android从零开始（五）读取网络图片

本文的目标是学习对网络图片的读取。

1、界面设计：

界面包括一个用于输入网络图片地址的TextView,一个Button用于提交用户请求。
界面代码如下：

<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"
    tools:context="${relativePackage}.${activityClass}" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />
<EditText android:id="@+id/imagepath"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="http://img05.tooopen.com/images/20140919/sy_71272488121.jpg"
    />
<Button android:id="@+id/submit"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/submit"/>
<ImageView android:id="@+id/imageView"
    android:layout_height="wrap_content"
    android:layout_width="wrap_content"/>"
</LinearLayout>

2.功能实现：

package pub.tobest.netimage;

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

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.os.Handler.Callback;
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 {
    EditText mEditText;
    Button submitButton;
    ImageView mImageView;
    Handler handle;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
        Callback callBack=new Callback() {

            @Override
            public boolean handleMessage(Message msg) {
                // TODO Auto-generated method stub
                byte[] data=(byte[])msg.obj;
                Bitmap bitMap=BitmapFactory.decodeByteArray(data, 0, data.length-1);
                mImageView.setImageBitmap(bitMap);
                return true;
            }
        };
         handle=new Handler(callBack);
    }
    private void initView() {
        // TODO Auto-generated method stub
        mEditText=(EditText) findViewById(R.id.imagepath);
        submitButton=(Button) findViewById(R.id.submit);
        mImageView=(ImageView) findViewById(R.id.imageView);
        submitButton.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                new Thread(new Runnable() {

                    @Override
                    public void run() {
                        // TODO Auto-generated method stub
                        try {
                            URL url=new URL(mEditText.getText().toString());
                            HttpURLConnection conn=(HttpURLConnection) url.openConnection();
                            conn.setReadTimeout(1000);
                            conn.setRequestMethod("GET");
                            InputStream inputStream=null;
                            if(conn.getResponseCode()==200){
                                 inputStream=conn.getInputStream();
                            }
                            ByteArrayOutputStream bOutPutStream=new ByteArrayOutputStream();
                            byte[] data=new byte[1024];
                            int len=0;
                            while((len=inputStream.read(data))!=-1){
                                bOutPutStream.write(data,0,data.length-1);
                            }
                            byte[] bytes=bOutPutStream.toByteArray();
                            Message msg=new Message();
                            msg.obj=bytes;
                            handle.sendMessage(msg);
                        } catch (Exception e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                    }
                }).start();
            }
        });
    }
}

3.总结：

对网络图片的读取，主要使用到HttpURLConnection类和InputStream、OutputStream类。