Spring boot异常统一处理方法：@ControllerAdvice注解的使用

1、首先创建异常处理包和类

2、使用@ControllerAdvice注解，全局捕获异常类，只要作用在@RequestMapping上，所有的异常都会被捕获

package com.example.demo.exception;

import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;

import java.util.HashMap;
import java.util.Map;

/**
 * 全局捕获异常类，只要作用在@RequestMapping上，所有的异常都会被捕获
 */
@ResponseBody
@ControllerAdvice
public class MyControllerAdvice {
    @ExceptionHandler(value = Exception.class)
    public Map<String,Object> errorHandle(Exception e){
        Map<String,Object> map = new HashMap<String,Object>();
        map.put("code",-1);
        map.put("msg",e.getMessage());
        return map;
    }
}

　　这上面有个需要注意的是要加上@ResponseBody注解，如果不加会怎么样呢，我们试下，报错：

javax.servlet.ServletException: Circular view path [hello]: would dispatch back to the current handler URL [/hello] again. 
Check your ViewResolver setup! (Hint: This may be the result of an unspecified view, due to default view name generation.)
    at org.springframework.web.servlet.view.InternalResourceView.prepareForRendering(InternalResourceView.java:209) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:147) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:314) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1325) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1069) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1008) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:866) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:635) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-8.5.31.jar:8.5.31]

　　因为是个json的格式，所以必须要有@ResponseBody

3、测试：在hello里面造个异常

package com.example.demo;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloController {
    @Value("${gwf.name}")
    private String msg;
    @RequestMapping("/hello")
    public String hello() {
        int num = 1/0;
        return this.msg;
    }
}

　　结果：