详解java实现HTTP请求的三种方式

目前java实现http请求的方法用的最多的有两种：一种是通过httpclient这种第三方的开源框架去实现。httpclient对http的封装性比较不错，通过它基本上能够满足我们大部分的需求，httpclient3.1 是 org.apache.commons.httpclient下操作远程 url的工具包，虽然已不再更新，但实现工作中使用httpclient3.1的代码还是很多，httpclient4.5是org.apache.http.client下操作远程 url的工具包，最新的；另一种则是通过httpurlconnection去实现，httpurlconnection是java的标准类，是java比较原生的一种实现方式。

自己在工作中三种方式都用到过，总结一下分享给大家，也方便自己以后使用，话不多说上代码。

第一种方式：java原生httpurlconnection

package com.powerx.httpclient;

import java.io.bufferedreader;
import java.io.ioexception;
import java.io.inputstream;
import java.io.inputstreamreader;
import java.io.outputstream;
import java.net.httpurlconnection;
import java.net.malformedurlexception;
import java.net.url;

public class httpclient {
  public static string doget(string httpurl) {
    httpurlconnection connection = null;
    inputstream is = null;
    bufferedreader br = null;
    string result = null;// 返回结果字符串
    try {
      // 创建远程url连接对象
      url url = new url(httpurl);
      // 通过远程url连接对象打开一个连接，强转成httpurlconnection类
      connection = (httpurlconnection) url.openconnection();
      // 设置连接方式：get
      connection.setrequestmethod("get");
      // 设置连接主机服务器的超时时间：15000毫秒
      connection.setconnecttimeout(15000);
      // 设置读取远程返回的数据时间：60000毫秒
      connection.setreadtimeout(60000);
      // 发送请求
      connection.connect();
      // 通过connection连接，获取输入流
      if (connection.getresponsecode() == 200) {
        is = connection.getinputstream();
        // 封装输入流is，并指定字符集
        br = new bufferedreader(new inputstreamreader(is, "utf-8"));
        // 存放数据
        stringbuffer sbf = new stringbuffer();
        string temp = null;
        while ((temp = br.readline()) != null) {
          sbf.append(temp);
          sbf.append("\r\n");
        }
        result = sbf.tostring();
      }
    } catch (malformedurlexception e) {
      e.printstacktrace();
    } catch (ioexception e) {
      e.printstacktrace();
    } finally {
      // 关闭资源
      if (null != br) {
        try {
          br.close();
        } catch (ioexception e) {
          e.printstacktrace();
        }
      }

      if (null != is) {
        try {
          is.close();
        } catch (ioexception e) {
          e.printstacktrace();
        }
      }

      connection.disconnect();// 关闭远程连接
    }

    return result;
  }

  public static string dopost(string httpurl, string param) {

    httpurlconnection connection = null;
    inputstream is = null;
    outputstream os = null;
    bufferedreader br = null;
    string result = null;
    try {
      url url = new url(httpurl);
      // 通过远程url连接对象打开连接
      connection = (httpurlconnection) url.openconnection();
      // 设置连接请求方式
      connection.setrequestmethod("post");
      // 设置连接主机服务器超时时间：15000毫秒
      connection.setconnecttimeout(15000);
      // 设置读取主机服务器返回数据超时时间：60000毫秒
      connection.setreadtimeout(60000);

      // 默认值为：false，当向远程服务器传送数据/写数据时，需要设置为true
      connection.setdooutput(true);
      // 默认值为：true，当前向远程服务读取数据时，设置为true，该参数可有可无
      connection.setdoinput(true);
      // 设置传入参数的格式:请求参数应该是 name1=value1&name2=value2 的形式。
      connection.setrequestproperty("content-type", "application/x-www-form-urlencoded");
      // 设置鉴权信息：authorization: bearer da3efcbf-0845-4fe3-8aba-ee040be542c0
      connection.setrequestproperty("authorization", "bearer da3efcbf-0845-4fe3-8aba-ee040be542c0");
      // 通过连接对象获取一个输出流
      os = connection.getoutputstream();
      // 通过输出流对象将参数写出去/传输出去,它是通过字节数组写出的
      os.write(param.getbytes());
      // 通过连接对象获取一个输入流，向远程读取
      if (connection.getresponsecode() == 200) {

        is = connection.getinputstream();
        // 对输入流对象进行包装:charset根据工作项目组的要求来设置
        br = new bufferedreader(new inputstreamreader(is, "utf-8"));

        stringbuffer sbf = new stringbuffer();
        string temp = null;
        // 循环遍历一行一行读取数据
        while ((temp = br.readline()) != null) {
          sbf.append(temp);
          sbf.append("\r\n");
        }
        result = sbf.tostring();
      }
    } catch (malformedurlexception e) {
      e.printstacktrace();
    } catch (ioexception e) {
      e.printstacktrace();
    } finally {
      // 关闭资源
      if (null != br) {
        try {
          br.close();
        } catch (ioexception e) {
          e.printstacktrace();
        }
      }
      if (null != os) {
        try {
          os.close();
        } catch (ioexception e) {
          e.printstacktrace();
        }
      }
      if (null != is) {
        try {
          is.close();
        } catch (ioexception e) {
          e.printstacktrace();
        }
      }
      // 断开与远程地址url的连接
      connection.disconnect();
    }
    return result;
  }
}

第二种方式：apache httpclient3.1

package com.powerx.httpclient;

import java.io.bufferedreader;
import java.io.ioexception;
import java.io.inputstream;
import java.io.inputstreamreader;
import java.io.unsupportedencodingexception;
import java.util.iterator;
import java.util.map;
import java.util.map.entry;
import java.util.set;

import org.apache.commons.httpclient.defaulthttpmethodretryhandler;
import org.apache.commons.httpclient.httpclient;
import org.apache.commons.httpclient.httpstatus;
import org.apache.commons.httpclient.namevaluepair;
import org.apache.commons.httpclient.methods.getmethod;
import org.apache.commons.httpclient.methods.postmethod;
import org.apache.commons.httpclient.params.httpmethodparams;

public class httpclient3 {

  public static string doget(string url) {
    // 输入流
    inputstream is = null;
    bufferedreader br = null;
    string result = null;
    // 创建httpclient实例
    httpclient httpclient = new httpclient();
    // 设置http连接主机服务超时时间：15000毫秒
    // 先获取连接管理器对象，再获取参数对象,再进行参数的赋值
    httpclient.gethttpconnectionmanager().getparams().setconnectiontimeout(15000);
    // 创建一个get方法实例对象
    getmethod getmethod = new getmethod(url);
    // 设置get请求超时为60000毫秒
    getmethod.getparams().setparameter(httpmethodparams.so_timeout, 60000);
    // 设置请求重试机制，默认重试次数：3次，参数设置为true，重试机制可用，false相反
    getmethod.getparams().setparameter(httpmethodparams.retry_handler, new defaulthttpmethodretryhandler(3, true));
    try {
      // 执行get方法
      int statuscode = httpclient.executemethod(getmethod);
      // 判断返回码
      if (statuscode != httpstatus.sc_ok) {
        // 如果状态码返回的不是ok,说明失败了,打印错误信息
        system.err.println("method faild: " + getmethod.getstatusline());
      } else {
        // 通过getmethod实例，获取远程的一个输入流
        is = getmethod.getresponsebodyasstream();
        // 包装输入流
        br = new bufferedreader(new inputstreamreader(is, "utf-8"));

        stringbuffer sbf = new stringbuffer();
        // 读取封装的输入流
        string temp = null;
        while ((temp = br.readline()) != null) {
          sbf.append(temp).append("\r\n");
        }

        result = sbf.tostring();
      }

    } catch (ioexception e) {
      e.printstacktrace();
    } finally {
      // 关闭资源
      if (null != br) {
        try {
          br.close();
        } catch (ioexception e) {
          e.printstacktrace();
        }
      }
      if (null != is) {
        try {
          is.close();
        } catch (ioexception e) {
          e.printstacktrace();
        }
      }
      // 释放连接
      getmethod.releaseconnection();
    }
    return result;
  }

  public static string dopost(string url, map<string, object> parammap) {
    // 获取输入流
    inputstream is = null;
    bufferedreader br = null;
    string result = null;
    // 创建httpclient实例对象
    httpclient httpclient = new httpclient();
    // 设置httpclient连接主机服务器超时时间：15000毫秒
    httpclient.gethttpconnectionmanager().getparams().setconnectiontimeout(15000);
    // 创建post请求方法实例对象
    postmethod postmethod = new postmethod(url);
    // 设置post请求超时时间
    postmethod.getparams().setparameter(httpmethodparams.so_timeout, 60000);

    namevaluepair[] nvp = null;
    // 判断参数map集合parammap是否为空
    if (null != parammap && parammap.size() > 0) {// 不为空
      // 创建键值参数对象数组，大小为参数的个数
      nvp = new namevaluepair[parammap.size()];
      // 循环遍历参数集合map
      set<entry<string, object>> entryset = parammap.entryset();
      // 获取迭代器
      iterator<entry<string, object>> iterator = entryset.iterator();

      int index = 0;
      while (iterator.hasnext()) {
        entry<string, object> mapentry = iterator.next();
        // 从mapentry中获取key和value创建键值对象存放到数组中
        try {
          nvp[index] = new namevaluepair(mapentry.getkey(),
              new string(mapentry.getvalue().tostring().getbytes("utf-8"), "utf-8"));
        } catch (unsupportedencodingexception e) {
          e.printstacktrace();
        }
        index++;
      }
    }
    // 判断nvp数组是否为空
    if (null != nvp && nvp.length > 0) {
      // 将参数存放到requestbody对象中
      postmethod.setrequestbody(nvp);
    }
    // 执行post方法
    try {
      int statuscode = httpclient.executemethod(postmethod);
      // 判断是否成功
      if (statuscode != httpstatus.sc_ok) {
        system.err.println("method faild: " + postmethod.getstatusline());
      }
      // 获取远程返回的数据
      is = postmethod.getresponsebodyasstream();
      // 封装输入流
      br = new bufferedreader(new inputstreamreader(is, "utf-8"));

      stringbuffer sbf = new stringbuffer();
      string temp = null;
      while ((temp = br.readline()) != null) {
        sbf.append(temp).append("\r\n");
      }

      result = sbf.tostring();
    } catch (ioexception e) {
      e.printstacktrace();
    } finally {
      // 关闭资源
      if (null != br) {
        try {
          br.close();
        } catch (ioexception e) {
          e.printstacktrace();
        }
      }
      if (null != is) {
        try {
          is.close();
        } catch (ioexception e) {
          e.printstacktrace();
        }
      }
      // 释放连接
      postmethod.releaseconnection();
    }
    return result;
  }
}

第三种方式：apache  httpclient4.5

package com.powerx.httpclient;

import java.io.ioexception;
import java.io.unsupportedencodingexception;
import java.util.arraylist;
import java.util.iterator;
import java.util.list;
import java.util.map;
import java.util.map.entry;
import java.util.set;

import org.apache.http.httpentity;
import org.apache.http.namevaluepair;
import org.apache.http.client.clientprotocolexception;
import org.apache.http.client.config.requestconfig;
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.impl.client.closeablehttpclient;
import org.apache.http.impl.client.httpclients;
import org.apache.http.message.basicnamevaluepair;
import org.apache.http.util.entityutils;

public class httpclient4 {

  public static string doget(string url) {
    closeablehttpclient httpclient = null;
    closeablehttpresponse response = null;
    string result = "";
    try {
      // 通过址默认配置创建一个httpclient实例
      httpclient = httpclients.createdefault();
      // 创建httpget远程连接实例
      httpget httpget = new httpget(url);
      // 设置请求头信息，鉴权
      httpget.setheader("authorization", "bearer da3efcbf-0845-4fe3-8aba-ee040be542c0");
      // 设置配置请求参数
      requestconfig requestconfig = requestconfig.custom().setconnecttimeout(35000)// 连接主机服务超时时间
          .setconnectionrequesttimeout(35000)// 请求超时时间
          .setsockettimeout(60000)// 数据读取超时时间
          .build();
      // 为httpget实例设置配置
      httpget.setconfig(requestconfig);
      // 执行get请求得到返回对象
      response = httpclient.execute(httpget);
      // 通过返回对象获取返回数据
      httpentity entity = response.getentity();
      // 通过entityutils中的tostring方法将结果转换为字符串
      result = entityutils.tostring(entity);
    } catch (clientprotocolexception e) {
      e.printstacktrace();
    } catch (ioexception e) {
      e.printstacktrace();
    } finally {
      // 关闭资源
      if (null != response) {
        try {
          response.close();
        } catch (ioexception e) {
          e.printstacktrace();
        }
      }
      if (null != httpclient) {
        try {
          httpclient.close();
        } catch (ioexception e) {
          e.printstacktrace();
        }
      }
    }
    return result;
  }

  public static string dopost(string url, map<string, object> parammap) {
    closeablehttpclient httpclient = null;
    closeablehttpresponse httpresponse = null;
    string result = "";
    // 创建httpclient实例
    httpclient = httpclients.createdefault();
    // 创建httppost远程连接实例
    httppost httppost = new httppost(url);
    // 配置请求参数实例
    requestconfig requestconfig = requestconfig.custom().setconnecttimeout(35000)// 设置连接主机服务超时时间
        .setconnectionrequesttimeout(35000)// 设置连接请求超时时间
        .setsockettimeout(60000)// 设置读取数据连接超时时间
        .build();
    // 为httppost实例设置配置
    httppost.setconfig(requestconfig);
    // 设置请求头
    httppost.addheader("content-type", "application/x-www-form-urlencoded");
    // 封装post请求参数
    if (null != parammap && parammap.size() > 0) {
      list<namevaluepair> nvps = new arraylist<namevaluepair>();
      // 通过map集成entryset方法获取entity
      set<entry<string, object>> entryset = parammap.entryset();
      // 循环遍历，获取迭代器
      iterator<entry<string, object>> iterator = entryset.iterator();
      while (iterator.hasnext()) {
        entry<string, object> mapentry = iterator.next();
        nvps.add(new basicnamevaluepair(mapentry.getkey(), mapentry.getvalue().tostring()));
      }

      // 为httppost设置封装好的请求参数
      try {
        httppost.setentity(new urlencodedformentity(nvps, "utf-8"));
      } catch (unsupportedencodingexception e) {
        e.printstacktrace();
      }
    }
    try {
      // httpclient对象执行post请求,并返回响应参数对象
      httpresponse = httpclient.execute(httppost);
      // 从响应对象中获取响应内容
      httpentity entity = httpresponse.getentity();
      result = entityutils.tostring(entity);
    } catch (clientprotocolexception e) {
      e.printstacktrace();
    } catch (ioexception e) {
      e.printstacktrace();
    } finally {
      // 关闭资源
      if (null != httpresponse) {
        try {
          httpresponse.close();
        } catch (ioexception e) {
          e.printstacktrace();
        }
      }
      if (null != httpclient) {
        try {
          httpclient.close();
        } catch (ioexception e) {
          e.printstacktrace();
        }
      }
    }
    return result;
  }
}

有时候我们在使用post请求时，可能传入的参数是json或者其他格式，此时我们则需要更改请求头及参数的设置信息，以httpclient4.5为例，更改下面两列配置：httppost.setentity(new stringentity("你的json串"));      httppost.addheader("content-type", "application/json")。

以上所述是小编给大家介绍的java实现http请求的三种方式详解整合，希望对大家有所帮助