据库ID是自增
        // 判断账户是否重复
//            ExampleMatcher matcher = ExampleMatcher.matching().withStringMatcher(ExampleMatcher.StringMatcher.EXACT);
//            ExampleMatcher matcher = ExampleMatcher.matching()
//                    .withMatcher("username", ExampleMatcher.GenericPropertyMatchers.exact());
//            Example<Admin> example = Example.of(admin, matcher);
        Admin dbAdmin = adminRepository.findByUsername(admin.getUsername());
        if (dbAdmin != null) {
            throw new CustomException("账号重复");
        }
        if (admin.getPassword() == null || admin.getPassword().isEmpty()) {
            admin.setPassword("admin");
        }
        if (admin.getName() == null || admin.getName().isEmpty()) {
            admin.setName("管理员");
        }
        admin.setRole("管理员");
    } else {
        Admin dbAdmin = adminRepository.findById(admin.getId()).orElse(null);
        if (dbAdmin != null) {
            BeanUtil.copyProperties(admin, dbAdmin, CopyOptions.create().setIgnoreNullValue(true));
            admin = dbAdmin;
        } else {
            throw new CustomException("数据不存在");
        }
    }
    adminRepository.save(admin);
}

/**
 * 删除数据
 */
@Operation(summary = "删除管理员", description = "删除管理员对象，根据ID删除")
@DeleteMapping("/deleteById/{id}")
public Result deleteById(@PathVariable Integer id) {
    adminService.deleteById(id);
    return Result.success();
}

/**
 * 批量删除数据
 */
@Operation(summary = "批量删除管理员", description = "批量删除管理员对象，根据ID数组删除")
@DeleteMapping("/deleteBatch")
public Result deleteBatch(@RequestBody List<Integer> ids) {
    adminService.deleteBatch(ids);
    return Result.success();
}

/**
 * 根据ID查询数据
 */
@Operation(summary = "查询单个管理员", description = "返回管理员")
@GetMapping("/findById/{id}")
public Result findById(@PathVariable Integer id) {
    Admin admin = adminService.findById(id);
    return Result.success(admin);
}

/**
 * 查询所有的数据
 */
@Operation(summary = "查询所有管理员", description = "返回管理员列表")
@GetMapping("/findAll")
public Result findAll() {
    List<Admin> list = adminService.findAll();
    return Result.success(list);
}

/**
 * 分页查询所有管理员
 */
@Operation(summary = "分页查询所有管理员", description = "返回管理员分页列表")
@GetMapping("/findPage")
public Result findPage(Admin admin,
                       @RequestParam(defaultValue = "1") Integer pageNum,
                       @RequestParam(defaultValue = "10") Integer pageSize) {
    PageInfo<Admin> pageInfo = adminService.findPage(admin, pageNum, pageSize);
    return Result.success(pageInfo);
}

public PageInfo<Admin> findPage(Admin admin, Integer pageNum, Integer pageSize) {
    ExampleMatcher matcher = ExampleMatcher.matching()
            .withStringMatcher(ExampleMatcher.StringMatcher.CONTAINING)
            .withIgnoreNullValues();
    Example<Admin> example = Example.of(admin, matcher);
    PageRequest pageRequest = PageRequest.of(pageNum - 1, pageSize).withSort(Sort.by(Sort.Direction.DESC, "id"));
    Page<Admin> page = adminRepository.findAll(example, pageRequest);
    return PageInfo.of(page);
}

@Data
@Builder
public class PageInfo<T> {
    private Long total;
    private List<T> list;

    public static <T> PageInfo<T> of(Page<T> page) {
        return PageInfo.<T>builder()
                .total(page.getTotalElements())
                .list(page.getContent())
                .build();
    }
}

package com.example.exception;

public class CustomException extends RuntimeException {

    public CustomException(String message) {
        super(message);
    }

}

package com.example.exception;

import com.example.common.Result;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;

@RestControllerAdvice
@Slf4j
public class GlobalExceptionHandler {

    /**
     * 处理业务异常（用户主动抛出的信息）
     */
    @ExceptionHandler(CustomException.class)
    public Result handleCustomException(CustomException e) {
        log.error("业务异常：", e); // 打印堆栈日志方便后端排查
        return Result.error("500", e.getMessage());
    }

    /**
     * 处理所有不可知的运行时异常（如数据库报错、空指针）
     */
    @ExceptionHandler(Exception.class)
    public Result handleException(Exception e) {
        log.error("系统异常：", e); // 打印堆栈日志方便后端排查
        return Result.error("500", "系统繁忙，请稍后再试");
    }

}