Android学习笔记_12_网络通信之从web获取资源数据到Android

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从web获取图片信息，并显示到android的imageView控件。

　　一、添加网络访问权限。

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

　　二、界面布局及activity的实现：

<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context=".MainActivity" >    <Button        android:id="@+id/btnImage"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentLeft="true"        android:layout_alignParentTop="true"        android:layout_marginLeft="34dp"        android:layout_marginTop="15dp"        android:text="查看图片" />    <ImageView        android:id="@+id/imageView"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignLeft="@+id/btnImage"        android:layout_below="@+id/btnImage"        android:layout_marginTop="20dp"         /></RelativeLayout>

package com.example.image;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.view.Menu;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.ImageView;public class MainActivity extends Activity {    private Button button = null;    private ImageView imageView;        @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        button = (Button) this.findViewById(R.id.btnImage);        imageView = (ImageView) this.findViewById(R.id.imageView);        final String path="http://192.168.8.103:8080/Simple/0001.jpg";        button.setOnClickListener(new OnClickListener() {                    @Override            public void onClick(View view) {                try {                    byte[] data = getImage(path);                    Bitmap bm=BitmapFactory.decodeByteArray(data, 0, data.length);                    imageView.setImageBitmap(bm);                } catch (Exception e) {                    e.printStackTrace();                }            }        });            }    /**     * 获取图片流     * @param path     * @return     * @throws Exception     */    public static byte[] getImage(String path) throws Exception{       //创建URL对象，获取HttpURLConnection
        HttpURLConnection conn = (HttpURLConnection) new URL(path).openConnection();        conn.setConnectTimeout(5000);        conn.setRequestMethod("GET");        if (conn.getResponseCode()==200) {            //处理从web返回的资源数据            return read(conn.getInputStream());        }                return null;    }    /**     * 将流转化成字节数组     * @param in     * @return     * @throws Exception     */    public static byte[] read(InputStream in) throws Exception{        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();        byte[] buf = new byte[1024];        int len=0;        while((len=in.read(buf))!=-1){            outputStream.write(buf,0,len);        }        outputStream.close();        return outputStream.toByteArray();        }    @Override    public boolean onCreateOptionsMenu(Menu menu) {        getMenuInflater().inflate(R.menu.main, menu);        return true;    }}

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