使用 Spring @Value 时如何进行简单的 属性 验证
How to make simple property validation when using Spring @Value
我如何检查 ${service.property} 是否不是空字符串，如果是，抛出某种可读异常？它必须在 Bean 创建期间发生。
@Component
public class Service {
@Value("${service.property}")
private String property;
}
我正在寻找最简单 的方法（最少编写的代码）。如果使用注释会很棒。
我目前的解决方案是在 setter 中为 属性 执行 "handwritten" 验证，但是对于这么简单的事情来说代码有点太多了。
提示：我正在寻找使用 SpEL 的方法，因为我已经在 @Value 中使用它，但据我所知，它不会是 easy/clean。但可能忽略了一些东西。
澄清：预期的行为是，应用程序将不会启动。目标是确保所有属性都已设置，尤其是 字符串属性不为空 。错误应该说清楚，缺少什么。我不想设置任何默认值！用户必须全部设置。
你所拥有的一切都会奏效。如果您不在属性文件中包含 属性，您将在服务器启动时收到 org.springframework.beans.factory.BeanCreationException 异常。
Apr 22, 2015 9:47:37 AM org.apache.catalina.core.ApplicationContext log
SEVERE: StandardWrapper.Throwable
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'service': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'service': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private java.lang.String com.util.Service.property; nested exception is java.lang.IllegalArgumentException: Could not resolve placeholder 'service.property' in string value "${service.property}"
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessPropertyValues(CommonAnnotationBeanPostProcessor.java:306)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1146)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458)
另一种方法是使用 initProperty 来处理或设置值，在这里您可以抛出某种可读异常。
@Component
public class Service {
private String property;
@Autowired
public void initProperty(@Value("${service.property}") String property) {
if(property == null) {
// Error handling here
}
}
}
这真的取决于您是否希望您的应用程序启动而不管 属性 是否设置，如果没有，向日志或控制台抛出一个可读的异常，然后将其设置为默认值，或者如果您希望在服务器启动和 bean 创建时抛出错误。
我猜第三个选项是如果 none 是通过使用默认 setter 给出的值。
@Component
public class Service {
@Value("${service.property:'This is my default setter string'}")
private String property;
}
这是我的解决方案，只需将 class 放入您的代码中（只需修复 "my.package" 字符串）：
/**
* Validates the environment-dependent properties during application start. Finds all spring beans, which classes are in
* defined package, validates them and in case of error tries to log the property name (not class field name), taken
* from {@link Value} annotation.
*
* @author Tomasz
*/
@Component
public class ConfigurationChecker implements ApplicationListener<ContextRefreshedEvent> {
private static final Logger LOG = LoggerFactory.getLogger(ConfigurationChecker.class);
// this is a property, that is set in XML, so we bind it here to be found by checker. For properties wired directly in Beans using @Value just add validation constraints
@Value("${authorization.ldap.url}")
@NotBlank
private String ldapUrl;
private static final String FAIL_FAST_PROPERTY = "hibernate.validator.fail_fast";
private Validator validator = Validation.byDefaultProvider().configure().addProperty(FAIL_FAST_PROPERTY, "false")
.buildValidatorFactory().getValidator();
/**
* Performs the validation and writes all errors to the log.
*/
@SneakyThrows
@Override
public void onApplicationEvent(ContextRefreshedEvent event) {
LOG.info("Validating properties");
Set<ConstraintViolation<Object>> allViolations = new HashSet<>();
// Find all spring managed beans (including ConfigurationChecker)...
for (String beanName : event.getApplicationContext().getBeanDefinitionNames()) {
Object bean = event.getApplicationContext().getBean(beanName);
// ...but validate only ours.
if (bean.getClass().getCanonicalName().startsWith("my.package")) {
Set<ConstraintViolation<Object>> viol = this.validator.validate(bean);
LOG.info("Bean '" + beanName + "': " + (viol.isEmpty() ? " OK" : viol.size() + " errors found"));
allViolations.addAll(viol);
} else {
continue;
}
}
// if any error found...
if (allViolations.size() > 0) {
for (ConstraintViolation<Object> violation : allViolations) {
// ...extract "property.name" from field annotation like @Value("${property.name}")
String propertyName = violation.getLeafBean().getClass()
.getDeclaredField(violation.getPropertyPath().toString()).getAnnotation(Value.class).value();
propertyName = StringUtils.substring(propertyName, 2, -1);
// .. log it ..
LOG.error(propertyName + " " + violation.getMessage());
}
// ... and do not let the app start up.
throw new IllegalArgumentException("Invalid configuration detected. Please check the log for details.");
}
}
}
这里是测试：
@RunWith(EasyMockRunner.class)
public class ConfigurationCheckerTest extends EasyMockSupport {
@TestSubject
private ConfigurationChecker checker = new ConfigurationChecker();
@Mock
private ContextRefreshedEvent event;
@Mock
private ApplicationContext applicationContext;
@Test(expected = IllegalArgumentException.class)
public void test() {
expect(this.event.getApplicationContext()).andReturn(this.applicationContext).anyTimes();
expect(this.applicationContext.getBeanDefinitionNames()).andReturn(new String[] { "configurationChecker" });
expect(this.applicationContext.getBean("configurationChecker")).andReturn(this.checker);
replayAll();
this.checker.onApplicationEvent(this.event);
verifyAll();
}
}
您可以将组件用作 属性 占位符本身。然后您可以使用任何您想要的验证。
@Component
@Validated
@PropertySource("classpath:my.properties")
@ConfigurationProperties(prefix = "my")
public class MyService {
@NotBlank
private String username;
public void setUsername(String username) {
this.username = username;
}
...
}
您的 my.properties 文件将如下所示：
my.username=felipe
我如何检查 ${service.property} 是否不是空字符串，如果是，抛出某种可读异常？它必须在 Bean 创建期间发生。
@Component
public class Service {
@Value("${service.property}")
private String property;
}
我正在寻找最简单 的方法（最少编写的代码）。如果使用注释会很棒。
我目前的解决方案是在 setter 中为 属性 执行 "handwritten" 验证，但是对于这么简单的事情来说代码有点太多了。
提示：我正在寻找使用 SpEL 的方法，因为我已经在 @Value 中使用它，但据我所知，它不会是 easy/clean。但可能忽略了一些东西。
澄清：预期的行为是，应用程序将不会启动。目标是确保所有属性都已设置，尤其是 字符串属性不为空 。错误应该说清楚，缺少什么。我不想设置任何默认值！用户必须全部设置。
你所拥有的一切都会奏效。如果您不在属性文件中包含 属性，您将在服务器启动时收到 org.springframework.beans.factory.BeanCreationException 异常。
Apr 22, 2015 9:47:37 AM org.apache.catalina.core.ApplicationContext log
SEVERE: StandardWrapper.Throwable
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'service': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'service': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private java.lang.String com.util.Service.property; nested exception is java.lang.IllegalArgumentException: Could not resolve placeholder 'service.property' in string value "${service.property}"
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessPropertyValues(CommonAnnotationBeanPostProcessor.java:306)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1146)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458)
另一种方法是使用 initProperty 来处理或设置值，在这里您可以抛出某种可读异常。
@Component
public class Service {
private String property;
@Autowired
public void initProperty(@Value("${service.property}") String property) {
if(property == null) {
// Error handling here
}
}
}
这真的取决于您是否希望您的应用程序启动而不管 属性 是否设置，如果没有，向日志或控制台抛出一个可读的异常，然后将其设置为默认值，或者如果您希望在服务器启动和 bean 创建时抛出错误。
我猜第三个选项是如果 none 是通过使用默认 setter 给出的值。
@Component
public class Service {
@Value("${service.property:'This is my default setter string'}")
private String property;
}
这是我的解决方案，只需将 class 放入您的代码中（只需修复 "my.package" 字符串）：
/**
* Validates the environment-dependent properties during application start. Finds all spring beans, which classes are in
* defined package, validates them and in case of error tries to log the property name (not class field name), taken
* from {@link Value} annotation.
*
* @author Tomasz
*/
@Component
public class ConfigurationChecker implements ApplicationListener<ContextRefreshedEvent> {
private static final Logger LOG = LoggerFactory.getLogger(ConfigurationChecker.class);
// this is a property, that is set in XML, so we bind it here to be found by checker. For properties wired directly in Beans using @Value just add validation constraints
@Value("${authorization.ldap.url}")
@NotBlank
private String ldapUrl;
private static final String FAIL_FAST_PROPERTY = "hibernate.validator.fail_fast";
private Validator validator = Validation.byDefaultProvider().configure().addProperty(FAIL_FAST_PROPERTY, "false")
.buildValidatorFactory().getValidator();
/**
* Performs the validation and writes all errors to the log.
*/
@SneakyThrows
@Override
public void onApplicationEvent(ContextRefreshedEvent event) {
LOG.info("Validating properties");
Set<ConstraintViolation<Object>> allViolations = new HashSet<>();
// Find all spring managed beans (including ConfigurationChecker)...
for (String beanName : event.getApplicationContext().getBeanDefinitionNames()) {
Object bean = event.getApplicationContext().getBean(beanName);
// ...but validate only ours.
if (bean.getClass().getCanonicalName().startsWith("my.package")) {
Set<ConstraintViolation<Object>> viol = this.validator.validate(bean);
LOG.info("Bean '" + beanName + "': " + (viol.isEmpty() ? " OK" : viol.size() + " errors found"));
allViolations.addAll(viol);
} else {
continue;
}
}
// if any error found...
if (allViolations.size() > 0) {
for (ConstraintViolation<Object> violation : allViolations) {
// ...extract "property.name" from field annotation like @Value("${property.name}")
String propertyName = violation.getLeafBean().getClass()
.getDeclaredField(violation.getPropertyPath().toString()).getAnnotation(Value.class).value();
propertyName = StringUtils.substring(propertyName, 2, -1);
// .. log it ..
LOG.error(propertyName + " " + violation.getMessage());
}
// ... and do not let the app start up.
throw new IllegalArgumentException("Invalid configuration detected. Please check the log for details.");
}
}
}
这里是测试：
@RunWith(EasyMockRunner.class)
public class ConfigurationCheckerTest extends EasyMockSupport {
@TestSubject
private ConfigurationChecker checker = new ConfigurationChecker();
@Mock
private ContextRefreshedEvent event;
@Mock
private ApplicationContext applicationContext;
@Test(expected = IllegalArgumentException.class)
public void test() {
expect(this.event.getApplicationContext()).andReturn(this.applicationContext).anyTimes();
expect(this.applicationContext.getBeanDefinitionNames()).andReturn(new String[] { "configurationChecker" });
expect(this.applicationContext.getBean("configurationChecker")).andReturn(this.checker);
replayAll();
this.checker.onApplicationEvent(this.event);
verifyAll();
}
}
您可以将组件用作 属性 占位符本身。然后您可以使用任何您想要的验证。
@Component
@Validated
@PropertySource("classpath:my.properties")
@ConfigurationProperties(prefix = "my")
public class MyService {
@NotBlank
private String username;
public void setUsername(String username) {
this.username = username;
}
...
}
您的 my.properties 文件将如下所示：
my.username=felipe