我正在尝试让我的 Spring rest Controller 返回 jsonp 但我并不高兴

如果我想返回 json，完全相同的代码可以正常工作，但我需要返回 jsonp 我添加了一个转换器，我在网上找到了用于执行 jsonp 转换的源代码

我正在使用 Spring 版本 4.1.1.RELEASE 和 Java 7

非常感谢任何帮助

这是有问题的代码

mvc-dispatcher-servlet.xml

    <beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:mvc="http://www.springframework.org/schema/mvc" 
    xsi:schemaLocation="
        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
         http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc.xsd">


  <bean id="contentNegotiationManager" class="org.springframework.web.accept.ContentNegotiationManagerFactoryBean">
       <property name="favorPathExtension" value="false" />
       <property name="favorParameter" value="true" />
       <property name="parameterName" value="mediaType" />
       <property name="ignoreAcceptHeader" value="false"/>
       <property name="useJaf" value="false"/>
       <property name="defaultContentType" value="application/json" />

       <property name="mediaTypes">
            <map>
                <entry key="atom"  value="application/atom+xml" />
                <entry key="html"  value="text/html" />
                <entry key="jsonp" value="application/javascript" />
                <entry key="json"  value="application/json" />
                <entry key="xml"   value="application/xml"/>
            </map>
        </property>
  </bean>

    <bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
        <property name="contentNegotiationManager" ref="contentNegotiationManager" />
        <property name="viewResolvers">
            <list>
                <bean class="org.springframework.web.servlet.view.BeanNameViewResolver" />
                <bean
                    class="org.springframework.web.servlet.view.InternalResourceViewResolver">
                    <property name="prefix" value="/WEB-INF/templates/slim/${views.template.directory}/" />
                    <property name="suffix" value=".jsp" />
                </bean>
            </list>
        </property>
        <property name="defaultViews">
            <list>
                <bean class="com.webapp.handler.MappingJacksonJsonpView" />
            </list>
        </property>
    </bean>

</beans>

com.webapp.handler.MappingJacksonJsonpView

package com.webapp.handler;

import java.util.Map;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.servlet.view.json.MappingJackson2JsonView;

public class MappingJacksonJsonpView extends MappingJackson2JsonView {
    /** Local log variable. **/
    private static final Logger LOG = LoggerFactory.getLogger(MappingJacksonJsonpView.class);

    /**
     * Default content type. Overridable as bean property.
     */
    public static final String DEFAULT_CONTENT_TYPE = "application/javascript";

    @Override
    public String getContentType() {
        return DEFAULT_CONTENT_TYPE;
    }

    /**
     * Prepares the view given the specified model, merging it with static
     * attributes and a RequestContext attribute, if necessary.
     * Delegates to renderMergedOutputModel for the actual rendering.
     * @see #renderMergedOutputModel
     */
    @Override
    public void render(Map<String, ?> model, HttpServletRequest request, HttpServletResponse response) throws Exception {
        LOG.info("Entered render Method :{}", request.getMethod());

        if("GET".equals(request.getMethod().toUpperCase())) {
            LOG.info("Request Method is a GET call");

            Map<String, String[]> params = request.getParameterMap();

            if(params.containsKey("callback")) {
                String callbackParam = params.get("callback")[0];
                LOG.info("callbackParam:{}", callbackParam);
                response.getOutputStream().write(new String(callbackParam + "(").getBytes());
                super.render(model, request, response);
                response.getOutputStream().write(new String(");").getBytes());
                response.setContentType(DEFAULT_CONTENT_TYPE);
            }
            else {
                LOG.info("Callback Param not contained in request");
                super.render(model, request, response);
            }
        }

        else {
            LOG.info("Request Method is NOT a GET call");
            super.render(model, request, response);
        }
    }
}

有问题的 Controller 方法

 @RequestMapping(value = { "/sources"}, method = RequestMethod.GET, 
        produces={MediaType.ALL_VALUE,
        "text/javascript",
        "application/javascript",
        "application/ecmascript",
        "application/x-ecmascript",
        "application/x-javascript", 
        MediaType.APPLICATION_JSON_VALUE})
@ResponseBody
public Object getSources(@PathVariable(value = API_KEY) String apiKey, 
        @RequestParam(value = "searchTerm", required = true) String searchTerm,
        @RequestParam(value = "callBack", required = false) String callBack) {
    LOG.info("Entered getSources - searchTerm:{}, callBack:{} ", searchTerm, callBack);

    List<SearchVO> searchVOList = myServices.findSources(searchTerm);

    if (CollectionUtils.isEmpty(searchVOList)) {
        LOG.error("No results exist for the searchterm of {}", searchTerm);
        return searchVOList;
    }         

    LOG.debug("{} result(s) exist for the searchterm of {}", searchVOList.size(), searchTerm);        

    LOG.info("Exiting getSources");
    return searchVOList;
}

**Jquery Ajax代码**

$.ajax({
                type: "GET",
                url: "http://localhost:8080/my-web/rest/sources,
                data: {
                    "searchTerm": request.term
                },
                //contentType: "application/json; charset=utf-8",
                //dataType: "json",
                contentType: "application/javascript",
                dataType: "jsonp",
                 success: function(data) {
                    alert("success");
                },
                error: function(XMLHttpRequest, textStatus, errorThrown) {
                    alert("Failure");
                }
            });

我得到的错误堆栈跟踪片段如下

org.springframework.web.HttpMediaTypeNotAcceptableException: Could not find acceptable representation
at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:168) ~[spring-webmvc-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:101) ~[spring-webmvc-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.handleReturnValue(RequestResponseBodyMethodProcessor.java:198) ~[spring-webmvc-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:71) ~[spring-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:122) ~[spring-webmvc-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:781) ~[spring-webmvc-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:721) ~[spring-webmvc-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:83) ~[spring-webmvc-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:943) ~[spring-webmvc-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:877) ~[spring-webmvc-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966) [spring-webmvc-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:857) [spring-webmvc-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:620) [servlet-api.jar:na]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842) [spring-webmvc-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727) [servlet-api.jar:na]

最佳答案

如 spring.io 上所述 blog关于 Spring 4.1 版本:

JSONP is now supported with Jackson. For response body methods declare an @ControllerAdvice as shown below. For View-based rendering simply configure the JSONP query parameter name(s) on MappingJackson2JsonView.

@ControllerAdvice
private static class JsonpAdvice extends AbstractJsonpResponseBodyAdvice {

    public JsonpAdvice() {
        super("callback");
    }

}

[...] In 4.1 an @ControllerAdvice can also implement ResponseBodyAdvice in which case it will be called after the controller method returns but before the response is written and therefore committed. This has a number of useful applications with @JsonView the JSONP already serving as two examples built on it.

Javadoc 取自 MappingJackson2JsonView :

Set JSONP request parameter names. Each time a request has one of those parameters, the resulting JSON will be wrapped into a function named as specified by the JSONP request parameter value. The parameter names configured by default are "jsonp" and "callback".

你不需要自己实现这些东西。只需重用 Spring 框架中的位即可。

Spring Boot 示例

以下简单的 Spring Boot 应用程序演示了在 Spring MVC 4.1 中使用内置 JSONP 支持。 示例至少需要 Spring Boot 1.2.0.RC1。

import com.fasterxml.jackson.annotation.JsonAutoDetect;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.web.HttpMessageConverters;
import org.springframework.context.annotation.Bean;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.servlet.mvc.method.annotation.AbstractJsonpResponseBodyAdvice;

import java.util.Collections;

import static com.fasterxml.jackson.annotation.JsonAutoDetect.Visibility.ANY;
import static org.springframework.http.MediaType.APPLICATION_JSON_VALUE;

@RestController
@SpringBootApplication
class Application {

    @JsonAutoDetect(fieldVisibility = ANY)
    static class MyBean {
        String attr = "demo";
    }

    @ControllerAdvice
    static class JsonpAdvice extends AbstractJsonpResponseBodyAdvice {
        public JsonpAdvice() {
            super("callback");
        }
    }

    @Bean
    public HttpMessageConverters customConverters() {
        return new HttpMessageConverters(false, Collections.<HttpMessageConverter<?> >singleton(new MappingJackson2HttpMessageConverter()));
    }

    @RequestMapping
    MyBean demo() {
        return new MyBean();
    }

    @RequestMapping(produces = APPLICATION_JSON_VALUE)
    String demo2() {
        return "demo2";
    }

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

URL http://localhost:8080/demo?callback=test 将 POJO 转换为 JSONP 响应:

test({"attr":"demo"});

URL http://localhost:8080/demo2?callback=test 将 String 转换为 JSONP 响应:

test("demo2");

关于java - Spring Rest 和 Jsonp，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/26974835/