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这期内容当中小编将会给大家带来有关使用Java 如何发送http请求，文章内容丰富且以专业的角度为大家分析和叙述，阅读完这篇文章希望大家可以有所收获。
1.情景展示
java发送get请求、post请求（form表单、json数据）至另一服务器；
可设置HTTP请求头部信息，可以接收服务器返回cookie信息，可以上传文件等；
2.代码实现
所需jar包：httpcore-4.4.1.jar；httpclient-4.4.1.jar；httpmime-4.4.1.jar；epoint-utils-9.3.3.jar
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.Charset;
import java.security.GeneralSecurityException;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSession;
import org.apache.http.Header;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
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.HttpDelete;
import org.apache.http.client.methods.HttpEntityEnclosingRequestBase;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPatch;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.methods.HttpRequestBase;
import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
import org.apache.http.conn.ssl.TrustStrategy;
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.StringBody;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.ssl.SSLContextBuilder;
import org.apache.http.util.EntityUtils;
import com.epoint.core.utils.string.StringUtil;
/**
* HttpClient工具类，使用http-client包实现，原先的common-httpclient已经淘汰
*
* @作者 ko
* @version [版本号, 2017年10月18日]
*/
public class HttpUtil
{
private static PoolingHttpClientConnectionManager connMgr;
private static RequestConfig requestConfig;
private static final int MAX_TIMEOUT = 7000;
/**
* 直接以流返回
*/
public static final int RTN_TYPE_1 = 1;
/**
* 直接以string返回
*/
public static final int RTN_TYPE_2 = 2;
/**
* 以map返回，reslut:接口结果string;statusCode:http状态码
*/
public static final int RTN_TYPE_3 = 3;
/**
* 以map返回，reslut:接口结果string;statusCode:http状态码;cookie:response的cookie
* cookie值键值对，格式 key1=value1;key2=value2;...
*/
public static final int RTN_TYPE_4 = 4;
/**
* 默认上传文件的文件流或file 的key Name
*/
private static final String DEFAULT_BINARYBODY_KEYNAME = "file";
static {
// 设置连接池
connMgr = new PoolingHttpClientConnectionManager();
// 设置连接池大小
connMgr.setMaxTotal(100);
connMgr.setDefaultMaxPerRoute(connMgr.getMaxTotal());
// 在提交请求之前 测试连接是否可用
connMgr.setValidateAfterInactivity(1);
RequestConfig.Builder configBuilder = RequestConfig.custom();
// 设置连接超时
configBuilder.setConnectTimeout(MAX_TIMEOUT);
// 设置读取超时
configBuilder.setSocketTimeout(MAX_TIMEOUT);
// 设置从连接池获取连接实例的超时
configBuilder.setConnectionRequestTimeout(MAX_TIMEOUT);
requestConfig = configBuilder.build();
}
/**
* 发送 GET请求
*
* @param apiUrl
* API接口URL
* @return String 响应内容
*/
public static String doGet(String apiUrl) {
return doHttp(apiUrl, null, "get", RTN_TYPE_2);
}
/**
* 发送POST请求
*
* @param apiUrl
* API接口URL
* @param params
* K-V参数
* @return String 响应内容
*/
public static String doPost(String apiUrl, Map<String, Object> params) {
return doHttp(apiUrl, params, "post", RTN_TYPE_2);
}
/**
* 发送POST请求
*
* @param apiUrl
* API接口URL
* @param json
* json参数
* @return String 响应内容
*/
public static String doPostJson(String apiUrl, String json) {
return doHttp(apiUrl, json, "post", RTN_TYPE_2);
}
/**
* 发送 http 请求
*
* @param apiUrl
* API接口URL
* @param params
* {Map<String, Object> K-V形式、json字符串}
* @param method
* {null、或者post:POST请求、patch:PATCH请求、delete:DELETE请求、get:GET请求}
* @param type
* {HttpUtil.RTN_TYPE_1:请求返回stream(此时流需要在外部手动关闭);HttpUtil.
* RTN_TYPE_2:string;HttpUtil.RTN_TYPE_3:返回一个map,map包含结果(
* 结果是string形式)以及http状态码;HttpUtil.RTN_TYPE_4:返回一个map,map包含结果(
* 结果是string形式), http状态码和cookie;其他情况返回string}
* 如果结果是个map,key为:result,statusCode,cookie,分别返回 结果
* string,http状态码，cookie; cookie值键值对，格式
* key1=value1;key2=value2;...
* @return stream或 string 或 map
*/
public static <T> T doHttp(String apiUrl, Object params, String method, int type) {
return doHttp(apiUrl, null, params, method, type);
}
/**
* 发送 http 请求
*
* @param apiUrl
* API接口URL
* @param headerMap
* header信息Map<String, String>,可设置cookie
* @param params
* {Map<String, Object> K-V形式、json字符串}
* @param method
* {null、或者post:POST请求、patch:PATCH请求、delete:DELETE请求、get:GET请求}
* @param type
* {HttpUtil.RTN_TYPE_1:请求返回stream(此时流需要在外部手动关闭);HttpUtil.
* RTN_TYPE_2:string;HttpUtil.RTN_TYPE_3:返回一个map,map包含结果(
* 结果是string形式)以及http状态码;HttpUtil.RTN_TYPE_4:返回一个map,map包含结果(
* 结果是string形式), http状态码和cookie;其他情况返回string}
* 如果结果是个map,key为:result,statusCode,cookie,分别返回 结果
* string,http状态码，cookie; cookie值键值对，格式
* key1=value1;key2=value2;...
* @return stream或 string 或 map
*/
public static <T> T doHttp(String apiUrl, Map<String, String> headerMap, Object params, String method, int type) {
CloseableHttpClient httpClient = null;
if (isSSL(apiUrl)) {
httpClient = HttpClients.custom().setSSLSocketFactory(createSSLConnSocketFactory())
.setConnectionManager(connMgr).setDefaultRequestConfig(requestConfig).build();
}
else {
httpClient = HttpClients.createDefault();
}
return doHttp(httpClient, apiUrl, headerMap, params, method, type);
}
/**
* 发送 http 请求
*
* @param httpClient
* httpclient对象 由外部传入，用户 需要保持登录状态等情况 此时如果要ssl,那么要在外部加入ssl特性
* httpClient =
* HttpClients.custom().setSSLSocketFactory(HttpUtil.
* createSSLConnSocketFactory())
* .setConnectionManager(HttpUtil.getConnMgr()).
* setDefaultRequestConfig(HttpUtil..getRequestConfig()).build();
* @param apiUrl
* API接口URL
* @param headerMap
* header信息Map<String, String>,可设置cookie
*
* @param params
* {Map<String, Object> K-V形式、json字符串}
* @param method
* {null、或者post:POST请求、patch:PATCH请求、delete:DELETE请求、get:GET请求}
* @param type
* {HttpUtil.RTN_TYPE_1:请求返回stream(此时流需要在外部手动关闭);HttpUtil.
* RTN_TYPE_2:string;HttpUtil.RTN_TYPE_3:返回一个map,map包含结果(
* 结果是string形式)以及http状态码;HttpUtil.RTN_TYPE_4:返回一个map,map包含结果(
* 结果是string形式), http状态码和cookie;其他情况返回string}
* 如果结果是个map,key为:result,statusCode,cookie,分别返回 结果
* string,http状态码，cookie; cookie值键值对，格式
* key1=value1;key2=value2;...
* @return stream或 string 或 map
*/
@SuppressWarnings("unchecked")
public static <T> T doHttp(CloseableHttpClient httpClient, String apiUrl, Map<String, String> headerMap,
Object params, String method, int type) {
HttpRequestBase httpPost = null;
if (StringUtil.isNotBlank(method)) {
if ("patch".equalsIgnoreCase(method)) {
httpPost = new HttpPatch(apiUrl);
}
else if ("delete".equalsIgnoreCase(method)) {
httpPost = new HttpDelete(apiUrl);
}
else if ("get".equalsIgnoreCase(method)) {
httpPost = new HttpGet(apiUrl);
}
else if ("post".equalsIgnoreCase(method)) {
httpPost = new HttpPost(apiUrl);
}
}
else {
httpPost = new HttpPost(apiUrl);
}
CloseableHttpResponse response = null;
try {
// 设置header信息
if (headerMap != null && !headerMap.isEmpty()) {
for (Map.Entry<String, String> entry : headerMap.entrySet()) {
httpPost.addHeader(entry.getKey(), entry.getValue());
}
}
if (isSSL(apiUrl)) {
httpPost.setConfig(requestConfig);
}
// 参数不为null、要处理参数
if (params != null) {
// get请求拼接在url后面
if (httpPost instanceof HttpGet) {
StringBuffer param = new StringBuffer();
if (params instanceof Map) {
Map<String, Object> paramsConvert = (Map<String, Object>) params;
int i = 0;
for (String key : paramsConvert.keySet()) {
if (i == 0)
param.append("?");
else
param.append("&");
param.append(key).append("=").append(paramsConvert.get(key));
i++;
}
}
else {
param.append("?" + params.toString());
}
apiUrl += param;
}
// delete请求暂不处理
else if (!(httpPost instanceof HttpDelete)) {
// K-V形式
if (params instanceof Map) {
Map<String, Object> paramsConvert = (Map<String, Object>) params;
List<NameValuePair> pairList = new ArrayList<>(paramsConvert.size());
for (Map.Entry<String, Object> entry : paramsConvert.entrySet()) {
NameValuePair pair = new BasicNameValuePair(entry.getKey(),
entry.getValue() == null ? "" : entry.getValue().toString());
pairList.add(pair);
}
((HttpEntityEnclosingRequestBase) httpPost)
.setEntity(new UrlEncodedFormEntity(pairList, Charset.forName("UTF-8")));
}
// json格式
else {
StringEntity stringEntity = new StringEntity(params.toString(), "UTF-8");
stringEntity.setContentEncoding("UTF-8");
stringEntity.setContentType("application/json");
((HttpEntityEnclosingRequestBase) httpPost).setEntity(stringEntity);
}
}
}
response = httpClient.execute(httpPost);
// int statusCode = response.getStatusLine().getStatusCode();
// if (statusCode != HttpStatus.SC_OK) {
// return null;
// }
HttpEntity entity = response.getEntity();
if (entity != null) {
if (type == RTN_TYPE_1) {
return (T) entity.getContent();
}
else if (RTN_TYPE_2 == type) {
return (T) EntityUtils.toString(entity, "UTF-8");
}
else if (RTN_TYPE_3 == type || RTN_TYPE_4 == type) {
Map<String, String> rtnMap = new HashMap<String, String>();
rtnMap.put("result", EntityUtils.toString(entity, "UTF-8"));
rtnMap.put("statusCode", response.getStatusLine().getStatusCode() + "");
if (RTN_TYPE_4 == type) {
rtnMap.put("cookie", getCookie(response));
}
return (T) rtnMap;
}
else {
return (T) EntityUtils.toString(entity, "UTF-8");
}
}
}
catch (Exception e) {
e.printStackTrace();
}
finally {
if (response != null && type != RTN_TYPE_1) {
try {
EntityUtils.consume(response.getEntity());
}
catch (IOException e) {
e.printStackTrace();
}
}
}
return null;
}
/**
* 上传附件(post形式)
*
* @param url
* 请求地址
* @param headerMap
* header参数map Map<String, String>
* @param paramMap
* 额外的参数map,Map<String, String>
* @param file
* 可以选择本地文件上传；如果传了file，又传了fileName，那么文件名以fileName为准，否则 是file的文件名
* @param fileName
* 以流传输时，必须指定文件名
* @param ssl
* 是否需要ssl
* @return result,返回上传结果，如果接口没有返回值，则为状态码
*/
public static String upload(String url, Map<String, String> headerMap, Map<String, String> paramMap, File file,
String fileName, boolean ssl) {
return upload(url, headerMap, paramMap, file, null, fileName, ssl);
}
/**
* 上传附件(post形式)
*
* @param url
* 请求地址
* @param headerMap
* header参数map Map<String, String>
* @param paramMap
* 额外的参数map,Map<String, String>
* @param in
* 文件流
* @param fileName
* 以流传输时，必须指定文件名
* @param ssl
* 是否需要ssl
* @return result,返回上传结果，如果接口没有返回值，则为状态码
*/
public static String upload(String url, Map<String, String> headerMap, Map<String, String> paramMap, InputStream in,
String fileName, boolean ssl) {
return upload(url, headerMap, paramMap, null, in, fileName, ssl);
}
/**
* 上传附件(post形式)
*
* @param httpClient
* 外部传入httpClient
* @param url
* 请求地址
* @param headerMap
* header参数map Map<String, String>
* @param paramMap
* 额外的参数map,Map<String, String>
* @param file
* 可以选择本地文件上传；如果传了file，又传了fileName，那么文件名以fileName为准，否则 是file的文件名
* @param fileName
* 以流传输时，必须指定文件名
* @param ssl
* 是否需要ssl
* @return result,返回上传结果，如果接口没有返回值，则为状态码
*/
public static String upload(CloseableHttpClient httpClient, String url, Map<String, String> headerMap,
Map<String, String> paramMap, File file, String fileName, boolean ssl) {
return upload(httpClient, url, headerMap, paramMap, file, null, fileName, ssl);
}
/**
* 上传附件(post形式)
*
* @param httpClient
* 外部传入httpClient
* @param url
* 请求地址
* @param headerMap
* header参数map Map<String, String>
* @param paramMap
* 额外的参数map,Map<String, String>
* @param in
* 文件流
* @param fileName
* 以流传输时，必须指定文件名
* @param ssl
* 是否需要ssl
* @return result,返回上传结果，如果接口没有返回值，则为状态码
*/
public static String upload(CloseableHttpClient httpClient, String url, Map<String, String> headerMap,
Map<String, String> paramMap, InputStream in, String fileName, boolean ssl) {
return upload(httpClient, url, headerMap, paramMap, null, in, fileName, ssl);
}
/**
* 上传附件(post形式)
*
* @param url
* 请求地址
* @param headerMap
* header参数map Map<String, String>
* @param paramMap
* 额外的参数map,Map<String, String>
* @param file
* 可以选择本地文件上传，file,in互斥；如果传了file，又传了fileName，那么文件名以fileName为准，否则
* 是file的文件名
* @param in
* 文件流
* @param fileName
* 以流传输时，必须指定文件名
* @param ssl
* 是否需要ssl
* @return result,返回上传结果，如果接口没有返回值，则为状态码
*/
private static String upload(String url, Map<String, String> headerMap, Map<String, String> paramMap, File file,
InputStream in, String fileName, boolean ssl) {
CloseableHttpClient httpClient = null;
if (ssl) {
httpClient = HttpClients.custom().setSSLSocketFactory(createSSLConnSocketFactory())
.setConnectionManager(connMgr).setDefaultRequestConfig(requestConfig).build();
}
else {
httpClient = HttpClients.createDefault();
}
return upload(httpClient, url, headerMap, paramMap, file, in, fileName, ssl);
}
/**
* 上传附件(post形式)
*
* @param httpClient
* 外部传入httpClient
* @param url
* 请求地址
* @param headerMap
* header参数map Map<String, String>
* @param paramMap
* 额外的参数map,Map<String, String>
* @param file
* 可以选择本地文件上传，file,in互斥；如果传了file，又传了fileName，那么文件名以fileName为准，否则
* 是file的文件名
* @param in
* 文件流
* @param fileName
* 以流传输时，必须指定文件名
* @param ssl
* 是否需要ssl
* @return result,返回上传结果，如果接口没有返回值，则为状态码
*/
private static String upload(CloseableHttpClient httpClient, String url, Map<String, String> headerMap,
Map<String, String> paramMap, File file, InputStream in, String fileName, boolean ssl) {
String result = "";
CloseableHttpResponse response = null;
try {
HttpPost httpPost = new HttpPost(url);
// 设置header信息
if (headerMap != null && !headerMap.isEmpty()) {
for (Map.Entry<String, String> entry : headerMap.entrySet()) {
httpPost.addHeader(entry.getKey(), entry.getValue());
}
}
if (ssl) {
httpPost.setConfig(requestConfig);
}
MultipartEntityBuilder builder = MultipartEntityBuilder.create();
// 选择以file形式上传
if (file != null && file.exists()) {
if (StringUtil.isNotBlank(fileName)) {
builder.addBinaryBody(DEFAULT_BINARYBODY_KEYNAME, file, ContentType.DEFAULT_BINARY, fileName);
}
else {
builder.addBinaryBody(DEFAULT_BINARYBODY_KEYNAME, file);
}
}
// 以流上传
else if (in != null && StringUtil.isNotBlank(fileName)) {
builder.addBinaryBody(DEFAULT_BINARYBODY_KEYNAME, in, ContentType.DEFAULT_BINARY, fileName);
}
if (paramMap != null && !paramMap.isEmpty()) {
for (Map.Entry<String, String> entry : paramMap.entrySet()) {
builder.addPart(entry.getKey(), new StringBody(entry.getValue(), ContentType.TEXT_PLAIN));
}
}
HttpEntity reqEntity = builder.build();
httpPost.setEntity(reqEntity);
response = httpClient.execute(httpPost);
HttpEntity entity = response.getEntity();
if (entity != null) {
result = EntityUtils.toString(entity, "UTF-8");
}
else {
result = response.getStatusLine().getStatusCode() + "";
}
}
catch (Exception e) {
e.printStackTrace();
}
finally {
if (response != null) {
try {
EntityUtils.consume(response.getEntity());
}
catch (IOException e) {
e.printStackTrace();
}
}
}
return result;
}
private static String getCookie(HttpResponse httpResponse) {
Map<String, String> cookieMap = new HashMap<String, String>(64);
Header headers[] = httpResponse.getHeaders("Set-Cookie");
if (headers == null || headers.length == 0) {
return null;
}
String cookie = "";
for (int i = 0; i < headers.length; i++) {
cookie += headers[i].getValue();
if (i != headers.length - 1) {
cookie += ";";
}
}
String cookies[] = cookie.split(";");
for (String c : cookies) {
c = c.trim();
if (cookieMap.containsKey(c.split("=")[0])) {
cookieMap.remove(c.split("=")[0]);
}
cookieMap.put(c.split("=")[0],
c.split("=").length == 1 ? "" : (c.split("=").length == 2 ? c.split("=")[1] : c.split("=", 2)[1]));
}
String cookiesTmp = "";
for (String key : cookieMap.keySet()) {
cookiesTmp += key + "=" + cookieMap.get(key) + ";";
}
return cookiesTmp.substring(0, cookiesTmp.length() - 2);
}
/**
* 创建SSL安全连接
*
* @return
*/
public static SSLConnectionSocketFactory createSSLConnSocketFactory() {
SSLConnectionSocketFactory sslsf = null;
try {
SSLContext sslContext = new SSLContextBuilder().loadTrustMaterial(null, new TrustStrategy()
{
public boolean isTrusted(X509Certificate[] chain, String authType) throws CertificateException {
return true;
}
}).build();
sslsf = new SSLConnectionSocketFactory(sslContext, new HostnameVerifier()
{
@Override
public boolean verify(String arg0, SSLSession arg1) {
return true;
}
});
}
catch (GeneralSecurityException e) {
e.printStackTrace();
}
return sslsf;
}
public static PoolingHttpClientConnectionManager getConnMgr() {
return connMgr;
}
public static RequestConfig getRequestConfig() {
return requestConfig;
}
private static boolean isSSL(String apiUrl) {
if (apiUrl.indexOf("https") != -1 ) {
return true;
}
else {
return false;
}
}
}上述就是小编为大家分享的使用Java 如何发送http请求了，如果刚好有类似的疑惑，不妨参照上述分析进行理解。如果想知道更多相关知识，欢迎关注亿速云行业资讯频道。
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