1、Handler
主文件：MainActivity.java
package com.example.asynctaskdownload; import java.io.IOException; import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.StatusLine;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils; import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView; public class MainActivity extends Activity {
protected static final int SHOW_RESPONSE = 0;
/** Called when the activity is first created. */
private TextView textView;
private String result = ""; /////////////////////////////////////////////////////////
private Handler handler = new Handler(){ public void handleMessage(Message msg)
{
switch(msg.what){
case SHOW_RESPONSE:
String result = (String)msg.obj;
//注意是在此处进行UI操作
textView.setText(result);
}
}
};
/////////////////////////////////////////////////////
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textView = (TextView) findViewById(R.id.TextView01);
Button button = (Button) findViewById(R.id.readWebpage);
button.setOnClickListener(new OnClickListener()
{ @Override
public void onClick(View v) {
//
//textView.setText(result);
if(v.getId() == R.id.readWebpage)
{
sendRequestHttpUrl();
}
} });
}
////////////////////////////////////////////////////////
protected void sendRequestHttpUrl() {
// TODO Auto-generated method stub
//
new Thread(new Runnable()
{ @Override
public void run() {
// try
{
HttpClient client = new DefaultHttpClient();
HttpGet httpGet = new HttpGet("http://10.0.2.2:8080/mp3/a1.lrc"); HttpResponse response = client.execute(httpGet);
StatusLine statusLine = response.getStatusLine();
int statusCode = statusLine.getStatusCode();
if (statusCode == 200) {
HttpEntity entity = response.getEntity();
//关于此处中文乱码问题解决？文本文件保存时，文本文档默认为ANSI编码格式，另存为时手动改为utf-8格式即可
result = EntityUtils.toString(entity, "utf-8");
}
Message message = new Message();
message.what = SHOW_RESPONSE;
message.obj = result.toString();
handler.sendMessage(message);
}catch(Exception ex)
{
ex.printStackTrace();
} } }
).start();
}
}
activity_main.xml文件
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" > <Button
android:id="@+id/readWebpage"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:onClick="onClick"
android:text="Load Webpage" >
</Button>
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="@+id/TextView01"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:text="Placeholder" >
</TextView>
</ScrollView> </LinearLayout>
运行结果：
2、AnyscTask
主代码：
package com.example.asynctaskdownload;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader; import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils; import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast; public class MainActivity extends Activity {
private TextView textView; private final String fileName = "a1.lrc";
//private final String fileUrl = "http://10.0.2.2:8080/mp3/a1.lrc";
private int result = Activity.RESULT_CANCELED;
private String response = ""; @Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textView = (TextView) findViewById(R.id.TextView01);
Button button = (Button) findViewById(R.id.readWebpage);
button.setOnClickListener(new OnClickListener()
{ @Override
public void onClick(View v) {
// DownloadWebPageTask task = new DownloadWebPageTask();
//task.execute(new String[] { "http://www.vogella.com" });
task.execute(new String[] { "http://10.0.2.2:8080/mp3/a1.lrc" });
Toast.makeText(MainActivity.this, "Download Success!", Toast.LENGTH_LONG).show(); // textView.setText(response);
} });
} private class DownloadWebPageTask extends AsyncTask<String, Void, Integer> {
@Override
protected Integer doInBackground(String... urls) {
//获取sdcard的路径，以及设置保存的文件名
File output = new File(Environment.getExternalStorageDirectory(), fileName);
if(output.exists())
{
output.delete();//若同名文件已存在则删除
} // String response = "";
InputStream content = null;
FileOutputStream fos = null;
//遍历url数组中的url，采用HttpClient(接口)的方式访问网络
for (String url : urls) {
//首先创建一个DefaultHttpClient实例
DefaultHttpClient client = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(url);//发起一个GET请求，创建一个HttpGet对象，并传入目标网络地址
try {
HttpResponse execute = client.execute(httpGet);//调用execute执行访问请求并返回一个HttpResponse对象
if(execute.getStatusLine().getStatusCode() == 200)
{
//注:下面两行code只能使用其中一个：content will be consume only once
//execute.getEntity()调用了两次
// content = execute.getEntity().getContent();//获取服务返回的具体内容
//调用EntityUtils.toString该静态方法将HttpEntity转换成字符串,为避免中文字符乱码，添加utf-8字符集参数
// response = EntityUtils.toString(execute.getEntity(), "utf-8");
//////////////////////////////////////////////////////////////////////////////
HttpEntity entity = execute.getEntity();
// response = EntityUtils.toString(entity, "utf-8");
content = entity.getContent(); } //利用管道 inputstream-->reader
InputStreamReader reader = new InputStreamReader(content);
fos = new FileOutputStream(output.getPath()); int next = -1;
while ((next = reader.read()) != -1) {
fos.write(next);
} result = Activity.RESULT_OK; // BufferedReader buffer = new BufferedReader(new InputStreamReader(content)); // String s = "";
// while ((s = buffer.readLine()) != null) {
// response += s;
// } } catch (Exception e) {
e.printStackTrace();
}finally {
if (content != null) {
try {
content.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (fos != null) {
try {
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
return result;
} protected void onPostExecute(Integer result) {
//此处可以根据后台任务完成后返回的结果进行一些UI操作 if(result == Activity.RESULT_OK)
{
textView.setText("mp3 file download success!!");
}
} /* public void onClick(View view) {
DownloadWebPageTask task = new DownloadWebPageTask();
//task.execute(new String[] { "http://www.vogella.com" });
task.execute(new String[] { "http://10.0.2.2:8080/mp3/a1.lrc" }); }*/ }
}
activity_main.xml文件同上
运行结果：成功下载文件a1.lrc到sdcard中