/// <summary>
        /// 下载网络图片 
        /// </summary>
        /// <param name="PicSourceUrl">图片的网络地址</param>
        /// <param name="filePath">图片保存在本地的路径</param>
        /// <returns></returns>
        public static bool DownPic(string PicSourceUrl,string filePath)
        {
            WebRequest request = WebRequest.Create(PicSourceUrl);
            WebResponse response = request.GetResponse();
            Stream reader = response.GetResponseStream();
            FileStream writer = new FileStream(filePath, FileMode.OpenOrCreate, FileAccess.Write);
            try
            {
                byte[] buff = new byte[512];
                int c = 0; //实际读取的字节数
                while ((c = reader.Read(buff, 0, buff.Length)) > 0)
                {
                    writer.Write(buff, 0, c);
                }
                writer.Close();
                writer.Dispose();
                reader.Close();
                reader.Dispose();
                response.Close();
            }
            catch (Exception ex)
            {
                return false;
            }
            finally
            {
                if (writer!=null)
                {
                    writer.Close();
                    writer.Dispose();
                }
                if (reader != null)
                {
                    reader.Close();
                    reader.Dispose();
                }
                if (response != null)
                {
                    response.Close();
                }
            }
            return true;
        }

/// <summary>
        /// 导出
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        protected void Users_Click(object sender, EventArgs e)
        {
            string sql = "select UserId as ID,Email as 邮箱,PhoneNumber as 电话号码,UserName as 用户名 from Users";
            DataSet ds = BLL.BLL.ExecuteDataset(CommandType.Text, sql);
            if (ds.Tables.Count == 0)
            {
                Response.Write("<script>alert('没有数据可供导出！');</script>");
                return;
            }
            DataTable dt = ds.Tables[0];

            HttpContext.Current.Response.Clear();
            System.IO.StringWriter sw = new System.IO.StringWriter();
            int iColCount = dt.Columns.Count;
            for (int i = 0; i < iColCount; i++)
            {
                sw.Write(dt.Columns[i]);
                if (i < iColCount - 1)
                {
                    sw.Write(",");
                }
            }
            sw.Write(sw.NewLine);
            foreach (DataRow dr in dt.Rows)
            {
                for (int i = 0; i < iColCount; i++)
                {
                    if (!Convert.IsDBNull(dr[i]))
                        sw.Write(dr[i].ToString());
                    else
                        sw.Write("\"\"");
                    if (i < iColCount - 1)
                    {
                        sw.Write(",");
                    }
                }
                sw.Write(sw.NewLine);
            }
            sw.Close();
            HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment; filename=users.csv");
            HttpContext.Current.Response.ContentType = "application/vnd.ms-excel";
            HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");
            HttpContext.Current.Response.Write(sw);
            HttpContext.Current.Response.End();
        }

Tab选项卡是一个非常方便的组件

今天查询资料知道了Android 多个Activity选项卡实现

本篇文章来源于好岸园it技术学习网 (http://www.hopean.com) 

原文链接：http://www.hopean.com/devlop/

创建多个Activity比如叫FirstActivity,SecondActivity,ThirdActivity

由于是简单实现, FirstActivity,SecondActivity,ThirdActivity三者代码基本相同。

下面以FirstActivity为例

package com.example.androidtabselector;

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;

public class FirstActivity extends Activity {
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		TextView textview = new TextView(this);
		textview.setText("这是Tab1"); 
		setContentView(textview);
		}  
}

修改main.xml文件代码

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

<TabHost xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@android:id/tabhost"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >
   

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:orientation="vertical" >
       

        <TabWidget
            android:id="@android:id/tabs"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content" />
       

        <FrameLayout
            android:id="@android:id/tabcontent"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:padding="5dp" />
   
    </LinearLayout>


</TabHost>

之后新建一个TabDemoActivity.java文件，详细代码如下：

package com.example.androidtabselector;

import android.app.TabActivity;
import android.content.Intent;
import android.content.res.Resources;
import android.os.Bundle;
import android.widget.TabHost;
import android.widget.TabHost.TabSpec;  


public class TabDemoActivity extends TabActivity {
	/** Called when the activity is first created. */ 
	@Override

	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);//这里使用了上面创建的xml文件（Tab页面的布局）
		Resources res = getResources(); // Resource object to get Drawables
		TabHost tabHost = getTabHost();  // The activity TabHost
		TabSpec spec;
		Intent intent;  // Reusable Intent for each tab 
		//第一个Tab
		intent = new Intent(this,FirstActivity.class);
		//新建一个Intent用作Tab1显示的内容
		spec = tabHost.newTabSpec("tab1")//新建一个 Tab      
				.setIndicator("Tab1", res.getDrawable(android.R.drawable.ic_menu_camera))//设置名称以及图标  25. 
				.setContent(intent);//设置显示的intent，这里的参数也可以是R.id.xxx
		tabHost.addTab(spec);//添加进tabHost 
		//第二个Tab  29. 
		intent = new Intent(this,SecondActivity.class);//第二个Intent用作Tab1显示的内容
		spec = tabHost.newTabSpec("tab2")//新建一个 Tab
				.setIndicator("Tab2", res.getDrawable(android.R.drawable.ic_menu_edit))//设置名称以及图标
				.setContent(intent);//设置显示的intent，这里的参数也可以是R.id.xxx
		tabHost.addTab(spec);//添加进tabHost 
		//第三个Tab  
		intent = new Intent(this,ThirdActivity.class);//第二个Intent用作Tab1显示的内容 
		spec = tabHost.newTabSpec("tab2")//新建一个 Tab 
				.setIndicator("Tab3", res.getDrawable(android.R.drawable.ic_menu_help))//设置名称以及图标 
				.setContent(intent);//设置显示的intent，这里的参数也可以是R.id.xxx 
		tabHost.addTab(spec);//添加进tabHost 
		tabHost.setCurrentTab(0);//设置当前的选项卡,这里为Tab1 
		}   
}

最后修改AndroidManifest.xml文件，详细代码如下所示：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.androidtabselector"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="16" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
<!--         <activity -->
<!--             android:name="com.example.androidtabselector.MainActivity" -->
<!--             android:label="@string/app_name" > -->
<!--             <intent-filter> -->
<!--                 <action android:name="android.intent.action.MAIN" /> -->

<!--                 <category android:name="android.intent.category.LAUNCHER" /> -->
<!--             </intent-filter> -->
<!--         </activity> -->
        <activity
        android:name=".TabDemoActivity"
        android:label="@string/app_name" >           
        <intent-filter>            
            <action android:name="android.intent.action.MAIN" />               
            <category android:name="android.intent.category.LAUNCHER" />           
        </intent-filter>    
    </activity>   
    <activity
        android:name=".FirstActivity"
        android:label="@string/app_name" >            
        <intent-filter>                
            <action android:name="android.intent.action.MAIN" />               
            <category android:name="android.intent.category.LAUNCHER" />          
        </intent-filter>    
    </activity>   
    <activity
        android:name=".SecondActivity"
        android:label="@string/app_name" >          
        <intent-filter>                
            <action android:name="android.intent.action.MAIN" />                
            <category android:name="android.intent.category.LAUNCHER" />       
        </intent-filter>
    </activity>
    <activity
        android:name=".ThirdActivity"
        android:label="@string/app_name" >          
        <intent-filter>                
            <action android:name="android.intent.action.MAIN" />                
            <category android:name="android.intent.category.LAUNCHER" />       
        </intent-filter>
    </activity>
    </application>

    
</manifest>

至此就可以实现简单的android 选项卡效果

本篇文章来源于好岸园it技术学习网 (http://www.hopean.com)  原文链接：http://www.hopean.com/devlop/

TabSelectorDemo 源码下载 http://www.hopean.com