HttpClient 远程接口调用方式

程序员文章站 2023-02-07 14:51:37

远程接口调用方式HttpClient 问题：现在我们已经开发好了接口了，那该如何调用这个接口呢？答：使用Httpclient客户端。 Httpclient简介什么是httpclient HttpClient 是 Apache Jakarta Common 下的子项目，用来提供高效的、最新的、功能 ......

远程接口调用方式httpclient

问题：现在我们已经开发好了接口了，那该如何调用这个接口呢？

答：使用httpclient客户端。

httpclient简介

什么是httpclient

httpclient 是 apache jakarta common 下的子项目，用来提供高效的、最新的、功能丰富的支持 http 协议的客户端编程工具包，并且它支持 http 协议最新的版本和建议。实现了所有 http 的方法（get,post,put,head 等）

下载地址：http://hc.apache.org/

httpclient作用

在java代码中，发送http请求。通常用来实现远程接口调用。

httpclient测试

在工程中添加httpclient的pom依赖。

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

执行get请求

public static void doget(){
 // 创建httpclient对象
        closeablehttpclient httpclient = httpclients.createdefault();
 
        // 创建http get请求
        httpget httpget = new httpget("http://www.oschina.net/");
 
        closeablehttpresponse response = null;
        try {
            // 执行请求
            response = httpclient.execute(httpget);
            system.out.println(response.getstatusline());
            // 判断返回状态是否为200
            if (response.getstatusline().getstatuscode() == 200) {
                string content = entityutils.tostring(response.getentity(), "utf-8");
                system.out.println("内容长度：" + content.length());
            }
        }catch(exception e){
         e.printstacktrace();
        
        } finally {
            if (response != null) {
                try {
response.close();
} catch (ioexception e) {
e.printstacktrace();
}
            }
            try {
httpclient.close();
} catch (ioexception e) {
e.printstacktrace();
}
        }
 

执行get带参数

public static void dogetparam(){
 // 创建httpclient对象
closeablehttpclient httpclient = httpclients.createdefault();
closeablehttpresponse response = null;
try {
 
        // 定义请求的参数
        uri uri = new uribuilder("http://www.baidu.com/s").setparameter("wd", "数据库").build();
 
        system.out.println(uri);
 
        // 创建http get请求
        httpget httpget = new httpget(uri);
 
            // 执行请求
            response = httpclient.execute(httpget);
            // 判断返回状态是否为200
            if (response.getstatusline().getstatuscode() == 200) {
                string content = entityutils.tostring(response.getentity(), "utf-8");
                system.out.println(content);
            }
        }catch(exception e){
         e.printstacktrace();
        
        }finally {
            if (response != null) {
                try {
response.close();
} catch (ioexception e) {
// todo auto-generated catch block
e.printstacktrace();
}
            }
            try {
httpclient.close();
} catch (ioexception e) {
// todo auto-generated catch block
e.printstacktrace();
}
        }
}

执行post请求

public static void dopost(){
 // 创建httpclient对象
        closeablehttpclient httpclient = httpclientbuilder.create().setredirectstrategy(new laxredirectstrategy()).build();
 
        // 创建http post请求
        httppost httppost = new httppost("http://www.oschina.net/");
 
        closeablehttpresponse response = null;
        try {
            // 执行请求
            response = httpclient.execute(httppost);
            system.out.println(response.getstatusline());
            // 判断返回状态是否为200
            if (response.getstatusline().getstatuscode() == 200) {
                string content = entityutils.tostring(response.getentity(), "utf-8");
                system.out.println(content);
            }
        }catch(exception e){
         e.printstacktrace();
        
        }finally {
            if (response != null) {
                try {
response.close();
} catch (ioexception e) {
// todo auto-generated catch block
e.printstacktrace();
}
            }
            try {
httpclient.close();
} catch (ioexception e) {
// todo auto-generated catch block
e.printstacktrace();
}
        }
    }

执行post带参数

public static void dopostparam() throws exception{
 // 创建httpclient对象
        closeablehttpclient httpclient = httpclientbuilder.create().setredirectstrategy(new laxredirectstrategy()).build();
 
        // 创建http post请求
        httppost httppost = new httppost("http://www.oschina.net/search");
       
        // 设置2个post参数，一个是scope、一个是q
        list<namevaluepair> parameters = new arraylist<namevaluepair>();
        parameters.add(new basicnamevaluepair("scope", "project"));
        parameters.add(new basicnamevaluepair("q", "java"));
        // 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);
            system.out.println(response.getstatusline());
            // 判断返回状态是否为200
            if (response.getstatusline().getstatuscode() == 200) {
                string content = entityutils.tostring(response.getentity(), "utf-8");
                system.out.println(content);
            }
        } finally {
            if (response != null) {
                response.close();
            }
            httpclient.close();
        }
}

httpclient常见问题及解决方案

请求参数乱码

设置请求的编码格式：

obj.addheader("content-type","application/x-www-form-urlencoded; charset=utf-8");

响应http/1.1 403 forbidden

原因：网站设置了反爬虫机制，禁止非法访问。

解决方案：伪装浏览器。

obj.addheader("user-agent"," mozilla/5.0 (windows nt 6.1) applewebkit/537. 36 (khtml, like gecko) chrome/31.0.1650.63")

封装通用工具类httpclientutils

package org.chu.ego.base.utils;

import java.io.ioexception;
import java.util.arraylist;
import java.util.list;
import java.util.map;

import org.apache.http.httpentity;
import org.apache.http.namevaluepair;
import org.apache.http.client.entity.urlencodedformentity;
import org.apache.http.client.methods.closeablehttpresponse;
import org.apache.http.client.methods.httpget;
import org.apache.http.client.methods.httppost;
import org.apache.http.client.utils.uribuilder;
import org.apache.http.impl.client.closeablehttpclient;
import org.apache.http.impl.client.httpclientbuilder;
import org.apache.http.impl.client.httpclients;
import org.apache.http.impl.client.laxredirectstrategy;
import org.apache.http.message.basicnamevaluepair;
import org.apache.http.util.entityutils;
/**
 * --发送get请求的api
 * closeablehttpclient类 ，client实现类
 * httpclients类 ，client工具类，用于创建客户端对象。
 * closeablehttpresponse接口，请求的响应对象
 * uribuilder类 ：url构建类，用于设置get请求的路径变量
 * httpget类 ：get请求的发送对象
 * entityutils类 实体处理类
 * 
 * --发送post 请求使用的api
 * closeablehttpclient类
 * httpclientbuilder client构建对象，用于创建客户端对象。
 * laxredirectstrategy类，post请求重定向的策略
 * closeablehttpresponse 请求的响应对象
 * httppost post请求的发送对象
 * namevaluepair 类，用于设置参数值
 * urlencodedformentity：用于设置表单参数给发送对象httppost
 * 
 * @author ranger
 *
 */
public class httpclientutils {

public static string doget(string url,map<string, string> params){
        
        //获取httpclient客户端
        closeablehttpclient httpclient = httpclients.createdefault();
        
        string resultstring = "";
        
        closeablehttpresponse response = null;
        
        try {
            uribuilder builder = new uribuilder(url);
            
            if(null!=params){
                for (string key:params.keyset()) {
                    builder.setparameter(key, params.get(key));
                }
            }
            
            httpget get = new httpget(builder.build());
            
            
            response = httpclient.execute(get);
            
            system.out.println(response.getstatusline());
            
            if(200==response.getstatusline().getstatuscode()){
                httpentity entity = response.getentity();
                resultstring = entityutils.tostring(entity, "utf-8");
            }
            
        } catch (exception e) {
            
            e.printstacktrace();
        } finally {
            if(null!=response){
                try {
                    response.close();
                } catch (ioexception e) {
                    // todo auto-generated catch block
                    e.printstacktrace();
                }
            }
            if(null!=httpclient){
                try {
                    httpclient.close();
                } catch (ioexception e) {
                    // todo auto-generated catch block
                    e.printstacktrace();
                }
            }
        }
        
        return resultstring;
    }
    
    public static string doget(string url){
        return doget(url, null);
    }
    
    public static string dopost(string url,map<string,string> params){
        /**
         * 在4.0及以上httpclient版本中，post需要指定重定向的策略，如果不指定则按默认的重定向策略。
         * 
         * 获取httpclient客户端
         */
        closeablehttpclient httpclient = httpclientbuilder.create().setredirectstrategy( new laxredirectstrategy()).build();
        
        string resultstring = "";
        
        closeablehttpresponse response = null;
        
        try {
            
            
            httppost post = new httppost(url);
            
            list<namevaluepair> paramaters = new arraylist<>();
            
            if(null!=params){
                for (string key : params.keyset()) {
                    paramaters.add(new basicnamevaluepair(key,params.get(key)));
                }
                
                urlencodedformentity  formentity = new urlencodedformentity (paramaters);
                
                post.setentity(formentity);
            }
            
            
            /**
             * http/1.1 403 forbidden
             *   原因：
             *      有些网站，设置了反爬虫机制
             *   解决的办法：
             *      设置请求头，伪装浏览器
             */
            post.addheader("user-agent", "mozilla/5.0 (windows nt 6.3; wow64) applewebkit/537.36 (khtml, like gecko) chrome/63.0.3239.132 safari/537.36");
            
            response = httpclient.execute(post);
            
            system.out.println(response.getstatusline());
            
            if(200==response.getstatusline().getstatuscode()){
                httpentity entity = response.getentity();
                resultstring = entityutils.tostring(entity, "utf-8");
            }
            
        } catch (exception e) {
            
            e.printstacktrace();
        } finally {
            if(null!=response){
                try {
                    response.close();
                } catch (ioexception e) {
                    // todo auto-generated catch block
                    e.printstacktrace();
                }
            }
            if(null!=httpclient){
                try {
                    httpclient.close();
                } catch (ioexception e) {
                    // todo auto-generated catch block
                    e.printstacktrace();
                }
            }
        }
        
        return resultstring;
    }
    
    public static string dopost(string url){
        return dopost(url, null);
    }
 
}

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