Android网络开发：通过URL获取网络资源

通过URL获取网络资源，需要在服务器上架设Tomcat，并将资源放到服务器上，然后在Android平台下开发与服务器通信的客户端，步骤如下：

1.Tomcat服务器搭建。关于配置Tomcat，请自行查阅相关资料。在Tomcat的webapps目录下新建一个项目，取名为MyUrlSample，将资源复制到该目录下。资源里有一个txt文件和一个png图片，资源链接：点击打开链接

2.布局文件activity_main.xml

<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" >

    <EditText
        android:id="@+id/editText1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10" >

        <requestFocus />
    </EditText>

    <Button
        android:id="@+id/button1"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="点击获取URL资源" />

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" 
        android:layout_gravity="center_horizontal"/>

</LinearLayout>

3.Activity文件，MainActivity.java

值得注意的是，Android4.0之后不允许在主线程中访问网络资源，所以访问时需另起线程。

package com.example.urltext;

import java.io.BufferedInputStream;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import org.apache.http.util.ByteArrayBuffer;
import org.apache.http.util.EncodingUtils;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;

public class MainActivity extends Activity {
	String stringURL = "http://115.28.143.001:8899/MyUrlSample/msg.txt";
	String bitmapURL = "http://115.28.143.001:8899/MyUrlSample/pic.png";
	Button myButton = null;
	EditText myET = null;
	ImageView myIM = null;
	String smsg =null;
	Bitmap bmp = null;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		myButton = (Button) findViewById(R.id.button1);
		myButton.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View arg0) {
				new Thread(){
					@Override
					public void run() {
						getStringURLResources();
						getBitmapURLResources();
						handler.sendEmptyMessage(0);

					}

				}.start();
			}
		});
	}
	private Handler handler = new Handler(){
		@Override
		public void handleMessage(Message msg) {
			// TODO Auto-generated method stub
			super.handleMessage(msg);
			myET = (EditText) findViewById(R.id.editText1);
			myET.setText(smsg);
			myIM = (ImageView) findViewById(R.id.imageView1);
			myIM.setImageBitmap(bmp);
		}	
	};
	public void getStringURLResources(){
		try{
			URL myURL = new URL(stringURL);
			URLConnection myConn = myURL.openConnection();
			InputStream in = myConn.getInputStream();
			BufferedInputStream bis = new BufferedInputStream(in);

			ByteArrayBuffer baf = new ByteArrayBuffer(bis.available());
			int data = 0;
			while((data = bis.read()) != -1){
				baf.append((byte)data);
			}
			smsg = EncodingUtils.getString(baf.toByteArray(), "UTF-8");		
		}catch(Exception e){
			e.printStackTrace();
		}
	}
	public void getBitmapURLResources(){
		try{
			URL myURL = new URL(bitmapURL);
			URLConnection myConn = myURL.openConnection();
			InputStream in = myConn.getInputStream();
			bmp = BitmapFactory.decodeStream(in);
		}catch(Exception e){
			e.printStackTrace();
		}
	}


}

4.记得在AndroidManifest.xml中添加访问网络权限

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

5.最终效果如图所示