SpringBoot(八)：系统错误统一拦截器

在日常 web 开发中发生了异常，往往需要通过一个统一的 异常处理，来保证客户端能够收到友好的提示。本文将会介绍 Spring Boot 中的 全局统一异常处理。

Springboot的全局异常查是通过两个注解@ControllerAdvice和@ExceptionHandler来实现的。
只有代码出错或者throw出来的异常才会被捕捉处理，如果被catch的异常，就不会被捕捉，除非catch之后再throw异常。

@ControllerAdvice：增强型控制器，对于控制器的全局配置放在同一个位置，全局异常的注解，放在类上。
@ControllerAdvice默认只会处理controller层抛出的异常，如果需要处理service层的异常，需要定义一个自定义的MyException来继承RuntimeException类，然后@ExceptionHandler（MyException）即可。
@ExceptionHandler：指明需要处理的异常类型以及子类。注解放在方法上面。

项目设置

GlobalExceptionHandler.java

package com.dx.controller;

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

import javax.servlet.http.HttpServletRequest;

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

@ControllerAdvice(basePackages = "com.dx.controller")
public class GlobalExceptionHandler {
    @ExceptionHandler(value = Exception.class)
    @ResponseBody
    public Map<String, Object> errorResult() {
        Map<String, Object> errorResult = new HashMap<String, Object>();
        errorResult.put("errorCode", "500");
        errorResult.put("errorMsg", "AOP捕获全局异常。");
        return errorResult;
    }

    // ⒈全局异常处理返回字符串
    @ExceptionHandler(MyPageException.class)
    @ResponseBody
    public String exception(MyPageException e) {// 未知的异常做出响应
        return "MyPageException";
    }

    // ⒉全局异常处理返回JSON
    @ExceptionHandler(value = MyJsonException.class)
    @ResponseBody
    public ErrorInfo<String> jsonErrorHandler(HttpServletRequest req, MyJsonException e) throws Exception {
        ErrorInfo<String> r = new ErrorInfo<String>();
        r.setMessage(e.getMessage());
        r.setCode(ErrorInfo.ERROR);
        r.setData("Some Data");
        r.setUrl(req.getRequestURL().toString());
        return r;
    }

    // ⒊全局异常处理返回JSP
    @ExceptionHandler(MyJspException.class)
    public String exception(Exception e) {
        return "MyJspException";
    }
}

ErrorInfo.java

package com.dx.controller;

public class ErrorInfo<T> {
    public static final Integer OK = 0;
    public static final Integer ERROR = 100;
    private Integer code;
    private String message;
    private String url;
    private T data;

    public Integer getCode() {
        return code;
    }

    public void setCode(Integer code) {
        this.code = code;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public T getData() {
        return data;
    }

    public void setData(T data) {
        this.data = data;
    }

}

MyJsonException.java

package com.dx.controller;

public class MyJsonException extends Exception {
    public MyJsonException(String message) {
        super(message);
    }
}

MyJspException.java

package com.dx.controller;

public class MyJspException extends Exception {
    public MyJspException(String message) {
        super(message);
    }
}

MyPageException.java

package com.dx.controller;

public class MyPageException extends Exception {
    public MyPageException(String message) {
        super(message);
    }
}

App.java

package com.dx;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class App {
    public static void main(String[] args) {
        SpringApplication.run(App.class, args);
    }

}

测试类：

TestController.java

package com.dx.controller.member;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import com.dx.controller.MyJsonException;
import com.dx.controller.MyJspException;
import com.dx.controller.MyPageException;

@Controller
public class TestController {
    @RequestMapping("/json")
    public String json() throws MyJsonException {
        if (1 == 1)
            throw new MyJsonException("");

        return "index";
    }

    @RequestMapping("/jsp")
    public String jsp() throws MyJspException {
        if (1 == 1)
            throw new MyJspException("");

        return "index";
    }

    @RequestMapping("/page")
    public String page() throws MyPageException {
        if (1 == 1)
            throw new MyPageException("");

        return "index";
    }

    @RequestMapping("/common1")
    public String common1() throws RuntimeException {
        if (1 == 1)
            throw new RuntimeException("");

        return "index";
    }

    @RequestMapping("/common2")
    public String common2() throws Exception {
        int i = 2 / 0;

        return "index";
    }
}

测试1 json：

http://localhost:8080/json

测试2 page:

http://localhost:8080/page

测试3 jsp:

http://localhost:8080/jsp

注：需要配置一下才能支持jsp

①需要在pom添加JSP的支持

        <!-- 对JSP的解析支持 -->
        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-jasper</artifactId>
            <scope>provided</scope>
        </dependency> <!-- 对JSTL的支持 -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
        </dependency>

②需要配置application.properties

在src/main/resources下添加application.properties配置文件，并配置如下内容：

# \u9875\u9762\u9ED8\u8BA4\u524D\u7F00\u76EE\u5F55
spring.mvc.view.prefix=/WEB-INF/
# \u54CD\u5E94\u9875\u9762\u9ED8\u8BA4\u540E\u7F00
spring.mvc.view.suffix=.jsp

③需要添加jsp文件

测试4 common1,common2:

http://localhost:8080/common1

http://localhost:8080/common2