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springmvc @RequestBody String類型參數(shù)的使用

更新時間：2021年10月28日 15:23:36 作者：zoyation

這篇文章主要介紹了springmvc @RequestBody String類型參數(shù)的使用，具有很好的參考價值，希望對大家有所幫助。如有錯誤或未考慮完全的地方，望不吝賜教

springmvc @RequestBody String類型參數(shù)

通過如下配置：

   <bean id="mappingJacksonHttpMessageConverter"
          class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
        <property name="supportedMediaTypes">
            <list>
                <value>text/html;charset=UTF-8</value>
                <value>application/json;charset=UTF-8</value>
            </list>
        </property>
    </bean>
    <!-- 啟動SpringMVC的注解功能，完成請求和注解POJO的映射 -->
    <bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping"/>
    <bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter">
        <property name="messageConverters">
            <list>
                <ref bean="mappingJacksonHttpMessageConverter"/>
                <!-- JSON轉(zhuǎn)換器 -->
            </list>
        </property>
    </bean>

在spring mvc的Controller層使用@RequestBody接收Content-Type為application/json的數(shù)據(jù)時，默認支持Map方式和對象方式參數(shù)

@RequestMapping(value = "/[code]/saveUser", method = RequestMethod.POST)
    @ResponseBody
    public JsonResult saveUser(@PathVariable("code") Integer code, @RequestBody Map<String, Object> datas,@RequestBody User user) {
    。。。
    }

如果是一個參數(shù)時也需要用個Map或者對象處理，使用String會報解析錯誤，具體看：AbstractJackson2HttpMessageConverter的方法read(Type type, Class

@Override
    public Object read(Type type, Class<?> contextClass, HttpInputMessage inputMessage)
            throws IOException, HttpMessageNotReadableException {
        JavaType javaType = getJavaType(type, contextClass);
        return readJavaType(javaType, inputMessage);
    }
    private Object readJavaType(JavaType javaType, HttpInputMessage inputMessage) {
        try {
            return this.objectMapper.readValue(inputMessage.getBody(), javaType);
        }
        catch (IOException ex) {
            throw new HttpMessageNotReadableException("Could not read JSON: " + ex.getMessage(), ex);
        }
    }

為了讓@RequestBody支持String參數(shù)(目前只支持接收單個參數(shù))

重寫org.springframework.http.converter.json.MappingJackson2HttpMessageConverter類

package com.test.converter.json
import org.springframework.http.HttpInputMessage;
import org.springframework.http.converter.HttpMessageNotReadableException;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import java.io.IOException;
import java.lang.reflect.Type;
import java.util.LinkedHashMap;
/**
 * 處理@RequestBody注解為String的情況，只支持接收單個參數(shù)的情況
 * Created by test
 * Date:2017/1/4
 * Time:17:33
 */
public class CustomerMappingJackson2HttpMessageConverter extends MappingJackson2HttpMessageConverter {
    @Override
    protected Object readInternal(Class<?> clazz, HttpInputMessage inputMessage) throws IOException, HttpMessageNotReadableException {
        Class<?> deseriClazz = getClazz(clazz);
        Object param = super.readInternal(deseriClazz, inputMessage);
        return getTrueObject(clazz, param);
    }
    @Override
    public Object read(Type type, Class<?> contextClass, HttpInputMessage inputMessage)
            throws IOException, HttpMessageNotReadableException {
        Type deseriType = getType(type);
        Object param = super.read(deseriType, contextClass, inputMessage);
        return getTrueObject(type, param);
    }
    /**
     * 通過返回參數(shù)類型決定是否處理參數(shù)，如果是String類型的參數(shù)，將解析后的HashMap里的值返回（只支持單個參數(shù)）
     *
     * @param type  返回參數(shù)類型
     * @param param 參數(shù)值
     * @return 實際參數(shù)值
     */
    private Object getTrueObject(Type type, Object param) {
        if (type == String.class) {
            Object backParam = null;
            if (param != null && param instanceof LinkedHashMap) {
                LinkedHashMap paramMap = (LinkedHashMap) param;
                if (paramMap.size() == 1) {
                    backParam = paramMap.get(paramMap.keySet().iterator().next());
                }
            }
            param = backParam;
        }
        return param;
    }
    /**
     * 獲取解析參數(shù)用的Type
     *
     * @param type 參數(shù)類型
     * @return
     */
    private Type getType(Type type) {
        Type deseriClazz;
        if (type == String.class) {
            //jackson不支持String默認用LinkedHashMap
            deseriClazz = LinkedHashMap.class;
        } else {
            deseriClazz = type;
        }
        return deseriClazz;
    }
    /**
     * 獲取解析參數(shù)用的Type
     * @param clazz 參數(shù)類型
     * @return
     */
    private Class<?> getClazz(Class<?> clazz) {
        Class<?> deseriClazz;
        if (clazz == String.class) {
            //jackson不支持String默認用LinkedHashMap
            deseriClazz = LinkedHashMap.class;
        } else {
            deseriClazz = clazz;
        }
        return deseriClazz;
    }
}

spring mvc xml配置文件修改：

<bean id="mappingJacksonHttpMessageConverter"
          class="com.test.converter.json.CustomerMappingJackson2HttpMessageConverter">
        <property name="supportedMediaTypes">
            <list>
                <value>text/html;charset=UTF-8</value>
                <value>application/json;charset=UTF-8</value>
            </list>
        </property>
    </bean>

Controller層：

@RequestMapping(value = "/delUser", method = RequestMethod.POST)
    @ResponseBody
    public JsonResult delUser(@RequestBody String id) {
    。。。
    }

springmvc用Map接收請求參數(shù)分析

第一種情況，什么也不設(shè)置，無參數(shù)傳遞

注解為 @Controller @RequestMapping

可以看到傳遞的為SpringMVC的BindingAwareModelMap類型，SpringMVC中的隱含模型就是這個類型，其作用域等價于 request 域，當添加Model、ModelMap參數(shù)時，SpringMVC實際傳入的就是這個隱含模型；向這個隱含模型種設(shè)置值后，在返回的頁面中就能通過request域取值。