springboot全局异常捕获处理

全局异常处理

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https://github.com/wangyuheng/spring-boot-sample

偷懒代码

偷懒是程序员的美德,但是有些偷懒是为了少写代码,有些则是少思考,直接copy。

不知道你有没有见过这种代码,在最外层catch Exception,避免抛出异常信息。。。

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@RestController
@RequestMapping("/user")
public class UserApi {

@Autowired
private UserService userService;

@GetMapping("/{id}")
public Object getInfo(@PathVariable("id") int id) {
try {
return userService.getUsernameById(id);
} catch (UserException) {
return "用户id异常";
} catch (Exception e) {
return "服务异常,请稍后再试!";
}
}

}

UserService用于模拟异常抛出

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@Service
public class UserService {

public String getUsernameById(long id) {
if (0 == id % 2) {
throw new IllegalArgumentException("error param!");
} else {
throw new UserException("custom exception!");
}
}
}

全局异常处理

自定义异常

通过自定义异常,区分业务异常,并增加errorCode支持,返回给接口调用方。

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public enum ErrorCode {
Error(10000, "服务异常"),
UserIdError(10001, "用户id异常");

private int code;
private String message;

ErrorCode(int code, String message) {
this.code = code;
this.message = message;
}

public int getCode() {
return code;
}

public String getMessage() {
return message;
}
}
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public class CustomException extends RuntimeException {

private int errorCode;

public CustomException(int errorCode, String message) {
super(message);
this.errorCode = errorCode;
}

public int getErrorCode() {
return errorCode;
}
}
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public class UserException extends CustomException {
public UserException(String message) {
super(ErrorCode.UserIdError.getCode(), message);
}

public UserException() {
super(ErrorCode.UserIdError.getCode(), ErrorCode.UserIdError.getMessage());
}
}

@ControllerAdvice

会应用到所有的Controller中的@RequestMapping注解的方法中,通过annotations = RestController.class指定代理的Controller类中。

@ExceptionHandler

用于捕获异常,@ExceptionHandler本身只能捕获当前类的异常信息,结合@ControllerAdvice可以捕获全部controller异常。

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@ControllerAdvice(annotations = RestController.class)
@ResponseBody
public class GlobalExceptionHandler {

private Map<String, Object> getErrorObject(int code, String message) {
Map<String, Object> error = new HashMap<>();
error.put("code", code);
error.put("message", message);
return error;
}

@ExceptionHandler(Exception.class)
public Object exceptionHandler() {
return getErrorObject(ErrorCode.Error.getCode(), ErrorCode.Error.getMessage());
}

@ExceptionHandler(CustomException.class)
public Object customException(CustomException e) {
return getErrorObject(e.getErrorCode(), e.getMessage());
}

}

优化代码

优化后的代码简洁了,无需每次try…catch,统一管理异常信息。

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@RestController
@RequestMapping("/user")
public class UserApi {

@Autowired
private UserService userService;

@GetMapping("/{id}")
public Object getInfo(@PathVariable("id") int id) {
return userService.getUsernameById(id);
}

}

测试

mockMvc请求api接口,判断返回值

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@RunWith(SpringRunner.class)
@SpringBootTest
public class UserApiTest {

private MockMvc mockMvc;

@Autowired
private WebApplicationContext context;

@Autowired
private UserApi userApi;

@Before
public void setup() {
mockMvc = MockMvcBuilders.webAppContextSetup(context).build();
}

private JSONObject getUserApiResult(int id) throws Exception {
String path = "/user/" + id;
return new JSONObject(mockMvc.perform(MockMvcRequestBuilders.get(path))
.andExpect(MockMvcResultMatchers.status().isOk())
.andDo(MockMvcResultHandlers.print())
.andReturn()
.getResponse()
.getContentAsString());
}

@Test
public void test_exception_handler() throws Exception {
int i = 1;
assertTrue(ErrorCode.UserIdError.getCode() == getUserApiResult(i).getInt("code"));
i++;
assertTrue(ErrorCode.Error.getCode() == getUserApiResult(i).getInt("code"));
}

}

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