初始化

backend/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-parent</artifactId>
+        <version>3.4.5</version>
+        <relativePath/>
+    </parent>
+
+    <groupId>com.example</groupId>
+    <artifactId>training-backend</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>training-backend</name>
+    <description>Training project backend service</description>
+
+    <properties>
+        <java.version>21</java.version>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.baomidou</groupId>
+            <artifactId>mybatis-plus-spring-boot3-starter</artifactId>
+            <version>3.5.12</version>
+        </dependency>
+        <dependency>
+            <groupId>com.baomidou</groupId>
+            <artifactId>mybatis-plus-jsqlparser</artifactId>
+            <version>3.5.12</version>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-validation</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.mysql</groupId>
+            <artifactId>mysql-connector-j</artifactId>
+            <scope>runtime</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.h2database</groupId>
+            <artifactId>h2</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <directory>${project.basedir}/build</directory>
+        <plugins>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+</project>

backend/src/main/java/com/example/training/TrainingApplication.java

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+package com.example.training;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class TrainingApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(TrainingApplication.class, args);
+    }
+}

backend/src/main/java/com/example/training/config/MybatisPlusConfig.java

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+package com.example.training.config;
+
+import com.baomidou.mybatisplus.annotation.DbType;
+import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
+import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+public class MybatisPlusConfig {
+
+    @Bean
+    public MybatisPlusInterceptor mybatisPlusInterceptor() {
+        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
+        interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
+        return interceptor;
+    }
+}

backend/src/main/java/com/example/training/controller/HealthController.java

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+package com.example.training.controller;
+
+import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
+
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("/api/health")
+public class HealthController {
+
+    @GetMapping
+    public HealthResponse health() {
+        return new HealthResponse("UP", "training-backend", OffsetDateTime.now(ZoneOffset.UTC));
+    }
+
+    public record HealthResponse(String status, String service, OffsetDateTime timestamp) {
+    }
+}

backend/src/main/java/com/example/training/controller/UserController.java

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+package com.example.training.controller;
+
+import java.time.LocalDateTime;
+import java.util.List;
+
+import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
+import com.example.training.domain.User;
+import com.example.training.service.UserService;
+import jakarta.validation.Valid;
+import jakarta.validation.constraints.Email;
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.Size;
+import org.springframework.dao.DataIntegrityViolationException;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.DeleteMapping;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.PutMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+import org.springframework.web.server.ResponseStatusException;
+
+@RestController
+@RequestMapping("/api/users")
+public class UserController {
+
+    private final UserService userService;
+
+    public UserController(UserService userService) {
+        this.userService = userService;
+    }
+
+    @GetMapping
+    public UserPage list(
+            @RequestParam(defaultValue = "") String keyword,
+            @RequestParam(defaultValue = "0") int page,
+            @RequestParam(defaultValue = "50") int size) {
+        int safePage = Math.max(page, 0);
+        int safeSize = Math.min(Math.max(size, 1), 100);
+        Page<User> resultPage = userService.pageUsers(keyword, safePage, safeSize);
+        return new UserPage(resultPage.getRecords().stream().map(UserResponse::from).toList(),
+                resultPage.getTotal(), (int) resultPage.getCurrent() - 1, (int) resultPage.getSize());
+    }
+
+    @PostMapping
+    public ResponseEntity<UserResponse> create(@Valid @RequestBody UserRequest request) {
+        User user = userService.createUser(request.fullName(), request.email(),
+                request.role(), request.status());
+        return ResponseEntity.status(HttpStatus.CREATED).body(UserResponse.from(user));
+    }
+
+    @PutMapping("/{id}")
+    public UserResponse update(@PathVariable Long id, @Valid @RequestBody UserRequest request) {
+        User user = userService.updateUser(id, request.fullName(), request.email(),
+                request.role(), request.status());
+        if (user == null) {
+            throw new ResponseStatusException(HttpStatus.NOT_FOUND, "User not found");
+        }
+        return UserResponse.from(user);
+    }
+
+    @DeleteMapping("/{id}")
+    public ResponseEntity<Void> delete(@PathVariable Long id) {
+        if (!userService.deleteUser(id)) {
+            throw new ResponseStatusException(HttpStatus.NOT_FOUND, "User not found");
+        }
+        return ResponseEntity.noContent().build();
+    }
+
+    @ExceptionHandler(DataIntegrityViolationException.class)
+    ResponseEntity<ApiError> handleDuplicateEmail() {
+        return ResponseEntity.status(HttpStatus.CONFLICT)
+                .body(new ApiError("该邮箱已被使用，请更换后重试"));
+    }
+
+    public record UserRequest(
+            @NotBlank @Size(max = 80) String fullName,
+            @NotBlank @Email @Size(max = 160) String email,
+            @NotBlank @Size(max = 40) String role,
+            @NotBlank @Size(max = 20) String status) {
+    }
+
+    public record UserPage(List<UserResponse> items, long total, int page, int size) {
+    }
+
+    public record UserResponse(Long id, String fullName, String email, String role,
+                               String status, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        static UserResponse from(User user) {
+            return new UserResponse(user.getId(), user.getFullName(), user.getEmail(),
+                    user.getRole(), user.getStatus(), user.getCreatedAt(), user.getUpdatedAt());
+        }
+    }
+
+    public record ApiError(String message) {
+    }
+}

backend/src/main/java/com/example/training/database/DatabaseConnectionVerifier.java

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+package com.example.training.database;
+
+import java.util.Map;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.boot.ApplicationArguments;
+import org.springframework.boot.ApplicationRunner;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.jdbc.core.JdbcTemplate;
+import org.springframework.stereotype.Component;
+
+@Component
+@ConditionalOnProperty(name = "app.database.verify-on-startup", havingValue = "true")
+public class DatabaseConnectionVerifier implements ApplicationRunner {
+
+    private static final Logger log = LoggerFactory.getLogger(DatabaseConnectionVerifier.class);
+
+    private final JdbcTemplate jdbcTemplate;
+    private final ConfigurableApplicationContext applicationContext;
+    private final boolean exitAfterVerify;
+
+    public DatabaseConnectionVerifier(
+            JdbcTemplate jdbcTemplate,
+            ConfigurableApplicationContext applicationContext,
+            @Value("${app.database.exit-after-verify:false}") boolean exitAfterVerify) {
+        this.jdbcTemplate = jdbcTemplate;
+        this.applicationContext = applicationContext;
+        this.exitAfterVerify = exitAfterVerify;
+    }
+
+    @Override
+    public void run(ApplicationArguments args) {
+        Map<String, Object> result = jdbcTemplate.queryForMap(
+                "SELECT DATABASE() AS database_name, CURRENT_USER() AS connected_user, VERSION() AS mysql_version");
+        log.info("Database connectivity verified: database={}, user={}, version={}",
+                result.get("database_name"), result.get("connected_user"), result.get("mysql_version"));
+        if (exitAfterVerify) {
+            SpringApplication.exit(applicationContext, () -> 0);
+        }
+    }
+}

backend/src/main/java/com/example/training/domain/User.java

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+package com.example.training.domain;
+
+import java.time.LocalDateTime;
+
+import com.baomidou.mybatisplus.annotation.IdType;
+import com.baomidou.mybatisplus.annotation.TableField;
+import com.baomidou.mybatisplus.annotation.TableId;
+import com.baomidou.mybatisplus.annotation.TableName;
+
+@TableName("users")
+public class User {
+
+    @TableId(value = "id", type = IdType.AUTO)
+    private Long id;
+
+    @TableField("full_name")
+    private String fullName;
+
+    private String email;
+    private String role;
+    private String status;
+
+    @TableField("created_at")
+    private LocalDateTime createdAt;
+
+    @TableField("updated_at")
+    private LocalDateTime updatedAt;
+
+    public User() {
+    }
+
+    public User(String fullName, String email, String role, String status) {
+        LocalDateTime now = LocalDateTime.now();
+        this.fullName = fullName;
+        this.email = email;
+        this.role = role;
+        this.status = status;
+        this.createdAt = now;
+        this.updatedAt = now;
+    }
+
+    public Long getId() { return id; }
+    public String getFullName() { return fullName; }
+    public String getEmail() { return email; }
+    public String getRole() { return role; }
+    public String getStatus() { return status; }
+    public LocalDateTime getCreatedAt() { return createdAt; }
+    public LocalDateTime getUpdatedAt() { return updatedAt; }
+
+    public void update(String fullName, String email, String role, String status) {
+        this.fullName = fullName;
+        this.email = email;
+        this.role = role;
+        this.status = status;
+        this.updatedAt = LocalDateTime.now();
+    }
+}

backend/src/main/java/com/example/training/mapper/UserMapper.java

@@ -0,0 +1,9 @@
+package com.example.training.mapper;
+
+import com.baomidou.mybatisplus.core.mapper.BaseMapper;
+import com.example.training.domain.User;
+import org.apache.ibatis.annotations.Mapper;
+
+@Mapper
+public interface UserMapper extends BaseMapper<User> {
+}

backend/src/main/java/com/example/training/service/UserService.java

@@ -0,0 +1,15 @@
+package com.example.training.service;
+
+import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
+import com.example.training.domain.User;
+
+public interface UserService {
+
+    Page<User> pageUsers(String keyword, int page, int size);
+
+    User createUser(String fullName, String email, String role, String status);
+
+    User updateUser(Long id, String fullName, String email, String role, String status);
+
+    boolean deleteUser(Long id);
+}

backend/src/main/java/com/example/training/service/impl/UserServiceImpl.java

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+package com.example.training.service.impl;
+
+import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
+import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
+import com.example.training.domain.User;
+import com.example.training.mapper.UserMapper;
+import com.example.training.service.UserService;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+@Service
+public class UserServiceImpl implements UserService {
+
+    private final UserMapper userMapper;
+
+    public UserServiceImpl(UserMapper userMapper) {
+        this.userMapper = userMapper;
+    }
+
+    @Override
+    @Transactional(readOnly = true)
+    public Page<User> pageUsers(String keyword, int page, int size) {
+        Page<User> requestPage = new Page<>(page + 1L, size);
+        LambdaQueryWrapper<User> query = new LambdaQueryWrapper<>();
+        if (keyword != null && !keyword.isBlank()) {
+            String trimmedKeyword = keyword.trim();
+            query.like(User::getFullName, trimmedKeyword)
+                    .or()
+                    .like(User::getEmail, trimmedKeyword);
+        }
+        query.orderByDesc(User::getCreatedAt);
+        return userMapper.selectPage(requestPage, query);
+    }
+
+    @Override
+    @Transactional
+    public User createUser(String fullName, String email, String role, String status) {
+        User user = new User(normalize(fullName), normalizeEmail(email), role, status);
+        userMapper.insert(user);
+        return user;
+    }
+
+    @Override
+    @Transactional
+    public User updateUser(Long id, String fullName, String email, String role, String status) {
+        User user = userMapper.selectById(id);
+        if (user == null) {
+            return null;
+        }
+        user.update(normalize(fullName), normalizeEmail(email), role, status);
+        userMapper.updateById(user);
+        return user;
+    }
+
+    @Override
+    @Transactional
+    public boolean deleteUser(Long id) {
+        if (userMapper.selectById(id) == null) {
+            return false;
+        }
+        return userMapper.deleteById(id) > 0;
+    }
+
+    private static String normalize(String value) {
+        return value.trim();
+    }
+
+    private static String normalizeEmail(String value) {
+        return normalize(value).toLowerCase();
+    }
+}

backend/src/main/resources/application.yml

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+spring:
+  config:
+    import: optional:file:../.env.example[.properties],optional:file:../.env[.properties]
+  application:
+    name: ${SPRING_APPLICATION_NAME:training-backend}
+  datasource:
+    url: jdbc:mysql://${MYSQL_HOST}:${MYSQL_PORT}/${MYSQL_DATABASE}?useUnicode=true&characterEncoding=utf8&serverTimezone=Asia/Shanghai&useSSL=false&allowPublicKeyRetrieval=true&connectTimeout=${MYSQL_CONNECT_TIMEOUT_MS:5000}&socketTimeout=${MYSQL_SOCKET_TIMEOUT_MS:10000}&tcpKeepAlive=true
+    username: ${MYSQL_USER}
+    password: ${MYSQL_PASSWORD}
+    driver-class-name: com.mysql.cj.jdbc.Driver
+    hikari:
+      minimum-idle: ${MYSQL_POOL_MINIMUM_IDLE:1}
+      maximum-pool-size: ${MYSQL_POOL_MAXIMUM_SIZE:5}
+      connection-timeout: ${MYSQL_POOL_CONNECTION_TIMEOUT_MS:10000}
+      validation-timeout: ${MYSQL_POOL_VALIDATION_TIMEOUT_MS:5000}
+  sql:
+    init:
+      mode: always
+      continue-on-error: false
+mybatis-plus:
+  configuration:
+    map-underscore-to-camel-case: true
+  global-config:
+    banner: false
+
+app:
+  database:
+    verify-on-startup: ${APP_DATABASE_VERIFY_ON_STARTUP:false}
+    exit-after-verify: ${APP_DATABASE_EXIT_AFTER_VERIFY:false}
+
+server:
+  port: ${SERVER_PORT:8080}
+  shutdown: graceful
+
+logging:
+  level:
+    com.example.training: ${LOGGING_LEVEL_COM_EXAMPLE_TRAINING:INFO}
+    com.baomidou.mybatisplus: INFO

backend/src/main/resources/schema.sql

@@ -0,0 +1,13 @@
+CREATE TABLE IF NOT EXISTS users (
+    id BIGINT NOT NULL AUTO_INCREMENT,
+    full_name VARCHAR(80) NOT NULL,
+    email VARCHAR(160) NOT NULL,
+    role VARCHAR(40) NOT NULL,
+    status VARCHAR(20) NOT NULL DEFAULT 'ACTIVE',
+    created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
+    PRIMARY KEY (id),
+    UNIQUE KEY uk_users_email (email),
+    KEY idx_users_full_name (full_name),
+    KEY idx_users_status (status)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

backend/src/test/java/com/example/training/TrainingApplicationTests.java

@@ -0,0 +1,29 @@
+package com.example.training;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
+import org.springframework.test.context.ActiveProfiles;
+import org.springframework.test.web.servlet.MockMvc;
+
+import com.example.training.controller.HealthController;
+
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+@WebMvcTest(HealthController.class)
+@ActiveProfiles("test")
+class TrainingApplicationTests {
+
+    @Autowired
+    private MockMvc mockMvc;
+
+    @Test
+    void healthEndpointReturnsUp() throws Exception {
+        mockMvc.perform(get("/api/health"))
+                .andExpect(status().isOk())
+                .andExpect(jsonPath("$.status").value("UP"))
+                .andExpect(jsonPath("$.service").value("training-backend"));
+    }
+}

backend/src/test/resources/application-test.yml

@@ -0,0 +1,20 @@
+spring:
+  config:
+    activate:
+      on-profile: test
+  datasource:
+    url: jdbc:h2:mem:training-test;MODE=MySQL;DB_CLOSE_DELAY=-1;DB_CLOSE_ON_EXIT=FALSE
+    username: sa
+    password:
+    driver-class-name: org.h2.Driver
+  sql:
+    init:
+      mode: never
+
+server:
+  port: 0
+
+logging:
+  level:
+    com.example.training: INFO
+    org.springframework: WARN