结对编程任意Demo

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical"
android:gravity="center"
tools:context="com.example.pj.download.MainActivity">

<ImageView
android:id="@+id/img"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<Button
android:id="@+id/btn_picture"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="20dp"
android:text="图片下载"
android:textSize="30sp"
android:gravity="center"/>
<Button
android:id="@+id/btn_introduction"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="20dp"
android:text="图书简介"
android:textSize="30sp"
android:gravity="center"/>
</LinearLayout>

package com.example.pj.download;

import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class MainActivity extends AppCompatActivity {

private Button btn_p;
private Button btn_i;
private ImageView img;

Handler handler = new Handler() {
public void handleMessage(android.os.Message msg) {
img.setImageBitmap((Bitmap) msg.obj);
}
};

public Bitmap getInternetPicture(String UrlPath) {
HttpURLConnection httpURLConnection = null;
Bitmap bm = null;
try {
URL url = new URL(UrlPath);
httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setRequestMethod("GET");
httpURLConnection.setReadTimeout(5000);
httpURLConnection.setConnectTimeout(10000);
int responseCode = httpURLConnection.getResponseCode();
if (responseCode == 200) {
InputStream is = httpURLConnection.getInputStream();
bm = BitmapFactory.decodeStream(is);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
if (httpURLConnection != null) {
httpURLConnection.disconnect();
}
}
return bm;
}

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

img = (ImageView) findViewById(R.id.img);
btn_p = (Button) findViewById(R.id.btn_picture);
btn_i = (Button) findViewById(R.id.btn_introduction);

btn_p.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View view) {
new Thread(new Runnable() {
@Override
public void run() {
String URL = "https://img3.doubanio.com/lpic/s1076932.jpg";
Bitmap bm = getInternetPicture(URL);
Message msg = new Message();
msg.obj = bm;
handler.sendMessage(msg);
}
}).start();
}
});
btn_i.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View v) {
Intent intent = new Intent(MainActivity.this,Introduction.class);
startActivity(intent);
}
});


}
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">

<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="
<Button
android:id="@+id/btn_return"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="返回"
android:layout_marginTop="20dp"/>

</LinearLayout>
package com.example.pj.download;

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;

/**
* Created by pj on 2017/3/28.
*/
public class Introduction extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.introduction);
Button btn_r = (Button)findViewById(R.id.btn_return);
btn_r.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View v) {
Intent intent = new Intent(Introduction.this,MainActivity.class);
startActivity(intent);
}
});
}
}