http 500 Internal Server Error的错误 ajax请求SpringMVC后台中返回500 Internal Server Error

使用httprequester接口测试能返回数据，但是用ajax返回json格式的时候返回报500Internal Server Error。

The server encountered an internal error that prevented it from fulfilling this request org.springframework .web.util.NestedServletException: Request processing failed; nested exception is…

springMVC+ajax 400 bad request —-请求的参数变量名-类型与后台的同名参数类型不匹配导致的，比如sys_no后台是String，前台页面传输的是数字类型就会出现这样的错误，springmvc直接将这个错误封装成400抛给了前端。开始提交是contentType : “application/json”形式，就报了400的错误,后面改成表单提交方式。

ajax提交参数到springmvc的后台，一直获取不到参数值，参数值为null——请求的方式不对，导致参数没有按后台约定的形式传递。比如下面实例的Controller接收的是一个名值对param是参数名、param的参数值是字符串类型。开始前台页面提交的数据是：data:param，后台获取param是得不到参数值的，因为到后台其实封装成了4个类似这样的参数名值对：sys_no=sys_no+”“,log_content=log_content+”“,page_size=15,page_no=page_no，并没有名称为param的参数，所以最后继续封装，将前端的param对象转成字符串，参数名为param，提交给后台：data : {“param”:JSON.stringify(param)},OK！

(本文章分享在CSDN平台，更多精彩请阅读东陆之滇的csdn博客：http://blog.csdn.net/zixiao217)

使用注解@ResponseBody可以将结果（一个包含字符串和JavaBean的Map），转换成JSON。使用 @RequestBody 注解前台只需要向 Controller 提交一段符合格式的 JSON，Spring 会自动将其拼装成 bean。 Spring这个转换是靠org.codehaus.jackson这个组件来实现的，所有需要引入jackson-core-asl和org.codehaus.jackson两个jar包：

pom.xml:

<!-- spring @Responsebody convert object to json 使用的是 codehaus 依赖start...-->
        <dependency>
            <groupId>org.codehaus.jackson</groupId>
            <artifactId>jackson-core-asl</artifactId>
            <version>1.9.13</version>
        </dependency>
        <dependency>
            <groupId>org.codehaus.jackson</groupId>
            <artifactId>jackson-mapper-asl</artifactId>
            <version>1.9.13</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.3.1</version>
        </dependency>
<!-- spring @Responsebody convert object to json 使用的是 codehaus 依赖END-->        <!-- fastjson依赖-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.6</version>
        </dependency>        <!--org.json依赖-->
        <dependency>
            <groupId>org.json</groupId>
            <artifactId>json</artifactId>
            <version>20140107</version>
        </dependency>
        <!--net.sf.json依赖-->
        <dependency>
            <groupId>net.sf.json-lib</groupId>
            <artifactId>json-lib</artifactId>
            <version>2.4</version>
            <classifier>jdk15</classifier>
        </dependency>

spring-mvc.xml文件配置:

<!-- 默认的注解映射的支持 -->
    <mvc:annotation-driven>
        <mvc:message-converters register-defaults="true">
            <bean class="org.springframework.http.converter.StringHttpMessageConverter">
                <constructor-arg value="UTF-8" />
            </bean>
            <bean
                class="com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter">
                <property name="supportedMediaTypes" value="application/json;charset=UTF-8" />
                <property name="features">
                    <array>
                        <value>WriteMapNullValue</value>
                        <value>WriteNullStringAsEmpty</value>
                    </array>
                </property>
            </bean>
            <bean 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>
                <property name="supportedMediaTypes">
                <list>
                    <value>text/json;charset=UTF-8</value>
                    <value>text/html;charset=utf-8</value>
                    <value>application/json;charset=UTF-8</value>
                    <value>application/json</value>
                </list>
            </property>
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>

Controller:

package org.byron4j.ynyn.controller;import java.io.IOException;import javax.servlet.http.HttpSession;import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;import org.byron4j.ynyn.base.BaseLoggerController;
import org.byron4j.ynyn.dto.response.QueryLoggerInfoResDto;
import org.byron4j.ynyn.service.QueryLoggerService;
import org.byron4j.ynyn.service.TaskListenerConfigService;
import com.fasterxml.jackson.core.JsonGenerationException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;@RestController
public class QueryLoggerInfoController extends BaseLoggerController{    @Autowired
    QueryLoggerService queryLoggerService;    @ResponseBody
    @RequestMapping(value="/queryLoggerInfo",method=RequestMethod.POST)
    public Object queryLoggerInfo(HttpSession session, String param) throws Exception{        QueryLoggerInfoResDto obj = queryLoggerService.queryLoggerInfo(param);        // 测试返回对象的Jackson json转换
        ObjectMapper om = new ObjectMapper();
        try {
                 om.writeValueAsString(obj);
        } catch (JsonGenerationException e) {
                 e.printStackTrace();
        } catch (JsonMappingException e) {
               e.printStackTrace();
        } catch (IOException e) {
                     e.printStackTrace();
        }        return obj ;
    }}

响应实体对象:

package org.byron4j.ynyn.dto.response;import java.util.List;import lombok.Getter;
import lombok.Setter;import org.byron4j.ynyn.base.BaseResDto;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonInclude.Include;/**
 *
 *  @Getter  @Setter 是lombok的注解--小而巧的代码生成插件--减少实体类代码量
 *  实例详解可参考：http://blog.csdn.net/zixiao217/article/category/6302134
 */
@Getter
@Setter
@JsonInclude(Include.ALWAYS)
public class QueryLoggerInfoResDto extends BaseResDto{    private static final long serialVersionUID = -6778903837998066869L;    private int total_amount;    List<LoggerInfoDto> log_list;}

响应实体类的基类：

package org.byron4j.ynyn.base;import java.io.Serializable;import lombok.Data;import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonInclude.Include;@Data
@JsonInclude(Include.ALWAYS)
public class BaseResDto implements Serializable{    private static final long serialVersionUID = 6926791530160100430L;    private String resultCode;    private String resultDesc;}

使用jquery的ajax的jsp代码：

        var param = {
            "sys_no":sys_no+"",
            "log_content":log_content+"",
            "page_size":15,
            "page_no":page_no
        }        $.ajax({
            type : "POST",
            async:false,
            url : window.location+"queryLoggerInfo",
            /*使用表单提交方式*/
            contentType : "application/x-www-form-urlencoded",
            dataType:"json",
            /*后台接收的是参数名为param(Controller方法的参数可以看出),所以需要封装成param:值的形式(字符串)*/
            data : {"param":JSON.stringify(param)},
            success : function(data) {
                ...
            }
        });

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