spring之消息转换器的实例代码

零下一度
零下一度 原创
2017-07-19 16:48:39 1034浏览

//domain

package com.crazy.goods.tools;/**
 * 0755-351512
 * @author Administrator
 * */public class Phone {private String qno;private String number;public String getQno() {return qno;
    }public void setQno(String qno) {this.qno = qno;
    }public String getNumber() {return number;
    }public void setNumber(String number) {this.number = number;
    }
    
}

//消息转换器 要实现一个抽象类AbstractHttpMessageConverter

package com.crazy.goods.tools;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import org.springframework.http.HttpInputMessage;import org.springframework.http.HttpOutputMessage;import org.springframework.http.converter.AbstractHttpMessageConverter;import org.springframework.http.converter.HttpMessageNotReadableException;import org.springframework.http.converter.HttpMessageNotWritableException;public class MyMessageConvertor extends AbstractHttpMessageConverter<Phone> {/** * 将请求头数据转换成Phone     */
    @Overrideprotected Phone readInternal(Class<? extends Phone> arg0,
            HttpInputMessage msg) throws IOException,
            HttpMessageNotReadableException {//参数必须使用post提交必须在body中InputStream is=msg.getBody();
        BufferedReader br=new BufferedReader(new InputStreamReader(is));
        String param=br.readLine();
        String phone=param.split("=")[1];
        Phone phoneObj=new Phone();
        phoneObj.setQno(phone.split("-")[0]);
        phoneObj.setNumber(phone.split("-")[1]);return phoneObj;
    }/** * 当前的转换器支持转换的类     */@Overrideprotected boolean supports(Class<?> arg0) {if(arg0==Phone.class){return true;
        }return false;
    }/** * 用于将返回的对象转换成字符串显示在网页     */@Overrideprotected void writeInternal(Phone phone, HttpOutputMessage arg1)throws IOException, HttpMessageNotWritableException {
        String p=phone.getQno()+"-"+phone.getNumber();
        arg1.getBody().write(p.getBytes("UTF-8"));
    }

}

//springmvc.xml 要配置bean:消息转换器,只有post提交方式才会被转换器拦截

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"xmlns:tx="http://www.springframework.org/schema/tx"xmlns:aop="http://www.springframework.org/schema/aop"xmlns:mvc="http://www.springframework.org/schema/mvc"xsi:schemaLocation="http://www.springframework.org/schema/beans 
        http://www.springframework.org/schema/context http://www.springframework.org/schema/tx http://www.springframework.org/schema/aop http://www.springframework.org/schema/mvc ">
    <!--springmvc只能扫描控制层  -->
    <context:component-scan base-package="com.crazy.goods">
        <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Service"/>
        <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Repository"/>
    </context:component-scan>
    
    <!--消息转换器 必须使用post提交   -->
    <mvc:annotation-driven>
        <mvc:message-converters>
            <bean class="com.crazy.goods.tools.MyMessageConvertor">
                <property name="supportedMediaTypes">
                    <list>
                        <value>text/html;charset=UTF-8</value>
                          <value>application/x-www-form-urlencoded</value>
                    </list>
                </property>
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>
</beans>

servlet测试


package com.crazy.goods.servlet;


import java.io.IOException;


import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;


import com.crazy.goods.tools.Phone;


/**
* @author Administrator
* 创建时间:2017年7月1日下午3:11:27
*/
@Controller
public class ReservePageServelt {


// /**
// * forward:转发
// * redirect:重定向
// * @param req
// * @param resp
// * @return
// * @throws ServletException
// * @throws IOException
// */
// @RequestMapping(value="/add",method={RequestMethod.GET})
// public String doGet(HttpServletRequest req, HttpServletResponse resp/*,@PathVariable("testid") String testid*/) throws ServletException, IOException {
// req.getRequestDispatcher("/reversegood.jsp").forward(req, resp);
// return "/reversegood.jsp";
// resp.getWriter().print(testid);
// }


//消息转换器思路,

//原理就是将请求体或者请求头的数据转换为action方法的参数,同时将方法的返回值的内容转换为响应头
//当url路径访问过来时,看到使用了@RequestBody注解,这个注解标识这个类要被消息转换器处理,就会springmvcxml文件中读到消息转换器,然后进入supports方法
//判断这个类是否被指定的转换器支持,如果支持,就调用readInternal方法,进行切割,然后将值传递到对象中,处理完成为对象之后,就会调用writeInternal转换为响应头
@RequestMapping(value="/add")
@ResponseBody
public Phone messageConvertor( @RequestBody Phone phone,HttpServletResponse response) {
System.out.println(phone.getQno()+phone.getNumber());
return phone;

}

}

 

总结:消息转换器的原理就是,自定义将请求体的数据转换为形参(对象),然后将方法的返回值内容转换为响应头

步骤:

当url路径访问过来时,看到使用了@RequestBody注解,这个注解标识这个类要被消息转换器处理,就会springmvcxml文件中读到消息转换器,然后进入supports方法
判断这个类是否被指定的转换器支持,如果支持,就调用readInternal方法,进行切割,然后将值传递到对象中.

处理完成为对象之后,就会调用writeInternal转换为响应头

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