Android网络请求

HTTP请求与响应

HTTP请求包结构

例：

POST /meme.php/home/user/login HTTP/1.1
    Host: 114.215.86.90
    Cache-Control: no-cache
    Postman-Token: bd243d6b-da03-902f-0a2c-8e9377f6f6ed
    Content-Type: application/x-www-form-urlencoded

    tel=13637829200&password=123456

HTTP响应包结构

例：

HTTP/1.1 200 OK
    Date: Sat, 02 Jan 2016 13:20:55 GMT
    Server: Apache/2.4.6 (CentOS) PHP/5.6.14
    X-Powered-By: PHP/5.6.14
    Content-Length: 78
    Keep-Alive: timeout=5, max=100
    Connection: Keep-Alive
    Content-Type: application/json; charset=utf-8

    {"status":202,"info":"\u6b64\u7528\u6237\u4e0d\u5b58\u5728\uff01","data":null}

Http请求方式

常用的是Post和Get

Get方式

在url中填写参数：http://xxxx.xx.com/xx.php?params1=value1&params2=value2

Post方式

参数是经过编码放在请求体中的。编码包括x-www-form-urlencoded 与 form-data。

x-www-form-urlencoded的编码方式是这样： tel=13637829200&password=123456

form-data的编码方式是这样：

----WebKitFormBoundary7MA4YWxkTrZu0gW
  Content-Disposition: form-data; name="tel"

  13637829200
  ----WebKitFormBoundary7MA4YWxkTrZu0gW
  Content-Disposition: form-data; name="password"

  123456
  ----WebKitFormBoundary7MA4YWxkTrZu0gW

x-www-form-urlencoded只能传键值对，form-data可以传二进制

HttpClient & HttpURLConnection

HttpClient已被废弃

HttpURLConnection的用法

public class NetUtils {
        public static String post(String url, String content) {
            HttpURLConnection conn = null;
            try {
                // 创建一个URL对象
                URL mURL = new URL(url);
                // 调用URL的openConnection()方法,获取HttpURLConnection对象
                conn = (HttpURLConnection) mURL.openConnection();

                conn.setRequestMethod("POST");// 设置请求方法为post
                conn.setReadTimeout(5000);// 设置读取超时为5秒
                conn.setConnectTimeout(10000);// 设置连接网络超时为10秒
                conn.setDoOutput(true);// 设置此方法,允许向服务器输出内容

                // post请求的参数
                String data = content;
                // 获得一个输出流,向服务器写数据,默认情况下,系统不允许向服务器输出内容
                OutputStream out = conn.getOutputStream();// 获得一个输出流,向服务器写数据
                out.write(data.getBytes());
                out.flush();
                out.close();

                int responseCode = conn.getResponseCode();// 调用此方法就不必再使用conn.connect()方法
                if (responseCode == 200) {

                    InputStream is = conn.getInputStream();
                    String response = getStringFromInputStream(is);
                    return response;
                } else {
                    throw new NetworkErrorException("response status is "+responseCode);
                }

            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                if (conn != null) {
                    conn.disconnect();// 关闭连接
                }
            }

            return null;
        }

        public static String get(String url) {
            HttpURLConnection conn = null;
            try {
                // 利用string url构建URL对象
                URL mURL = new URL(url);
                conn = (HttpURLConnection) mURL.openConnection();

                conn.setRequestMethod("GET");
                conn.setReadTimeout(5000);
                conn.setConnectTimeout(10000);

                int responseCode = conn.getResponseCode();
                if (responseCode == 200) {

                    InputStream is = conn.getInputStream();
                    String response = getStringFromInputStream(is);
                    return response;
                } else {
                    throw new NetworkErrorException("response status is "+responseCode);
                }

            } catch (Exception e) {
                e.printStackTrace();
            } finally {

                if (conn != null) {
                    conn.disconnect();
                }
            }

            return null;
        }

        private static String getStringFromInputStream(InputStream is)
                throws IOException {
            ByteArrayOutputStream os = new ByteArrayOutputStream();
            // 模板代码 必须熟练
            byte[] buffer = new byte[1024];
            int len = -1;
            while ((len = is.read(buffer)) != -1) {
                os.write(buffer, 0, len);
            }
            is.close();
            String state = os.toString();// 把流中的数据转换成字符串,采用的编码是utf-8(模拟器默认编码)
            os.close();
            return state;
        }
    }

添加网络权限：<uses-permission android:name="android.permission.INTERNET"/>

同步&异步

异步方式：

//在主线程new的Handler，就会在主线程进行后续处理。
    private Handler handler = new Handler();
    private TextView textView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textView = (TextView) findViewById(R.id.text);
        new Thread(new Runnable() {
            @Override
            public void run() {
                    //从网络获取数据
                final String response = NetUtils.get("http://www.baidu.com");
                    //向Handler发送处理操作
                handler.post(new Runnable() {
                    @Override
                    public void run() {
                            //在UI线程更新UI
                        textView.setText(response);
                    }
                });
            }
        }).start();
    }

参考文献：http://www.jianshu.com/p/3141d4e46240