android 檔案監聽器

標籤：android   style   blog   class   code   java   

（1）程式說明

     1）首先要添加檔案建立，刪除，和寫入資料的許可權

      2）接著擴充fileobseerver，寫SDk檔案監聽類。可以查看下文的檔案監聽器源碼

      3）如何開機檔案監控？

            對於Activity來說通常在onResume（）方法中調用startwatching（）來開機檔案監控。

         在onPause（）方法中調用stopwatching（）來取消檔案監控。   

（2）布局檔案

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:orientation="vertical" >    <RelativeLayout        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:orientation="vertical" >        <TextView            android:id="@+id/label_01"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="@string/name"            android:textSize="20dp" />        <EditText            android:id="@+id/filename"            android:layout_width="160dp"            android:layout_height="wrap_content"            android:layout_alignTop="@id/label_01"            android:layout_toRightOf="@id/label_01" />    </RelativeLayout>    <TextView        android:id="@+id/label_02"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="@string/neirong" />    <EditText        android:id="@+id/content"        android:layout_width="fill_parent"        android:layout_height="120px"        android:ems="10" >        <requestFocus />    </EditText>    <LinearLayout        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:orientation="horizontal" >        <Button            android:id="@+id/savebutton"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:gravity="right"            android:text="@string/save" />        <Button            android:id="@+id/readbutton"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:gravity="right"            android:text="@string/read" />    </LinearLayout>    <TextView        android:id="@+id/textcontent"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_weight="0.10" /></LinearLayout>

（3）檔案監聽器源碼：

      1）擴充的Fileobserver，實現檔案或者檔案夾的監聽   

package com.liuzuyi.fileobserver;import android.os.FileObserver;import android.util.Log;public class SDCardListener extends FileObserver {public SDCardListener(String path) {    super(path);}public void onEvent(int event, String path) {switch (event) {case FileObserver.CREATE :Log.d("creat", "filename"+path);break;case FileObserver.ALL_EVENTS :Log.d("all", "filename"+path);break;}}}   

       2）主程式碼

package com.liuzuyi.fileobserver;import java.io.ByteArrayOutputStream;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.InputStream;import java.io.OutputStream;import android.app.Activity;import android.os.Bundle;import android.os.Environment;import android.util.Log;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;import android.widget.TextView;import android.widget.Toast;public class MainActivity extends Activity { private EditText filename; private EditText content; private TextView textcontent; private static final String TAG ="simplefile";  SDCardListener myfileListener = new SDCardListener("/sdcard");public void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);filename =(EditText)findViewById(R.id.filename);content =(EditText)findViewById(R.id.content);textcontent =(TextView)findViewById(R.id.textcontent);Button savebutton =(Button)this.findViewById(R.id.savebutton);Button viewbutton =(Button)this.findViewById(R.id.readbutton);savebutton.setOnClickListener(listener);viewbutton.setOnClickListener(listener); }public void onResume(){  super.onResume();  myfileListener.startWatching();}public void onPause(){ super.onPause(); myfileListener.stopWatching();}private View.OnClickListener listener = new OnClickListener() {public void onClick(View v) {Button button =(Button)v;String namestr =filename.getText().toString().trim();String contentStr =content.getText().toString();switch ( button.getId() ) {case R.id.savebutton: String res ="success"; try { if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED))   {FileOutputStream outstream = new FileOutputStream("/sdcard/"+namestr+".txt");outstream.write(contentStr.getBytes() );outstream.close();   }  else return ; } catch (Exception e) { res= "failure"; e.printStackTrace();} Toast.makeText(MainActivity.this,  res ,Toast.LENGTH_LONG).show();Log.i(TAG, namestr);Log.i(TAG, contentStr);break;case R.id.readbutton:String resid_v ="success";String contentst = null;try {if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED))  {File SDCardDir=Environment.getExternalStorageDirectory();File saveFile = new File(SDCardDir,namestr+".txt");FileInputStream instream = new FileInputStream(saveFile);ByteArrayOutputStream Ostream = new ByteArrayOutputStream();byte[] buffer = new byte[1024];int len = -1;  while( (len = instream.read(buffer)) != -1 )    {  Ostream.write(buffer,0,len);  }  contentst = Ostream.toString();  Ostream.close();  instream.close();   }else{Toast.makeText(MainActivity.this, "SD卡不存在", Toast.LENGTH_LONG).show();}} catch (Exception e) { resid_v ="faile"; e.printStackTrace();}textcontent.setText( contentst);Log.i(TAG, contentst);Toast.makeText(MainActivity.this, resid_v,Toast.LENGTH_LONG).show();Log.i(TAG,namestr);break;}}}; }