SpringMVC 访问Controller 报错:e No converter found for return value of type: class java.util.ArrayLis
程序员文章站
2022-03-26 22:33:59
...
1、controller方法如下:
@RequestMapping("/a2")
public List<User> ajaxtest(){
List<User> userList = new ArrayList<User>();
userList.add(new User("妗妗1",1,"女"));
userList.add(new User("妗妗12",2,"女"));
userList.add(new User("妗妗13",3,"女"));
User user4 = new User("妗妗14",1,"女");
System.out.println(userList);
return userList;
}
2、请求该方法,返回如下信息
3、经查明,是controller 不支持直接返回对象,可将java对象,转为json对象,再返回。
导入json包,并配置对象转换成json对象的配置后,可直接返回对象,具体步骤如下
(1)导入jackjson包
<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-core -->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.9.8</version>
</dependency>
(2)配置json乱码问题
<mvc:annotation-driven>
<mvc:message-converters register-defaults="true">
<bean class="org.springframework.http.converter.StringHttpMessageConverter">
<constructor-arg value="UTF-8"/>
</bean>
<bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
<property name="objectMapper">
<bean class="org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean">
<property name="failOnEmptyBeans" value="false"/>
</bean>
</property>
</bean>
</mvc:message-converters>
</mvc:annotation-driven>
4、再次方法该方法,正常。
@RequestMapping("/a2")
public List<User> ajaxtest(){
List<User> userList = new ArrayList<User>();
userList.add(new User("妗妗1",1,"女"));
userList.add(new User("妗妗12",2,"女"));
userList.add(new User("妗妗13",3,"女"));
User user4 = new User("妗妗14",1,"女");
System.out.println(userList);
return userList;
}