Android Studio学习路程（9）

今天学习怎样调用互联网的API，下面是一些代码：

package com.example.hp.app3;

/*
学会调用互联网API（公共的）
 */

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.view.View;
import android.widget.TextView;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class MainActivity extends ActionBarActivity implements View.OnClickListener {
    private  int GET_DATA_SUCCESS = 101;//获取信息成功的标志
    private TextView mTvShow;
    private BufferedReader bufferedreader;
    private InputStream inputstream;
    private StringBuilder stringBuilder;
    private HttpURLConnection connection;

    //多线程传输数据  Handler
    Handler mHandler = new Handler(new Handler.Callback() {
        @Override
        public boolean handleMessage(Message message) {
            if(message.what==GET_DATA_SUCCESS){
             String data = message.getData().getString("data");
                Log.i("MainActivity",data);
                mTvShow.setText(data);
            }
            return false;
        }
    });

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

        //初始化控件
        initUI();
        //初始化数据
        initData();
    }

    private void initUI() {
        //获取文本框
       mTvShow = (TextView) findViewById(R.id.tv_show);
        //获取按钮
        findViewById(R.id.btn).setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        //初始化数据
        initData();
    }

    private void initData() {
        //请求网络（创建一个主线程，否则数据太多过不来）
        new Thread(new Runnable() {

            @Override
            public void run() {
                //定义一个方法，从服务器获取数据。
                String data = getDataFromServer();
                //创建信息对象
                Message message = Message.obtain();
                Bundle bundle = new Bundle();
                bundle.putString("data",data);
                message.setData(bundle);
                //设置一个标志：
                message.what = GET_DATA_SUCCESS;

                //向主线程发信息
                mHandler.sendMessage(message);
            }

        }).start();
    }
    //从服务器获取数据
    private String getDataFromServer() {
        try{
            //1.创建一个URL
            URL url = new URL("https://v1.hitokoto.cn/?c=f&encode=text");
            //2.打开链接
            connection = (HttpURLConnection) url.openConnection();
            //3.判断并处理结果
            if(connection.getResponseCode()==200){
                //获取链接的输入流
              inputstream = connection.getInputStream();
                
              //判断读取的数据
                bufferedreader = new BufferedReader(new InputStreamReader(inputstream));
                stringBuilder=new StringBuilder();
                for(String line = "";(line=bufferedreader.readLine())!=null;){
                    stringBuilder.append(line);
                }
                return stringBuilder.toString();
            }

        }catch(Exception e){
            e.printStackTrace();
        }finally {
            try{
               if(inputstream!=null)inputstream.close();
                if(bufferedreader!=null)bufferedreader.close();
                if(connection!=null)connection.disconnect();
            }catch(Exception e){
                e.printStackTrace();
            }
        }

        return "";

    }
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.hp.app3.MainActivity">

    <TextView
        android:id="@+id/tv_show"
        android:textSize="16dp"
        android:background="@android:color/holo_blue_bright"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!" />

    <Button
        android:id="@+id/btn"
        android:text="                              刷新数据"
        android:textSize="20dp"
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:layout_centerVertical="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true" />
</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.hp.app3">
    
    //需要添加：
   <uses-permission android:name="android.permission.INTERNET">

   </uses-permission>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>