1. spring-mvc.xml

<bean id="fastJsonHttpMessageConverter" class="com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter4">
        <property name="defaultCharset" value="UTF-8"/>
        <property name="supportedMediaTypes">
            <list>
                <!-- 这里顺序不能反，一定先写text/html,不然ie下出现下载提示 -->
                <value>text/html;charset=UTF-8</value>
                <value>application/json;charset=UTF-8</value>
            </list>
        </property>
        <property name="fastJsonConfig">
            <bean class="com.alibaba.fastjson.support.config.FastJsonConfig">
                <!-- 默认编码 -->
                <property name="charset" value="UTF-8"/>
                <!-- 日期格式化 -->
                <property name="dateFormat" value="yyyy-MM-dd HH:mm:ss"/>
                <!-- 序列化配置 -->
                <property name="serializerFeatures">
                    <array value-type="com.alibaba.fastjson.serializer.SerializerFeature">
                        <!-- 输出key时是否使用双引号,默认为true -->
                        <value>QuoteFieldNames</value>
                        <!-- 避免循环引用 -->
                        <value>DisableCircularReferenceDetect</value>
                        <!-- 是否输出值为null的字段 -->
                        <value>WriteMapNullValue</value>
                        <!-- 数值字段如果为null,输出为0,而非null -->
                        <value>WriteNullNumberAsZero</value>
                        <!-- 字符类型字段如果为null,输出为"",而非null -->
                        <value>WriteNullStringAsEmpty</value>
                        <!-- list字段如果为null,输出为[],而非null -->
                        <value>WriteNullListAsEmpty</value>
                        <!-- boolean字段如果为null,输出为false,而非null -->
                        <value>WriteNullBooleanAsFalse</value>
                        <!-- 设置使用文本方式输出日期，fastjson默认是long -->
                        <value>WriteDateUseDateFormat</value>
                        <!-- 兼容 IE6 -->
                        <value>BrowserCompatible</value>
                    </array>
                </property>

                <!-- SerializeFilter -->
                <property name="serializeFilters">
                    <list>
                        <bean class="com.zxk175.ssm.common.util.json.FastJsonValueFilter"/>
                    </list>
                </property>
            </bean>
        </property>
    </bean>

2. FastJsonValueFilter

public class FastJsonValueFilter implements ValueFilter {
    /**
     * fastjson 值过滤器
     */
    @Override
    public Object process(Object object, String name, Object value) {
        if (value == null)
            return "";
        return value;
    }
}