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 / x
		FileOutputStream 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
[img]http://dl.iteye.com/upload/attachment/0066/0006/8a180bcd-a9ab-3bbf-8557-e790ffbe1078.jpg[/img]
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() {
			@Override
			public 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();
				}
			}
		});
    }
}