Android 异步加载数据 AsyncTask+Handler+AsyncHttpClient+Universal_Image_loader+Volley

1.怎么使用AsyncTask+Handler传值

地址：http://www.oschina.net/code/snippet_725438_49858

[1].[代码] [Java]代码 跳至 [1] [2] [3] [4]

布局文件：
<LinearLayout 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:orientation= "vertical"
   >

   <ImageView android:id= "@+id/im1"
      android:layout_width= "wrap_content"
       android:layout_height= "wrap_content"
       android:src= "@drawable/ic_launcher" />

    <ImageView android:id= "@+id/im2"
      android:layout_width= "wrap_content"
       android:layout_height= "wrap_content"
       android:src= "@drawable/ic_launcher" />

</LinearLayout>

[2].[代码] [Java]代码 跳至 [1] [2] [3] [4]

2 .第一种，回调方法方式：
package com.androidwallpaper;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.app.Activity;
import android.app.WallpaperManager;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.ProgressBar;
import android.widget.Toast;

public class MainActivity extends Activity implements OnClickListener{


    ImageView im1;
    ImageView im2;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super .onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        im1 = (ImageView) findViewById(R.id.im1);
        im2 = (ImageView) findViewById(R.id.im2);

        try {
            final ImageViewAsyncTask task = new ImageViewAsyncTask( "http://static.oschina.net/uploads/ad/new_banner_one_ronglianyun_WrqUs.png" );
            task.setOnDataFinishedListener( new OnDataFinishedListener() {

                @Override
                public void onDataSuccessfully(Object data) {
                    try {
                        im1.setImageBitmap((Bitmap) data);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
                @Override
                public void onDataFailed() {
                    Toast.makeText(MainActivity. this , "加载失败！" , Toast.LENGTH_SHORT).show();
                }
            });
            task.execute();
        } catch (Exception e) {
            e.printStackTrace();
        }



    }


    class ImageViewAsyncTask extends AsyncTask<String, Integer, Bitmap> {

        String mUrl;
        OnDataFinishedListener onDataFinishedListener;

        public ImageViewAsyncTask(String url){
            this .mUrl = url;
        }



        public void setOnDataFinishedListener(
                OnDataFinishedListener onDataFinishedListener) {
            this .onDataFinishedListener = onDataFinishedListener;
        }


        @Override
        protected Bitmap doInBackground(String... params) {
            InputStream ins = null ;
            Bitmap bitmap = null ;
            try {
                URL url = new URL(mUrl);
                HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                if (connection.getResponseCode()==HttpURLConnection.HTTP_OK){
                    ins = connection.getInputStream();
                    bitmap = BitmapFactory.decodeStream(ins);
                    return bitmap;
                }
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                if (ins!= null ){
                    try {
                        ins.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
            return null ;
        }

        @Override
        protected void onPreExecute() {
            super .onPreExecute();
            progressBar.setVisibility(View.VISIBLE);
        }

        @Override
        protected void onPostExecute(Bitmap result) {
            progressBar.setVisibility(View.GONE);
            if (result!= null ){
                onDataFinishedListener.onDataSuccessfully(result);
            } else {
                onDataFinishedListener.onDataFailed();
            }
        }

        @Override
        protected void onProgressUpdate(Integer... values) {
            super .onProgressUpdate(values);
        }

    }
}

[3].[代码] [Java]代码 跳至 [1] [2] [3] [4]

回调接口：
public interface OnDataFinishedListener {

    public void onDataSuccessfully(Object data);

    public void onDataFailed();

}

[4].[代码] [Java]代码 跳至 [1] [2] [3] [4]

第二种：使用handler:

1 .修改ImageViewAsyncTask:
public class ImageViewAsyncTask extends AsyncTask<String, Integer, Bitmap> {

    String mUrl;
    Handler mHandler;

    public ImageViewAsyncTask(String url,Handler handler){
        this .mUrl = url;
        this .mHandler = handler;
    }

    @Override
    protected Bitmap doInBackground(String... params) {
        InputStream ins = null ;
        Bitmap bitmap = null ;
        try {
            URL url = new URL(mUrl);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            if (connection.getResponseCode()==HttpURLConnection.HTTP_OK){
                ins = connection.getInputStream();
                bitmap = BitmapFactory.decodeStream(ins);
                return bitmap;
            }
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (ins!= null ){
                try {
                    ins.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return null ;
    }

    @Override
    protected void onPreExecute() {
        super .onPreExecute();
    }

    @Override
    protected void onPostExecute(Bitmap result) {
        super .onPostExecute(result);
        Message msg = mHandler.obtainMessage();
        if (result!= null ){
            msg.what = 1 ;
            msg.obj = result;
        } else {
            msg.what = 2 ;
        }
        mHandler.sendMessage(msg);
    }

    @Override
    protected void onProgressUpdate(Integer... values) {
        super .onProgressUpdate(values);
    }



}
2 .调用方式：
ImageViewAsyncTask task2 = new ImageViewAsyncTask( "http://static.oschina.net/uploads/ad/new_banner_one_ronglianyun_WrqUs.png" , handler);
        task2.execute();

Handler handler = new Handler(){

        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
            case 1 :
                Bitmap bitmap = (Bitmap) msg.obj;
                im2.setImageBitmap(bitmap);
                break ;

            default :
                break ;
            }
        }

    };

2.Volley  这个不贴码  只贴地址：

Android Volley完全解析(一)，初识Volley的基本用法

Android Volley完全解析(二)，使用Volley加载网络图片

Android Volley完全解析(三)，定制自己的Request

Android Volley完全解析(四)，带你从源码的角度理解Volley

3.json解析   异步请求之后需要把返回的值变成对象 使用gson

一、 谷歌GSON这个Java类库可以把Java对象转换成JSON，也可以把JSON字符串转换成一个相等的Java对象。Gson支持任意复杂Java对象包括没有源代码的对象。


 二、Gson解析Json步骤
 A、服务器端将数据转换成json字符串
   首先、服务器端项目要导入Gson的jar包到BuiltPath中。（
Gson的jar：http://code.google.com/p/google-gson/   我们还可以下载gson的帮助文档）






然后将数据转为json字符串，核心函数是：
    public static String createJsonString(Object value)
    {
        Gson gson = new Gson();
        String str = gson.toJson(value);
        return str;
    }
B、客户端将json字符串转换为相应的javaBean
    首先客户端也要导入gson的两个jar包，json的jar就不需要导入了（因为android项目中已经集成了json的jar包所以这里无需导入）
   1、客户端获取json字符串
public class HttpUtil
{
   
    public static String getJsonContent(String urlStr)
    {
        try
        {// 获取HttpURLConnection连接对象
            URL url = new URL(urlStr);
            HttpURLConnection httpConn = (HttpURLConnection) url
                    .openConnection();
            // 设置连接属性
            httpConn.setConnectTimeout(3000);
            httpConn.setDoInput(true);
            httpConn.setRequestMethod("GET");
            // 获取相应码
            int respCode = httpConn.getResponseCode();
            if (respCode == 200)
            {
                return ConvertStream2Json(httpConn.getInputStream());
            }
        }
        catch (MalformedURLException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        catch (IOException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return "";
    }

   
    private static String ConvertStream2Json(InputStream inputStream)
    {
        String jsonStr = "";
        // ByteArrayOutputStream相当于内存输出流
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int len = 0;
        // 将输入流转移到内存输出流中
        try
        {
            while ((len = inputStream.read(buffer, 0, buffer.length)) != -1)
            {
                out.write(buffer, 0, len);
            }
            // 将内存流转换为字符串
            jsonStr = new String(out.toByteArray());
        }
        catch (IOException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return jsonStr;
    }
}
2、使用泛型获取javaBean（核心函数）
    public static <T> T getPerson(String jsonString, Class<T> cls) {
        T t = null;
        try {
            Gson gson = new Gson();
            t = gson.fromJson(jsonString, cls);
        } catch (Exception e) {
            // TODO: handle exception
        }
        return t;
    }

public static <T> List<T> getPersons(String jsonString, Class<T> cls) {
        List<T> list = new ArrayList<T>();
        try {
            Gson gson = new Gson();
            list = gson.fromJson(jsonString, new TypeToken<List<cls>>() {
            }.getType());
        } catch (Exception e) {
        }
        return list;
    }
public static List<Map<String, Object>> listKeyMaps(String jsonString) {
        List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
        try {
            Gson gson = new Gson();
            list = gson.fromJson(jsonString,
                    new TypeToken<List<Map<String, Object>>>() {
                    }.getType());
        } catch (Exception e) {
            // TODO: handle exception
        }
        return list;
    }

原文地址：http://blog.sina.com.cn/s/blog_7ffb8dd501013q9c.html

这里介绍的是泛型  我觉得很好，或者你也可以用到什么什么的时候就解析什么  随便

3.1使用gson解析json数据，这个里面讲的蛮好，

   下面我将以一个具体的列子来说明通过Gson方式解析复杂的json数据
1.将要解析的数据如下面的格式

{
    "error": 0,
    "status": "success",
    "date": "2014-05-10",
    "results": [
        {
            "currentCity": "南京",
            "weather_data": [
                {
                    "date": "周六(今天, 实时：19℃)",
                    "dayPictureUrl": "http://api.map.baidu.com/images/weather/day/dayu.png",
                    "nightPictureUrl": "http://api.map.baidu.com/images/weather/night/dayu.png",
                    "weather": "大雨",
                    "wind": "东南风5-6级",
                    "temperature": "18℃"
                },
                {
                    "date": "周日",
                    "dayPictureUrl": "http://api.map.baidu.com/images/weather/day/zhenyu.png",
                    "nightPictureUrl": "http://api.map.baidu.com/images/weather/night/duoyun.png",
                    "weather": "阵雨转多云",
                    "wind": "西北风4-5级",
                    "temperature": "21 ~ 14℃"
                }
            ]
        }
    ]
}
2.必须定义如下一些的javaBean数据
Status.java

 public class Status
 {
         private String error;
         private String status;
         private String date;
         private List<Results> results;
         public String getError()
         {
             return error;
         }
         public void setError(String error)
         {
             this.error = error;
         }

         public String getStatus()
         {
             return status;
         }
         public void setStatus(String status)
         {
             this.status = status;
         }
         public String getDate()
         {
             return date;
         }
         public void setDate(String date)
         {
             this.date = date;
         }
         public List<Results> getResults()
         {
             return results;
         }
         public void setResults(List<Results> results)
         {
             this.results = results;
         }
         @Override
         public String toString()
         {
             return "Status [error=" + error + ", status=" + status
                     + ", date=" + date + ", results=" + results + "]";
         }
 </span>

Results.java

 public class Results
 {
     private String currentCity;
     private List<Weather> weather_data;
     public String getCurrentCity()
     {
         return currentCity;
     }
     public void setCurrentCity(String currentCity)
     {
         this.currentCity = currentCity;
     }
     public List<Weather> getWeather_data()
     {
         return weather_data;
     }
     public void setWeather_data(List<Weather> weather_data)
     {
         this.weather_data = weather_data;
     }
     @Override
     public String toString()
     {
         return "Results [currentCity=" + currentCity + ", weather_data="
                 + weather_data + "]";
     }

Weather.java

 public class Weather {
     private String date;
                 private String dayPictureUrl;
                 private String nightPictureUrl;
                 private String weather;
                 private String wind;
                 private String temperature;
                 public String getDate() {
                     return date;
                 }
                 public void setDate(String date) {
                     this.date = date;
                 }
                 public String getDayPictureUrl() {
                     return dayPictureUrl;
                 }
                 public void setDayPictureUrl(String dayPictureUrl) {
                     this.dayPictureUrl = dayPictureUrl;
                 }
                 public String getNightPictureUrl() {
                     return nightPictureUrl;
                 }
                 public void setNightPictureUrl(String nightPictureUrl) {
                     this.nightPictureUrl = nightPictureUrl;
                 }
                 public String getWeather() {
                     return weather;
                 }
                 public void setWeather(String weather) {
                     this.weather = weather;
                 }
                 public String getWind() {
                     return wind;
                 }
                 public void setWind(String wind) {
                     this.wind = wind;
                 }
                 public String getTemperature() {
                     return temperature;
                 }
                 public void setTemperature(String temperature) {
                     this.temperature = temperature;
                 }
                 @Override
                 public String toString() {
                     return "Weather [date=" + date + ", dayPictureUrl="
                             + dayPictureUrl + ", nightPictureUrl="
                             + nightPictureUrl + ", weather=" + weather
                             + ", wind=" + wind + ", temperature=" + temperature
                             + "]";
                 }

4.如果只是解决图片缓存加载的问题  就只使用Universal_Image_loader就够了

5.频繁操作的话选择Volley  但是传递的数据量不能很大 而且到底在使用post方法的时候没法直接用，必须自己去定制，那么我还不如自己写吧，

GetHttp

public class GetHttp {
	
	public static String RequstGetHttp(String strUrl) {
		URL url = null;
		String result="";
		try {
			url = new URL(strUrl);
			HttpURLConnection urlconn = (HttpURLConnection) url.openConnection();
			urlconn.setConnectTimeout(1000);
			urlconn.setReadTimeout(15000);

			urlconn.connect();// 链接服务器并发送消息


			// 开始接收返回的数据
			InputStreamReader is = new InputStreamReader(urlconn.getInputStream());
			BufferedReader bufferedReader = new BufferedReader(is);
			String readLine = "";
			while ((readLine = bufferedReader.readLine()) != null) {
				result += readLine;
			}
			
			is.close();
			urlconn.disconnect();
			

		} catch (MalformedURLException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}

		
		return result;
	}

}

PostHttp:

public class PostHttp {

	public static String RequstPostHttp(String strUrl) {
		URL url = null;
		String result="";
		try {
			url = new URL(strUrl);
			HttpURLConnection urlconn = (HttpURLConnection) url.openConnection();
			urlconn.setDoInput(true);// 设置输入流采用字节流模式
			urlconn.setDoOutput(true);
			urlconn.setRequestMethod("POST");
			urlconn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
			urlconn.setRequestProperty("Charset", "UTF-8");
			urlconn.setConnectTimeout(10000);
			urlconn.setReadTimeout(15000);

			urlconn.connect();// 链接服务器并发送消息

			OutputStream outStream = urlconn.getOutputStream();
			outStream.flush();// 发送，清除缓存
			outStream.close();// 关闭

			// 开始接收返回的数据
			InputStream is = urlconn.getInputStream();
			BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(is, "UTF-8"));
			String readLine = "";
			while ((readLine = bufferedReader.readLine()) != null) {
				result += readLine;
			}
			
			bufferedReader.close();
			urlconn.disconnect();
			

		} catch (MalformedURLException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}

		
		return result;
	}

}

其实异步加载思路应该蛮清晰的，

a.要准备开一个异步线程，当然在这之前你需要准备一个URL 和对返回值处理的数据结构

b.我觉得还是使用Gson解析复杂的json数据

c.在activity里面启动子线程，在handler里面对返回结果进行处理

下面的需要去弄清楚AsyncTask的原理le