SpringMVC杂记(七) Jackson与Hibernate LazyLoding无法正常工作解决方法

SpringMVC杂记(七) Jackson与Hibernate LazyLoding无法正常工作解决办法
SpringMVC杂记(七) Jackson与Hibernate LazyLoding无法正常工作解决办法

1) 如下代码

@Controller
@RequestMapping("/just")
public class TestController {

	@Resource
	private EmployeeDao dao;

	@ResponseBody
	@RequestMapping("/test")
	public List<Employee> test() {
		return dao.findAllEmployees();
	}
}

如果dao查找出来的列表中包含不完整的Entity最终SpringMVC会出现一个内部异常。

2) 有人写了一个插件专门来解决这个问题。

<dependency>
  <groupId>com.fasterxml</groupId>
  <artifactId>jackson-module-hibernate</artifactId>
  <version>0.7.0</version>
</dependency>

这里包含一个Moduel("com.fasterxml.jackson.module.hibernate.HibernateModule")实现，就像所有Jackson标准的Model注册一下就可以用了。

ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new HibernateModule());

3) 可以自己写一个ObjectMapper的子类注册给"org.springframework.http.converter.json.MappingJacksonHttpMessageConverter"

package com.wicresoft.jpo.demo.json;

import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.map.SerializationConfig.Feature;

import com.fasterxml.jackson.module.hibernate.HibernateModule;

public class HibernateAwareObjectMapper extends ObjectMapper {

	public HibernateAwareObjectMapper() {
		HibernateModule hm = new HibernateModule();
		registerModule(hm);
		configure(Feature.FAIL_ON_EMPTY_BEANS, false);
	}

	public void setPrettyPrint(boolean prettyPrint) {
		configure(Feature.INDENT_OUTPUT, prettyPrint);
	}
}

<mvc:annotation-driven conversion-service="conversion-service" validator="validator">
	<mvc:message-converters register-defaults="false">
		<bean class="org.springframework.http.converter.ByteArrayHttpMessageConverter" />
		<bean class="org.springframework.http.converter.FormHttpMessageConverter" />
		<bean class="org.springframework.http.converter.xml.SourceHttpMessageConverter" />
		<!-- 修改为以下配置即可 -->
		<bean class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter">
			<property name="objectMapper">
				<bean class="com.wicresoft.jpo.demo.json.HibernateAwareObjectMapper">
					<property name="prettyPrint" value="true" />
				</bean>
			</property>
		</bean>
		<bean class="org.springframework.http.converter.StringHttpMessageConverter" />
		<bean class="com.wicresoft.jpo.demo.http.converter.UTF8StringHttpMessageConverter" />
	</mvc:message-converters>
</mvc:annotation-driven>