java - jackson 没工作？

Question

所以我有这个 spring mvc 应用程序正在努力做我想做的事情。它看起来像这样:

import com.jensen.neural.app.MyRequest;
import com.jensen.neural.app.NeuralResponse;
import com.jensen.neural.app.NumberCruncher;
import com.jensen.neural.app.TrainingResults;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
@RequestMapping("/neural")
public class NeuralController
{
    @Autowired
    NumberCruncher numberCruncher;

    @ResponseBody
    @RequestMapping(value="number", method = RequestMethod.POST, consumes = "application/json")
    public String getNumber(@RequestBody MyRequest myRequest)
    {
        NeuralResponse neuralResponse = new NeuralResponse();
        neuralResponse.setStr("SLDKFJSD");
//      return neuralResponse;
        return "RESPONSE";
    }



    @RequestMapping(value = "train", method = RequestMethod.GET)
    @ResponseBody
    public TrainingResults train()
    {
        return numberCruncher.train();
    }
}

我发现:如果我将签名更改为 public public String getNumber(@RequestBody String myRequest)，它发送和接收就很好。如果我发布一个对象(例如 MyRequest)，则会收到如下错误:

DEBUG: org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver - Resolving exception from handler [public java.lang.String com.jensen.neural.web.NeuralController.getNumber(com.jensen.neural.app.MyRequest)]: org.springframework.web.HttpMediaTypeNotSupportedException: Content type 'application/json;charset=UTF-8' not supported

如果我尝试从 Controller 返回一个对象，则会收到此错误:

DEBUG: org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver - Resolving exception from handler [public com.jensen.neural.app.TrainingResults com.jensen.neural.web.NeuralController.train()]: org.springframework.web.HttpMediaTypeNotAcceptableException: Could not find acceptable representation

我只能假设 jackson 配置错误或其他什么原因，但我已经让几个人看过这个，但没有人能弄清楚发生了什么。

我的请求:

public class MyRequest
{
    private String input = "";

    public MyRequest()
    {

    }

    public String getInput()
    {
        return input;
    }

    public void setInput(String input)
    {
        this.input = input;
    }
}

神经响应:

public class NeuralResponse
{
    private String str = "";

    public String getStr()
    {
        return str;
    }

    public void setStr(String str)
    {
        this.str = str;
    }
}

servlet 上下文:

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

    <!-- DispatcherServlet Context: defines this servlet's request-processing infrastructure -->

    <!-- Enables the Spring MVC @Controller programming model -->
    <annotation-driven />

    <!-- Handles HTTP GET requests for /resources/** by efficiently serving up static resources in the ${webappRoot}/resources directory -->
    <resources mapping="/resources/**" location="/resources/" />

    <!-- Resolves views selected for rendering by @Controllers to .jsp resources in the /WEB-INF/views directory -->
    <beans:bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <beans:property name="prefix" value="/WEB-INF/views/" />
        <beans:property name="suffix" value=".jsp" />
    </beans:bean>

    <context:component-scan base-package="com.jensen.neural" />



</beans:beans>

root-context:(只是 NumberCruncher.java 的 bean 声明)

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

    <!-- The definition of the Root Spring Container shared by all Servlets and Filters -->
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/spring/root-context.xml</param-value>
    </context-param>

    <!-- Creates the Spring Container shared by all Servlets and Filters -->
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

    <!-- Processes application requests -->
    <servlet>
        <servlet-name>appServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/spring/appServlet/servlet-context.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>appServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

</web-app>

来自 chrome 的请求是什么样的:

Request URL:http://localhost/neural/number
Request Method:POST
Status Code:415 Unsupported Media Type
Request Headersview source
Accept:application/json, text/plain, */*
Accept-Encoding:gzip,deflate,sdch
Accept-Language:en-US,en;q=0.8
Connection:keep-alive
Content-Length:18
Content-Type:application/json;charset=UTF-8
Host:localhost
Origin:http://localhost
Referer:http://localhost/
User-Agent:Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
X-Requested-With:XMLHttpRequest
Request Payloadview source
{input:STRING}
input: "STRING"

Response Headersview source
Content-Length:1048
Content-Type:text/html;charset=utf-8
Date:Fri, 13 Dec 2013 18:14:02 GMT
Server:Apache-Coyote/1.1

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.jensen</groupId>
    <artifactId>neural</artifactId>
    <name>neural</name>
    <packaging>war</packaging>
    <version>1.0.0-BUILD-SNAPSHOT</version>
    <properties>
        <java-version>1.6</java-version>
        <org.springframework-version>3.1.1.RELEASE</org.springframework-version>
        <org.aspectj-version>1.6.10</org.aspectj-version>
        <org.slf4j-version>1.6.6</org.slf4j-version>
        <jackson-mapper.version>2.1.0</jackson-mapper.version>
    </properties>
    <dependencies>
        <!-- Spring -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${org.springframework-version}</version>
            <exclusions>
                <!-- Exclude Commons Logging in favor of SLF4j -->
                <exclusion>
                    <groupId>commons-logging</groupId>
                    <artifactId>commons-logging</artifactId>
                 </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${org.springframework-version}</version>
        </dependency>

        <!-- AspectJ -->
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjrt</artifactId>
            <version>${org.aspectj-version}</version>
        </dependency>   

        <!-- Logging -->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>${org.slf4j-version}</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>jcl-over-slf4j</artifactId>
            <version>${org.slf4j-version}</version>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>${org.slf4j-version}</version>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.15</version>
            <exclusions>
                <exclusion>
                    <groupId>javax.mail</groupId>
                    <artifactId>mail</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>javax.jms</groupId>
                    <artifactId>jms</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>com.sun.jdmk</groupId>
                    <artifactId>jmxtools</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>com.sun.jmx</groupId>
                    <artifactId>jmxri</artifactId>
                </exclusion>
            </exclusions>
            <scope>runtime</scope>
        </dependency>

        <!-- Jackson JSON Processor -->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>${jackson-mapper.version}</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>${jackson-mapper.version}</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-annotations</artifactId>
            <version>${jackson-mapper.version}</version>
        </dependency>

        <!-- @Inject -->
        <dependency>
            <groupId>javax.inject</groupId>
            <artifactId>javax.inject</artifactId>
            <version>1</version>
        </dependency>

        <!-- Servlet -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>servlet-api</artifactId>
            <version>2.5</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>jsp-api</artifactId>
            <version>2.1</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>

        <!-- Test -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.7</version>
            <scope>test</scope>
        </dependency>        
    </dependencies>
...

我尝试将消费/生产放在 Controller 和其他一些东西上。我愿意接受任何建议，请帮忙。

Answer 1

由于您使用的是 spring 版本 3.1.1 和 com.fasterxml.jackson，您将需要仅引入的 MappingJackson2HttpMessageConverter在3.1.2中。

升级到3.1.2

MappingJackson2HttpMessageConverter bean 是通过使用annotation-driven 标记隐式创建的。