Android学习笔记---23_网络通信之网络图片查看器

Android学习笔记---23_网络通信之网络图片查看器

23_网络通信之网络图片查看器

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1.从Internet获取数据

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利用HttpURLConnection对象,我们可以从网络中获取网页数据.

URL url = new URL("http://www.sohu.com");

HttpURLConnection conn = (HttpURLConnection) url.openConnection();

conn.setConnectTimeout(5* 1000);//设置连接超时

conn.setRequestMethod(“GET”);//以get方式发起请求

if (conn.getResponseCode() != 200) throw new RuntimeException("请求url失败");

InputStream is = conn.getInputStream();//得到网络返回的输入流

String result = readData(is, "GBK");

conn.disconnect();

//第一个参数为输入流,第二个参数为字符集编码

public static String readData(InputStream inSream, String charsetName) throws 

Exception{

ByteArrayOutputStream outStream = new ByteArrayOutputStream();

byte[] buffer = new byte[1024];

int len = -1;

while( (len = inSream.read(buffer)) != -1 ){

outStream.write(buffer, 0, len);

}

byte[] data = outStream.toByteArray();

outStream.close();

inSream.close();

return new String(data, charsetName);

}

利用HttpURLConnection对象,我们可以从网络中获取文件数据.

URL url = new URL("http://photocdn.sohu.com/20100125/Img269812337.jpg");

HttpURLConnection conn = (HttpURLConnection) url.openConnection();

conn.setConnectTimeout(5* 1000);

conn.setRequestMethod("GET");

if (conn.getResponseCode() != 200) throw new RuntimeException("请求url失败");

InputStream is = conn.getInputStream();

readAsFile(is, "Img269812337.jpg"); 

public static void readAsFile(InputStream inSream, File file) throws Exception{

FileOutputStream outStream = new FileOutputStream(file);

byte[] buffer = new byte[1024];

int len = -1;

while( (len = inSream.read(buffer)) != -1 ){

outStream.write(buffer, 0, len);

}

 outStream.close();

inSream.close();

}

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2.下面是一个应用:

  通过用户输入的一个网络图片的地址,来获取网络图片

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3.创建项目:netimage

/netimage/src/com/credream/netimage/NetimageActivity.java

 package com.credream.netimage;

import com.credream.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;

import android.widget.SimpleAdapter.ViewBinder;

public class NetimageActivity extends Activity {

   

 /** Called when the activity is first created. */

  

 private EditText pathText;

  

 private ImageView imageView;

 

  @Override

   

 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 

ButtonOnClickListener());

   

    }

  

  private final class ButtonOnClickListener implements View.OnClickListener{

@Override

public void onClick(View v)

{

String path=pathText.getText().toString();

//以字节数组存放图片的数据

byte[] data;

try

{

data = ImageService.getImage(path);

Bitmap bitmap=BitmapFactory.decodeByteArray(data, 0, data.length);

//使用数组的全部数据来创建位图对象

imageView.setImageBitmap(bitmap);

} 

catch (Exception e)

{

e.printStackTrace();

Toast.makeText(getApplicationContext(), R.string.error, 1).show();

//当用户访问网络的时候,需要访问网络权限,因为可能把用户手机的东西传到网上

}

}

    

  

  } 

}

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3./netimage/src/com/credream/service/ImageService.java

package com.credream.service;

import java.io.InputStream;

import java.net.HttpURLConnection;

import java.net.URL;

import com.credream.util.StreamTool;

public class ImageService

{

/**

 * 获取网络图片的数据

 * @param path 网络图片的路径

 * @return

 */

public static byte[] getImage(String path)throws Exception

{

URL url=new URL(path);

HttpURLConnection conn=(HttpURLConnection) url.openConnection();//基于

Http协议链接对象

conn.setConnectTimeout(5000);

conn.setRequestMethod("GET");

//InputStream inputStream=conn.getInputStream();//得到的返回数据,可能是错

误的比如,404

//错误的时候,也返回数据,但是返回的事错误数据不是所需要的

if(conn.getResponseCode()==200){

InputStream inStream=conn.getInputStream();

returnStreamTool.read(inStream);//返回从流中读取的2进制数据

}

return null;

}

}

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4./netimage/src/com/credream/util/StreamTool.java

package com.credream.util;

import java.io.ByteArrayOutputStream;

import java.io.InputStream;

/**

 * 读取流中的数据

 * @author xiaofeng

 *

 */

public class StreamTool

{

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);//往内存写数据

}

inStream.close();

return outStream.toByteArray();

}

}

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4./netimage/res/layout/main.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="fill_parent"

    android:layout_height="fill_parent"

    android:orientation="vertical" >

    <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:id="@+id/imagepath" 

        android:text="http://192.168.1.110:6118/web/logo.gif"/>

  <!--http://localhost:6118/web/logo.gif注意这个网站的地址是不能访问的,因为这个时

候,他会从android的系统中找这个

  部署的项目,但是找不到所以,要使用局域网的ip来访问,这个地址

  http://192.168.1.110:6118/web/logo.gif也就是本机的ip地址.-->

  <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>

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5./netimage/res/values/strings.xml

<?xml version="1.0" encoding="utf-8"?>

<resources>

    <string name="hello">Hello World, NetimageActivity!</string>

    <string name="app_name">网络通信之网络图片查看器</string>

     <string name="imagepath">网络图片路径</string>

       <string name="button">查看图片</string>

         <string name="error">获取图片失败</string>

</resources>

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6./netimage/AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.credream.netimage"

    android:versionCode="1"

    android:versionName="1.0" >

    <uses-sdk android:minSdkVersion="8" />

    <application

        android:icon="@drawable/ic_launcher"

        android:label="@string/app_name" >

        <activity

            android:label="@string/app_name"

            android:name=".NetimageActivity" >

            <intent-filter >

                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

    </application>

<!-- 访问internet权限 -->

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

        

</manifest>

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7.新建一个web项目:web

 a./web/WebContent/logo.gif

   直接访问就好了

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8.开始测试:

  a.首先把netimage项目部署在android的平台上

  c.运行web项目,右键run on server

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1.注意获取网络上的任何数据都是一样的:

  a.首先获取数据流

  b.得到二进制数据,得到二进制数据后,然后就可以生成你需要格式的文件

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