JAVA中的HTTP请求怎么利用HttpClient实现发送？很多新手对此不是很清楚，为了帮助大家解决这个难题，下面小编将为大家详细讲解，有这方面需求的人可以来学习下，希望你能有所收获。
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HttpClient介绍
HttpClient 不是一个浏览器。它是一个客户端的 HTTP 通信实现库。HttpClient的目标是发 送和接收HTTP 报文。HttpClient不会去缓存内容，执行 嵌入在 HTML 页面中的javascript 代码，猜测内容类型，重新格式化请求/重定向URI，或者其它和 HTTP 运输无关的功能。
HttpClient使用
使用需要引入jar包，maven项目引入如下：
org.apache.httpcomponents
httpclient
4.5
org.apache.httpcomponents
httpcore
4.4.4
org.apache.httpcomponents
httpmime
4.5
使用方法，代码如下：
package com.test;
import java.io.File;
import java.io.IOException;
import java.security.KeyManagementException;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import org.apache.http.HttpEntity;
import org.apache.http.HttpStatus;
import org.apache.http.client.config.RequestConfig;
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.config.Registry;
import org.apache.http.config.RegistryBuilder;
import org.apache.http.conn.socket.ConnectionSocketFactory;
import org.apache.http.conn.socket.PlainConnectionSocketFactory;
import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
import org.apache.http.conn.ssl.SSLContextBuilder;
import org.apache.http.conn.ssl.TrustSelfSignedStrategy;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;
import org.apache.http.entity.mime.MultipartEntityBuilder;
import org.apache.http.entity.mime.content.FileBody;
import org.apache.http.entity.mime.content.StringBody;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.DefaultHttpRequestRetryHandler;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.apache.http.util.EntityUtils;
/**
*
* @author H__D
* @date 2016年10月19日 上午11:27:25
*
*/
public class HttpClientUtil {
// utf-8字符编码
public static final String CHARSET_UTF_8 = "utf-8";
// HTTP内容类型。
public static final String CONTENT_TYPE_TEXT_HTML = "text/xml";
// HTTP内容类型。相当于form表单的形式，提交数据
public static final String CONTENT_TYPE_FORM_URL = "application/x-www-form-urlencoded";
// HTTP内容类型。相当于form表单的形式，提交数据
public static final String CONTENT_TYPE_JSON_URL = "application/json;charset=utf-8";
// 连接管理器
private static PoolingHttpClientConnectionManager pool;
// 请求配置
private static RequestConfig requestConfig;
static {
try {
//System.out.println("初始化HttpClientTest~~~开始");
SSLContextBuilder builder = new SSLContextBuilder();
builder.loadTrustMaterial(null, new TrustSelfSignedStrategy());
SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(
builder.build());
// 配置同时支持 HTTP 和 HTPPS
Registry socketFactoryRegistry = RegistryBuilder. create().register(
"http", PlainConnectionSocketFactory.getSocketFactory()).register(
"https", sslsf).build();
// 初始化连接管理器
pool = new PoolingHttpClientConnectionManager(
socketFactoryRegistry);
// 将最大连接数增加到200，实际项目最好从配置文件中读取这个值
pool.setMaxTotal(200);
// 设置最大路由
pool.setDefaultMaxPerRoute(2);
// 根据默认超时限制初始化requestConfig
int socketTimeout = 10000;
int connectTimeout = 10000;
int connectionRequestTimeout = 10000;
requestConfig = RequestConfig.custom().setConnectionRequestTimeout(
connectionRequestTimeout).setSocketTimeout(socketTimeout).setConnectTimeout(
connectTimeout).build();
//System.out.println("初始化HttpClientTest~~~结束");
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
} catch (KeyStoreException e) {
e.printStackTrace();
} catch (KeyManagementException e) {
e.printStackTrace();
}
// 设置请求超时时间
requestConfig = RequestConfig.custom().setSocketTimeout(50000).setConnectTimeout(50000)
.setConnectionRequestTimeout(50000).build();
}
public static CloseableHttpClient getHttpClient() {
CloseableHttpClient httpClient = HttpClients.custom()
// 设置连接池管理
.setConnectionManager(pool)
// 设置请求配置
.setDefaultRequestConfig(requestConfig)
// 设置重试次数
.setRetryHandler(new DefaultHttpRequestRetryHandler(0, false))
.build();
return httpClient;
}
/**
* 发送Post请求
*
* @param httpPost
* @return
*/
private static String sendHttpPost(HttpPost httpPost) {
CloseableHttpClient httpClient = null;
CloseableHttpResponse response = null;
// 响应内容
String responseContent = null;
try {
// 创建默认的httpClient实例.
httpClient = getHttpClient();
// 配置请求信息
httpPost.setConfig(requestConfig);
// 执行请求
response = httpClient.execute(httpPost);
// 得到响应实例
HttpEntity entity = response.getEntity();
// 可以获得响应头
// Header[] headers = response.getHeaders(HttpHeaders.CONTENT_TYPE);
// for (Header header : headers) {
// System.out.println(header.getName());
// }
// 得到响应类型
// System.out.println(ContentType.getOrDefault(response.getEntity()).getMimeType());
// 判断响应状态
if (response.getStatusLine().getStatusCode() >= 300) {
throw new Exception(
"HTTP Request is not success, Response code is " + response.getStatusLine().getStatusCode());
}
if (HttpStatus.SC_OK == response.getStatusLine().getStatusCode()) {
responseContent = EntityUtils.toString(entity, CHARSET_UTF_8);
EntityUtils.consume(entity);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
// 释放资源
if (response != null) {
response.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
return responseContent;
}
/**
* 发送Get请求
*
* @param httpGet
* @return
*/
private static String sendHttpGet(HttpGet httpGet) {
CloseableHttpClient httpClient = null;
CloseableHttpResponse response = null;
// 响应内容
String responseContent = null;
try {
// 创建默认的httpClient实例.
httpClient = getHttpClient();
// 配置请求信息
httpGet.setConfig(requestConfig);
// 执行请求
response = httpClient.execute(httpGet);
// 得到响应实例
HttpEntity entity = response.getEntity();
// 可以获得响应头
// Header[] headers = response.getHeaders(HttpHeaders.CONTENT_TYPE);
// for (Header header : headers) {
// System.out.println(header.getName());
// }
// 得到响应类型
// System.out.println(ContentType.getOrDefault(response.getEntity()).getMimeType());
// 判断响应状态
if (response.getStatusLine().getStatusCode() >= 300) {
throw new Exception(
"HTTP Request is not success, Response code is " + response.getStatusLine().getStatusCode());
}
if (HttpStatus.SC_OK == response.getStatusLine().getStatusCode()) {
responseContent = EntityUtils.toString(entity, CHARSET_UTF_8);
EntityUtils.consume(entity);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
// 释放资源
if (response != null) {
response.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
return responseContent;
}
/**
* 发送 post请求
*
* @param httpUrl
* 地址
*/
public static String sendHttpPost(String httpUrl) {
// 创建httpPost
HttpPost httpPost = new HttpPost(httpUrl);
return sendHttpPost(httpPost);
}
/**
* 发送 get请求
*
* @param httpUrl
*/
public static String sendHttpGet(String httpUrl) {
// 创建get请求
HttpGet httpGet = new HttpGet(httpUrl);
return sendHttpGet(httpGet);
}
/**
* 发送 post请求（带文件）
*
* @param httpUrl
* 地址
* @param maps
* 参数
* @param fileLists
* 附件
*/
public static String sendHttpPost(String httpUrl, Map maps, List fileLists) {
HttpPost httpPost = new HttpPost(httpUrl);// 创建httpPost
MultipartEntityBuilder meBuilder = MultipartEntityBuilder.create();
if (maps != null) {
for (String key : maps.keySet()) {
meBuilder.addPart(key, new StringBody(maps.get(key), ContentType.TEXT_PLAIN));
}
}
if (fileLists != null) {
for (File file : fileLists) {
FileBody fileBody = new FileBody(file);
meBuilder.addPart("files", fileBody);
}
}
HttpEntity reqEntity = meBuilder.build();
httpPost.setEntity(reqEntity);
return sendHttpPost(httpPost);
}
/**
* 发送 post请求
*
* @param httpUrl
* 地址
* @param params
* 参数(格式:key1=value1&key2=value2)
*
*/
public static String sendHttpPost(String httpUrl, String params) {
HttpPost httpPost = new HttpPost(httpUrl);// 创建httpPost
try {
// 设置参数
if (params != null && params.trim().length() > 0) {
StringEntity stringEntity = new StringEntity(params, "UTF-8");
stringEntity.setContentType(CONTENT_TYPE_FORM_URL);
httpPost.setEntity(stringEntity);
}
} catch (Exception e) {
e.printStackTrace();
}
return sendHttpPost(httpPost);
}
/**
* 发送 post请求
*
* @param maps
* 参数
*/
public static String sendHttpPost(String httpUrl, Map maps) {
String parem = convertStringParamter(maps);
return sendHttpPost(httpUrl, parem);
}
/**
* 发送 post请求 发送json数据
*
* @param httpUrl
* 地址
* @param paramsJson
* 参数(格式 json)
*
*/
public static String sendHttpPostJson(String httpUrl, String paramsJson) {
HttpPost httpPost = new HttpPost(httpUrl);// 创建httpPost
try {
// 设置参数
if (paramsJson != null && paramsJson.trim().length() > 0) {
StringEntity stringEntity = new StringEntity(paramsJson, "UTF-8");
stringEntity.setContentType(CONTENT_TYPE_JSON_URL);
httpPost.setEntity(stringEntity);
}
} catch (Exception e) {
e.printStackTrace();
}
return sendHttpPost(httpPost);
}
/**
* 发送 post请求 发送xml数据
*
* @param httpUrl 地址
* @param paramsXml 参数(格式 Xml)
*
*/
public static String sendHttpPostXml(String httpUrl, String paramsXml) {
HttpPost httpPost = new HttpPost(httpUrl);// 创建httpPost
try {
// 设置参数
if (paramsXml != null && paramsXml.trim().length() > 0) {
StringEntity stringEntity = new StringEntity(paramsXml, "UTF-8");
stringEntity.setContentType(CONTENT_TYPE_TEXT_HTML);
httpPost.setEntity(stringEntity);
}
} catch (Exception e) {
e.printStackTrace();
}
return sendHttpPost(httpPost);
}
/**
* 将map集合的键值对转化成：key1=value1&key2=value2 的形式
*
* @param parameterMap
* 需要转化的键值对集合
* @return 字符串
*/
public static String convertStringParamter(Map parameterMap) {
StringBuffer parameterBuffer = new StringBuffer();
if (parameterMap != null) {
Iterator iterator = parameterMap.keySet().iterator();
String key = null;
String value = null;
while (iterator.hasNext()) {
key = (String) iterator.next();
if (parameterMap.get(key) != null) {
value = (String) parameterMap.get(key);
} else {
value = "";
}
parameterBuffer.append(key).append("=").append(value);
if (iterator.hasNext()) {
parameterBuffer.append("&");
}
}
}
return parameterBuffer.toString();
}
public static void main(String[] args) throws Exception {
System.out.println(sendHttpGet("http://www.baidu.com"));
}
}看完上述内容是否对您有帮助呢？如果还想对相关知识有进一步的了解或阅读更多相关文章，请关注创新互联行业资讯频道，感谢您对创新互联的支持。
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