（4）在业务中添加事务管理

• 创建平台事务管理器==》实际是jdbc的事务

public class JdbcConfig {@Beanpublic PlatformTransactionManager transactionManager(DataSource ds){DataSourceTransactionManager transactionManager =new    DataSourceTransactionManager();transactionManager.setDataSource(ds);return transactionManager;}
}

• 开启事务管理器注解支持

@EnableTransactionManagement
public class SpringConfig {}

• 在接口上开启事务管理

@Transactional
public interface BookService {...}

（5）封装表现层数据

• 前端接收数据格式==》创建结果模型类

  • 封装数据到data中

  • 封装操作结果到code中==》不同code对应不同操作结果

  • 封装特殊消息到message（msg）属性中

  • 期待格式

• 

• 设置统一数据返回结果类

public class Result {private Object data;private Integer code;private String msg;setter、getter...
}

• 该结果类的成员属性不固定，根据需求添加

• 该结果类的构造方法书写多个，方便返回灵活的数据

• 封装对应的code编码==》不是标准，前后端协议沟通一致即可

public class Code {public static final Integer SAVE_OK = 20011;//新增成功public static final Integer SAVE_ERR = 20010;//新增失败public static final Integer DELETE_OK = 20021;//删除成功public static final Integer DELETE_ERR = 20020;//删除失败public static final Integer UPDATE_OK = 20031;//更新成功public static final Integer UPDATE_ERR = 20030;//更新失败public static final Integer GET_OK = 20041;//查询成功public static final Integer GET_ERR = 20040;//查询失败
}

• 将表现层返回数据类型统一为Result类

@PostMapping
public Result save(@RequestBody Book book) {System.out.println("save...");Boolean status = bookService.saveBook(book);System.out.println("save...");return new Result(status ? Code.SAVE_OK : Code.SAVE_ERR, status);
}
​
@DeleteMapping("/{id}")public Result delete(@PathVariable Integer id) {Boolean status = bookService.deleteBook(id);return new Result(status ? Code.DELETE_OK : Code.DELETE_ERR, status);
}
​
@PutMapping
public Result update(@RequestBody Book book) {Boolean status = bookService.updateBook(book);return new Result(status ? Code.UPDATE_OK : Code.UPDATE_ERR, status);
}
​
@GetMapping
public Result getAllBook() {List<Book> books = bookService.selectAllBook();Integer code = books != null ? Code.GET_OK : Code.GET_ERR;String msg = books != null ? "" : "查询失败，请重试!";return new Result(code,books,msg);
}
​
@GetMapping("/{id}")
public Result getBookById(@PathVariable Integer id) {Book book = bookService.selectBookById(id);Integer code = book != null ? Code.GET_OK : Code.GET_ERR;String msg = book != null ? "" : "查询失败，请重试!";return new Result(code,book,msg);
}