使用@responseBody遇见的异常

最新推荐文章于 2022-08-18 17:12:50 发布

原创最新推荐文章于 2022-08-18 17:12:50 发布 · 2k 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#spring

spring 同时被 2 个专栏收录

12 篇文章

订阅专栏

异常

6 篇文章

订阅专栏

本文介绍了一个使用Spring MVC中@ResponseBody注解返回JSON数据的例子，并详细展示了配置文件的设置及依赖库，帮助解决常见错误。

下面是一个使用@responseBody的小例子：
必须有正确spring配置文件：

<mvc:annotation-driven>
         <mvc:message-converters>
             <bean id="mappingJacksonHttpMessageConverter" class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">

                 <property name="objectMapper">
                     <bean class="com.fasterxml.jackson.databind.ObjectMapper">
                         <property name="dateFormat">
                             <bean class="java.text.SimpleDateFormat">
                                 <constructor-arg type="java.lang.String" value="yyyy-MM-dd HH:mm:ss"/>
                             </bean>
                         </property>
                     </bean>
                 </property>
             </bean>
             <!-- 解决乱码问题 -->
             <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>text/html;charset=UTF-8</value>   
                                   </list>   
                              </property>   
                           </bean>   
                       </list>   
                 </property>  
            </bean>
         </mvc:message-converters>
     </mvc:annotation-driven>

所需的maven的依赖库(必不可少)：

<dependencies>

        <dependency>
            <groupId>com.test1</groupId>
            <artifactId>subtest1</artifactId>
            <version>0.0.2-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>org.apache.axis2</groupId>
            <artifactId>axis2-adb</artifactId>
            <version>${axis2.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.axis2</groupId>
            <artifactId>axis2-transport-http</artifactId>
            <version>${axis2.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.axis2</groupId>
            <artifactId>axis2-transport-local</artifactId>
            <version>${axis2.version}</version>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>2.9.0.pr2</version>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-annotations</artifactId>
            <version>2.9.0.pr2</version>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.9.0.pr2</version>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <scope>provided</scope>
            <version>3.1.0</version>  
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>4.3.8.RELEASE</version>
        </dependency>

    </dependencies>

控制层代码：

import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import com.pojo.TestBean;

@Controller
public class ServiceC {

    @RequestMapping(value="/jsontest")  
    public @ResponseBody List<TestBean> getJSON() {  
        List<TestBean> testBean = new ArrayList<TestBean>();  
        testBean.add(TestBean.generateContent("ee", new Date(), "test", "test"));  
        testBean.add(TestBean.generateContent("ee", new Date(), "test", "test"));  
        testBean.add(TestBean.generateContent("ee", new Date(), "test", "test"));  
        testBean.add(TestBean.generateContent("呃呃", new Date(), "呃呃", "test"));  

        return testBean;  
    }  

}

在浏览器中访问：http://localhost:8080/（项目名）/jsontest，即可访问，页面中会返回一个上面testBean生成的json字符串

一. 浏览器返回406
@requestMapping中的注解参数可能有问题，它没有把返回值当成json处理。

二.浏览器返回500，javax.servlet.ServletException: Circular view path […]: would dispatch back to the current handler URL [/…] again. Check your ViewResolver setup! (Hint: This may be the result of an unspecified view, due to default view name generation.)
对照以上正确的例子，@responseBody要加上，配置文件里的内容要写对。这里注意，配置文件中的类是新版本的json处理包com.fasterxml.jackson.core中的MappingJackson2HttpMessageConverter，而不是MappingJacksonHttpMessageConverter。