文件读写

Android SDCard操作(文件读写,容量计算) ：http://zhuyonghui116.blog.hexun.com/56778119_d.html
Android中读写文件： http://blog.csdn.net/cocodehouse/article/details/5974288

增加权限：<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
String sDStateString = android.os.Environment.getExternalStorageState();

// 拥有可读可写权限
if (sDStateString.equals(android.os.Environment.MEDIA_MOUNTED)) {
... ...
}

然后用FileInputStream和FileOutputStream进行读写。

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="com.file.rw"    android:versionCode="1"    android:versionName="1.0" >    <uses-sdk android:minSdkVersion="10" />    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>    <application        android:icon="@drawable/ic_launcher"        android:label="@string/app_name" >        <activity            android:name=".ReadWriteFilesActivity"            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>

<?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" >    <TextView        android:id="@+id/textview"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:text="@string/hello" />    <EditText        android:id="@+id/editText1"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="a.txt" />    <Button        android:id="@+id/button1"        android:layout_width="70dp"        android:layout_height="wrap_content"        android:text="Load" />    <EditText        android:id="@+id/editText2"        android:layout_width="match_parent"        android:layout_height="wrap_content" >        <requestFocus />    </EditText>    <Button        android:id="@+id/button2"        android:layout_width="68dp"        android:layout_height="wrap_content"        android:text="Save" /></LinearLayout>

package com.file.rw;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import android.app.Activity;import android.os.Bundle;import android.view.View;import android.widget.Button;import android.widget.EditText;import android.widget.TextView;public class ReadWriteFilesActivity extends Activity {    /** Called when the activity is first created. */private Button button1,button2;private EditText editText1,editText2;private TextView textview;    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        button1=(Button)findViewById(R.id.button1);        button2=(Button)findViewById(R.id.button2);        editText1 = (EditText)findViewById(R.id.editText1);        editText2 = (EditText)findViewById(R.id.editText2);        textview =(TextView)findViewById(R.id.textview);        //load file from sd card        button1.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubtextview.setText("Load............");String sdStatus = android.os.Environment.getExternalStorageState();if(sdStatus.equalsIgnoreCase(android.os.Environment.MEDIA_MOUNTED)){textview.setText(editText1.getText());File rootDir = android.os.Environment.getExternalStorageDirectory();File readFile = new File(rootDir.getAbsolutePath()+File.separator+editText1.getText());if(!readFile.exists()){textview.setText(editText1.getText()+"不存在.");}else{try {FileInputStream in = new FileInputStream(readFile);byte[] buffer = new byte[in.available()];in.read(buffer);in.close();editText2.setText(new String(buffer));} catch (Exception e) {// TODO: handle exceptione.printStackTrace();}}}//end of android.os.Environment.MEDIA_MOUNTED}});                button2.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubif(editText1.getText()==null||editText1.getText().toString().trim().length()==0){textview.setText("第一个输入框没有输入文件名.");return;}if(editText2.getText()==null||editText2.getText().toString().trim().length()==0){textview.setText("第而个输入框没有输入文件内容.");return;}String sdStatus = android.os.Environment.getExternalStorageState();if(android.os.Environment.MEDIA_MOUNTED.equalsIgnoreCase(sdStatus)){File root = android.os.Environment.getExternalStorageDirectory();File newFile = new File(root.getAbsolutePath()+File.separator+editText1.getText());try {if(!newFile.exists()){newFile.createNewFile();}FileOutputStream out = new FileOutputStream(newFile);out.write(editText2.getText().toString().getBytes());out.close();textview.setText("写文件成功.");} catch (Exception e) {// TODO: handle exception}}}});            }}

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