小知识，大挑战！本文正在参与“程序员必备小知识”创作活动。
如何用java代码，自定义的异常信息在页面显示呢？
1.自定义异常类，需要继承RuntimeException类
public class ProdProcessOrderException extends RuntimeException {
private static final long serialVersionUID = 1L;
public ProdProcessOrderException(String message) {
super(message);
}
}
2.service层的代码，主要由service层的抛出异常信息
@Service
public class GeneralDpPpOrderServiceImpl implements GeneralDpPpOrderService {
public ResponseEntity<byte[]> downLoadExcel(GeneralDpPpOrder generalDpPpOrder) {
String key = costItemFormulaConfig.getCostItem().getId().toString()
+ (costItemFormulaConfig.getOrderType() == null ? ""
: costItemFormulaConfig.getOrderType().getId().toString());
List<HouseCustomCostItemFormulaConfig> costConfigs = costItemFormulaConfigRepo.findByHouseCustomCostConfigKey(
key, costItemFormulaConfig.getId() != null ? costItemFormulaConfig.getId() : 0);
//省略代码
if (pOrderRouting == null) {
//此处抛出异常
throw new ProdProcessOrderException("当前门板流程单没有设置生产工艺.");
}
}
}
3.controller层的代码，controller类继承主异常类
@RestController
@RequestMapping("/api/mes/gene-dp-pp-order")
public class GeneralDpPpOrderController extends ExceptionResponse{ //继承主异常类
@Autowired
private GeneralDpPpOrderService generalDpPpOrderService;
@RequestMapping(value = "/download-excel", method = RequestMethod.PUT, consumes = "application/json;charset=UTF-8", produces = "application/xls")
public ResponseEntity<byte[]> downLoadExcel(@RequestBody GeneralDpPpOrder gdp) {
return generalDpPpOrderService.downLoadExcel(gdp);
}
}
4.主异常类代码，定义的主异常类，里面可以写多个自己定义的异常类
public abstract class ExceptionResponse {
@ExceptionHandler(ProdProcessOrderException.class)
@ResponseStatus(value = HttpStatus.INTERNAL_SERVER_ERROR)
public SystemMessage prodProcessOrderException(ProdProcessOrderException e) {
return new SystemMessage(500, e.getMessage());
}
}
说明： ①、@ExceptionHandler是用来统一处理方法抛出的异常的注解，@ExceptionHandler注解中可以添加参数，参数是某个异常类的class，代表这个方法专门处理该类异常，添加ProdProcessOrderException.class，专门处理ProdProcessOrderException类
②、@ResponseStatus的作用是为了改变HTTP响应的状态码
5.信息类主体，里面填错误码，以及异常信息等
public class SystemMessage {
private int code;
private String message;
public SystemMessage(int code, String message) {
super();
this.code = code;
this.message = message;
}
public int getCode() {
return code;
}
public void setCode(int code) {
this.code = code;
}
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
}
总结： 定义一个主异常类（比如AA），里面可以自定义多个异常类(比如aa,bb,cc)。controller层继承主异常类（AA），serevice层抛出异常（aa），大概思路是这样。
