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。
正文 1. 创建项目利用 Spring Initializer 创建一个 gradle 项目 spring-boot-global-exception-handle创建时添加相关依赖。得到的初始 build.gradle 如下
buildscript {
ext {
springBootVersion = '2.0.3.RELEASE'
}
repositories {
mavenCentral()
}
dependencies {
classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
}
}
apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'org.springframework.boot'
apply plugin: 'io.spring.dependency-management'
group = 'io.ostenant.springboot.sample'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = 1.8
repositories {
mavenCentral()
}
dependencies {
compile('org.springframework.boot:spring-boot-starter-web')
compile('org.projectlombok:lombok')
compile('org.apache.commons:commons-lang3:3.1')
compile('com.google.guava:guava:19.0')
testCompile('org.springframework.boot:spring-boot-starter-test')
}
@SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
首先安装 Intellij Idea 的 lombok 插件这里不做详细的介绍。切记需要在设置中将 Enable annotation processing 勾选上否则 测试代码 在 编译时 会无法对 lombok 插件配置的 注解 进行处理。
使用 lombok 工具提供的 注解 配置一个实体类
import lombok.Data;
@Data
public class User implements Serializable {
private Long id;
private String username;
private String accountName;
}
ErrorMessage 实体用于记录具体的 异常信息并响应 客户端。
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;
import lombok.ToString;
@NoArgsConstructor
@Setter
@Getter
@ToString
public class ErrorMessage {
public static final Integer OK = 0;
public static final Integer ERROR = 100;
private Integer code;
private String message;
private String url;
private T data;
}
SessionNotFoundException.java
public class SessionNotFoundException extends Exception {
@Getter
@Setter
protected String message;
public SessionNotFoundException() {
setMessage("Session is not found!");
}
public SessionNotFoundException(String message) {
this.message = message;
}
}
NullOrEmptyException.java
public class NullOrEmptyException extends Exception {
@Getter
@Setter
protected String message;
public NullOrEmptyException() {
setMessage("Parameter is null or empty!");
}
public NullOrEmptyException(String message) {
this.message = message;
}
}
IllegalPropertiesException.java
public class IllegalPropertiesException extends Exception {
@Getter
@Setter
protected String message;
public IllegalPropertiesException() {
setMessage("Prop is illegal!");
}
public IllegalPropertiesException(String message) {
this.message = message;
setMessage(String.format("Prop: %s is illegal!", message));
}
}
从 spring 3.2 开始新增了 @ControllerAdvice 注解可以用于定义 @ExceptionHandler并应用到配置了 @RequestMapping 的控制器中。
@ControllerAdvice
public class GlobalExceptionHandler {
@ExceptionHandler(SessionNotFoundException.class)
@ResponseBody
public ErrorMessage sessionNotFoundExceptionHandler(HttpServletRequest request, SessionNotFoundException exception) throws Exception {
return handleErrorInfo(request, exception.getMessage(), exception);
}
@ExceptionHandler(NullOrEmptyException.class)
@ResponseBody
public ErrorMessage nullOrEmptyExceptionHandler(HttpServletRequest request, NullOrEmptyException exception) throws Exception {
return handleErrorInfo(request, exception.getMessage(), exception);
}
@ExceptionHandler(IllegalPropertiesException.class)
@ResponseBody
public ErrorMessage illegalPropExceptionHandler(HttpServletRequest request, IllegalPropertiesException exception) throws Exception {
return handleErrorInfo(request, exception.getMessage(), exception);
}
@ExceptionHandler(Exception.class)
@ResponseBody
public ErrorMessage exceptionHandler(HttpServletRequest request, Exception exception) throws Exception {
return handleErrorInfo(request, exception.getMessage(), exception);
}
private ErrorMessage handleErrorInfo(HttpServletRequest request, String message, Exception exception) {
ErrorMessage errorMessage = new ErrorMessage<>();
errorMessage.setMessage(message);
errorMessage.setCode(ErrorMessage.ERROR);
errorMessage.setData(message);
errorMessage.setUrl(request.getRequestURL().toString());
return errorMessage;
}
}
上述代码指定了 3 个 特定 的异常处理器和 1 个 默认 的异常处理器。当请求处理出现异常时会根据 异常处理器 的 配置顺序 依次尝试 异常匹配 和 处理。
当异常不在 SessionNotFoundException、NullOrEmptyException、IllegalPropertiesException 中时Spring 会委托 默认 的 exceptionHandler 进行处理。
7. 配置控制器根据请求数据的差异控制器能覆盖以上 3 种异常处理路径。
@RestController
public class UserController {
@PostMapping("user")
public ResponseEntity save(HttpServletRequest request, HttpSession session) throws Exception {
String sessionId = (String) session.getAttribute("sessionId");
if (StringUtils.isBlank(sessionId)) {
throw new SessionNotFoundException();
}
String userPlainText = request.getParameter("user");
if (StringUtils.isBlank(userPlainText) || StringUtils.equalsIgnoreCase("{}", userPlainText)) {
throw new NullOrEmptyException();
}
ObjectMapper objectMapper = new ObjectMapper();
User user = objectMapper.readValue(userPlainText, User.class);
if (StringUtils.isBlank(user.getUsername())) {
throw new IllegalPropertiesException("username");
}
if (StringUtils.isBlank(user.getAccountName())) {
throw new IllegalPropertiesException("accountName");
}
return ResponseEntity.ok("Successful");
}
}
Spring Mock 的相关配置这里就不详细介绍了以下测试类覆盖了 UserController 的所有执行路径。
@RunWith(SpringJUnit4ClassRunner.class)
@SpringBootApplication
@WebAppConfiguration
@Slf4j(topic = "UserControllerTester")
public class ApplicationTests {
@Autowired
private WebApplicationContext context;
private MockMvc mockMvc;
private MockHttpSession session;
@Autowired
private UserController userController;
private ImmutableMap> map = new ImmutableMap.Builder>()
.put(0x00001L, Pair.of("user", ""))
.put(0x00002L, Pair.of("user", "{}"))
.put(0x00003L, Pair.of("user", "{"username": "", "accountName": ""}"))
.put(0x00004L, Pair.of("user", "{"username": "Harrison", "accountName": ""}"))
.put(0x00005L, Pair.of("user", "{"username": "Harrison", "accountName": "ostenant"}"))
.build();
@Before
public void setUp() throws Exception {
boolean singleRunner = false;
if (singleRunner) {
this.mockMvc = MockMvcBuilders.standaloneSetup(userController).build();
} else {
this.mockMvc = MockMvcBuilders.webAppContextSetup(context).build();
}
session = new MockHttpSession();
session.setAttribute("sessionId", StringUtils.replace(UUID.randomUUID().toString(), "-", ""));
log.debug("sessionId: {}", session.getAttribute("sessionId"));
}
@Test
public void testSessionNotFoundException() throws Exception {
session.clearAttributes();
// 模拟发送请求
mockMvc.perform(
MockMvcRequestBuilders.post("/user")
.param(map.get(0x00005L).getKey(), map.get(0x00005L).getValue())
.session(session))
.andExpect(MockMvcResultMatchers.handler().handlerType(UserController.class))
.andExpect(MockMvcResultMatchers.handler().methodName(("save")))
.andDo(MockMvcResultHandlers.print())
.andReturn();
}
@Test
public void testNullOrEmptyException() throws Exception {
mockMvc.perform(
MockMvcRequestBuilders.post("/user")
.param(map.get(0x00001L).getKey(), map.get(0x00001L).getValue())
.session(session))
.andExpect(MockMvcResultMatchers.handler().handlerType(UserController.class))
.andExpect(MockMvcResultMatchers.handler().methodName(("save")))
.andDo(MockMvcResultHandlers.print())
.andReturn();
mockMvc.perform(
MockMvcRequestBuilders.post("/user")
.param(map.get(0x00002L).getKey(), map.get(0x00002L).getValue())
.session(session))
.andExpect(MockMvcResultMatchers.handler().handlerType(UserController.class))
.andExpect(MockMvcResultMatchers.handler().methodName(("save")))
.andDo(MockMvcResultHandlers.print())
.andReturn();
}
@Test
public void testIllegalPropException() throws Exception {
mockMvc.perform(
MockMvcRequestBuilders.post("/user")
.param(map.get(0x00003L).getKey(), map.get(0x00003L).getValue())
.session(session))
.andExpect(MockMvcResultMatchers.handler().handlerType(UserController.class))
.andExpect(MockMvcResultMatchers.handler().methodName(("save")))
.andDo(MockMvcResultHandlers.print())
.andReturn();
mockMvc.perform(
MockMvcRequestBuilders.post("/user")
.param(map.get(0x00004L).getKey(), map.get(0x00004L).getValue())
.session(session))
.andExpect(MockMvcResultMatchers.handler().handlerType(UserController.class))
.andExpect(MockMvcResultMatchers.handler().methodName(("save")))
.andDo(MockMvcResultHandlers.print())
.andReturn();
}
@Test
public void testNormal() throws Exception {
mockMvc.perform(
MockMvcRequestBuilders.post("/user")
.param(map.get(0x00005L).getKey(), map.get(0x00005L).getValue())
.session(session))
.andExpect(MockMvcResultMatchers.handler().handlerType(UserController.class))
.andExpect(MockMvcResultMatchers.handler().methodName(("save")))
.andDo(MockMvcResultHandlers.print())
.andReturn();
}
}
批量运行测试测试结果如下所有的测试用例全部通过。
小结使用 @ControllerAdvice 处理异常也有一定的 局限性。只有进入 Controller 层的错误才会由 @ControllerAdvice 处理。拦截器 抛出的错误以及 访问错误地址 的情况 @ControllerAdvice 处理不了由 Spring Boot 默认的 异常处理机制 处理。
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