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问题:
I'm trying to cast the output of a value to an integer:
@Value("${api.orders.pingFrequency}")
private Integer pingFrequency;
The above throws the error
org.springframework.beans.TypeMismatchException:
Failed to convert value of type 'java.lang.String' to required type 'java.lang.Integer';
nested exception is java.lang.NumberFormatException:
For input string: "(java.lang.Integer)${api.orders.pingFrequency}"
I've also tried @Value("(java.lang.Integer)${api.orders.pingFrequency}")
Google doesn't appear to say much on the subject. I'd like to always be dealing with an integer instead of having to parse this value everywhere it's used.
Workaround
I realize a workaround may be to use a setter method to run the conversion for me, but if Spring can do it I'd rather learn something about Spring.
回答1:
Assuming you have a properties file on your classpath that contains
api.orders.pingFrequency=4
I tried inside a @Controller
@Controller
public class MyController {
@Value("${api.orders.pingFrequency}")
private Integer pingFrequency;
...
}
With my servlet context containing :
<context:property-placeholder location="classpath:myprops.properties" />
It worked perfectly.
So either your property is not an integer type, you don't have the property placeholder configured correctly, or you are using the wrong property key.
I tried running with an invalid property value, 4123;
. The exception I got is
java.lang.NumberFormatException: For input string: "4123;"
which makes me think the value of your property is
api.orders.pingFrequency=(java.lang.Integer)${api.orders.pingFrequency}
回答2:
I was looking for the answer on internet and I found the following
@Value("#{new java.text.SimpleDateFormat('${aDateFormat}').parse('${aDateStr}')}")
Date myDate;
So in your case you could try with this
@Value("#{new Integer.parseInt('${api.orders.pingFrequency}')}")
private Integer pingFrequency;
回答3:
If you want to convert a property to an integer from properties file there are 2 solutions which I found:
Given scenario: customer.properties contains customer.id = 100 as a field and you want to access it in spring configuration file as integer.The property customerId is declared as type int in the Bean Customer
Solution 1:
<property name="customerId" value="#{T(java.lang.Integer).parseInt('${customer.id}')}" />
In the above line, the string value from properties file is converted to int type.
solution 2: Use some other extension inplace of propeties.For Ex.- If your properties file name is
customer.properties then make it customer.details and in the configuration file use the below code
<property name="customerId" value="${customer.id}" />
回答4:
I had the exact same situation. It was caused by not having a PropertySourcesPlaceholderConfigurer in the Spring context, which resolves values against the @Value
annotation inside of classes.
Include a property placeholder to solve the problem, no need to use Spring expressions for integers (the property file does not have to exist if you use ignore-resource-not-found="true"
):
<context:property-placeholder location="/path/to/my/app.properties"
ignore-resource-not-found="true" />
回答5:
I had the same issue I solved using this. Refer this Spring MVC: @Value annotation to get int value defined in *.properties file
@Value(#{propertyfileId.propertyName})
works
回答6:
If you are using @Configuation then instantiate below static bean. If not static @Configutation is instantiated very early and and the BeanPostProcessors responsible for resolving annotations like @Value, @Autowired etc, cannot act on it. Refer here
@Bean
public static PropertySourcesPlaceholderConfigurer propertyConfigurer() {
return new PropertySourcesPlaceholderConfigurer();
}
回答7:
This problem also occurs when you have 2 resources with the same file name; say "configurations.properties" within 2 different jar or directory path configured within the classpath. For example:
You have your "configurations.properties" in your process or web application (jar, war or ear). But another dependency (jar) have the same file "configurations.properties" in the same path. Then I suppose that Spring have no idea (@_@?) where to get the property and just sends the property name declared within the @Value annotation.
回答8:
In my case, the problem was that my POST request was sent to the same url as GET (with get parameters using "?..=..") and that parameters had the same name as form parameters. Probably Spring is merging them into an array and parsing was throwing error.
回答9:
when use @Value, you should add @PropertySource annotation on Class, or specify properties holder in spring's xml file.
eg.
@Component
@PropertySource("classpath:config.properties")
public class BusinessClass{
@Value("${user.name}")
private String name;
@Value("${user.age}")
private int age;
@Value("${user.registed:false}")
private boolean registed;
}
config.properties
user.name=test
user.age=20
user.registed=true
this works!
Of course, you can use placeholder xml configuration instead of annotation.
spring.xml
<context:property-placeholder location="classpath:config.properties"/>