SpringBoot custom parameter binding steps detailed

Normally, parameters passed by the front end can be directly received by SpringMVC, but there are some special cases, such as Date object, when I send a date from the front end, the server needs to define the parameter binding to convert the front end date. Customizing parameter bindings is also simple and consists of two steps:

1. Custom parameter converter

The custom parameter converter implements the Converter interface as follows:

public class DateConverter implements Converter<String,Date> {
 private SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
 @Override
 public Date convert(String s) {
  if ("".equals(s) || s == null) {
   return null;
  }
  try {
   return simpleDateFormat.parse(s);
  } catch (ParseException e) {
   e.printStackTrace();
  }
  return null;
 }
}

The convert method takes a string argument, which is the date string from the front end. This string is in the yyyy-MM-dd format, and it is returned by SimpleDateFormat as an Date object.

2. Configure the converter

Custom WebMvcConfig inherits WebMvcConfigurerAdapter and is configured in the addFormatters method:

@Configuration
public class WebMvcConfig extends WebMvcConfigurerAdapter {
 @Override
 public void addFormatters(FormatterRegistry registry) {
  registry.addConverter(new DateConverter());
 }
}

OK, after the above two steps, we can on the server receives a front end of the string from the date and place it into Java Date object, front end date controls are as follows:

<el-date-picker
 v-model="emp.birthday"
 size="mini"
 value-format="yyyy-MM-dd HH:mm:ss"
 style="width: 150px"
 type="date"
 placeholder=" Date of birth ">
</el-date-picker>

The server interface is as follows:

@RequestMapping(value = "/emp", method = RequestMethod.POST)
public RespBean addEmp(Employee employee) {
 if (empService.addEmp(employee) == 1) {
  return new RespBean("success", " Add a success !");
 }
 return new RespBean("error", " Add failure !");
}

There is an attribute named birthday in Employee, whose data type is 1 Date