How to return JSON data from spring Controller using @ResponseBody

问题

Spring version 4.2.0, Hibernate 4.1.4 Here is my Controller function:

@RequestMapping(value = \"/mobile/getcomp\", method = RequestMethod.GET)
@ResponseBody
public List<Company>  listforCompanies() {      
    List<Company> listOfCompanies= new ArrayList<Company>();        
    listOfCompanies = companyManager.getAllCompanies();
    return listOfCompanies;
}

Jackson JSON mapper dependency in Pom.xml:

    <!-- Jackson JSON Mapper -->
    <dependency>
        <groupId>org.codehaus.jackson</groupId>
        <artifactId>jackson-mapper-asl</artifactId>
        <version>${jackson.version}</version>
    </dependency>

Getting the list in my ArrayList, but when returning the following error is shown:

SEVERE: Servlet.service() for servlet [dispatcherServlet] in context with path [/IrApp] threw exception [Request processing failed; nested exception is java.lang.IllegalArgumentException: No converter found for return value of type: class java.util.ArrayList] with root cause
    java.lang.IllegalArgumentException: No converter found for return value of type: class java.util.ArrayList
        at org.springframework.util.Assert.isTrue(Assert.java:68)
        at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:124)

Link to the example I\'m following.

回答1:

Add the below dependency to your pom.xml:

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.5.0</version>
</dependency>

回答2:

I was facing same issue. I did not put @ResponseBody since I was using @RestController. But still I was getting error because I did not put the getter/setter method for the Company class. So after putting the getter/setter my problem was resolved.

回答3:

You also need to be sure that returned bean is not empty (and can be serialized by Jackson). In my particular case I tried to return an instance of an object without getters and setters and without any jackson annotation and with fields equals to null. I got following message:

com.fasterxml.jackson.databind.JsonMappingException:
    No serializer found for class com.foo.bar.Baz and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) )

回答4:

When I was facing this issue, I simply put just getter setter methods and my issues were resolved.

I am using Spring boot version 2.0.

回答5:

Considering @Arpit answer, for me it worked only when I add two jackson dependencies:

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-core</artifactId>
    <version>2.4.3</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.4.3</version>
</dependency>

and configured, of cause, web.xml <mvc:annotation-driven/>.

Original answer that helped me is here: https://stackoverflow.com/a/33896080/3014866

回答6:

I was using groovy+springboot and got this error.

Adding getter/setter is enough if we are using below dependency.

implementation 'org.springframework.boot:spring-boot-starter-web'

As Jackson core classes come with it.

回答7:

In my case I was using jackson-databind-2.8.8.jar that is not compatible with JDK 1.6 I need to use so Spring wasn't loading this converter. I downgraded the version and it works now.

来源：https://stackoverflow.com/questions/32905917/how-to-return-json-data-from-spring-controller-using-responsebody

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java

json

Spring

spring-mvc

spring-4