Android文件的读写

       Android建议采用MVC开发模式，所以我们在Android应用开发中最好使用MVC设计模式。MVC设计模式使三层分离，从而很好的解耦，何乐而不为。

       首先我们向工程中添加一个FileService.java：

package com.jbridge.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 {

// Activity的父类的父类就是context，context与其他框架中的context相同为我们以供了一些核心操作工具。

private Context context;

public FileService(Context context) {

this.context = context;

}

public void saveToSDCard(String filename, String content) throws Exception{

if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){

File file = new File(Environment.getExternalStorageDirectory(), filename);

FileOutputStream outStream = new FileOutputStream(file);

outStream.write(content.getBytes());

outStream.close();

}

}

public void save(String filename, String content) throws Exception{

FileOutputStream outStream = context.openFileOutput(filename, Context.MODE_PRIVATE);

outStream.write(content.getBytes());

outStream.close();

}

然后再向工程中添加FileButtonOnClickEvent.java：

package com.jbridge.event;

import com.jbridge.file.R;

import com.jbridge.service.FileService;

import android.app.Activity;

import android.util.Log;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.EditText;

import android.widget.Toast;

public class FileButtonOnClickEvent implements OnClickListener {

 // 通过activity获取其他控件

    private Activity activity;

    // 通过FileService读写文件

    private FileService fileService;

    // 打印信息用的标签

    private static final String TAG = "FileButtonOnClickEvent";

    public FileButtonOnClickEvent(Activity activity) {

     this.activity = activity;

           this.fileService = new FileService(activity);

    }

public void onClick(View v) {

Button button = (Button) v;

        switch (button.getId()) {

        case R.id.bt_save: 

               // 获取文件名

               EditText etFileNameS = (EditText) this.activity

                             .findViewById(R.id.et_file_name);

               String fileNameS = etFileNameS.getText().toString();

               // 获取文件内容

               EditText etFileConS = (EditText) this.activity

                             .findViewById(R.id.et_file_content);

               String fileContentS = etFileConS.getText().toString();

               // 保存

               try {

                      this.fileService.save(fileNameS, fileContentS);

                      // 在窗口中显示一个特效信息框

                      Toast.makeText(this.activity, R.string.file_save_success,

                                    Toast.LENGTH_LONG).show();

                      Log.i(TAG, "save file success!");

               } catch (Exception e) {

                      Toast.makeText(this.activity, R.string.file_save_failed,

                                    Toast.LENGTH_LONG).show();

                      Log.e(TAG, e.toString());

               }

               break;

        case R.id.bt_read:

               // 获取文件名

               EditText etFileNameR = (EditText) this.activity

                             .findViewById(R.id.et_file_name);

               String fileNameR = etFileNameR.getText().toString();

               // 读取文件

               try {

                      String fielContentR = this.fileService.readFile(fileNameR);

                      EditText etFileConR = (EditText) this.activity

                                    .findViewById(R.id.et_file_content);

                      etFileConR.setText(fielContentR);

                      Log.i(TAG, "read file success!");

               } catch (Exception e) {

                      Toast.makeText(this.activity, R.string.file_read_failed,

                                    Toast.LENGTH_LONG).show();

                      Log.e(TAG, e.toString());

               }

               break;

        default:

               break;

        }

}

}

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();

}

public void saveReadable(String filename, String content) throws Exception{// ctrl+shift+y / x

FileOutputStream outStream = context.openFileOutput(filename, Context.MODE_WORLD_READABLE);

outStream.write(content.getBytes());

outStream.close();

}

public void saveWriteable(String filename, String content) throws Exception{// ctrl+shift+y / x

FileOutputStream outStream = context.openFileOutput(filename, Context.MODE_WORLD_WRITEABLE);

outStream.write(content.getBytes());

outStream.close();

}

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();

}

public void savePRW(String filename, String content) throws Exception{

FileOutputStream outStream = context.openFileOutput(filename, 

Context.MODE_WORLD_READABLE+ Context.MODE_WORLD_WRITEABLE+Context.MODE_APPEND);

outStream.write(content.getBytes());

outStream.close();

}

public String readFile(String filename) throws Exception{

FileInputStream inStream = context.openFileInput(filename);

byte[] data = readData(inStream);//?????????????????

return new String(data);

}

private byte[] readData(FileInputStream inStream) throws Exception{

ByteArrayOutputStream outStream = new ByteArrayOutputStream();

byte[] buffer = new byte[1024];

int len = 0;

while( (len = inStream.read(buffer))!= -1){

outStream.write(buffer, 0, len);

}

outStream.close();

inStream.close();

return outStream.toByteArray();

}

}