如何在SpringBoot中优雅的处理异常
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SpringBoot 统一异常处理 像这种统一异常的文章博客有许多，但是每个人使用都有自己的心得，我来总结一下自己使用的心得统一异常，顾名思义，就是统一管理项目中会方法的异常，然后进行一个处理，Spring发生错误后，底层会去请求一个/error的地址，抛出对应的异常到页面上，对客户或者开发来说都不是特别的友好使用统一异常处理的话，可以返回自定义的异常数据，阅读性提高，优雅的处理异常
使用异常
使用异常的方式很简单，Spring提供了两个注解：@ControllerAdvice和@ExceptionHandler
@ControllerAdvice 控制器增强，使@ExceptionHandler、@InitBinder、@ModelAttribute注解的方法应用到所有的 @RequestMapping注解的方法 @ExceptionHandler 异常处理器，此注解的作用是当出现其定义的异常时进行处理的方法
创建统一异常类
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.TypeMismatchException;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.autoconfigure.web.AbstractErrorController;
import org.springframework.boot.autoconfigure.web.ErrorAttributes;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.stereotype.Controller;
import org.springframework.web.HttpRequestMethodNotSupportedException;
import org.springframework.web.bind.MissingServletRequestParameterException;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartException;
import org.springframework.web.servlet.NoHandlerFoundException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.sql.SQLException;
import java.util.Map;
/**
* 全局异常处理
* 一般情况下，方法都有异常处理机制，但不能排除有个别异常没有处理，导致返回到前台，因此在这里做一个异常拦截，统一处理那些未被处理过的异常
*
* @author ${author} on ${date}
*/
@ControllerAdvice
@Controller
@RequestMapping
public class GlobalExceptionHandler extends AbstractErrorController {
private static final Logger LOGGER = LoggerFactory.getLogger(GlobalExceptionHandler.class);
public GlobalExceptionHandler(ErrorAttributes errorAttributes) {
super(errorAttributes);
}
@Value("${server.error.path:${error.path:/error}}")
private static String errorPath = "/error";
/**
* sql异常
*
* @param req
* @param rsp
* @param ex
* @return
* @throws Exception
*/
@ResponseBody
@ExceptionHandler(SQLException.class)
public Result<String> sqlException(HttpServletRequest req, HttpServletResponse rsp, Exception ex) {
LOGGER.error("!!! request uri:{} from {} server exception:{}", req.getRequestURI(), RequestUtil.getIpAddress(req), ex == null ? null : ex);
return ResponseMsgUtil.builderResponse(1002, ex == null ? null : ex.getMessage(), null);
}
/**
* 500错误.
*
* @param req
* @param rsp
* @param ex
* @return
* @throws Exception
*/
@ResponseBody
@ResponseStatus(code = HttpStatus.INTERNAL_SERVER_ERROR)
@ExceptionHandler(Exception.class)
public Result<String> serverError(HttpServletRequest req, HttpServletResponse rsp, Exception ex) throws Exception {
LOGGER.error("!!! request uri:{} from {} server exception:{}", req.getRequestURI(), RequestUtil.getIpAddress(req), ex == null ? null : ex);
return ResponseMsgUtil.builderResponse(1002, ex == null ? null : ex.getMessage(), null);
}
/**
* 404的拦截.
*
* @param request
* @param response
* @param ex
* @return
* @throws Exception
*/
@ResponseBody
@ResponseStatus(code = HttpStatus.NOT_FOUND)
@ExceptionHandler(NoHandlerFoundException.class)
public Result<String> notFound(HttpServletRequest request, HttpServletResponse response, Exception ex) throws Exception {
LOGGER.error("!!! request uri:{} from {} not found exception:{}", request.getRequestURI(), RequestUtil.getIpAddress(request), ex);
return ResponseMsgUtil.builderResponse(404, ex == null ? null : ex.getMessage(), null);
}
@ExceptionHandler(MissingServletRequestParameterException.class)
@ResponseBody
public Result<String> paramException(MissingServletRequestParameterException ex) {
LOGGER.error("缺少请求参数:{}", ex.getMessage());
return ResponseMsgUtil.builderResponse(99999, "缺少参数:" + ex.getParameterName(), null);
}
//参数类型不匹配
//getPropertyName()获取数据类型不匹配参数名称
//getRequiredType()实际要求客户端传递的数据类型
@ExceptionHandler(TypeMismatchException.class)
@ResponseBody
public Result<String> requestTypeMismatch(TypeMismatchException ex) {
LOGGER.error("参数类型有误:{}", ex.getMessage());
return ResponseMsgUtil.builderResponse(99999, "参数类型不匹配,参数" + ex.getPropertyName() + "类型应该为" + ex.getRequiredType(), null);
}
@ExceptionHandler(HttpRequestMethodNotSupportedException.class)
@ResponseBody
public Result<String> requestMethod(HttpRequestMethodNotSupportedException ex) {
LOGGER.error("请求方式有误：{}", ex.getMethod());
return ResponseMsgUtil.builderResponse(99999, "请求方式有误:" + ex.getMethod(), null);
}
@ExceptionHandler(MultipartException.class)
@ResponseBody
public Result<String> fileSizeLimit(MultipartException m) {
LOGGER.error("超过文件上传大小限制");
return ResponseMsgUtil.builderResponse(99999, "超过文件大小限制,最大10MB", null);
}
/**
* 重写/error请求, ${server.error.path:${error.path:/error}} IDEA报红无需处理，作用是获取spring底层错误拦截
*
* @param request
* @param response
* @return
* @throws Exception
*/
@ResponseBody
@RequestMapping(value = "${server.error.path:${error.path:/error}}")
public Result<String> handleErrors(HttpServletRequest request, HttpServletResponse response) throws Exception {
HttpStatus status = getStatus(request);
if (status == HttpStatus.NOT_FOUND) {
throw new NoHandlerFoundException(request.getMethod(), request.getRequestURL().toString(), new HttpHeaders());
}
Map<String, Object> body = getErrorAttributes(request, true);
return ResponseMsgUtil.builderResponse(Integer.parseInt(body.get("status").toString()), body.get("message").toString(), null);
}
@Override
public String getErrorPath() {
return errorPath;
}
}
从上面可以看出来，我定义了sql异常，500异常，404异常该做的事情，通过@ExceptionHandler注解来拦截程序中的异常，比如执行SQL时，抛出了异常，就会被统一异常给拦截，然后返回我们想要返回的数据
@ResponseStatus注解可加可不加，就是对响应码进行拦截，如代码上，对404响应码进行了拦截
最下面的handleErrors方法，是对Spring底层访问/error的时候进行了一次拦截，获取当前请求码，如果是404.抛出404的异常
优化处理异常怎么能没有自定义返回数据呢
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.serializer.SerializerFeature;
/**
* 返回数据结果集合
*/
public class Result<T> {
private Integer code;
private String resMsg;
private T data;
public Result() {
}
public Integer getCode() {
return this.code;
}
public void setCode(Integer resCode) {
this.code = resCode;
}
public String getResMsg() {
return this.resMsg;
}
public void setResMsg(String resMsg) {
this.resMsg = resMsg;
}
public T getData() {
return this.data;
}
public void setData(T data) {
this.data = data;
}
public String toJson() {
return this.data == null ? JSON.toJSONString(this) : this.toJson(SerializerFeature.WriteNullListAsEmpty, SerializerFeature.WriteNullStringAsEmpty, SerializerFeature.WriteMapNullValue);
}
public String toJson(SerializerFeature... features) {
return features == null ? this.toJson() : JSON.toJSONString(this, features);
}
public String toString() {
return "Result{code=" + this.code + ", resMsg='" + this.resMsg + '\'' + ", data=" + this.data + '}';
}
}
/**
* 返回数据结果集合
* @author RuXuanWo on 2019/02/21
*/
public class ResponseMsgUtil {
public ResponseMsgUtil() {
}
public static <T> Result<T> builderResponse(int code, String msg, T data) {
Result<T> res = new Result();
res.setCode(code);
res.setResMsg(msg);
res.setData(data);
return res;
}
public static <T> Result<T> success(String msg) {
return builderResponse(0, msg, null);
}
public static <T> Result<T> success(String msg, T data) {
return builderResponse(0, msg, data);
}
public static <T> Result<T> success(T data) {
return builderResponse(0, "Success", data);
}
public static <T> Result<T> success() {
return builderResponse(0, "Success", null);
}
public static <T> Result<T> failure() {
return builderResponse(1, "Failure", null);
}
public static <T> Result<T> failure(String msg) {
return builderResponse(1, msg, null);
}
public static <T> Result<T> failure(T date) {
return builderResponse(-1, "Failure", date);
}
public static <T> Result<T> illegalRequest() {
return builderResponse(1008, "Illegal request", (T) null);
}
public static <T> Result<T> exception() {
return builderResponse(1002, "request exception", (T) null);
}
public static <T> Result<T> paramsEmpty() {
return builderResponse(1009, "the input parameter is null", (T) null);
}
}
测试
将这些准备都做好以后，项目跑起来，访问一个接口，故意不传某个必填项，就会被统一异常拦截，如下
{
code: 1002,
data: null,
msg: "Required String parameter 'id' is not present"
}
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