216 lines
5.4 KiB
Markdown
216 lines
5.4 KiB
Markdown
## 统一异常处理
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### 后端异常处理
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在开发过程中，不可避免的是需要处理各种异常，异常处理方法随处可见，所以代码中就会出现大量的`try {...} catch {...} finally {...}` 代码块，不仅会造成大量的冗余代码，而且还影响代码的可读性，所以对异常统一处理非常有必要。为此，我们定义了一个统一的异常类`LuckException` 与异常管理类 `DefaultExceptionHandlerConfig`。
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我们先来看下 `LuckException`的代码
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```java
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public class LuckException extends RuntimeException {
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private static final long serialVersionUID = 1L;
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private Object object;
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/**
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* 响应状态码枚举
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*/
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private ResponseEnum responseEnum;
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public LuckException(String msg) {
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super(msg);
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}
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public LuckException(String msg, Object object) {
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super(msg);
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this.object = object;
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}
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public LuckException(String msg, Throwable cause) {
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super(msg, cause);
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}
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public LuckException(ResponseEnum responseEnum) {
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super(responseEnum.getMsg());
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this.responseEnum = responseEnum;
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}
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public LuckException(ResponseEnum responseEnum,Object object) {
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super(responseEnum.getMsg());
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this.responseEnum = responseEnum;
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this.object = object;
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}
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public Object getObject() {
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return object;
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}
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public ResponseEnum getResponseEnum() {
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return responseEnum;
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}
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}
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```
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`ResponseEnum`为我们自定义的返回状态码的枚举类，定义为一个枚举类，更直观处理异常返回的状态码及异常内容，以后每增加一种异常情况，只需增加一个枚举实例即可，不用每一种异常都定义一个异常类。
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```java
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public enum ResponseEnum {
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/**
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* ok
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*/
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OK("00000", "ok"),
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/**
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* 用于直接显示提示用户的错误，内容由输入内容决定
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*/
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SHOW_FAIL("A00001", ""),
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/**
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* 方法参数没有校验，内容由输入内容决定
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*/
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METHOD_ARGUMENT_NOT_VALID("A00002", ""),
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/**
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* 无法读取获取请求参数
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*/
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HTTP_MESSAGE_NOT_READABLE("A00003", "请求参数格式有误"),
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/**
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* 未授权
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*/
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UNAUTHORIZED("A00004", "Unauthorized"),
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/**
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* 服务器出了点小差
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*/
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EXCEPTION("A00005", "服务器出了点小差");
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private final String code;
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private final String msg;
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public String value() {
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return code;
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}
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public String getMsg() {
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return msg;
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}
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ResponseEnum(String code, String msg) {
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this.code = code;
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this.msg = msg;
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}
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@Override
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public String toString() {
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return "ResponseEnum{" + "code='" + code + '\'' + ", msg='" + msg + '\'' + "} " + super.toString();
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}
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}
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```
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再来看看 `DefaultExceptionHandlerConfig`类
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```java
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@RestController
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@RestControllerAdvice
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public class DefaultExceptionHandlerConfig {
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private static final Logger logger = LoggerFactory.getLogger(DefaultExceptionHandlerConfig.class);
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@ExceptionHandler(LuckException.class)
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public ResponseEntity<ServerResponseEntity<Object>> luckExceptionHandler(LuckException e) {
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logger.error("mall4cloudExceptionHandler", e);
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ResponseEnum responseEnum = e.getResponseEnum();
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// 失败返回失败消息 + 状态码
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if (responseEnum != null) {
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return ResponseEntity.status(HttpStatus.OK).body(ServerResponseEntity.fail(responseEnum, e.getObject()));
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}
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// 失败返回消息 状态码固定为直接显示消息的状态码
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return ResponseEntity.status(HttpStatus.OK).body(ServerResponseEntity.showFailMsg(e.getMessage()));
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}
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}
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```
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---
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### 前端异常处理
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前端请求与相应做了封装，请求响应的内容会被拦截器所拦截，当后台返回给前台特定的状态码，前台将显示不同报错信息。请求响应非常常见，我们查看在`src\utils\request.js`里面的其中一段代码
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```javascript
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service.interceptors.response.use(
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response => {
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const res = response.data
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if (res.code === '00000') {
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return res.data
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}
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// A00001 用于直接显示提示用户的错误，内容由输入内容决定
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// A00003 无法读取获取请求参数
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if (res.code === 'A00001' || res.code === 'A00003' || res.code === 'A00005') {
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Message({
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message: res.msg || 'Error',
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type: 'error',
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duration: 1.5 * 1000
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})
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return Promise.reject(res)
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}
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// A00002 方法参数没有校验，内容由输入内容决定
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if (res.code === 'A00002') {
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if (res.data && res.data.length) {
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res.data.forEach(errorMsg => {
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Message({
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message: errorMsg || 'Error',
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type: 'error',
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duration: 1.5 * 1000
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})
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})
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} else {
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Message({
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message: res.msg || 'Error',
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type: 'error',
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duration: 1.5 * 1000
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})
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}
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return Promise.reject()
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}
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// A00004 未授权
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if (res.code === 'A00004') {
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// to re-login
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MessageBox.confirm('您已注销，您可以取消停留在该页上，或重新登录', '确认注销', {
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confirmButtonText: '重新登陆',
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cancelButtonText: '取消',
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type: 'warning'
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}).then(() => {
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store.dispatch('user/resetToken').then(() => {
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location.reload()
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})
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})
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return Promise.reject()
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}
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return Promise.reject(res)
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},
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error => {
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console.log('err' + error) // for debug
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Message({
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message: error.message,
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type: 'error',
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duration: 1.5 * 1000
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})
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return Promise.reject(error)
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}
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)
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```
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这里将会统一拦截返回的状态码如`A00001`，进行错误提示。
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