Spring远程调用HttpClient/RestTemplate的方法

一、httpclient

两个系统间如何互相访问？两个tomcat上的项目如何互相访问？

       采用httpclient实现跨系统的接口调用。

介绍：

官网：http://hc.apache.org/index.html

现在也叫：httpcomponents

httpclient可以发送get、post、put、delete、...等请求

使用：

导入坐标

<dependency>
  <groupid>org.apache.httpcomponents</groupid>
  <artifactid>httpclient</artifactid>
  <version>4.4</version>
</dependency>

//1、使用httpclient发起get请求
public class doget {
 
  public static void main(string[] args) throws exception {
    // 创建httpclient对象,相当于打开了浏览器
    closeablehttpclient httpclient = httpclients.createdefault();
 
    // 创建httpget请求，相当于在浏览器输入地址
    httpget httpget = new httpget("http://www.baidu.com/");
 
    closeablehttpresponse response = null;
    try {
      // 执行请求，相当于敲完地址后按下回车。获取响应
      response = httpclient.execute(httpget);
      // 判断返回状态是否为200
      if (response.getstatusline().getstatuscode() == 200) {
        // 解析响应，获取数据
        string content = entityutils.tostring(response.getentity(), "utf-8");
        system.out.println(content);
      }
    } finally {
      if (response != null) {
        // 关闭资源
        response.close();
      }
      // 关闭浏览器
      httpclient.close();
    }
 
  }
}
 
 
//2、使用httpclient发起带参数的get请求
public class dogetparam {
 
  public static void main(string[] args) throws exception {
    // 创建httpclient对象
    closeablehttpclient httpclient = httpclients.createdefault();
    // 创建uri对象，并且设置请求参数
    uri uri = new uribuilder("http://www.baidu.com/s").setparameter("wd", "java").build();
    
    // 创建http get请求
    httpget httpget = new httpget(uri);
 
    // httpget get = new httpget("http://www.baidu.com/s?wd=java");
    
    closeablehttpresponse response = null;
    try {
      // 执行请求
      response = httpclient.execute(httpget);
      // 判断返回状态是否为200
      if (response.getstatusline().getstatuscode() == 200) {
        // 解析响应数据
        string content = entityutils.tostring(response.getentity(), "utf-8");
        system.out.println(content);
      }
    } finally {
      if (response != null) {
        response.close();
      }
      httpclient.close();
    }
  }
}
 
 
//3、使用httpclient发起post请求
public class dopost {
  public static void main(string[] args) throws exception {
    // 创建httpclient对象
    closeablehttpclient httpclient = httpclients.createdefault();
    // 创建http post请求
    httppost httppost = new httppost("http://www.oschina.net/");
    // 把自己伪装成浏览器。否则开源中国会拦截访问
    httppost.setheader("user-agent", "mozilla/5.0 (windows nt 10.0; wow64) applewebkit/537.36 (khtml, like gecko) chrome/56.0.2924.87 safari/537.36");
 
    closeablehttpresponse response = null;
    try {
      // 执行请求
      response = httpclient.execute(httppost);
      // 判断返回状态是否为200
      if (response.getstatusline().getstatuscode() == 200) {
        // 解析响应数据
        string content = entityutils.tostring(response.getentity(), "utf-8");
        system.out.println(content);
      }
    } finally {
      if (response != null) {
        response.close();
      }
      // 关闭浏览器
      httpclient.close();
    }
 
  }
}
 
 
//4、使用httpclient发起带有参数的post请求
public class dopostparam {
 
  public static void main(string[] args) throws exception {
    // 创建httpclient对象
    closeablehttpclient httpclient = httpclients.createdefault();
    // 创建http post请求，访问开源中国
    httppost httppost = new httppost("http://www.oschina.net/search");
 
    // 根据开源中国的请求需要，设置post请求参数
    list<namevaluepair> parameters = new arraylist<namevaluepair>(0);
    parameters.add(new basicnamevaluepair("scope", "project"));
    parameters.add(new basicnamevaluepair("q", "java"));
    parameters.add(new basicnamevaluepair("fromerr", "8bdnuwwc"));
    // 构造一个form表单式的实体
    urlencodedformentity formentity = new urlencodedformentity(parameters);
    // 将请求实体设置到httppost对象中
    httppost.setentity(formentity);
 
    closeablehttpresponse response = null;
    try {
      // 执行请求
      response = httpclient.execute(httppost);
      // 判断返回状态是否为200
      if (response.getstatusline().getstatuscode() == 200) {
        // 解析响应体
        string content = entityutils.tostring(response.getentity(), "utf-8");
        system.out.println(content);
      }
    } finally {
      if (response != null) {
        response.close();
      }
      // 关闭浏览器
      httpclient.close();
    }
  }
}

 二、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

http开发是用apache的httpclient开发，代码复杂，还得操心资源回收等。代码很复杂，冗余代码多。

导入坐标

<dependency>
  <groupid>org.springframework.boot</groupid>
  <artifactid>spring-boot-starter-web</artifactid>
</dependency>

创建resttemplate对象

@configuration//加上这个注解作用，可以被spring扫描
public class resttemplateconfig {
  /**
   * 创建resttemplate对象，将resttemplate对象的生命周期的管理交给spring
   * @return
   */
  @bean
  public resttemplate resttemplate(){
    resttemplate resttemplate = new resttemplate();
    //主要解决中文乱码
    resttemplate.getmessageconverters().set(1, new stringhttpmessageconverter(standardcharsets.utf_8));
    return resttemplate;
  }
}

resttempcontroller

import org.springframework.http.responseentity;
import org.springframework.stereotype.controller;
import org.springframework.web.bind.annotation.getmapping;
import org.springframework.web.bind.annotation.requestmapping;
import org.springframework.web.client.resttemplate;
 
import javax.annotation.resource;
 
@restcontroller
@requestmapping("/consumer")
public class consumercontroller {
  // 从spring的容器中获取resttemplate
  @resource
  private resttemplate resttemplate;
 
  /**
   * 通过get请求，保存数据
   */
  @getmapping("/{id}")
  public responseentity<string> findbyid(@pathvariable integer id){
    //发起远程请求:通过resttemplate发起get请求
    responseentity<string> entity = resttemplate.getforentity("http://localhost:8090/goods2/1", string.class);
    system.out.println("entity.getstatuscode():"+entity.getstatuscode());
    system.out.println(entity.getbody());
    return entity;
  }
 
  /**
   * 通过post请求，保存数据
   */
  @postmapping
  public responseentity<string> savegoods(@requestbody goods goods){
    //通过resttemplate发起远程请求
    /**
     * 第一个参数：远程地址uri
     * 第二个参数：数据
     * 第三个参数：返回值类型
     */
    responseentity<string> entity = resttemplate.postforentity("http://localhost:8090/goods2", goods, string.class);
    system.out.println("entity.getstatuscode():"+entity.getstatuscode());
    system.out.println(entity.getbody());
    return entity;
  }
 
  @putmapping
  public responseentity<string> updategoods(@requestbody goods goods){
    resttemplate.put("http://localhost:8090/goods2",goods);
    return new responseentity<>("修改成功", httpstatus.ok);
  }
 
  @deletemapping("/{id}")
  public responseentity<string> deletebyid(@pathvariable integer id){
    resttemplate.delete("http://localhost:8090/goods2/"+id);
    return new responseentity<>("删除成功", httpstatus.ok);
  }
}

只用maven不用springboot框架时只需要导入依赖到pom文件

<dependency>
  <groupid>org.springframework</groupid>
  <artifactid>spring-web</artifactid>
</dependency>

直接new resttemplate()对象使用即可

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