@RequestMapping(value = {"/categories"}, method = RequestMethod.GET, headers = "Accept=application/json")
@ResponseBody
public ResponseEntity<String> getCategories() throws ParseException, UnsupportedEncodingException {

    List<Category> categories= postService.getCategories();

    HttpHeaders headers = new HttpHeaders();
    headers.add("Content-Type", "application/json; charset=utf-8");

    if (categories == null) {
        return new ResponseEntity<String>(headers, HttpStatus.NOT_FOUND);
    }

    return new ResponseEntity<String>(JSONResponseUtil.getJSONString(categories), headers, HttpStatus.OK);
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:jdbc="http://www.springframework.org/schema/jdbc"
xmlns:mybatis-spring="http://mybatis.org/schema/mybatis-spring"
xsi:schemaLocation="http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.0.xsd
    http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
    http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
    http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
    http://mybatis.org/schema/mybatis-spring http://mybatis.org/schema/mybatis-spring-1.2.xsd
    http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
    http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd">


<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
    <property name="driverClassName" value="oracle.jdbc.driver.OracleDriver" />
    <property name="url" value="jdbc:oracle:thin:@:1521:ORCL" />
    <property name="username" value="" />
    <property name="password" value="" />
    <property name="maxActive" value="20" />
    <property name="maxWait" value="6000" />
    <property name="poolPreparedStatements" value="true" />
    <property name="defaultAutoCommit" value="true" />
    <property name="initialSize" value="10" />
    <property name="maxIdle" value="20" />
    <property name="validationQuery" value="select sysdate from dual" />
    <property name="testWhileIdle" value="true" />
    <property name="timeBetweenEvictionRunsMillis" value="7200000" />
</bean>


<bean id="transactionManager"
    class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
    <property name="dataSource" ref="dataSource" />
</bean>


<bean id="sqlSessionFactoryBean" class="org.mybatis.spring.SqlSessionFactoryBean">
    <property name="typeAliasesPackage" value="acutls.model" />
    <property name="dataSource" ref="dataSource" />
    <property name="configLocation" value="/WEB-INF/mybatis-config.xml" />
    <property name="mapperLocations">
        <array>
            <value>classpath*:/acutls/mybatis/repository/mapper/**/*.xml</value>
        </array>
    </property>
</bean>

<bean id="sqlSessionTemplate" class="org.mybatis.spring.SqlSessionTemplate">
    <constructor-arg name="sqlSessionFactory" ref="sqlSessionFactoryBean" />
</bean>

<tx:annotation-driven transaction-manager="transactionManager" />

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/mvc    http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
    http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd">

<context:component-scan base-package="acutls" />

<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
</bean>
<context:annotation-config />
<mvc:annotation-driven/>
<mvc:resources location="/UploadedImage/" mapping="/UploadedImage/**"/>
<mvc:resources location="/resources/" mapping="/resources/**"/>

 <mvc:view-controller path="/Login" view-name="/resources/templates/login.html"/>
<mvc:view-controller path="/" view-name="/resources/templates/index.html"/>

<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
    <property name="messageConverters">
        <list>
            <bean class="org.springframework.http.converter.StringHttpMessageConverter">
                <property name="supportedMediaTypes">
                    <list>
                        <value>application/json;charset=utf-8</value>
                        <value>application/json</value>
                    </list>
                </property>
            </bean>
        </list>
    </property>
</bean>


</beans>