Android客户端单线程下载_移动开发_编程开发_程序员俱乐部

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：

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 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"/>