The postman request returns blank, that is, nothing is returned

Field not to

Java.net.ConnectException: Connection timed out: connect the computer networking

Mybatis database has a value but returns Null data

  • The entity class does not correspond to the database data type
  • The attribute name of the entity class is different from the field name of the table, and the automatic mapping fails. In this case, you must manually map or the attribute name must be the same as the field name. Mybatis generated by table code will follow camel name when database fields have “_”, this is when manual mapping is required
  • The SQL statement has an alias, so the column should also have an alias
  • When this parameter is not passed, it is automatically assigned to NULL, so the database data is null instead of the default value, where dynamic SQL comes into play

When you want to pass in JSON data (with an object as a parameter), annotate @requestBody with @pathVariable for content-Type: Application/JSON restful request