Android客户端单线程下载

具体效果如上图所示，具体操作步骤如：

1、先新建一个工程名为getDataInternet的应用；

2、修改res/values中的string.xml文件，具体代码如下：

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

 2 <resources>

 3 

 4     <string name="app_name">Android客户端单线程下载</string>

 5     <string name="hello_world">Hello world!</string>

 6     <string name="action_settings">Settings</string>

 7     <string name="path">图片路径</string>

 8     <string name="getBtnValue">获取图片</string>

 9 

10 </resources>

3、编写res/Layout中的fragment_main.xml文件，具体代码如下：

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

 2     xmlns:tools="http://schemas.android.com/tools"

 3     android:layout_width="match_parent"

 4     android:layout_height="match_parent"

 5     android:paddingBottom="@dimen/activity_vertical_margin"

 6     android:paddingLeft="@dimen/activity_horizontal_margin"

 7     android:paddingRight="@dimen/activity_horizontal_margin"

 8     android:paddingTop="@dimen/activity_vertical_margin"

 9     tools:context="com.example.getdatatointernet.MainActivity$PlaceholderFragment" >

10 

11     <LinearLayout 

12         android:layout_width="fill_parent"

13         android:layout_height="fill_parent"

14         android:orientation="vertical"

15         >

16         <TextView 

17             android:layout_width="fill_parent"

18             android:layout_height="wrap_content"

19             android:text="@string/path"

20             />

21         <EditText 

22             android:layout_width="fill_parent"

23             android:layout_height="wrap_content"

24             android:text="http://b.hiphotos.baidu.com/image/pic/item/1ad5ad6eddc451da70d0dc8db4fd5266d01632b6.jpg"

25             android:id="@+id/path"

26             />

27         <Button 

28             android:layout_width="wrap_content"

29             android:layout_height="wrap_content"

30             android:text="@string/getBtnValue"

31             android:id="@+id/sendBtn"

32             />

33         <ImageView 

34             android:layout_width="wrap_content"

35             android:layout_height="wrap_content"

36             android:id="@+id/imageView"

37             />

38     </LinearLayout>

39 

40 </RelativeLayout>

4、编写NetTool.java类，该类用于操作图片的下载，具体代码如下：

 1 package com.example.getdatatointernet;

 2 

 3 import java.io.ByteArrayOutputStream;

 4 import java.io.InputStream;

 5 import java.net.HttpURLConnection;

 6 import java.net.URL;

 7 

 8 public class NetTool {

 9 

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

11         //简历URL路径

12         URL url=new URL(path);

13         

14         //得到HttpURLConnection对象

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

16         conn.setRequestMethod("GET");//声明请求方式

17         conn.setConnectTimeout(6*1000);//设置链接超时

18         int a=conn.getResponseCode();

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

20         {

21             InputStream iStream=conn.getInputStream();//得到输入流

22             return readInstream(iStream);//返回得到的输入流

23         }

24         

25         return null;

26     }

27     

28     //读取文件流的内容

29     public static byte[] readInstream(InputStream inputStream) throws Exception{

30         //创建ByteArrayOutputStream类

31         ByteArrayOutputStream baoStream=new ByteArrayOutputStream();

32         byte[] buffer=new byte[1024];//声明缓冲区

33         int length=-1;//定义读取默认的长度

34         while((length=inputStream.read(buffer))!=-1){

35             baoStream.write(buffer,0,length);//把缓冲区中输出到内存中

36         }

37         

38         baoStream.close();//关闭输出流

39         inputStream.close();//关闭输入流

40         return baoStream.toByteArray();//返回输出流的字节数组

41     }

42 }

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5、编写核心代码MainActivity.java类，具体代码如下：

  1 package com.example.getdatatointernet;

  2 

  3 import android.annotation.SuppressLint;

  4 import android.graphics.Bitmap;

  5 import android.graphics.BitmapFactory;

  6 import android.os.Bundle;

  7 import android.os.StrictMode;

  8 import android.support.v4.app.Fragment;

  9 import android.support.v7.app.ActionBarActivity;

 10 import android.util.Log;

 11 import android.view.LayoutInflater;

 12 import android.view.Menu;

 13 import android.view.MenuItem;

 14 import android.view.View;

 15 import android.view.ViewGroup;

 16 import android.widget.Button;

 17 import android.widget.EditText;

 18 import android.widget.ImageView;

 19 import android.widget.Toast;

 20 

 21 @SuppressLint("ValidFragment")

 22 public class MainActivity extends ActionBarActivity {

 23 

 24     @Override

 25     protected void onCreate(Bundle savedInstanceState) {

 26         super.onCreate(savedInstanceState);

 27         setContentView(R.layout.activity_main);

 28 

 29         if (savedInstanceState == null) {

 30             getSupportFragmentManager().beginTransaction()

 31                     .add(R.id.container, new PlaceholderFragment()).commit();

 32         }

 33     }

 34 

 35     @Override

 36     public boolean onCreateOptionsMenu(Menu menu) {

 37 

 38         // Inflate the menu; this adds items to the action bar if it is present.

 39         getMenuInflater().inflate(R.menu.main, menu);

 40         return true;

 41     }

 42 

 43     @Override

 44     public boolean onOptionsItemSelected(MenuItem item) {

 45         // Handle action bar item clicks here. The action bar will

 46         // automatically handle clicks on the Home/Up button, so long

 47         // as you specify a parent activity in AndroidManifest.xml.

 48         int id = item.getItemId();

 49         if (id == R.id.action_settings) {

 50             return true;

 51         }

 52         return super.onOptionsItemSelected(item);

 53     }

 54 

 55     /**

 56      * A placeholder fragment containing a simple view.

 57      */

 58     public  class PlaceholderFragment extends Fragment {

 59 

 60         public PlaceholderFragment() {

 61         }

 62 

 63         @Override

 64         public View onCreateView(LayoutInflater inflater, ViewGroup container,

 65                 Bundle savedInstanceState) {

 66             View rootView = inflater.inflate(R.layout.fragment_main, container,

 67                     false);

 68             

 69             StrictMode.setThreadPolicy(new 

 70                      StrictMode.ThreadPolicy.Builder().detectDiskReads().detectDiskWrites().detectNetwork().penaltyLog().build());

 71                              StrictMode.setVmPolicy(

 72                      new StrictMode.VmPolicy.Builder().detectLeakedSqlLiteObjects().detectLeakedClosableObjects().penaltyLog().penaltyDeath().build());

 73 

 74             final EditText imageText=(EditText)rootView.findViewById(R.id.path);

 75             final ImageView imageView=(ImageView)rootView.findViewById(R.id.imageView);

 76             final Button btn=(Button)rootView.findViewById(R.id.sendBtn);

 77             

 78             btn.setOnClickListener(new View.OnClickListener() {

 79                 

 80                 @Override

 81                 public void onClick(View v) {

 82                     // TODO Auto-generated method stub

 83                     String path=imageText.getText().toString();

 84                     try

 85                     {

 86                         byte[]data=NetTool.getImage(path);

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

 88                         imageView.setImageBitmap(bm);

 89                     }catch(Exception e)

 90                     {

 91                         Log.i("MyTest",e.getMessage());

 92                         Toast.makeText(MainActivity.this, e.getMessage(), 1).show();

 93                     }

 94                 }

 95             });

 96             return rootView;

 97         }

 98     }

 99 

100 }

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 6、在AndroidManifest.xml中添加服务权限

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