SpringBoot：使用SpringBoot2.0开发Web应用时如何处理全局异常

深碍√TFBOYSˉ_ 2024-04-18 10:52 58阅读 0赞

**目录**

一、如何知道客户端可以处理什么格式的数据

二、使用@ControllerAdvice来统一处理全局异常

三、定义处理/error的Controller

--------------------

在使用Spring开发WEB应用时，一般需要定义全局异常处理器，对应用中抛出的异常统一进行处理。但此时面临的一个问题就是，生成的异常信息需要是客户端能够处理的格式：比如：

*  客户端只能处理json，那异常信息就应该是json格式。
 *  客户端需要一个错误页面，那异常信息就应该生成在一个错误页面上，再返回给客户端。

### 一、如何知道客户端可以处理什么格式的数据 ###

HTTP中定义了Accept请求头，客户端就是通过传递Accept的值，来告诉Web服务器它可以处理什么格式的数据的。

下面准备一个测试页面，此处使用freemarker作为模板引擎，测试页面为login.ftl

<!doctype html>
    <html lang="en">
    <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
    <link rel="stylesheet" href="${request.contextPath}/static/bootstrap/3.4.1/css/bootstrap.min.css"
    	integrity="sha384-HSMxcRTRxnN+Bdg0JdbxYKrThecOKuH5zCYotlSAcp1+c8xmyTe9GYg1l9a69psu" crossorigin="anonymous">
    <title>Hello, world!</title>
    </head>
    <body style="background: #d2d6de; text-align: center;">
    	<div class="container" style="max-width: 450px; margin: 5% auto;">
    		<div class="row">
    			<div class="col-md-12">
    				<h1 style="margin: 20px;">登录测试系统</h1>
    			</div>
    		</div>
    		<form id="submitForm" action="${request.contextPath}/sys/login" method="post" style="background: #fff; padding: 20px;">
    			<div class="row">
    				<div class="col-md-12">
    					<p>登录您的账号</p>
    					<div class="form-group has-feedback">
    						<input type="text" name="username" class="form-control" placeholder="账户"> <span
    							class="glyphicon glyphicon-envelope form-control-feedback"></span>
    					</div>
    					<div class="form-group has-feedback">
    						<input type="password" name="password" class="form-control" placeholder="密码"> <span
    							class="glyphicon glyphicon-lock form-control-feedback"></span>
    					</div>
    				</div>
    			</div>
    			<div class="row">
    				<div class="col-5 col-md-5">
    					<button id="submitBtn" type="button" class="btn btn-primary btn-block btn-flat">登录</button>
    				</div>
    			</div>
    		</form>
    	</div>
    	<script src="${request.contextPath}/static/jquery/3.4.1/jquery-3.4.1.min.js"></script>
    	<script src="${request.contextPath}/static/bootstrap/3.4.1/js/bootstrap.min.js"
    		integrity="sha384-aJ21OjlMXNL5UyIl/XNwTMqvzeRMZH2w8c5cRVpzpU8Y5bApTppSuUkhZXN0VxHd" crossorigin="anonymous"></script>
    </body>
    <script type="text/javascript">
    $("#submitBtn").click(function(){
    	$.ajax({
    	    url: "${request.contextPath}/sys/login",
    	    type: "POST",
    	    dataType: "json",
    	    data: $("#submitForm").serialize(),
    	    processData: false,
    	    success: function (data) {
        		alert(JSON.stringify(data));
    		// alert((new XMLSerializer()).serializeToString(data));
    		// alert(data);
    	    },
    	    error: function () {
    	        alert("error");
    	    }
    	});
    });
    </script>
    </html>

可以通过修改dataType的值，告诉WEB服务器应该返回什么格式的数据，常用值：json、text、html、xml、script等。以下是使用chrome发起请求时ACCEPT的值：

<table> 
 <tbody> 
  <tr> 
   <td style="width:91px;">Type</td> 
   <td>Accept</td> 
  </tr> 
  <tr> 
   <td style="width:91px;">xml</td> 
   <td>application/xml, text/xml, */*; q=0.01</td> 
  </tr> 
  <tr> 
   <td style="width:91px;">json</td> 
   <td>application/json, text/javascript, */*; q=0.01</td> 
  </tr> 
  <tr> 
   <td style="width:91px;">text</td> 
   <td>text/plain, */*; q=0.01</td> 
  </tr> 
  <tr> 
   <td style="width:91px;">html</td> 
   <td>text/html, */*; q=0.01</td> 
  </tr> 
  <tr> 
   <td style="width:91px;">script</td> 
   <td>text/javascript, application/javascript, application/ecmascript, application/x-ecmascript, */*; q=0.01</td> 
  </tr> 
 </tbody> 
</table>

以上页面是通过JQuery做异常提交，也可以改成form直接提交：

<!doctype html>
    <html lang="en">
    <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
    <link rel="stylesheet" href="${request.contextPath}/static/bootstrap/3.4.1/css/bootstrap.min.css"
    	integrity="sha384-HSMxcRTRxnN+Bdg0JdbxYKrThecOKuH5zCYotlSAcp1+c8xmyTe9GYg1l9a69psu" crossorigin="anonymous">
    <title>Hello, world!</title>
    </head>
    <body style="background: #d2d6de; text-align: center;">
    	<div class="container" style="max-width: 450px; margin: 5% auto;">
    		<div class="row">
    			<div class="col-md-12">
    				<h1 style="margin: 20px;">登录测试系统</h1>
    			</div>
    		</div>
    		<form id="submitForm" action="${request.contextPath}/sys/login" method="post" style="background: #fff; padding: 20px;">
    			<div class="row">
    				<div class="col-md-12">
    					<p>登录您的账号</p>
    					<div class="form-group has-feedback">
    						<input type="text" name="username" class="form-control" placeholder="账户"> <span
    							class="glyphicon glyphicon-envelope form-control-feedback"></span>
    					</div>
    					<div class="form-group has-feedback">
    						<input type="password" name="password" class="form-control" placeholder="密码"> <span
    							class="glyphicon glyphicon-lock form-control-feedback"></span>
    					</div>
    				</div>
    			</div>
    			<div class="row">
    				<div class="col-5 col-md-5">
    					<button id="submitBtn" type="submit" class="btn btn-primary btn-block btn-flat">登录</button>
    				</div>
    			</div>
    		</form>
    	</div>
    	<script src="${request.contextPath}/static/jquery/3.4.1/jquery-3.4.1.min.js"></script>
    	<script src="${request.contextPath}/static/bootstrap/3.4.1/js/bootstrap.min.js"
    		integrity="sha384-aJ21OjlMXNL5UyIl/XNwTMqvzeRMZH2w8c5cRVpzpU8Y5bApTppSuUkhZXN0VxHd" crossorigin="anonymous"></script>
    </body>
    </html>

使用chrome发起form提交时ACCEPT的值：

<table> 
 <tbody> 
  <tr> 
   <td style="width:63px;">Type</td> 
   <td>Accept</td> 
  </tr> 
  <tr> 
   <td style="width:63px;">form</td> 
   <td>text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3</td> 
  </tr> 
 </tbody> 
</table>

如何针对不同的ACCEPT值做不同的处理，下面举例说明如何解决这个问题。

### 二、使用@ControllerAdvice来统一处理全局异常 ###

import javax.servlet.http.HttpServletRequest;
    import org.springframework.web.bind.annotation.ControllerAdvice;
    import org.springframework.web.bind.annotation.ExceptionHandler;
    import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler;
    
    @ControllerAdvice
    public class GlobalControllerAdvice extends ResponseEntityExceptionHandler {
    	@ExceptionHandler
    	public String errorController(HttpServletRequest request, Throwable ex) {
    		request.setAttribute("exception", ex);
    
    		return "forward:/error";
    	}
    }

@ExceptionHandler默认会处理所有Throwable异常，在方法errorController中，将捕获的异常存放到HttpServletRequest中，然后使用forward:/error将请求转到可以处理/error的Controller中，forward表示将HttpServletRequest中的所有信息一起带入可以处理/error的Controller中。

### 三、定义处理/error的Controller ###

import java.util.HashMap;
    import java.util.Map;
    
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.RequestAttribute;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.ResponseBody;
    
    @RequestMapping("/")
    @Controller
    public class BaseController {
    	private static final Logger LOG = LoggerFactory.getLogger(BaseController.class);
    
    	@GetMapping("index.html")
    	public String doIndex() {
    		return "login";
    	}
    
    	@RequestMapping(value = "error", produces = { "text/html", "text/plain" })
    	public String handleErrorPage(@RequestAttribute("exception") Throwable ex) {
    		LOG.error("handlePage", ex);
    
    		return "index";
    	}
    
    	@RequestMapping(value = "error", produces = { "application/json" })
    	@ResponseBody
    	public Map<String, Object> handleErrorJson(@RequestAttribute("exception") Throwable ex) {
    		LOG.error("handleJson", ex);
    
    		Map<String, Object> retMap = new HashMap<>();
    		retMap.put("code", 200);
    		retMap.put("msg", ex.getMessage());
    
    		return retMap;
    	}
    	@RequestMapping(value = "error", produces = { "application/xml", "text/xml" })
    	public HttpEntity<Map<String, Object>> handleErrorXml(@RequestAttribute("exception") Throwable ex) {
    		LOG.error("handleErrorXml", ex);
    
    		Map<String, Object> retMap = new HashMap<>();
    		retMap.put("code", 200);
    		retMap.put("msg", ex.getMessage());
    
    		return ResponseEntity.status(HttpStatus.OK).body(retMap);
    	}
    }

其中，@RequestMapping中的produces表示客户端请求报文头中Accept的值，只有满足条件的才能由对应的异常处理方法处理。@RequestAttribute("exception")表示从HttpServletRequest中取出异常。

*  handleErrorPage可以针对text、html两种类型的请求，通过index.ftl，生成返回页面。
 *  handleErrorJson可以针对json类型的请求，生成json返回
 *  handleErrorXml可以针对xml类型的请求，生成xml返回

以上代码即可以针对form提交进行处理，也可以针对JQuery发起的异步请求做处理。如果需要生成xml或其它类型的数据，则可以添加相应的处理方法。

页面index.ftl的内容如下：

<!doctype html>
    <html lang="en">
    <head>
    
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
    <link rel="stylesheet" href="${request.contextPath}/bootstrap/4.3.1/css/bootstrap.min.css">
    <title>Hello, world!</title>
    </head>
    <body>
    	<h1>Hello, world!</h1>
    	<script src="${request.contextPath}/jquery/3.4.1/jquery-3.4.1.min.js"></script>
    	<script src="${request.contextPath}/bootstrap/4.3.1/js/bootstrap.bundle.min.js"></script>
    	<script src="${request.contextPath}/bootstrap/4.3.1/js/bootstrap.min.js"></script>
    </body>
    </html>

App.java内容如下：

import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.boot.autoconfigure.web.servlet.error.ErrorMvcAutoConfiguration;
    import org.springframework.context.ConfigurableApplicationContext;
    
    @SpringBootApplication
    @EnableAutoConfiguration(exclude = { ErrorMvcAutoConfiguration.class })
    public class App {
    
    	private static final Logger LOG = LoggerFactory.getLogger(App.class);
    
    	public static void main(String[] args) {
    		ConfigurableApplicationContext ctx = SpringApplication.run(App.class, args);
    		ctx.registerShutdownHook();
    
    		LOG.info("=========app started!=========");
    	}
    }

参考文档

[Spring Web MVC - 1.1.7. Exceptions][]  
[Spring Web MVC - 1.3.6. Exceptions][]  
[Spring Web MVC - 1.3.7. Controller Advice][]  
[Spring Boot Reference Guide - 29.2.5 Error Handling][]  
[jQuery ajax - ajax() 方法][jQuery ajax - ajax_]  
[Spring MVC - @ExceptionHandler based on Accept header][Spring MVC - _ExceptionHandler based on Accept header]

[Spring Web MVC - 1.1.7. Exceptions]: https://docs.spring.io/spring/docs/5.1.9.RELEASE/spring-framework-reference/web.html#mvc-exceptionhandlers
[Spring Web MVC - 1.3.6. Exceptions]: https://docs.spring.io/spring/docs/5.1.9.RELEASE/spring-framework-reference/web.html#mvc-ann-exceptionhandler
[Spring Web MVC - 1.3.7. Controller Advice]: https://docs.spring.io/spring/docs/5.1.9.RELEASE/spring-framework-reference/web.html#mvc-ann-controller-advice
[Spring Boot Reference Guide - 29.2.5 Error Handling]: https://docs.spring.io/spring-boot/docs/2.1.7.RELEASE/reference/html/boot-features-developing-web-applications.html#boot-features-webflux-error-handling
[jQuery ajax - ajax_]: https://www.w3school.com.cn/jquery/ajax_ajax.asp
[Spring MVC - _ExceptionHandler based on Accept header]: https://stackoverflow.com/questions/17322267/spring-mvc-exceptionhandler-based-on-accept-header