Android入门之网络图片查看器

效果图：

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="@string/imagepath"
    />

    <EditText
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="http://jinkaixqj.azurewebsites.net/me.jpg"
    android:id="@+id/imagepath"
    />

    <Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/button"
    android:id="@+id/button"
    />

    <ImageView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/imageView"
    />
</LinearLayout>

manifest.xml里添加语句

  <uses-permission android:name="android.permission.INTERNET" />

string.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="hello">Hello World, MainActivity!</string>
    <string name="app_name">网络图片查看器</string>
    <string name="imagepath">网络图片路径</string>
    <string name="button">查看</string>
     <string name="error">获取图片失败</string>
</resources>

MainActivity.java

import cn.itcast.service.ImageService;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.Toast;

public class MainActivity extends Activity {
	private EditText pathText;
	private ImageView imageView;

	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);

		pathText = (EditText) this.findViewById(R.id.imagepath);
		imageView = (ImageView) this.findViewById(R.id.imageView);
		Button button = (Button) this.findViewById(R.id.button);
		button.setOnClickListener(new ButtonClickListener());
	}

	private final class ButtonClickListener implements View.OnClickListener {
		public void onClick(View v) {
			String path = pathText.getText().toString();
			try {
				byte[] data = ImageService.getImage(path);
				Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);
				imageView.setImageBitmap(bitmap);     // 显示图片
			} catch (Exception e) {
				e.printStackTrace();
				Toast.makeText(getApplicationContext(), R.string.error, 1).show();
			}
		}
	}
}

ImageService.java

import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import cn.itcast.utils.StreamTool;

public class ImageService {
	/**
	 * 获取网络图片的数据
	 * @param path 网络图片路径
	 * @return
	 */
	public static byte[] getImage(String path) throws Exception{
		URL url = new URL(path);
		HttpURLConnection conn = (HttpURLConnection) url.openConnection();//基于HTTP协议连接对象
		conn.setConnectTimeout(5000);
		conn.setRequestMethod("GET");
		if(conn.getResponseCode() == 200){
			InputStream inStream = conn.getInputStream();
			return StreamTool.read(inStream);
		}
		return null;
	}
}

StreamTool.java

import java.io.ByteArrayOutputStream;
import java.io.InputStream;

public class StreamTool {
	/**
	 * 读取流中的数据
	 * @param inStream
	 * @return
	 * @throws Exception
	 */
	public static byte[] read(InputStream inStream) throws Exception{
		ByteArrayOutputStream outStream = new ByteArrayOutputStream();
		byte[] buffer = new byte[1024];
		int len = 0;
		while( (len = inStream.read(buffer)) != -1){
			outStream.write(buffer, 0, len);
		}
		inStream.close();
		return outStream.toByteArray();
	}
}