JAVA网络请求--------Okhttp3

2019-10-30 20:18:19

只记录使用方法，只记录使用方法，只记录使用方法。

okhttp3是一个能在java和安卓上使用的网络请求框架

一丶导入

　　.maven导入方式

<dependency>
　　<groupId>com.squareup.okhttp3</groupId>
　　<artifactId>okhttp</artifactId>
　　<version>4.2.2</version>
</dependency>

　　.gradle引入方式

compile 'com.squareup.okhttp3:okhttp:4.2.2'

　　.jar包导入

　　　　-链接:https://pan.baidu.com/s/1BFMcd0ntRTzjhbrBEcis_g 提取码:74fb

二丶get请求

package com.lxl.learn.okhttp3;

import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public class Learn_Okhttp3 {

    public static void main(String[] args) throws Exception {
        OkHttpClient client = new OkHttpClient();
        Request req = new Request.Builder().url("https://www.baidu.com/").build();
        Response rep = client.newCall(req).execute();
        System.out.println("返回码："+rep.code());
        //rep.header("这里写头，可以得到相关值")
        //rep.body().string() 只能被调用一次，在要对返回内容做多次操作时用字符串存一下
        System.out.println("返回内容："+rep.body().string());
    }

}

　　1.添加请求头参数

package com.lxl.learn.okhttp3;

import java.io.IOException;

import okhttp3.Call;
import okhttp3.Callback;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public class Learn_Okhttp3 {

    public static void main(String[] args) throws Exception {
        OkHttpClient client = new OkHttpClient();
        Request req = new Request.Builder()
                .url("https://www.baidu.com/")
                .addHeader("键", "值")
                .addHeader("键", "值")
                //.......
                .build();
        //异步请求
        client.newCall(req).enqueue(new Callback() {
            
            @Override
            public void onResponse(Call arg0, Response arg1) throws IOException {
                //请求成功会执行
                System.out.println("返回码："+arg1.code());
                System.out.println(arg1.body().string());
            }
            
            @Override
            public void onFailure(Call arg0, IOException arg1) {
                //请求失败或网络错误会执行这里
                System.out.println("请求失败");
            }
        });
    }

}

三丶POST请求

package com.lxl.learn.okhttp3;


import okhttp3.Call;
import okhttp3.FormBody;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;

public class Learn_Okhttp3 {

    public static void main(String[] args) throws Exception {
        OkHttpClient client = new OkHttpClient();
        RequestBody body = new FormBody.Builder()
                .add("键", "值")
                //例如 .add("user","123456")
                //     .add("passwd","abc1234")
                .build();
        Request req = new Request.Builder()
                .url("https://www.baidu.com/")
                .addHeader("键", "值")　　　　//header方法是覆盖，addHeader才是添加
                .addHeader("键", "值")
                .post(body)
                .build();
        //同步请求
        Call call = client.newCall(req);
        Response response = call.execute();
        System.out.println("返回码："+response.code());
        System.out.println(response.body().toString());
    }
}

RequestBody 一般用于普通表单提交
其中提交数据不只是有普通表单，有时是json，有时是数据文件，这时就必须写上RequestBody的数据格式，一般常见的三种：

application/x-www-form-urlencoded 数据是个普通表单
multipart/form-data 数据里有文件
application/json 数据是json

普通表单数据格式可以省略：因为FormBody继承了RequestBody，它已经指定了数据类型为application/x-www-form-urlencoded。
　　1.json数据提交

package com.lxl.learn.okhttp3;


import org.json.simple.JSONObject;

import okhttp3.Call;
import okhttp3.MediaType;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;

public class Learn_Okhttp3 {

    public static void main(String[] args) throws Exception {
        OkHttpClient client = new OkHttpClient();
        
        MediaType JSON = MediaType.parse("application/json; charset=utf-8");
        
        JSONObject json = new JSONObject();
        json.put("user", "123456");
        
        RequestBody body = RequestBody.create(JSON,json.toJSONString());
        
        Request req = new Request.Builder()
                .url("https://www.baidu.com/")
                .post(body)
                .build();
        //同步请求
        Call call = client.newCall(req);
        Response response = call.execute();
        System.out.println("返回码："+response.code());
        System.out.println(response.body().toString());
    }
}

　　　2.数据文件提交

package com.lxl.learn.okhttp3;


import java.io.File;

import okhttp3.Call;
import okhttp3.MediaType;
import okhttp3.MultipartBody;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;

public class Learn_Okhttp3 {

    public static void main(String[] args) throws Exception {
        OkHttpClient client = new OkHttpClient();
        File file = new File("e:\\a.jpg");
        //MultipartBody也是继承了RequestBody
        /*源码可知它适用于这五种Content-Type:
         * 
         * public static final MediaType MIXED = MediaType.parse("multipart/mixed");
         * public static final MediaType ALTERNATIVE = MediaType.parse("multipart/alternative");
         * public static final MediaType DIGEST = MediaType.parse("multipart/digest");
         * public static final MediaType PARALLEL = MediaType.parse("multipart/parallel");
         * public static final MediaType FORM = MediaType.parse("multipart/form-data");
         * 
         */
        RequestBody body = new MultipartBody.Builder()
                .setType(MultipartBody.FORM)
                .addFormDataPart("file", file.getName(), RequestBody.create(MediaType.parse("image/png"), file))
                .build();
        
        Request req = new Request.Builder()
                .url("https://www.baidu.com/")
                .post(body)
                .build();
        //同步请求
        Call call = client.newCall(req);
        Response response = call.execute();
        System.out.println("返回码："+response.code());
        System.out.println(response.body().toString());
    }
}

　　3.使用异步请求

　　　　在android中一般都是使用异步的处理，OkHttpClient.newCall(Request req).enqueue(Callback call),但是在异步请求后不能直接修改ui控件，android中不允许后台线程修改ui，只允许主线程修改

　　 4.下载文件

package com.lxl.learn.okhttp3;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;

import okhttp3.Call;
import okhttp3.Callback;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public class Learn_Okhttp3 {

    public static void main(String[] args) throws Exception {
        String url = "http://b.hiphotos.baidu.com/image/pic/item/908fa0ec08fa513db777cf78376d55fbb3fbd9b3.jpg";
        Request request = new Request.Builder().url(url).build();
        new OkHttpClient().newCall(request).enqueue(new Callback() {
            
            @Override
            public void onResponse(Call arg0, Response arg1) throws IOException {
                System.out.println("大小:"+arg1.body().contentLength()/1024+"kb");
                InputStream is = arg1.body().byteStream();

                byte[] buf = new byte[2048];

                File file = new File("E:\\a.jpg");
                if(file.exists()) file.createNewFile();
                FileOutputStream fo = new FileOutputStream(file);
                
                int len = 0;
                while((len = is.read(buf)) != -1) {
                    fo.write(buf,0,len);
                }
                fo.flush();
                if(is != null)
                    is.close();
                if(fo != null)
                    fo.close();
                System.out.println("下载完成");
            }
            
            @Override
            public void onFailure(Call arg0, IOException arg1) {
                
            }
        });

    }
}

　　暂时记这点，有时间详细看看源码。

JAVA网络请求--------Okhttp3

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