引言
OkHttp作为时下最火的http框架,以它的轻量级、高效率的优势，深受广大开发者的喜爱，使用它的人越来越多。说到这我就比较惭愧了，因为我最近才开始学习OkHttp,经过一番学习，掌握了OkHttp的基本使用，下面我就介绍一下OkHttp的基本用法。
配置方法
（一）导入jar包
点击下面链接下载OkHttp最新jar包
https://repo1.maven.org/maven2/com/squareup/okhttp3/okhttp/3.9.1/okhttp-3.9.1.jar
（二）通过构建方式导入
MAVEN
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<dependency> <groupId>com.squareup.okhttp3</groupId> <artifactId>okhttp</artifactId> <version>3.9.1</version> </dependency> |
GRADLE
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compile 'com.squareup.okhttp3:okhttp:3.9.1' |
请求和响应
Request（请求）
每一个HTTP请求中都应该包含一个URL，一个GET或POST方法以及Header或其他参数，当然还可以含特定内容类型的数据流。
Responses（响应）
响应则包含一个回复代码（200代表成功，404代表未找到），Header和定制可选的body
基本使用
在日常开发中，最常用到的网络请求就是POST和GET两种请求方式。
Http GET
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OkHttpClient client = new OkHttpClient(); String run(String url) throws IOException { Request request = new Request.Builder().url(url).build(); Response response = client.newCall(request).execute(); if (response.isSuccessful()) { return response.body().string(); } else { throw new IOException("Unexpected code " + response); } } |
上面这段代码中，Request是OkHttp中访问的请求，Builder是辅助类，，Response即OkHttp中的响应。
Response类：
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public boolean isSuccessful() Returns true if the code is in [200..300), which means the request was successfully received, understood, and accepted. response.body()返回ResponseBody类 |
可以方便的获取String：
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public final String string() throws IOException Returns the response as a string decoded with the charset of the Content-Type header. If that header is either absent or lacks a charset, this will attempt to decode the response body as UTF-8. Throws: IOException |
获取流：
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public final InputStream byteStream() |
Http POST
对于POST方式，我们最常提交的就是json数据和键值对了，我们来看看这两种情况怎么写。
POST提交Json数据
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public static final MediaType JSON = MediaType.parse("application/json; charset=utf-8"); OkHttpClient client = new OkHttpClient(); String post(String url, String json) throws IOException { RequestBody body = RequestBody.create(JSON, json); Request request = new Request.Builder() .url(url) .post(body) .build(); Response response = client.newCall(request).execute(); f (response.isSuccessful()) { return response.body().string(); } else { throw new IOException("Unexpected code " + response); } } |
使用Request的post方法来提交请求体RequestBody。
（这里附上OkHttp MediaType的使用：）
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public static final MediaType MEDIA_TYPE_MARKDOWN = MediaType.parse("text/x-markdown; charset=utf-8"); 属性： text/html ： HTML格式 text/plain ：纯文本格式 text/xml ： XML格式 image/gif ：gif图片格式 image/jpeg ：jpg图片格式 image/png：png图片格式 以application开头的媒体格式类型： application/xhtml+xml ：XHTML格式 application/xml ： XML数据格式 application/atom+xml ：Atom XML聚合格式 application/json ： JSON数据格式 application/pdf ：pdf格式 application/msword ： Word文档格式 application/octet-stream ： 二进制流数据（如常见的文件下载） application/x-www-form-urlencoded ： <form encType=””>中默认的encType，form表单数据被编码为key/value格式发送到服务器（表单默认的提交数据的格式） |
POST提交键值对
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OkHttpClient client = new OkHttpClient(); String post(String url, String json) throws IOException { RequestBody formBody = new FormEncodingBuilder() .add("platform", "android") .add("name", "bug") .add("subject", "XXXXXXXXXXXXXXX") .build(); Request request = new Request.Builder() .url(url) .post(body) .build(); Response response = client.newCall(request).execute(); if (response.isSuccessful()) { return response.body().string(); } else { throw new IOException("Unexpected code " + response); } } |
Demo
下面是我写的一个小demo，就是通过提交用户名和密码到服务器来登录的一个小案例。使用了GET和POST两种方式。
布局文件
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<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" tools:context="com.jyx.demo.myapplication.OkHttpActivity"> <EditText android:id="@+id/et_userName" android:layout_width="match_parent" android:layout_height="wrap_content" /> <EditText android:id="@+id/et_password" android:layout_width="match_parent" android:layout_height="50dp" /> <Button android:id="@+id/btn_send_get" android:layout_width="match_parent" android:layout_height="50dp" android:text="get登录"/> <Button android:id="@+id/btn_send_post" android:layout_width="match_parent" android:layout_height="50dp" android:text="post登录"/> </LinearLayout> |
Activity
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package com.jyx.demo.myapplication; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.Toast; import com.squareup.okhttp.Callback; import com.squareup.okhttp.FormEncodingBuilder; import com.squareup.okhttp.MediaType; import com.squareup.okhttp.OkHttpClient; import com.squareup.okhttp.Request; import com.squareup.okhttp.RequestBody; import com.squareup.okhttp.Response; import java.io.IOException; public class OkHttpActivity extends AppCompatActivity implements View.OnClickListener { private EditText mUserName; private EditText mPassword; private Button mLoginGet; private Button mLoginPost; private String loginName; private String loginPwd; private String url = "http://192.168.0.101:8080/ServerJing/LoginServlet"; private OkHttpClient client; public static final MediaType JSON = MediaType.parse("application/json; charset=utf-8"); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_ok_http); mUserName = (EditText) findViewById(R.id.et_userName); mPassword = (EditText) findViewById(R.id.et_password); mLoginGet = (Button) findViewById(R.id.btn_send_get); mLoginPost = (Button) findViewById(R.id.btn_send_post); client = new OkHttpClient(); mLoginGet.setOnClickListener(this); mLoginPost.setOnClickListener(this); } @Override public void onClick(View view) { loginName = mUserName.getText().toString(); loginPwd = mPassword.getText().toString(); switch (view.getId()){ case R.id.btn_send_post: loginByPost(loginName,loginPwd); break; case R.id.btn_send_get: try { loginByGet(loginName,loginPwd); } catch (IOException e) { e.printStackTrace(); } break; } } //异步get private void loginByGet(String name,String pwd) throws IOException { String finalUrl = url + "?" +"username=" + name +"&password=" + pwd; Request request = new Request.Builder().url(finalUrl).build(); client.newCall(request).enqueue(new Callback() { @Override public void onFailure(Request request, IOException e) { Toast.makeText(OkHttpActivity.this,"failed",Toast.LENGTH_SHORT).show(); } @Override public void onResponse(Response response) throws IOException { byte[] bytes = response.body().bytes(); final String responseMsg = new String(bytes,"GBK"); runOnUiThread(new Runnable() { @Override public void run() { Toast.makeText(getApplicationContext(),responseMsg,Toast.LENGTH_SHORT).show(); } }); } }); } //异步post private void loginByPost(String name,String pwd){ RequestBody formBody = new FormEncodingBuilder().add("username",name) .add("password",pwd).build(); Request request = new Request.Builder().url(url).post(formBody).build(); client.newCall(request).enqueue(new Callback() { @Override public void onFailure(Request request, IOException e) { Toast.makeText(OkHttpActivity.this,"failed",Toast.LENGTH_SHORT).show(); } @Override public void onResponse(final Response response) throws IOException { byte[] bytes = response.body().bytes(); final String responseMsg = new String(bytes,"GBK"); runOnUiThread(new Runnable() { @Override public void run() { Toast.makeText(getApplicationContext(),responseMsg,Toast.LENGTH_SHORT).show(); } }); } }); } } |
看完上面的代码，大家可能会有疑问，为什么和我开始列举的写法不一样呢，因为这个demo里面我用的是异步的方式。异步方式也很简单，就是将Request加入调度，然后等待任务执行完成，在Callback中可以直接得到结果，我写个小例子方便大家更直观的理解：
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//创建okHttpClient对象 OkHttpClient mOkHttpClient = new OkHttpClient(); //创建一个Request final Request request = new Request.Builder() .url("https://github.com/woaixiaoronger") .build(); //new call Call call = mOkHttpClient.newCall(request); //请求加入调度 call.enqueue(new Callback() { @Override public void onFailure(Request request, IOException e) { } @Override public void onResponse(final Response response) throws IOException { //String htmlStr = response.body().string(); } }); |
好，移动端代码写完了，们看下效果：
没错，就是这么一个简单的界面了。下面附上服务端代码，这里我就写了个简单的serverlet，然后部署到了tomcat上，如下：
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package com.jing.servlet; import java.io .IOException; import java.util.ArrayList; import java.util.List; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.xml.crypto.Data; import com.jing.dao.UsersDao; import com.jing.domain.Users; /** * Servlet implementation class LoginServlet */ public class LoginServlet extends HttpServlet { private static final long serialVersionUID = 1L; /** * @see HttpServlet#HttpServlet() */ public LoginServlet() { super(); } /** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { System.out.println("doGet"); String username = request.getParameter("username"); String password = request.getParameter("password"); if("123".equals(username) && "123".equals(password)){ response.getOutputStream().write("登录成功".getBytes()); }else{ response.getOutputStream().write("登录信息有误".getBytes()); } } /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub System.out.println("doPost"); doGet(request, response); } } |
移动端和服务端代码都有了，下面我们来测试下（由于我部署到tomcat上，我这里是把移动端安装到手机上，然后用手机连接笔记本的wifi进行测试的，IP地址ipconfig获取一下就好。）：
图1.GET方法登录成功
图2.GET方法登录失败
图1.POST方法登录成功
好了，OkHttp的基本使用我就讲到这里了，因为更深层次的我还需要继续学习呀，下面附上官方的OkHttp官方Recipes链接：https://github.com/square/okhttp/wiki/Recipes，我们共同学习。最后欢迎指正，感谢阅读。