14-SpringBoot——Spring MVC基础-自定义HttpMessageConverter

Spring MVC基础-自定义HttpMessageConverter

【博文目录>>>】

【项目源码>>>】

【自定义HttpMessageConverter】

HttpMessageConveter 是用来处理request 和response 里的数据的。Spring 为我们内置了大量的HttpMessageConverter，例如， MappingJackson2HttpMessageConverter 、StringHttpMessageConverter 等。我们实现一个自定义的HttpMessageConverter，他将接收以“-”号连接的数据，将数据转换成自定义的对象。

【代码实现】

package com.example.spring.framework.converter.domain;

/**
 * Author: 王俊超
 * Date: 2017-07-11 22:07
 * All Rights Reserved !!!
 */
public class DemoObj {
    private Long id;
    private String name;

    public DemoObj() {
        super();
    }

    public DemoObj(Long id, String name) {
        super();
        this.id = id;
        this.name = name;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}
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package com.example.spring.framework.converter.controller;

import com.example.spring.framework.converter.domain.DemoObj;
import org.springframework.stereotype.Controller;
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;

/**
 * Author: 王俊超
 * Date: 2017-07-13 07:56
 * All Rights Reserved !!!
 */
@Controller
public class ConverterController {

    /**
     * 指定返回的媒体类型为我们自定义的媒体类型application/x惆wisely
     */
    @RequestMapping(method = RequestMethod.POST, value = "/convert",
            produces = "application/x-wisely")
    public @ResponseBody
    DemoObj converter(@RequestBody DemoObj obj) {
        return obj;
    }
}
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package com.example.spring.framework.converter.config;

import com.example.spring.framework.converter.MyMessageConverter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
import org.springframework.web.servlet.view.InternalResourceViewResolver;
import org.springframework.web.servlet.view.JstlView;

import java.util.List;

/**
 * Author: 王俊超
 * Date: 2017-07-12 07:22
 * All Rights Reserved !!!
 */
@Configuration
@EnableWebMvc
@ComponentScan("com.example.spring.framework.converter")
public class MyMvcConfig extends WebMvcConfigurerAdapter {
    @Bean
    public InternalResourceViewResolver viewResolver() {
        InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
        viewResolver.setPrefix("/WEB-INF/classes/views/");
        viewResolver.setSuffix(".jsp");
        viewResolver.setViewClass(JstlView.class);

        return viewResolver;
    }

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {

        registry.addResourceHandler("/assets/**").addResourceLocations("classpath:/assets/");
        super.addResourceHandlers(registry);
    }


    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/converter").setViewName("/converter");
    }

    /**
     * 配置自定义的HttpMessageConverter 的Bean ，在Spring MVC 里注册HttpMessageConverter有两个方法：
     * 1、configureMessageConverters ：重载会覆盖掉Spring MVC 默认注册的多个HttpMessageConverter
     * 2、extendMessageConverters ：仅添加一个自定义的HttpMessageConverter ，不覆盖默认注册的HttpMessageConverter
     * 在这里重写extendMessageConverters
     */
    @Override
    public void extendMessageConverters(List<HttpMessageConverter<?>> converters) {

        converters.add(converter());

    }

    @Bean
    public MyMessageConverter converter() {
        return new MyMessageConverter();
    }


}
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package com.example.spring.framework.converter;

import com.example.spring.framework.converter.domain.DemoObj;
import org.springframework.http.HttpInputMessage;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.converter.AbstractHttpMessageConverter;
import org.springframework.http.converter.HttpMessageNotReadableException;
import org.springframework.http.converter.HttpMessageNotWritableException;
import org.springframework.util.StreamUtils;

import java.io.IOException;
import java.nio.charset.Charset;

/**
 * 继承AbstractHttpMessageConverter 接口来实现自定义的HttpMessageConverter
 * Author: 王俊超
 * Date: 2017-07-13 07:44
 * All Rights Reserved !!!
 */
public class MyMessageConverter extends AbstractHttpMessageConverter<DemoObj> {


    public MyMessageConverter() {
        // 新建一个我们自定义的媒体类型application/x-wisely
        super(new MediaType("application", "x-wisely", Charset.forName("UTF-8")));
    }

    @Override
    protected boolean supports(Class<?> clazz) {
        // 表明本HttpMessageConverter 只处理DemoObj 这个类。
        return DemoObj.class.isAssignableFrom(clazz);
    }

    /**
     * 重写readlntenal 方法，处理请求的数据。代码表明我们处理由“四”隔开的数据，并转成 DemoObj 的对象。
     */
    @Override
    protected DemoObj readInternal(Class<? extends DemoObj> clazz,
            HttpInputMessage inputMessage) throws IOException,
            HttpMessageNotReadableException {
        String temp = StreamUtils.copyToString(inputMessage.getBody(), Charset.forName("UTF-8"));
        String[] tempArr = temp.split("-");

        return new DemoObj(new Long(tempArr[0]), tempArr[1]);
    }

    /**
     * 重写writeInternal ，处理如何输出数据到response。此例中，我们在原样输出前面加上"hello ："。
     */
    @Override
    protected void writeInternal(DemoObj demoObj,
            HttpOutputMessage outputMessage)
            throws IOException, HttpMessageNotWritableException {
        String out = "hello: " + demoObj.getId() + "-" + demoObj.getName();
        outputMessage.getBody().write(out.getBytes());
    }
}
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package com.example.spring.framework.converter;

import com.example.spring.framework.converter.config.MyMvcConfig;
import org.springframework.web.WebApplicationInitializer;
import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
import org.springframework.web.servlet.DispatcherServlet;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRegistration;

/**
 * Author: 王俊超
 * Date: 2017-07-11 21:51
 * All Rights Reserved !!!
 */
public class WebInitializer implements WebApplicationInitializer {
    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
        AnnotationConfigWebApplicationContext ctx = new AnnotationConfigWebApplicationContext();
        ctx.register(MyMvcConfig.class);
        ctx.setServletContext(servletContext);

        ServletRegistration.Dynamic servlet = servletContext.addServlet("dispatcher",
                new DispatcherServlet(ctx));
        servlet.addMapping("/");
        servlet.setLoadOnStartup(1);
    }
}
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<%@ page language="java" contentType="text/html; charset=UTF-8"
         pageEncoding="UTF-8" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>HttpMessageConverter Demo</title>
</head>
<body>
<div id="resp"></div>
<input type="button" onclick="req();" value="请求"/>
<script src="assets/assets.js/jquery.assets.js" type="text/javascript"></script>
<script>
    function req() {
        $.ajax({
            url: "convert",
            data: "1-wangjunchao", // 注意这里的数据格式，后台处理按此格式处理，用“-”隔开。
            type: "POST",
            contentType: "application/x-wisely", // contentType 设置的媒体类型是我们自定义的application/x-wisely
            success: function (data) {
                $("#resp").html(data);
            }
        });
    }

</script>
</body>
</html>
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