java抛出的异常信息如何在页面显示

如何只用java代码，抛出的异常信息在页面显示呢？

1.自定义异常类

public class ProdProcessOrderException extends RuntimeException {
	private static final long serialVersionUID = 1L;

	public ProdProcessOrderException(String message) {
		super(message);
	}
}

2.service层的代码

@Service
public class GeneralDpPpOrderServiceImpl implements GeneralDpPpOrderService {
	public ResponseEntity<byte[]> downLoadExcel(GeneralDpPpOrder generalDpPpOrder) {
		//.........
		//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.");
		}
	}
}

service层的抛出异常类

3.controller层的代码

@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);
	}

}

controller类继承主异常类

4.主异常类代码

public abstract class ExceptionResponse {
	@ExceptionHandler(ProdProcessOrderException.class)
	@ResponseStatus(value = HttpStatus.INTERNAL_SERVER_ERROR)
	public SystemMessage prodProcessOrderException(ProdProcessOrderException e) {
		return new SystemMessage(500, e.getMessage());
	}
}

定义的主异常类，里面可以写多个自己定义的异常类

5.信息类代码

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;
	}

}

通过以上五步，就可以把后台抛出的异常信息，在前端页面显示了