android文件操作
AndroidManifest.xml配置

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"      package="cn.itcast.file"      android:versionCode="1"      android:versionName="1.0">    <application android:icon="@drawable/icon" android:label="@string/app_name">         <uses-library android:name="android.test.runner" />        <activity android:name=".MainActivity"                  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>    <uses-sdk android:minSdkVersion="8" /><instrumentation android:name="android.test.InstrumentationTestRunner"  android:targetPackage="cn.itcast.file" android:label="Tests for My App" />    <!-- 在SDCard中创建与删除文件权限 --><uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/><!-- 往SDCard写入数据权限 --><uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>  </manifest> 

strings.xml

<?xml version="1.0" encoding="utf-8"?><resources>    <string name="hello">Hello World, MainActivity!</string>    <string name="app_name">文件操作</string>    <string name="filename">文件名称</string>    <string name="filecontent">请输入文件的内容</string>    <string name="button">保存</string>    <string name="success">文件保存成功</string>    <string name="error">文件保存失败</string>    <string name="sdcarderror">SDCard不存在，或者写保护了</string></resources>

layout/main.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    ><TextView      android:layout_width="fill_parent"     android:layout_height="wrap_content"     android:text="@string/filename"    /><EditText    android:layout_width="fill_parent"     android:layout_height="wrap_content"     android:id="@+id/filename"    /><TextView      android:layout_width="fill_parent"     android:layout_height="wrap_content"     android:text="@string/filecontent"    /><EditText    android:layout_width="fill_parent"     android:layout_height="wrap_content"     android:minLines="3"    android:id="@+id/filecontent"    /><Button android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:text="@string/button"    android:id="@+id/button"    /></LinearLayout>

FileService.java

package cn.itcast.service;import java.io.ByteArrayOutputStream;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import android.content.Context;import android.os.Environment;public class FileService {private Context context;public FileService(Context context) {this.context = context;}/** * 以私有文件保存内容 * @param filename 文件名称 * @param content 文件内容 * @throws Exception */public void saveToSDCard(String filename, String content) throws Exception{File file = new File(Environment.getExternalStorageDirectory(), filename);FileOutputStream outStream = new FileOutputStream(file);outStream.write(content.getBytes());outStream.close();}/** * 以私有文件保存内容 * @param filename 文件名称 * @param content 文件内容 * @throws Exception */public void save(String filename, String content) throws Exception{FileOutputStream outStream = context.openFileOutput(filename, Context.MODE_PRIVATE);outStream.write(content.getBytes());outStream.close();}/** * 以追加方式保存内容 * @param filename 文件名称 * @param content 文件内容 * @throws Exception */public void saveAppend(String filename, String content) throws Exception{// ctrl+shift+y / xFileOutputStream outStream = context.openFileOutput(filename, Context.MODE_APPEND);outStream.write(content.getBytes());outStream.close();}/** * 保存内容,注：允许其他应用从该文件中读取内容 * @param filename 文件名称 * @param content 文件内容 * @throws Exception */public void saveReadable(String filename, String content) throws Exception{FileOutputStream outStream = context.openFileOutput(filename, Context.MODE_WORLD_READABLE);outStream.write(content.getBytes());outStream.close();}/** * 保存内容,注：允许其他应用往该文件写入内容 * @param filename 文件名称 * @param content 文件内容 * @throws Exception */public void saveWriteable(String filename, String content) throws Exception{FileOutputStream outStream = context.openFileOutput(filename, Context.MODE_WORLD_WRITEABLE);outStream.write(content.getBytes());outStream.close();}/** * 保存内容,注：允许其他应用对该文件读和写 * @param filename 文件名称 * @param content 文件内容 * @throws Exception */public void saveRW(String filename, String content) throws Exception{FileOutputStream outStream = context.openFileOutput(filename, Context.MODE_WORLD_READABLE+ Context.MODE_WORLD_WRITEABLE);outStream.write(content.getBytes());outStream.close();}/** * 读取文件内容 * @param filename 文件名称 * @return * @throws Exception */public String readFile(String filename) throws Exception{FileInputStream inStream = context.openFileInput(filename);byte[] buffer = new byte[1024];int len = 0;ByteArrayOutputStream outStream = new ByteArrayOutputStream();while( (len = inStream.read(buffer))!= -1){outStream.write(buffer, 0, len);}byte[] data = outStream.toByteArray();//得到文件的二进制数据outStream.close();inStream.close();return new String(data);}}

文件模式

FileServiceTest.java

package cn.itcast.file;import cn.itcast.service.FileService;import android.test.AndroidTestCase;import android.util.Log;public class FileServiceTest extends AndroidTestCase {private static final String TAG = "FileServiceTest";public void testSave() throws Throwable{FileService service = new FileService(this.getContext());service.save("itcast.txt", "www.itcast.cn");}public void testReadFile() throws Throwable{FileService service = new FileService(this.getContext());String result = service.readFile("www.txt");Log.i(TAG, result);}public void testSaveAppend() throws Throwable{FileService service = new FileService(this.getContext());service.saveAppend("append.txt", ",www.csdn.cn");}public void testSaveReadable() throws Throwable{FileService service = new FileService(this.getContext());service.saveReadable("readable.txt", "www.sohu.com");}public void testSaveWriteable() throws Throwable{FileService service = new FileService(this.getContext());service.saveWriteable("writeable.txt", "www.sina.com.cn");}public void testSaveRW() throws Throwable{FileService service = new FileService(this.getContext());service.saveRW("rw.txt", "www.joyo.com");}}

MainActivity.java

package cn.itcast.file;import cn.itcast.service.FileService;import android.app.Activity;import android.os.Bundle;import android.os.Environment;import android.util.Log;import android.view.View;import android.widget.Button;import android.widget.EditText;import android.widget.Toast;public class MainActivity extends Activity {private static final String TAG = "MainActivity";    private FileService fileService;        @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);             fileService = new FileService(this);                Button button = (Button) this.findViewById(R.id.button);        button.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {EditText filenameText = (EditText) findViewById(R.id.filename);EditText contentText = (EditText) findViewById(R.id.filecontent);String filename = filenameText.getText().toString();String content = contentText.getText().toString();try {//判断sdcard是否存在于手机上，并且可以进行读写访问if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){fileService.saveToSDCard(filename, content);Toast.makeText(MainActivity.this, R.string.success, 1).show();}else{Toast.makeText(MainActivity.this, R.string.sdcarderror, 1).show();}} catch (Exception e) {Log.e(TAG, e.toString());Toast.makeText(MainActivity.this, R.string.error, 1).show();}}});    }}