handling exceptions

controller中处理异常的方式

• 常见的 Spring exceptions 异常自动转化成对应的http code
• @ResponseStatus 定义异常时指定返回的http code
• @ExceptionHandler 指定异常类型调用的方法
• @ControllerAdvice 处理所有controller的异常

spring exceptions 异常自动转化

• 一般不用，可以忽略

• 使用姿势：在controller中抛出错误，下面的日子返回500 错误

package spittr.web;
// 定义异常类型
public class SpittleNotFoundException extends RuntimeException {
}

@RequestMapping(value="/{spittleId}", method=RequestMethod.GET)
public String spittle(
    @PathVariable("spittleId") long spittleId,
    Model model) {
  Spittle spittle = spittleRepository.findOne(spittleId);
  if (spittle == null) {
    throw new SpittleNotFoundException();
  }
  model.addAttribute(spittle);
  return "spittle";
}

@ResponseStatus

在定义异常时，指定返回的http code

package spittr.web;
import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.ResponseStatus;
@ResponseStatus(value=HttpStatus.NOT_FOUND,
                reason="Spittle Not Found")
public class SpittleNotFoundException extends RuntimeException {
}

@ExceptionHandler 处理指定的异常类型

@ExceptionHandler(DuplicateSpittleException.class)
public String handleDuplicateSpittle() {
  return "error/duplicate";
}

@ControllerAdvice 处理所有controller的异常

• @ControllerAdvice 也是@Conponent会被spring加载
• 处理的方法，实现跟@RequestMapping处理相同

package spitter.web;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
@ControllerAdvice
public class AppWideExceptionHandler {
  @ExceptionHandler(DuplicateSpittleException.class)
  public String duplicateSpittleHandler() {
    return "error/duplicate";
  }
}