JdbcTemplate中如何处理Blob和Clob类型的数据？代码举例讲解

在JdbcTemplate中处理Blob和Clob类型的数据,可以通过以下步骤进行:

1. 添加Maven依赖:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jdbc</artifactId>
</dependency>

2. 定义数据源和JdbcTemplate:

@Bean
public DataSource dataSource() {
    return new DriverManagerDataSource(url, username, password);
}

@Bean
public JdbcTemplate jdbcTemplate(DataSource dataSource) {
    return new JdbcTemplate(dataSource); 
}

3. 编写方法读取Blob和Clob数据:

@Repository
public class UserDao {
    @Autowired
    private JdbcTemplate jdbcTemplate;

    public byte[] getAvatar(int id) {
        return jdbcTemplate.queryForObject("SELECT avatar FROM user WHERE id = ?", 
            new Object[]{id}, 
            (rs, rowNum) -> rs.getBytes("avatar"));
    } 

    public String getDescription(int id) {
        return jdbcTemplate.queryForObject("SELECT description FROM user WHERE id = ?",
             new Object[]{id},   
             (rs, rowNum) -> rs.getString("description"));
    }
} 

• getAvatar()方法使用rs.getBytes("avatar")读取Blob类型的avatar字段。
• getDescription()方法使用rs.getString("description")读取Clob类型的description字段。

1. 在Service层调用:

@Service
public class UserService {
    @Autowired
    private UserDao userDao;

    public byte[] getAvatar(int id) {
        return userDao.getAvatar(id);
    }

    public String getDescription(int id) {
        return userDao.getDescription(id);
    }
}

5. 在Controller层接收请求并返回结果:

@RestController
public class UserController {
    @Autowired
    private UserService userService;

    @GetMapping("/avatar/{id}")
    public ResponseEntity<byte[]> getAvatar(@PathVariable int id) {
        byte[] avatar = userService.getAvatar(id);
        return ResponseEntity.ok(avatar);
    }  

    @GetMapping("/description/{id}")
    public ResponseEntity<String> getDescription(@PathVariable int id) {
        String description = userService.getDescription(id);
        return ResponseEntity.ok(description);
    }
}