1. 自己定义的异常，继承RuntimeException。可以建个exception包，专门放自定义异常。自定义的异常用来描述自己程序中特有的异常。

public class CustomGenericException extends RuntimeException {    private String errCode;    private String errMsg;    public CustomGenericException(String errCode, String errMsg) {        this.errCode = errCode;        this.errMsg = errMsg;    }    public String getErrCode() {        return errCode;    }    public void setErrCode(String errCode) {        this.errCode = errCode;    }    public String getErrMsg() {        return errMsg;    }    public void setErrMsg(String errMsg) {        this.errMsg = errMsg;    }}

2. 定义一个专用做处理异常的类，如下， @ExceptionHandler（）括号中的异常类.class表示这个方法用来处理哪种异常。

@ControllerAdvice(annotations = Controller.class)public class GlobalExceptionController {    @ExceptionHandler(CustomGenericException.class)    public ModelAndView handleCustomerException(CustomGenericException ex) {        ModelAndView model = new ModelAndView("error/generic_error");        model.addObject("errCode", ex.getErrCode());        model.addObject("errMsg", ex.getErrMsg());        return model;    }    @ExceptionHandler(Exception.class)    public ModelAndView handleAllException(Exception ex) {        ModelAndView model = new ModelAndView("error/generic_error");        model.addObject("errMsg", "this is Exception.class");        return model;    }}

3. 程序中只管抛异常就可以, 可以抛自定义的异常，或其他异常，异常处理类中对应的异常处理办法会起作用。 

@Controllerpublic class MainController {    @RequestMapping(value = "/{type}", method = RequestMethod.GET)    public ModelAndView getPages(@PathVariable("type") String type) throws IOException {        if("error".equals(type)) {            throw new CustomGenericException("E888", "This is custom message");        } else if("io-error".equals(type)) {            throw new IOException();        } else {            return new ModelAndView("index").addObject("msg", type);        }    }