创建JSON时JTS失败

Question

朋友们。我在我的应用程序中对点和多边形使用生动解决方案的库JTS (1.13)，但是当我试图将几何对象转换为JSON时，我的应用程序失败了。这是我的消息来源：

@RequestMapping(value = "/test_point", method = RequestMethod.GET, produces = "application/json;charset=UTF-8")
@ResponseBody
public Map<String, Object> testPoint() {

    Point point = geometryFactory.createPoint(new Coordinate(37.73, 60.45));

    return RequestMapBuilder.getInstance()
            .addAttribute("point", point)
            .build();
}

还有客户端收到的JSON：

{"point":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope":{"envelope": AND SO ON...

另外，我的应用程序抛出了这个异常：

java.lang.IllegalStateException: Cannot call sendError() after the response has been committed
at org.apache.catalina.connector.ResponseFacade.sendError(ResponseFacade.java:478)
at javax.servlet.http.HttpServletResponseWrapper.sendError(HttpServletResponseWrapper.java:129)
at javax.servlet.http.HttpServletResponseWrapper.sendError(HttpServletResponseWrapper.java:129)
at org.springframework.security.web.context.SaveContextOnUpdateOrErrorResponseWrapper.sendError(SaveContextOnUpdateOrErrorResponseWrapper.java:92)
at org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver.sendServerError(DefaultHandlerExceptionResolver.java:313)
at org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver.handleHttpMessageNotWritable(DefaultHandlerExceptionResolver.java:370)
at org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver.doResolveException(DefaultHandlerExceptionResolver.java:140)
at org.springframework.web.servlet.handler.AbstractHandlerExceptionResolver.resolveException(AbstractHandlerExceptionResolver.java:138)
at org.springframework.web.servlet.DispatcherServlet.processHandlerException(DispatcherServlet.java:1183)
at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1020)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:971)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:857)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:316)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:126)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:90)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:114)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:122)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:111)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
at org.springframework.security.web.authentication.rememberme.RememberMeAuthenticationFilter.doFilter(RememberMeAuthenticationFilter.java:149)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:168)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:48)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:205)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:120)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:64)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:53)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:91)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:213)
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:176)
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:344)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:261)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:668)
at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:223)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1517)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1474)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:744)

有什么不对吗？提前谢谢。

Answer 1

这不是很好的解决办法，但它帮助我解决问题。

因此，问题在于Jackson如何序列化JTS多边形和Point对象。这个问题是由项目杰克逊-数据类型-jts解决的。您可以在github - https://github.com/bedatadriven/jackson-datatype-jts上显示此库源。

我只需要运行我的test_point：

1)为jackson-datatype-jts添加依赖关系和存储库：

<dependencies>
    <dependency>
        <groupId>com.bedatadriven</groupId>
        <artifactId>jackson-datatype-jts</artifactId>
        <version>1.0-SNAPSHOT</version>
    </dependency>

</dependencies>

<repositories>
    <repository>
        <id>sonatype-oss</id>
        <url>https://oss.sonatype.org/content/groups/public</url>
    </repository>
</repositories>

2)以这种方式修改源代码：

@RequestMapping(value = "/test_point", method = RequestMethod.GET, produces = "application/json;charset=UTF-8")
@ResponseBody
public Point testPoint() {

    Point point =geometryFactory.createPoint(new Coordinate(37.77, 60.01));
    String result = "";
    ObjectMapper objectMapper = new ObjectMapper();
    objectMapper.registerModule(new JtsModule());
    try {
        result = objectMapper.writeValueAsString(point);
    } catch (JsonProcessingException e) {
        e.printStackTrace();
    }

    return point;
}

这确实有效，但我想在我的另一个POJO中返回点是什么？Spring有解决方案: 1)重复上一节中的步骤1)创建扩展ObjectMapper类的类：

public class CustomMapper extends ObjectMapper {

public CustomMapper() {
    super();
    this.registerModule(new JtsModule());
}
}

3)编辑spring配置xml (for me - servlet.xml)，添加下一个字符串：

<mvc:annotation-driven>
        <mvc:message-converters>
            <bean class="org.springframework.http.converter.StringHttpMessageConverter"/>
            <bean class="org.springframework.http.converter.ByteArrayHttpMessageConverter"/>
            <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
                <property name="objectMapper" ref="jacksonObjectMapper" />
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>

    <bean id="jacksonObjectMapper" class="ru.trollsmedjan.web.dao.CustomMapper"/>

现在，您的ObjectMapper实例被自定义对象映射器实现所替代。它很管用！

Answer 2

如果您使用Spring，这就足够了：

pom.xml

<dependency>
    <groupId>com.bedatadriven</groupId>
    <artifactId>jackson-datatype-jts</artifactId>
    <version>2.3</version>
</dependency>

JacksonConfig.java

package org.lskk.lumen.helpdesk;

import com.bedatadriven.jackson.datatype.jts.JtsModule;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class JacksonConfig {
    @Bean
    public JtsModule jtsModule() {
        return new JtsModule();
    }
}