【Android】【转】文件保存与读取

原文地址： http://tdq222.iteye.com/blog/701161

注： 在Activity中有 getFileDir() 和 getCacheDir(); 方法可以获得当前的手机自带的存储空间中的当前包文件的路径
getFileDir() ----- /data/data/cn.xxx.xxx(当前包)/files
getCacheDir() ----- /data/data/cn.xxx.xxx（当前包）/cache

 

?

1. 编写文件读取与写入功能实现类 FileService

 

    packagecn.android.service;

 

    importjava.io.ByteArrayOutputStream;

    importjava.io.FileInputStream;

    importjava.io.FileOutputStream;

 

    importandroid.content.Context;

    importandroid.util.Log;

 

    /**

     * 文件保存与读取功能实现类

     * @author Administrator

     *

     * 2010-6-28 下午08:15:18

     */

    publicclass FileService {

        publicstatic final String TAG = "FileService";

        privateContext context;

 

        //得到传入的上下文对象的引用

        publicFileService(Context context) {

            this.context = context;

        }

 

        /**

         * 保存文件

         *

         * @param fileName 文件名

         * @param content  文件内容

         * @throws Exception

         */

        publicvoid save(String fileName, String content)throws Exception {

 

            // 由于页面输入的都是文本信息，所以当文件名不是以.txt后缀名结尾时，自动加上.txt后缀

            if(!fileName.endsWith(".txt")) {

                fileName = fileName +".txt";

            }

             

            byte[] buf = fileName.getBytes("iso8859-1");

             

            Log.e(TAG,new String(buf,"utf-8"));

             

            fileName =new String(buf,"utf-8");

             

            Log.e(TAG, fileName);

             

            // Context.MODE_PRIVATE：为默认操作模式，代表该文件是私有数据，只能被应用本身访问，在该模式下，写入的内容会覆盖原文件的内容，如果想把新写入的内容追加到原文件中。可以使用Context.MODE_APPEND

            // Context.MODE_APPEND：模式会检查文件是否存在，存在就往文件追加内容，否则就创建新文件。

            // Context.MODE_WORLD_READABLE和Context.MODE_WORLD_WRITEABLE用来控制其他应用是否有权限读写该文件。

            // MODE_WORLD_READABLE：表示当前文件可以被其他应用读取；MODE_WORLD_WRITEABLE：表示当前文件可以被其他应用写入。

            // 如果希望文件被其他应用读和写，可以传入：

            // openFileOutput("output.txt", Context.MODE_WORLD_READABLE + Context.MODE_WORLD_WRITEABLE);

 

            FileOutputStream fos = context.openFileOutput(fileName, context.MODE_PRIVATE);

            fos.write(content.getBytes());

            fos.close();

        }

 

        /**

         * 读取文件内容

         *

         * @param fileName 文件名

         * @return 文件内容

         * @throws Exception

         */

        publicString read(String fileName) throwsException {

 

            // 由于页面输入的都是文本信息，所以当文件名不是以.txt后缀名结尾时，自动加上.txt后缀

            if(!fileName.endsWith(".txt")) {

                fileName = fileName +".txt";

            }

 

            FileInputStream fis = context.openFileInput(fileName);

            ByteArrayOutputStream baos =new ByteArrayOutputStream();

 

            byte[] buf =new byte[1024];

            intlen = 0;

 

            //将读取后的数据放置在内存中---ByteArrayOutputStream

            while((len = fis.read(buf)) != -1) {

                baos.write(buf,0, len);

            }

 

            fis.close();

            baos.close();

 

            //返回内存中存储的数据

            returnbaos.toString();

 

        }

 

    }

 

2. 编写Activity类：

    packagecn.android.test;

 

    importandroid.app.Activity;

    importandroid.os.Bundle;

    importandroid.util.Log;

    importandroid.view.View;

    importandroid.widget.Button;

    importandroid.widget.EditText;

    importandroid.widget.Toast;

    importcn.android.service.FileService;

 

    publicclass TestAndroidActivityextends Activity {

        /** Called when the activity is first created. */

         

        //得到FileService对象

        privateFileService fileService = newFileService(this);

        //定义视图中的filename输入框对象

        privateEditText fileNameText;

        //定义视图中的contentText输入框对象

        privateEditText contentText;

        //定义一个土司提示对象

        privateToast toast;

 

         

        @Override

        publicvoid onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);

           

        //得到视图中的两个输入框和两个按钮的对象引用

        Button button = (Button)this.findViewById(R.id.button);

        Button read = (Button)this.findViewById(R.id.read);

        fileNameText = (EditText)this.findViewById(R.id.filename);

        contentText = (EditText)this.findViewById(R.id.content);

         

        //为保存按钮添加保存事件

        button.setOnClickListener(newView.OnClickListener() {

                @Override

                publicvoid onClick(View v) {

                     

                    String fileName = fileNameText.getText().toString();

                    String content = contentText.getText().toString();

                     

                    //当文件名为空的时候，提示用户文件名为空，并记录日志。

                    if(isEmpty(fileName)) {

                        toast = Toast.makeText(TestAndroidActivity.this, R.string.empty_filename, Toast.LENGTH_LONG);

                        toast.setMargin(RESULT_CANCELED,0.345f);                                  

                        toast.show();  

                        Log.w(fileService.TAG,"The file name is empty");

                        return;

                    }

                     

                    //当文件内容为空的时候，提示用户文件内容为空，并记录日志。

                    if(isEmpty(content)) {

                        toast = Toast.makeText(TestAndroidActivity.this, R.string.empty_content, Toast.LENGTH_LONG);

                        toast.setMargin(RESULT_CANCELED,0.345f);                                  

                        toast.show();  

                        Log.w(fileService.TAG,"The file content is empty");

                        return;

                    }

                     

                    //当文件名和内容都不为空的时候，调用fileService的save方法

                    //当成功执行的时候，提示用户保存成功，并记录日志

                    //当出现异常的时候，提示用户保存失败，并记录日志

                    try{

                        fileService.save(fileName, content);

                        toast = Toast.makeText(TestAndroidActivity.this, R.string.success, Toast.LENGTH_LONG);

                        toast.setMargin(RESULT_CANCELED,0.345f);                                  

                        toast.show();  

                        Log.i(fileService.TAG,"The file save successful");

                    }catch (Exception e) {

                        toast = Toast.makeText(TestAndroidActivity.this, R.string.fail, Toast.LENGTH_LONG);

                        toast.setMargin(RESULT_CANCELED,0.345f);                                  

                        toast.show();  

                        Log.e(fileService.TAG,"The file save failed");

                    }

                     

                }

        });

         

         

        //为读取按钮添加读取事件

        read.setOnClickListener(newView.OnClickListener() {

                @Override

                publicvoid onClick(View v) {

                     

                    //得到文件名输入框中的值

                    String fileName = fileNameText.getText().toString();

                     

                    //如果文件名为空，则提示用户输入文件名，并记录日志

                    if(isEmpty(fileName)) {

                        toast = Toast.makeText(TestAndroidActivity.this, R.string.empty_filename, Toast.LENGTH_LONG);

                        toast.setMargin(RESULT_CANCELED,0.345f);                                  

                        toast.show();  

                        Log.w(fileService.TAG,"The file name is empty");

                        return;

                    }

                     

                    //调用fileService的read方法，并将读取出来的内容放入到文本内容输入框里面

                    //如果成功执行，提示用户读取成功，并记录日志。

                    //如果出现异常信息（例：文件不存在），提示用户读取失败，并记录日志。

                    try{

                        contentText.setText(fileService.read(fileName));

                        toast = Toast.makeText(TestAndroidActivity.this, R.string.read_success, Toast.LENGTH_LONG);

                        toast.setMargin(RESULT_CANCELED,0.345f);                                  

                        toast.show();  

                        Log.i(fileService.TAG,"The file read successful");

                    }catch (Exception e) {

                        toast = Toast.makeText(TestAndroidActivity.this, R.string.read_fail, Toast.LENGTH_LONG);

                        toast.setMargin(RESULT_CANCELED,0.345f);                                  

                        toast.show();  

                        Log.e(fileService.TAG,"The file read failed");

                    }

                }

        });

         

         

        }

         

        //编写一个isEmpty方法，判断字符串是否为空

        privateboolean isEmpty(String s) {

        if(s ==null || "".equals(s.trim())) {

            returntrue;

        }

        returnfalse;

        }

         

    }

?