什么是OKHttp
一般在java平台上，我们会使用apache httpclient作为http客户端，用于发送 http 请求，并对响应进行处理。举个例子，可以把http客户端与第三方服务比如sso服务整合起来，同时也能爬取互联网上的数据。okhttp与httpclient类似，也是一个http客户端，提供了对 http/2 和 spdy 的支持，并提供了连接池，gzip 压缩和 http 响应缓存功能；
OkHttp是目前非常火的网络库，它有以下特性：
1.支持HTTP/2，允许所有同一个主机地址的请求共享同一个socket连接
2.连接池减少请求延时
3.透明的GZIP压缩减少响应数据的大小
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4.缓存响应内容，避免一些完全重复的请求
OkHttp基本使用
OkHttpClient：客户端对象
Request：访问请求，Post请求中需要包含RequestBody
RequestBody：请求数据，在Post请求中用到
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Response：即网络请求的响应结果
MediaType：数据类型，用来表明数据是json，image，pdf等一系列格式
client.newCall(request).execute()：同步的请求方法
client.newCall(request).enqueue(Callback callBack)：异步的请求方法，但Callback是执行在子线程中的，因此不能在此进行UI更新操作
官网：http://square.github.io/okhttp/
添加依赖
com.squareup.okhttp3 okhttp 3.10.0 com.alibaba fastjson 1.2.60
OkHttp工具类
package com.loginsimpl.utils;
import com.alibaba.fastjson.JSON;
import okhttp3.*;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSocketFactory;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;
import java.io.IOException;
import java.net.URLEncoder;
import java.security.SecureRandom;
import java.security.cert.X509Certificate;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;
public class OkHttpUtils {
private static volatile OkHttpClient okHttpClient = null;
private static volatile Semaphore semaphore = null;
private Map headerMap;
private Map paramMap;
private String url;
private Request.Builder request;
/**
* 初始化okHttpClient，并且允许https访问
*/
private OkHttpUtils() {
if (okHttpClient == null) {
synchronized (OkHttpUtils.class) {
if (okHttpClient == null) {
TrustManager[] trustManagers = buildTrustManagers();
okHttpClient = new OkHttpClient.Builder()
.connectTimeout(15, TimeUnit.SECONDS)
.writeTimeout(20, TimeUnit.SECONDS)
.readTimeout(20, TimeUnit.SECONDS)
.sslSocketFactory(createSSLSocketFactory(trustManagers), (X509TrustManager) trustManagers[0])
.hostnameVerifier((hostName, session) -> true)
.retryOnConnectionFailure(true)
.build();
addHeader("User-Agent", "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36");
}
}
}
}
/**
* 用于异步请求时，控制访问线程数，返回结果
*
* @return
*/
private static Semaphore getSemaphoreInstance() {
//只能1个线程同时访问
synchronized (OkHttpUtils.class) {
if (semaphore == null) {
semaphore = new Semaphore(0);
}
}
return semaphore;
}
/**
* 创建OkHttpUtils
*
* @return
*/
public static OkHttpUtils builder() {
return new OkHttpUtils();
}
/**
* 添加url
*
* @param url
* @return
*/
public OkHttpUtils url(String url) {
this.url = url;
return this;
}
/**
* 添加参数
*
* @param key 参数名
* @param value 参数值
* @return
*/
public OkHttpUtils addParam(String key, String value) {
if (paramMap == null) {
paramMap = new LinkedHashMap<>(16);
}
paramMap.put(key, value);
return this;
}
/**
* 添加请求头
*
* @param key 参数名
* @param value 参数值
* @return
*/
public OkHttpUtils addHeader(String key, String value) {
if (headerMap == null) {
headerMap = new LinkedHashMap<>(16);
}
headerMap.put(key, value);
return this;
}
/**
* 初始化get方法
*
* @return
*/
public OkHttpUtils get() {
request = new Request.Builder().get();
StringBuilder urlBuilder = new StringBuilder(url);
if (paramMap != null) {
urlBuilder.append("?");
try {
for (Map.Entry entry : paramMap.entrySet()) {
urlBuilder.append(URLEncoder.encode(entry.getKey(), "utf-8")).
append("=").
append(URLEncoder.encode(entry.getValue(), "utf-8")).
append("&");
}
} catch (Exception e) {
e.printStackTrace();
}
urlBuilder.deleteCharAt(urlBuilder.length() - 1);
}
request.url(urlBuilder.toString());
return this;
}
/**
* 初始化post方法
*
* @param isJsonPost true等于json的方式提交数据，类似postman里post方法的raw
* false等于普通的表单提交
* @return
*/
public OkHttpUtils post(boolean isJsonPost) {
RequestBody requestBody;
if (isJsonPost) {
String json = "";
if (paramMap != null) {
json = JSON.toJSONString(paramMap);
}
requestBody = RequestBody.create(MediaType.parse("application/json; charset=utf-8"), json);
} else {
FormBody.Builder formBody = new FormBody.Builder();
if (paramMap != null) {
paramMap.forEach(formBody::add);
}
requestBody = formBody.build();
}
request = new Request.Builder().post(requestBody).url(url);
return this;
}
/**
* 同步请求
*
* @return
*/
public String sync() {
setHeader(request);
try {
Response response = okHttpClient.newCall(request.build()).execute();
assert response.body() != null;
return response.body().string();
} catch (IOException e) {
e.printStackTrace();
return "请求失败：" + e.getMessage();
}
}
/**
* 异步请求，有返回值 (限流的,同一时间只允许一个访问,其他等待)
*/
public String async() {
StringBuilder buffer = new StringBuilder("");
setHeader(request);
okHttpClient.newCall(request.build()).enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
buffer.append("请求出错：").append(e.getMessage());
}
@Override
public void onResponse(Call call, Response response) throws IOException {
assert response.body() != null;
buffer.append(response.body().string());
getSemaphoreInstance().release();
}
});
try {
getSemaphoreInstance().acquire();
} catch (InterruptedException e) {
e.printStackTrace();
}
return buffer.toString();
}
/**
* 异步请求，带有接口回调
*
* @param callBack
*/
public void async(ICallBack callBack) {
setHeader(request);
okHttpClient.newCall(request.build()).enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
callBack.onFailure(call, e.getMessage());
}
@Override
public void onResponse(Call call, Response response) throws IOException {
assert response.body() != null;
callBack.onSuccessful(call, response.body().string());
}
});
}
/**
* 为request添加请求头
*
* @param request
*/
private void setHeader(Request.Builder request) {
if (headerMap != null) {
try {
for (Map.Entry entry : headerMap.entrySet()) {
request.addHeader(entry.getKey(), entry.getValue());
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
/**
* 生成安全套接字工厂，用于https请求的证书跳过
*
* @return
*/
private static SSLSocketFactory createSSLSocketFactory(TrustManager[] trustAllCerts) {
SSLSocketFactory ssfFactory = null;
try {
SSLContext sc = SSLContext.getInstance("SSL");
sc.init(null, trustAllCerts, new SecureRandom());
ssfFactory = sc.getSocketFactory();
} catch (Exception e) {
e.printStackTrace();
}
return ssfFactory;
}
private static TrustManager[] buildTrustManagers() {
return new TrustManager[]{
new X509TrustManager() {
@Override
public void checkClientTrusted(X509Certificate[] chain, String authType) {
}
@Override
public void checkServerTrusted(X509Certificate[] chain, String authType) {
}
@Override
public X509Certificate[] getAcceptedIssuers() {
return new X509Certificate[]{};
}
}
};
}
/**
* 自定义一个接口回调
*/
public interface ICallBack {
void onSuccessful(Call call, String data);
void onFailure(Call call, String errorMsg);
}
} 使用案例
发送get请求
String sync = OkHttpUtils.builder().url("http://localhost:9100/user/all")
.addHeader("token", "xxxxxxx")
.addParam("name", "xxx").addParam("pass", "xxx")
.get()
.sync();
System.out.println(sync);发送Post请求
String sync = OkHttpUtils.builder().url("http://localhost:9100/user/all")
.addHeader("token", "xxxxxxx")
.addParam("name", "xxx").addParam("pass", "xxx")
.post(true) // true 为json提交方式
.sync();
System.out.println(sync);发送异步请求
需要实现ICallBack接口
//回调实现类
public class AsyncHttpServiceImpl implements OkHttpUtils.ICallBack {
@Override
public void onSuccessful(Call call, String data) {
//接口正常返回的内容
System.out.println("onSuccessful"+data);
}
@Override
public void onFailure(Call call, String errorMsg) {
//接口错误返回的内容
System.out.println("onFailure"+errorMsg);
}
}发送异步请求
OkHttpUtils.builder().url("http://localhost:9100/user/all")
.addHeader("token", "xxxxxxx")
.addParam("name", "xxx").addParam("pass", "xxx")
.post(true)
.async(new AsyncHttpServiceImpl()); 
