RestTemplate配置

什么是RestTemplate？

RestTemplate是Spring提供的用于访问Rest服务的客户端，RestTemplate提供了多种便捷访问远程Http服务的方法，能够大大提高客户端的编写效率。
调用RestTemplate的默认构造函数，RestTemplate对象在底层通过使用java.net包下的实现创建HTTP 请求，可以通过使用ClientHttpRequestFactory指定不同的HTTP请求方式。
ClientHttpRequestFactory接口主要提供了两种实现方式

• 一种是SimpleClientHttpRequestFactory，使用J2SE提供的方式（既java.net包提供的方式）创建底层的Http请求连接。
• 一种方式是使用HttpComponentsClientHttpRequestFactory方式，底层使用HttpClient访问远程的Http服务，使用HttpClient可以配置连接池和证书等信息。

RestTemplate默认是使用SimpleClientHttpRequestFactory，内部是调用jdk的HttpConnection，默认超时为-1

基于jdk的spring的RestTemplate

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans 
　　　　http://www.springframework.org/schema/beans/spring-beans.xsd"
       default-autowire="byName" default-lazy-init="true">

    <!--方式一、使用jdk的实现-->
    <bean id="ky.requestFactory" class="org.springframework.http.client.SimpleClientHttpRequestFactory">
        <property name="readTimeout" value="10000"/>
        <property name="connectTimeout" value="5000"/>
    </bean>

    <bean id="simpleRestTemplate" class="org.springframework.web.client.RestTemplate">
        <constructor-arg ref="ky.requestFactory"/>
        <property name="messageConverters">
            <list>
                <bean class="org.springframework.http.converter.FormHttpMessageConverter"/>
                <bean class="org.springframework.http.converter.xml.MappingJackson2XmlHttpMessageConverter"/>
                <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"/>
                <bean class="org.springframework.http.converter.StringHttpMessageConverter">
                    <property name="supportedMediaTypes">
                        <list>
                            <value>text/plain;charset=UTF-8</value>
                        </list>
                    </property>
                </bean>
            </list>
        </property>
    </bean>

</beans>

使用Httpclient连接池的方式(推荐)

<!--使用httpclient的实现，带连接池-->
<!--在httpclient4.3版本后才有-->
<bean id="httpClientBuilder" class="org.apache.http.impl.client.HttpClientBuilder" factory-method="create">
    <property name="connectionManager">
        <bean class="org.apache.http.impl.conn.PoolingHttpClientConnectionManager">
            <!--整个连接池的并发-->
            <property name="maxTotal" value="50"/>
            <!--每个主机的并发-->
            <property name="defaultMaxPerRoute" value="50"/>
        </bean>
    </property>
    <!--开启重试-->
    <property name="retryHandler">
        <bean class="org.apache.http.impl.client.DefaultHttpRequestRetryHandler">
            <constructor-arg value="2"/>
            <constructor-arg value="true"/>
        </bean>
    </property>
    <property name="defaultHeaders">
        <list>
            <bean class="org.apache.http.message.BasicHeader">
                <constructor-arg value="Content-Type"/>
                <constructor-arg value="text/html;charset=UTF-8"/>
            </bean>
            <bean class="org.apache.http.message.BasicHeader">
                <constructor-arg value="Accept-Encoding"/>
                <constructor-arg value="gzip,deflate"/>
            </bean>
            <bean class="org.apache.http.message.BasicHeader">
                <constructor-arg value="Accept-Language"/>
                <constructor-arg value="zh-CN"/>
            </bean>
        </list>
    </property>
</bean>

<bean id="httpClient" factory-bean="httpClientBuilder" factory-method="build"/>

<bean id="restTemplate" class="org.springframework.web.client.RestTemplate">
    <property name="messageConverters">
        <list value-type="org.springframework.http.converter.HttpMessageConverter">
            <bean class="org.springframework.http.converter.StringHttpMessageConverter">
                <property name="supportedMediaTypes">
                    <value>text/html;charset=UTF-8</value>
                </property>
            </bean>
            <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
                <property name="supportedMediaTypes">
                    <value>application/json;charset=UTF-8</value>
                </property>
            </bean>
            <bean class="org.springframework.http.converter.ResourceHttpMessageConverter"/>
            <bean class="org.springframework.http.converter.support.AllEncompassingFormHttpMessageConverter"/>
            <bean class="org.springframework.http.converter.FormHttpMessageConverter"/>
            <bean class="org.springframework.http.converter.xml.MappingJackson2XmlHttpMessageConverter"/>
        </list>
    </property>
    <property name="requestFactory">
        <bean class="org.springframework.http.client.HttpComponentsClientHttpRequestFactory">
            <constructor-arg ref="httpClient"/>
            <!--连接时间(毫秒)-->
            <property name="connectTimeout" value="20000"/>
            <!--读取时间(毫秒)-->
            <property name="readTimeout" value="20000"/>
        </bean>
    </property>
</bean>

初体验(POST)

package com.winner.rest;

import com.alibaba.fastjson.JSON;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

import javax.annotation.Resource;
import java.io.UnsupportedEncodingException;

/**
 * Created by winner_0715 on 2017/1/7.
 */
@Service
public class TestGet {

    @Resource
    private RestTemplate restTemplate;

    /**
     * 要请求的url，一般放在配置文件中
     */
    @Value(value = "@{remote.url}")
    private String remoteUrl;

    public String postRemoteData(ParameterRo ro) throws UnsupportedEncodingException {
        /**
         * 设置请求头
         */
        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.parseMediaType("application/json;charset=UTF-8"));
        headers.add("Accept", MediaType.APPLICATION_JSON.toString());

        /**
         * POST请求参数，根据需要进行封装
         */
        String bodyData = new String(Base64Util.encodeData(JSON.toJSONString(ro)).getBytes("UTF-8"), "UTF-8");

        /**
         * 查看HttpEntity的构造方法，包含只有请求头和只有请求体的情况
         */
        HttpEntity<String> httpEntity = new HttpEntity<String>(bodyData, headers);

        /**
         * 执行操作
         */
        String result = restTemplate.postForObject(remoteUrl, httpEntity, String.class);

        return result;
    }

    /**
     * 模拟请求参数
     */
    private class ParameterRo {

        private Integer id = 123;

        public Integer getId() {
            return id;
        }

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

初体验(GET)

package com.winner.rest;

import com.alibaba.fastjson.JSON;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

import javax.annotation.Resource;
import java.io.UnsupportedEncodingException;

/**
 * Created by winner_0715 on 2017/1/7.
 */
@Service
public class TestGet {

    @Resource
    private RestTemplate restTemplate;

    /**
     * 要请求的url，一般放在配置文件中
     */
    @Value(value = "@{remote.url}")
    private String remoteUrl;

    public String getRemoteData(ParameterRo ro) throws UnsupportedEncodingException {

        //根据需要也可以设置请求头

        /**
         * get请求参数，根据需要进行封装(加密等)
         */
        String getData = new String(Base64Util.encodeData(JSON.toJSONString(ro)).getBytes("UTF-8"), "UTF-8");

        /**
         * 执行操作
         */
        String result = restTemplate.getForObject(remoteUrl + "?" + getData, String.class);

        return result;
    }

    /**
     * 模拟请求参数
     */
    private class ParameterRo {

        private Integer id = 123;

        public Integer getId() {
            return id;
        }

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