2--安卓网络编程之http协议简介+小案例引入

#请求行:使用HTTP/1.1协议发送GET方式请求，访问域名下的/swords/find/21资源
GET /swords/find/21 HTTP/1.1
#请求的域名和端口
Host: localhost:8080
#维持长连接
Connection: keep-alive
Pragma: no-cache
#浏览器缓存类型
Cache-Control: no-cache
Upgrade-Insecure-Requests: 1
#浏览器的厂商信息
User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko)
Chrome/69.0.3497.100 Safari/537.36
#浏览器可接收的数据类型：
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8
#声明浏览器支持的编码类型
Accept-Encoding: gzip, deflate, br
#声明浏览器支持的语言
Accept-Language: zh-CN,zh;q=0.9,en;q=0.8

#返回内容类型
Content-Type: application/json;charset=UTF-8
#时间
Date: Mon, 15 Oct 2018 00:26:33 GMT
#分块编码
Transfer-Encoding: chunked

{"id":21,
"name":"Excalibur",
"info":"Excalibur是传说中不列颠国王亚瑟王从湖之仙女那得到的圣剑。
此剑在是精灵在阿瓦隆（Avalon）所打造，剑锷由黄金所铸、剑柄上镶有宝石，并因其锋刃削铁如泥",
"imgurl":"http://localhost:8080/imgs/timg.jpg",
"create_time":"2018-07-17T08:29:36.000+0000",
"modify_time":"2018-07-17T08:29:36.000+0000",
"origin":"亚瑟王"}

<uses-permission android:name="android.permission.INTERNET"/>

String path = "http://192.168.43.60:8080/swords/find/21";
//新开线程访问网络
new Thread(() -> {
    String result = getRes(path);
    Log.e(TAG, "onViewClicked: " + result);
}).start();

/**
 * 通过url访问服务器,并接收服务器响应数据
 *
 * @param path url
 */
private String getRes(String path) {
    InputStream is = null;
    try {
        //1.创建URL对象url
        URL url = new URL(path);
        //2.使用url连接并获取HttpURLConnection对象conn
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        //3.为conn对象设置请求信息
        conn.setRequestMethod("GET");
        conn.setConnectTimeout(5000);
        //4.校验响应码,200代表请求成功
        if (conn.getResponseCode() == 200) {
            //5.通过conn获取服务器传来的输入流
            is = conn.getInputStream();
            //6.对流进行操作
            StringBuilder sb = new StringBuilder();
            int len = 0;
            byte[] buf = new byte[1024];
            while ((len = is.read(buf)) != -1) {
                sb.append(new String(buf, 0, len));
            }
            return sb.toString();
        }
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        try {
            if (is != null) {
                is.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    return "error";
}

new Thread(() -> {
    Bitmap img = decodeImg(mIdEtUrl.getText().toString());
    runOnUiThread(() -> {
        mIdIvImg.setImageBitmap(img);
        });
    }).start();

/**
 * 通过url返回一个Bitmap
 * @param path url
 * @return 图片
 */
private Bitmap decodeImg(String path) {
    InputStream is = null;
    OutputStream os = null;
    try {
        //1.创建URL对象url
        URL url = new URL(path);
        //2.使用url连接并获取HttpURLConnection对象conn
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        //3.为conn对象设置请求信息
        conn.setRequestMethod("GET");
        conn.setConnectTimeout(5000);
        //4.校验响应码,200代表请求成功
        if (conn.getResponseCode() == 200) {
            //5.通过conn获取服务器传来的输入流
            is = conn.getInputStream();
            //6.对流进行操作
            return BitmapFactory.decodeStream(is);
        }
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        try {
            if (is != null) {
                is.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    return null;
}