1. 创建请求工厂（可选）

@Bean
    @ConditionalOnMissingBean({ClientHttpRequestFactory.class})
    public ClientHttpRequestFactory requestFactory() {
        SimpleClientHttpRequestFactory factory = new SimpleClientHttpRequestFactory();
        //ms
        factory.setConnectTimeout(15000);
        factory.setReadTimeout(15000);
        return factory;
    }

为啥是可选的呢 因为你即使不创建 springboot在检测为空时也会为你创建一个SimpleClientHttpRequestFactory 类型的工程，当然如果你想使用其他的技术那就要指定了
比如httpclient

图片.png

当然肯定是需要其他的依赖包的

2. 实例化一个RestTemplate

这个是我我们直接使用的请求类
先上代码

@Bean
    @ConditionalOnMissingBean({RestTemplate.class})
    public RestTemplate restTemplate(ClientHttpRequestFactory factory) {
        RestTemplate restTemplate = new RestTemplate(factory);

        //换上fastjson
        List<HttpMessageConverter<?>> httpMessageConverterList= restTemplate.getMessageConverters();
        Iterator<HttpMessageConverter<?>> iterator=httpMessageConverterList.iterator();
        if(iterator.hasNext()){
            HttpMessageConverter<?> converter=iterator.next();
            //原有的String是ISO-8859-1编码 去掉
            if(converter instanceof StringHttpMessageConverter){
                iterator.remove();
            }

            //由于系统中默认有jackson 在转换json时自动会启用  但是我们不想使用它 可以直接移除或者将fastjson放在首位
            /*if(converter instanceof GsonHttpMessageConverter || converter instanceof MappingJackson2HttpMessageConverter){
                iterator.remove();
            }*/

        }
        httpMessageConverterList.add(new StringHttpMessageConverter(Charset.forName("utf-8")));
        FastJsonHttpMessageConverter fastJsonHttpMessageConverter = new FastJsonHttpMessageConverter();
        FastJsonConfig fastJsonConfig = new FastJsonConfig();
        fastJsonConfig.setSerializerFeatures(
                SerializerFeature.WriteMapNullValue,
                SerializerFeature.WriteNullStringAsEmpty,
                SerializerFeature.WriteNullListAsEmpty,
                SerializerFeature.DisableCircularReferenceDetect);

        fastJsonHttpMessageConverter.setFastJsonConfig(fastJsonConfig);
        httpMessageConverterList.add(0,fastJsonHttpMessageConverter);

        return restTemplate;

    }

创建RestTemplate最简单的方式就是注入一个RestTemplateBuilder 直接.build()即可 但是这样我们就无法定制了 还要使用fastjson呢

在阅读源码时我们发现转化列表中有个StringHttpMessageConverter对象它的默认编码是“ISO-8859-1”,顺手给换个“UTF-8”的吧

由于springboot中集成了jackson所以里边队友json的处理也都是jackson,但是本人不太喜欢用Jackson，那么咱就换成国产的Fastjson，这里主要是要将GsonHttpMessageConverter和FastJsonHttpMessageConverter两个转换器去除然后加上新的FastJsonHttpMessageConverter,在源码中我们发现一旦有适合处理的转换器，就不会再找下一个了，这样我们就可以直接将自定义的FastJsonHttpMessageConverter放在列表的首位就行了

完整源码如下

package com.marry.dezhou.fg.config;

import com.alibaba.fastjson.serializer.SerializerFeature;
import com.alibaba.fastjson.support.config.FastJsonConfig;
import com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.web.client.RestTemplateBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.client.ClientHttpRequestFactory;
import org.springframework.http.client.SimpleClientHttpRequestFactory;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.StringHttpMessageConverter;
import org.springframework.web.client.RestTemplate;

import java.nio.charset.Charset;
import java.util.Iterator;
import java.util.List;

/**
 * @author ml
 * @create 2017-10-27--15:53
 */
@Configuration
public class RestConfiguration {

    @Autowired
    private RestTemplateBuilder builder;

    @Bean
    @ConditionalOnMissingBean({RestTemplate.class})
    public RestTemplate restTemplate(ClientHttpRequestFactory factory) {
        //return builder.build();
        RestTemplate restTemplate = new RestTemplate(factory);

        //换上fastjson
        List<HttpMessageConverter<?>> httpMessageConverterList= restTemplate.getMessageConverters();
        Iterator<HttpMessageConverter<?>> iterator=httpMessageConverterList.iterator();
        if(iterator.hasNext()){
            HttpMessageConverter<?> converter=iterator.next();
            //原有的String是ISO-8859-1编码 去掉
            if(converter instanceof StringHttpMessageConverter){
                iterator.remove();
            }

            //由于系统中默认有jackson 在转换json时自动会启用  但是我们不想使用它 可以直接移除或者将fastjson放在首位
            /*if(converter instanceof GsonHttpMessageConverter || converter instanceof MappingJackson2HttpMessageConverter){
                iterator.remove();
            }*/

        }
        httpMessageConverterList.add(new StringHttpMessageConverter(Charset.forName("utf-8")));
        FastJsonHttpMessageConverter fastJsonHttpMessageConverter = new FastJsonHttpMessageConverter();
        FastJsonConfig fastJsonConfig = new FastJsonConfig();
        fastJsonConfig.setSerializerFeatures(
                SerializerFeature.WriteMapNullValue,
                SerializerFeature.WriteNullStringAsEmpty,
                SerializerFeature.WriteNullListAsEmpty,
                SerializerFeature.DisableCircularReferenceDetect);

        fastJsonHttpMessageConverter.setFastJsonConfig(fastJsonConfig);
        httpMessageConverterList.add(0,fastJsonHttpMessageConverter);

        return restTemplate;

    }

    @Bean
    @ConditionalOnMissingBean({ClientHttpRequestFactory.class})
    public ClientHttpRequestFactory requestFactory() {
        SimpleClientHttpRequestFactory factory = new SimpleClientHttpRequestFactory();
        //ms
        factory.setConnectTimeout(15000);
        factory.setReadTimeout(15000);
        return factory;
    }
}