042 Android 使用URL访问网络资源

1.介绍

2.使用方法

3.java后台代码

package com.lucky.test51url;

import android.annotation.SuppressLint;
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.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;

public class MainActivity extends AppCompatActivity {
    Button button1;
    ImageView imageView1;
    Bitmap bitmap1;
    String pathString="https://ss0.bdstatic.com/94oJfD_bAAcT8t7mm9GUKT-xh_/timg?image&quality=100&size=b4000_4000&sec=1552803802&di=e730996ff6ab40c6102de6cab6d6ab52&src=http://img4.duitang.com/uploads/item/201406/28/20140628082503_HcGBS.jpeg";
    @SuppressLint("HandlerLeak")
    Handler handler=new Handler(){  //利用hander接收线程中发送的数据，并在UI界面中显示出来
        @Override
        public void handleMessage(Message msg) {
            if(msg.what==0x01){
                imageView1.setImageBitmap(bitmap1);
            }
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        button1=findViewById(R.id.button);
        imageView1=findViewById(R.id.imageView);
        button1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //开辟一个新的线程
                new Thread(){
                    @Override
                    public void run() {
                        try {
                            //利用URL访问网络
                            URL url=new URL(pathString);
                            URLConnection connection=url.openConnection();//获得网络连接
                            InputStream inputStream=connection.getInputStream();//利用connection的输入流访问网络
                            bitmap1=BitmapFactory.decodeStream(inputStream);
                            handler.sendEmptyMessage(0x01);
                        } catch (MalformedURLException e) {
                            e.printStackTrace();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }.start();
            }
        });

    }

}