springmvc @RequestBody String类型参数的使用

程序员文章站 2022-03-04 11:03:32

目录springmvc @requestbody string类型参数springmvc用map接收请求参数分析第一种情况，什么也不设置，无参数传递第二种情况，加个参数试试 => .../tes...

springmvc @requestbody string类型参数

通过如下配置：

   <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>
    <!-- 启动springmvc的注解功能，完成请求和注解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转换器 -->
            </list>
        </property>
    </bean>

在spring mvc的controller层使用@requestbody接收content-type为application/json的数据时，默认支持map方式和对象方式参数

@requestmapping(value = "/[code]/saveuser", method = requestmethod.post)
    @responsebody
    public jsonresult saveuser(@pathvariable("code") integer code, @requestbody map<string, object> datas,@requestbody user user) {
    。。。
    }

如果是一个参数时也需要用个map或者对象处理，使用string会报解析错误，具体看：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);
        }
    }

为了让@requestbody支持string参数(目前只支持接收单个参数)

重写org.springframework.http.converter.json.mappingjackson2httpmessageconverter类

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;
/**
 * 处理@requestbody注解为string的情况，只支持接收单个参数的情况
 * 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);
    }
    /**
     * 通过返回参数类型决定是否处理参数，如果是string类型的参数，将解析后的hashmap里的值返回（只支持单个参数）
     *
     * @param type  返回参数类型
     * @param param 参数值
     * @return 实际参数值
     */
    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;
    }
    /**
     * 获取解析参数用的type
     *
     * @param type 参数类型
     * @return
     */
    private type gettype(type type) {
        type desericlazz;
        if (type == string.class) {
            //jackson不支持string默认用linkedhashmap
            desericlazz = linkedhashmap.class;
        } else {
            desericlazz = type;
        }
        return desericlazz;
    }
    /**
     * 获取解析参数用的type
     * @param clazz 参数类型
     * @return
     */
    private class<?> getclazz(class<?> clazz) {
        class<?> desericlazz;
        if (clazz == string.class) {
            //jackson不支持string默认用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层：

@requestmapping(value = "/deluser", method = requestmethod.post)
    @responsebody
    public jsonresult deluser(@requestbody string id) {
    。。。
    }

springmvc用map接收请求参数分析

第一种情况，什么也不设置，无参数传递

注解为 @controller @requestmapping

springmvc @RequestBody String类型参数的使用

可以看到传递的为springmvc的bindingawaremodelmap类型，springmvc中的隐含模型就是这个类型，其作用域等价于 request 域，当添加model、modelmap参数时，springmvc实际传入的就是这个隐含模型；向这个隐含模型种设置值后，在返回的页面中就能通过request域取值。