Java微服务相关

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<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>3.5.3.2</version>
</dependency>

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<dependencies>
	<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>3.5.3.2</version>
  </dependency>
  <dependency>
    <groupId>com.mysql</groupId>
    <artifactId>mysql-connector-j</artifactId>
    <scope>runtime</scope>
  </dependency>
</dependencies>

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public interface UserMapper extends BaseMapper<User>{}

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@SpringBootTest
class UserMapperTest {
  	@Autowired
  	private UserMapper userMapper;
  	@Test
    void testInsert() {
      User user = new User();
      user.setId(5L);
      // ...
     	userMapper.insert(user); // 新增一条用户信息
      // userMapper.deleteById(5L); // 通过id删除用户信息
      // userMapper.updateById(user); // 通过id修改用信息
      // User user = userMapper.selectById(5L); // 通过id查询用户信息
      // List<User> users = userMapper.selectBatchIds(List.of(1L, 2L, 3L, 4L)); // select id in查询
      
    }
}

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@TableName("user") // 可以不写
public class User {
    private Long id;
    private String name;
}

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public class User {
    @TableId
    private Long id;
    private String name;
}

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public class User {
    private Long id;
    private String name;
    private Integer age;
    @TableField("`concat`") // 时机2
    private String concat;
  	@TableField("isMarried") // 时机3
    private Boolean isMarried;
}

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mybatis-plus:
	mapper-locations: "classpath*:/mapper/**/*.xml" # Mapper.xml文件地址，当前这个是默认值。
  type-aliases-package: com.itheima.mp.domain.po # 别名扫描包
  configuration:
    map-underscore-to-camel-case: true # 是否开启下划线和驼峰的映射
    cache-enabled: false # 是否开启二级缓存
  global-config:
    db-config:
      id-type: auto # 全局id类型为自增长 assign_id # id为雪花算法生成
      update-strategy: not_null # 更新策略：只更新非空字段 

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@Autowired
private UserMapper userMapper;

@Test
public void testQueryWrapper1() {
  QueryWrapper<User> queryWrapper = new QueryWrapper<>();
  // 1、查询
  queryWrapper.select("id", "username", "info", "balance").like("username", "o").ge("balance", 1000);
  List<User> list = userMapper.selectList(queryWrapper);
  // 2、更新
  queryWrapper.eq("username", "jack");
  User user = new User();
  user.setBalance(2000);
  userMapper.update(user, queryWrapper);
}

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@Autowired
private UserMapper userMapper;

@Test
public void testUpdateWrapper(){
  //1、构造更新条件对象
  UpdateWrapper<User> updateWrapper = new UpdateWrapper<>();
  // set balance = balance - 200
  updateWrapper.setSql("balance = balance - 200");
  // where id in (1,2,4)
  updateWrapper.in("id", 1, 2, 4);
  //2、更新
  userMapper.update(null, updateWrapper);
}

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@Test
public void testLambdaQueryWrapper() {
  //1、构造查询条件；构造 where username like 'o' and balance >= 1000
  LambdaQueryWrapper<User> queryWrapper = new LambdaQueryWrapper<>();
  queryWrapper.
    select(User::getId, User::getUsername, User::getInfo, User::getBalance)
    .like(User::getUsername, "o")
    .ge(User::getBalance, 1000);
  //2、查询
  List<User> list = userMapper.selectList(queryWrapper);
}

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@Test
public void testCustomWrapper(){
  //1、构造更新条件对象
  QueryWrapper<User> queryWrapper = new QueryWrapper<>();
  queryWrapper.in("id", 1, 2, 4);

  //2、更新; 调用自定义的更新方法，传入更新数值与查询条件对象
  userMapper.updateBalanceByWrapper(200, queryWrapper);
}

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@Update("UPDATE user SET balance = balance - #{amount} ${ew.customSqlSegment}")
void updateBalanceByWrapper(@Param("amount") int amount, @Param("ew") QueryWrapper<User> queryWrapper);

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public interface IUserService extends IService<User> {
}

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@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements IUserService {
}

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@ApiOperation("根据查询条件userQuery 查询用户列表")
@PostMapping("/list")
public List<UserVO> queryList(@RequestBody UserQuery userQuery) {
  String userName = userQuery.getName();
  Integer status = userQuery.getStatus();
  Integer minBalance = userQuery.getMinBalance();
  Integer maxBalance = userQuery.getMaxBalance();
  LambdaQueryWrapper<User> queryWrapper = new QueryWrapper<User>().lambda()
    .like(StrUtil.isNotBlank(userName), User::getUsername, userName) 
    .eq(status != null, User::getStatus, status)// status != null动态判断，是否增加这个where条件
    .ge(minBalance != null, User::getBalance, minBalance)
    .le(maxBalance != null, User::getBalance, maxBalance);

  List<User> userList = userService.list(queryWrapper);
  return BeanUtil.copyToList(userList, UserVO.class);
}

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@ApiOperation("根据查询条件userQuery 查询用户列表")
    @PostMapping("/list")
    public List<UserVO> queryList(@RequestBody UserQuery userQuery) {
        String userName = userQuery.getName();
        Integer status = userQuery.getStatus();
        Integer minBalance = userQuery.getMinBalance();
        Integer maxBalance = userQuery.getMaxBalance();
        // Lambda查询优化
        //改造为service中的lambdaQuery()
        List<User> userList = userService.lambdaQuery()
                .like(StrUtil.isNotBlank(userName), User::getUsername, userName)
                .eq(status != null, User::getStatus, status)
                .ge(minBalance != null, User::getBalance, minBalance)
                .le(maxBalance != null, User::getBalance, maxBalance)
                .list(); // 返回集合结果
      					// .one()：最多1个结果
      					// .count()：返回计数结果
        return BeanUtil.copyToList(userList, UserVO.class);
    }

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@Override
public void deductBalance(Long id, Integer amount) {
  //1、查询用户
  User user = this.getById(id);
  //2、判断状态
  if (user == null || user.getStatus() == 2) {
    throw new RuntimeException("用户状态异常");
  }
  //3、判断余额
  if (user.getBalance() < amount) {
    throw new RuntimeException("用户余额不足");
  }
  //4、扣减余额
  //baseMapper.deductBalance(id, amount);
  int remainBalance = user.getBalance() - amount;
  this.lambdaUpdate()
    .set(User::getBalance, remainBalance) //更新余额
    .set(remainBalance == 0, User::getStatus, 2) //动态判断，是否更新status
    .eq(User::getId, id)
    .eq(User::getBalance, user.getBalance()) // 乐观锁
    .update();
}

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//批量插入
@Test
public void testSaveBatch() {
  long begin = System.currentTimeMillis();
  List<User> list = new ArrayList<>(1000);
  for (int i = 1; i <= 10000; i++) {
    list.add(buildUser(i));
    if (i % 1000 == 0) {
      userService.saveBatch(list); 
      list.clear();
    }
  }
  long end = System.currentTimeMillis();
  System.out.println("耗时：" + (end - begin) + "ms");
}

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spring:
  datasource:
    url: jdbc:mysql://127.0.0.1:3306/mp?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&serverTimezone=Asia/Shanghai&rewriteBatchedStatements=true
    driver-class-name: com.mysql.cj.jdbc.Driver
    username: root
    password: root

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User user = Db.getById(1L, User.class);

 List<User> userList = Db.lambdaQuery(User.class)
                .like(User::getUsername, "o")
                .ge(User::getBalance, 1000)
                .list();

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@Getter
public enum UserStatus {
    NORMAL(1, "正常"),
    FREEZE(2, "冻结");

    @EnumValue //枚举中的哪个字段的值作为数据库值
    private Integer code;
    @JsonValue //标记JSON序列化时展示的字段
    private String message;

    UserStatus(Integer code, String message) {
        this.code = code;
        this.message = message;
    }
}

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private UserStatus status;

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mybatis-plus:
  configuration:
    default-enum-type-handler: com.baomidou.mybatisplus.core.handlers.MybatisEnumTypeHandler

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@Test
void testSelectById() {
  User user = userMapper.selectById(5L);
  System.out.println("user = " + user);
}

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username="luck"
status={UserStatus@11451}FREEZE
	code={Integer}2
	message="冻结"
	name="FREEZE"
	ordinal=1

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@Data
public class UserInfo {
    //年龄
    private Integer age;
    //简介
    private String intro;
    //性别
    private String gender;
}

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@TableName(value="user",autoResultMap=true)
public class User{
  private Long id;
  
  @TableField(typeHandler=JacksonTypeHandler.class)
  private UserInfo info;
}

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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 MybatisConfig {

    //配置Mybatis plus分页拦截器
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
        interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
        return interceptor;
    }
}

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//测试分页
@Test
public void testQueryPage() {
  Page<User> p = new Page<>(2, 2);
  //根据balance字段升序排列
  p.addOrder(new OrderItem("balance", true));
	Page<User> page = userService.page(p);
  //总记录数
  System.out.println("总记录数：" + page.getTotal());
  //总页数
  System.out.println("总页数：" + page.getPages());
  for (User user : page.getRecords()) {
    System.out.println(user);
  }
}