@ControllerAdvice实现优雅地处理异常
@ControllerAdvice，是Spring3.2提供的新注解,它是一个Controller增强器,可对controller中被 @RequestMapping注解的方法加一些逻辑处理。最常用的就是异常处理
### 统一异常处理
需要配合@ExceptionHandler使用。
当将异常抛到controller时,可以对异常进行统一处理,规定返回的json格式或是跳转到一个错误页面
```java
//全局异常捕捉处理
@ControllerAdvice
public class CustomExceptionHandler {
@ResponseBody
@ExceptionHandler(value = Exception.class)
public Map errorHandler(Exception ex) {
Map map = new HashMap();
map.put("code", 400);
//判断异常的类型,返回不一样的返回值
if(ex instanceof MissingServletRequestParameterException){
map.put("msg","缺少必需参数："+((MissingServletRequestParameterException) ex).getParameterName());
}
else if(ex instanceof MyException){
map.put("msg","这是自定义异常");
}
return map;
}
}
```
```java
//自定义异常类
@Data
public class MyException extends RuntimeException {
private long code;
private String msg;
public MyException(Long code, String msg){
super(msg);
this.code = code;
this.msg = msg;
}
public MyException(String msg){
super(msg);
this.msg = msg;
}
}
@RestController
public class TestController {
@RequestMapping("testException")
public String testException() throws Exception{
throw new MissingServletRequestParameterException("name","String");
}
@RequestMapping("testMyException")
public String testMyException() throws MyException{
throw new MyException("i am a myException");
}
}
```
分别访问testException和testMyException接口,可得到以下结果
```java
{"msg":"缺少必需参数：name","code":400}
{"msg":"这是自定义异常","code":400}
```
如果不需要返回json数据，而要渲染某个页面模板返回给浏览器，那么可以这么实现：
```java
@ExceptionHandler(value = MyException.class)
public ModelAndView myErrorHandler(MyException ex) {
ModelAndView modelAndView = new ModelAndView();
//指定错误页面的模板页
modelAndView.setViewName("error");
modelAndView.addObject("code", ex.getCode());
modelAndView.addObject("msg", ex.getMsg());
return modelAndView;
}
```
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