AsyncTask的使用方法

package com.example.usingasyntask;


import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;


import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.TextView;


public class MainActivity extends Activity {
    
TextView text;

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

text=(TextView) findViewById(R.id.textView1);

findViewById(R.id.read).setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
//readURL("http://www.baidu.com");
new Thread(){
public void run() {
try {
sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
};
}.start();

}
});

}


public void voidreaUrl1(String url){
new AsyncTask<String, Void, String>(){
//是个String 的数组
@Override
protected String doInBackground(String... arg0) {
try {
URL url=new URL(arg0[0]);
//获取当前网络连接
URLConnection connection=url.openConnection();
InputStream istream=connection.getInputStream();
InputStreamReader isr = new InputStreamReader(istream);
BufferedReader br = new BufferedReader(isr);
String line;
StringBuilder builder=new StringBuilder();
//如果不等于空的话说明当前行是用信息的
while((line=br.readLine())!=""){
builder.append(line);
}
br.close();
istream.close();
return builder.toString();
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}


@Override
protected void onCancelled() {
// TODO Auto-generated method stub
super.onCancelled();
}


@Override
protected void onCancelled(String result) {
// TODO Auto-generated method stub
super.onCancelled(result);
}


@Override
protected void onPostExecute(String result) {
text.setText(result);
super.onPostExecute(result);
}


@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
}


@Override
protected void onProgressUpdate(Void... values) {
// TODO Auto-generated method stub
super.onProgressUpdate(values);
}

}.execute(url);
}


public void readURL(String url){
//第一个参数 初始化传递数据的数据类型
//第二个 返回时的数据类型
//返回结果的数据类型
new AsyncTask<String, Void, String>() {


@Override
protected String doInBackground(String... arg0) {
try {
URL url=new URL(arg0[0]);
   URLConnection connection=url.openConnection();
   InputStream istream=connection.getInputStream();
InputStreamReader isr=new InputStreamReader(istream);
BufferedReader br=new BufferedReader(isr);
   String line;
StringBuilder builder=new StringBuilder();
while ((line=br.readLine())!="") {
builder.append(line);
}
br.close();
istream.close();
return builder.toString();
} catch (MalformedURLException e) {

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

e.printStackTrace();
}
return null;
}


@Override
protected void onCancelled() {
// TODO Auto-generated method stub
super.onCancelled();
}


@Override
protected void onCancelled(String result) {
// TODO Auto-generated method stub
super.onCancelled(result);
}


@Override
protected void onPostExecute(String result) { // 最后会回到这个方法
text.setText(result);
super.onPostExecute(result);
}


@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
}


@Override
protected void onProgressUpdate(Void... values) {
// TODO Auto-generated method stub
super.onProgressUpdate(values);
}
}.execute(url);
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}


}