接口回调经典案例－－网络请求回调

回调的好处：

降低代码的耦合性，使代码更灵活、简洁

步骤一 ：定义回调接口

**
 * Created by pengkv on 15/10/22.
 * 网络请求回调接口
 */
public interface HttpCallBackListener {
    void onFinish(String respose);

    void onError(Exception e);
}

步骤二：定义回调函数（将接口作为参数）

/**
 * Created by pengkv on 15/10/22.
 * 网络请求工具类
 */
public class HttpUtil {

    public static void requestData(final String urlStr, final HttpCallBackListener listener) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                HttpURLConnection connection = null;
                try {
                    URL url = new URL(urlStr);
                    connection = (HttpURLConnection) url.openConnection();
                    connection.setRequestMethod("GET");
                    connection.setConnectTimeout(8000);
                    connection.setReadTimeout(8000);
                    connection.setDoInput(true);
                    connection.setDoOutput(true);
                    InputStream in = connection.getInputStream();
                    BufferedReader br = new BufferedReader(new InputStreamReader(in));
                    StringBuilder sb = new StringBuilder();
                    String line;
                    while ((line = br.readLine()) != null) {
                        sb.append(line);
                    }
                    if (listener != null) {
                        //回调onFinish方法
                        listener.onFinish(sb.toString());
                    }
                } catch (Exception e) {
                    if (listener != null) {
                        //回调onError方法
                        listener.onError(e);
                    }
                } finally {
                    if (connection != null) {
                        connection.disconnect();
                    }
                }
            }
        }).start();
    }
}

步骤三：使用回调方法一

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        HttpUtil.requestData("请求的网址", new HttpCallBackListener() {
            @Override
            public void onFinish(String respose) {
                //处理请求
            }

            @Override
            public void onError(Exception e) {
                //处理异常
            }
        });
    }

}

步骤三：使用回调方法二

public class MainActivity extends AppCompatActivity implements HttpCallBackListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        HttpUtil.requestData("请求的网址", this);
    }


    @Override
    public void onFinish(String respose) {
        //处理请求
    }

    @Override
    public void onError(Exception e) {
        //处理异常
    }

}