Android實現文件存儲并讀取的示例代碼

2019-12-12 03:51:27

字體：大中小

來源：轉載

供稿：網友

要求：

輸入文件名，文件內容分別存儲在手機內存和外存中，并且都可以讀去取出來。

步驟：

1.創建一個名為CDsaveFile的Android項目

2.編寫布局文件activity_main.xml：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" tools:context="hhh.exercise.cdsavefile.MainActivity" > <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" > <TextView  android:layout_width="wrap_content"  android:layout_height="wrap_content"  android:text="@string/textView_inputFileName"  android:textColor="#00ff00"  android:textSize="26sp" /> <EditText  android:id="@+id/editView_fileName"  android:layout_width="match_parent"  android:layout_height="wrap_content"  android:gravity="center"  android:hint="@string/editView_fileName"  android:maxLines="1"  android:textColor="#ff0000"  android:textSize="26sp" /> <requestFocus /> </LinearLayout> <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text="@string/textView_inputFileContent" android:textColor="#00ff00" android:textSize="26sp" /> <EditText android:id="@+id/editView_fileContent" android:layout_width="match_parent" android:layout_height="wrap_content" android:gravity="center" android:hint="@string/editView_fileContent" android:maxLines="2" android:minLines="2" android:textColor="#ff0000" android:textSize="26sp" /> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" > <Button  android:id="@+id/button_saveToPhone"  android:layout_width="0dp"  android:layout_height="wrap_content"  android:layout_weight="1"  android:text="@string/button_saveToPhone"  android:textColor="#ff00ff"  android:textSize="24sp" /> <Button  android:id="@+id/button_readFromPhone"  android:layout_width="0dp"  android:layout_height="wrap_content"  android:layout_weight="1"  android:text="@string/button_readFromPhone"  android:textColor="#00ffff"  android:textSize="24sp" /> </LinearLayout> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" > <Button  android:id="@+id/button_saveToSD"  android:layout_width="0dp"  android:layout_height="wrap_content"  android:layout_weight="1"  android:text="@string/button_saveToSD"  android:textColor="#ff00ff"  android:textSize="24sp" /> <Button  android:id="@+id/button_readFromSD"  android:layout_width="0dp"  android:layout_height="wrap_content"  android:layout_weight="1"  android:text="@string/button_readFromSD"  android:textColor="#00ffff"  android:textSize="24sp" /> </LinearLayout> <EditText android:id="@+id/editText_showResult" android:layout_width="match_parent" android:layout_height="wrap_content" android:gravity="center" android:maxLines="3" android:minLines="3" android:hint="@string/editText_showResult" android:textColor="#cccc00" android:textSize="30sp" /></LinearLayout>

3.編寫主活動中代碼MainActivity.Java：

package hhh.exercise.cdsavefile;import android.annotation.SuppressLint;import android.annotation.TargetApi;import android.app.Activity;import android.os.Build;import android.os.Bundle;import android.os.Environment;import android.os.StatFs;import android.view.View;import android.view.Window;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;import android.widget.Toast;import hhh.exercise.service.FileService;public class MainActivity extends Activity implements OnClickListener { private EditText editView_fileName; private EditText editView_fileContent; private EditText editText_showResult; private FileService service; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); requestWindowFeature(Window.FEATURE_NO_TITLE); setContentView(R.layout.activity_main); // 實例化 FileService 類，該類用于處理按鈕觸發的事件的具體操作 service = new FileService(getApplicationContext()); // 獲取布局中的控件 editView_fileName = (EditText) findViewById(R.id.editView_fileName); editView_fileContent = (EditText) findViewById(R.id.editView_fileContent); editText_showResult = (EditText) findViewById(R.id.editText_showResult); // 獲取按鈕并創建觸發事件 ((Button) findViewById(R.id.button_saveToPhone)).setOnClickListener(this); ((Button) findViewById(R.id.button_readFromPhone)).setOnClickListener(this); ((Button) findViewById(R.id.button_saveToSD)).setOnClickListener(this); ((Button) findViewById(R.id.button_readFromSD)).setOnClickListener(this); } /** * 為每一個按鈕創建觸發的事件 *  * @param v觸發事件的View對象 */ @Override public void onClick(View v) { String fileName = editView_fileName.getText().toString(); String fileContent = editView_fileContent.getText().toString(); // 判斷文件名，文件名要求不為空 if (fileName == null || "".equals(fileName.trim())) {  Toast.makeText(getApplicationContext(), R.string.toast_missFileName, 0).show(); } else {  // 輸入的文件名不為空，對每個按鈕的觸發事件進行處理  String result = null;  switch (v.getId()) {  case R.id.button_saveToPhone:  try {   // 存儲文件到手機上   service.saveToPhone(fileName, fileContent);   // 清空內容輸入框   editView_fileContent.setText("");   Toast.makeText(getApplicationContext(), R.string.toast_saveToPhone_success, 0).show();  } catch (Exception e) {   Toast.makeText(getApplicationContext(), R.string.toast_saveToPhone_fail, 0).show();   e.printStackTrace();  }  break;  case R.id.button_readFromPhone:  try {   // 讀取手機文件中的內容   result = service.readFromPhone(fileName);   // 將內容顯示在空間中   editText_showResult.setText(result);  } catch (Exception e) {   Toast.makeText(getApplicationContext(), R.string.toast_readFromPhone_fail, 0).show();   e.printStackTrace();  }  break;  case R.id.button_saveToSD:  // 判斷sd卡是否存在，并且可以使用，空間足夠  int flag = judgeSD();  if (flag == 0 || flag == 1) {   Toast.makeText(getApplicationContext(), R.string.toast_noSD, 0).show();  } else {   try {   service.saveToSD(fileName, fileContent);   editView_fileContent.setText("");   Toast.makeText(getApplicationContext(), R.string.toast_saveToSD_success, 0).show();   } catch (Exception e) {   Toast.makeText(getApplicationContext(), R.string.toast_saveToSD_fail, 0).show();   e.printStackTrace();   }  }  break;  case R.id.button_readFromSD:  // 判斷SD卡能夠讀取  int flag2 = judgeSD();  if (flag2 != 0) {   try {   result = service.readFromSD(fileName);   editText_showResult.setText(result);   } catch (Exception e) {   Toast.makeText(getApplicationContext(), R.string.toast_readFromSD_fail, 0).show();   e.printStackTrace();   }  } else {   Toast.makeText(getApplicationContext(), R.string.toast_noSD, 0).show();  }  break;  default:  break;  } } } /** * 判斷SD卡是否存在，并且可以讀寫，空間足夠。 *  * @return */ @TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR2) @SuppressLint("NewApi") @SuppressWarnings("deprecation") private int judgeSD() { int flag = 0; // SD卡存在且可以讀取 if (Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())) {  // 獲取SD卡的路勁  String path = Environment.getExternalStorageDirectory().getPath();  // 調用C的類庫  StatFs fs = new StatFs(path);  long availabeBolocks = 0;  long bolockSize = 0;  // 為了兼容低版本，所以獲取當前應用所在系統的版本號，進而判斷  // 分為兩種。版本低于4.3的和高于等于4.3的(4.3的版本等級為18)  if (Build.VERSION.SDK_INT >= 18) {  // 獲取可用的塊  availabeBolocks = fs.getAvailableBlocksLong();  // 獲取每個塊的大小  bolockSize = fs.getBlockSizeLong();  } else {  // 獲取可用的塊  availabeBolocks = fs.getAvailableBlocks();  // 獲取每個塊的大小  bolockSize = fs.getBlockSize();  }  // 計算sd卡可用空間的大小（單位用MB）  long availableByte = availabeBolocks * bolockSize;  float availableMB = (float) availableByte / 1024 / 1024;  // 空間小于1MB，不允許寫入數據（實際上時空間小于寫入文件的大小，就不允許寫入，這里時認為文件大小為1MB）  if (availableMB < 1) {  flag = 1;  } else {  flag = 2;  }  return flag; } else {  return flag; } }}

其中主活動中FileService類是用來處理按鈕點擊后的事務的具體操作的。代碼如下：

package hhh.exercise.service;import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.File;import java.io.FileReader;import java.io.FileWriter;import java.io.InputStream;import java.io.InputStreamReader;import java.io.OutputStream;import java.io.OutputStreamWriter;import android.content.Context;import android.os.Environment;/** * @author HHH * */public class FileService { public Context context; public FileService(Context context) { super(); this.context = context; } /** * 保存文件到手機內存中 *  * @param fileName * @param fileContent * @return * @throws Exception */ public void saveToPhone(String fileName, String fileContent) throws Exception { OutputStream outputStream = context.openFileOutput(fileName, Context.MODE_PRIVATE); BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream)); bufferedWriter.write(fileContent); bufferedWriter.close(); } /** * 從手機中讀取文件 *  * @param fileName * @return * @throws Exception */ public String readFromPhone(String fileName) throws Exception { StringBuilder sBuilder = new StringBuilder(); InputStream inputStream = context.openFileInput(fileName); BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream)); String line = null; while ((line = bufferedReader.readLine()) != null) {  sBuilder.append(line); } bufferedReader.close(); return sBuilder.toString(); } /** * 把輸入的內容存入到SD卡中 *  * @param fileName * @param fileContent * @throws Exception */ public void saveToSD(String fileName, String fileContent) throws Exception { // 獲取sd卡的路徑 String path = Environment.getExternalStorageDirectory().getPath(); File file = new File(path, fileName); BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(file)); bufferedWriter.write(fileContent); bufferedWriter.close(); } /** * 從sd卡中讀取文件 *  * @param fileContent * @return * @throws Exception */ public String readFromSD(String fileName) throws Exception { StringBuilder sBuilder = new StringBuilder(); String path = Environment.getExternalStorageDirectory().getPath(); BufferedReader bufferedReader = new BufferedReader(new FileReader(new File(path, fileName))); String line = null; while ((line = bufferedReader.readLine()) != null) {  sBuilder.append(line); } bufferedReader.close(); return sBuilder.toString(); }}

strings.xml的代碼如下：

<?xml version="1.0" encoding="utf-8"?><resources> <string name="app_name">CDsaveFile</string> <string name="hello_world">Hello world!</string> <string name="action_settings">Settings</string> <string name="textView_inputFileName">請輸入文件名</string> <string name="editView_fileName">FileName</string> <string name="textView_inputFileContent">請輸入文件內容</string> <string name="editView_fileContent">FileContent</string> <string name="button_saveToPhone">存到手機</string> <string name="button_saveToSD">存到SD卡</string> <string name="button_readFromPhone">讀取手機</string> <string name="button_readFromSD">讀取SD</string> <string name="editText_showResult">Here is the result of the reading</string> <string name="toast_missFileName">請輸入文件名，文件名不可為空</string> <string name="toast_saveToPhone_success">存儲到手機成功</string> <string name="toast_saveToPhone_fail">存儲到手機失敗啦......</string> <string name="toast_saveToSD_success">存儲到SD成功</string> <string name="toast_saveToSD_fail">存儲到SD失敗啦......</string> <string name="toast_noSD">sd不存在或空間不足</string> <string name="toast_readFromPhone_fail">無法讀取手機文件</string> <string name="toast_readFromSD_fail">無法讀取SD文件</string></resources>

4.在AndroidManifest.xml添加權限

 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/> <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

5.項目部署在模擬器上：

進入程序后：

這里寫圖片描述