Android实现文件存储并读取的示例代码

概述要求：输入文件名，文件内容分别存储在手机内存和外存中，并且都可以读去取出来。

要求：

输入文件名，文件内容分别存储在手机内存和外存中，并且都可以读去取出来。

步骤：

1.创建一个名为CDsavefile的AndroID项目

2.编写布局文件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.编写主活动中代码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); // 实例化 fileService 类，该类用于处理按钮触发的事件的具体 *** 作 service = new fileService(getApplicationContext()); // 获取布局中的控件 editVIEw_filename = (EditText) findVIEwByID(R.ID.editVIEw_filename); editVIEw_fileContent = (EditText) findVIEwByID(R.ID.editVIEw_fileContent); editText_showResult = (EditText) findVIEwByID(R.ID.editText_showResult); // 获取按钮并创建触发事件 ((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); } /** * 为每一个按钮创建触发的事件 *  * @param v触发事件的VIEw对象 */ @OverrIDe public voID onClick(VIEw v) { String filename = editVIEw_filename.getText().toString(); String fileContent = editVIEw_fileContent.getText().toString(); // 判断文件名，文件名要求不为空 if (filename == null || "".equals(filename.trim())) {  Toast.makeText(getApplicationContext(),R.string.toast_missfilename,0).show(); } else {  // 输入的文件名不为空，对每个按钮的触发事件进行处理  String result = null;  switch (v.getID()) {  case R.ID.button_savetoPhone:  try {   // 存储文件到手机上   service.savetoPhone(filename,fileContent);   // 清空内容输入框   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 {   // 读取手机文件中的内容   result = service.readFromPhone(filename);   // 将内容显示在空间中   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:  // 判断sd卡是否存在，并且可以使用，空间足够  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:  // 判断SD卡能够读取  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(),0).show();  }  break;  default:  break;  } } } /** * 判断SD卡是否存在，并且可以读写，空间足够。 *  * @return */ @TargetAPI(Build.VERSION_CODES.JELLY_BEAN_MR2) @Suppresslint("NewAPI") @SuppressWarnings("deprecation") private int judgeSD() { int flag = 0; // SD卡存在且可以读取 if (Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())) {  // 获取SD卡的路劲  String path = Environment.getExternalStorageDirectory().getPath();  // 调用C的类库  StatFs fs = new StatFs(path);  long availabeBolocks = 0;  long bolockSize = 0;  // 为了兼容低版本，所以获取当前应用所在系统的版本号，进而判断  // 分为两种。版本低于4.3的和高于等于4.3的(4.3的版本等级为18)  if (Build.VERSION.SDK_INT >= 18) {  // 获取可用的块  availabeBolocks = fs.getAvailableBlocksLong();  // 获取每个块的大小  bolockSize = fs.getBlockSizeLong();  } else {  // 获取可用的块  availabeBolocks = fs.getAvailableBlocks();  // 获取每个块的大小  bolockSize = fs.getBlockSize();  }  // 计算sd卡可用空间的大小（单位用MB）  long availableByte = availabeBolocks * bolockSize;  float availableMB = (float) availableByte / 1024 / 1024;  // 空间小于1MB，不允许写入数据（实际上时空间小于写入文件的大小，就不允许写入，这里时认为文件大小为1MB）  if (availableMB < 1) {  flag = 1;  } else {  flag = 2;  }  return flag; } else {  return flag; } }}

其中主活动中fileService类是用来处理按钮点击后的事务的具体 *** 作的。代码如下：

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; } /** * 保存文件到手机内存中 *  * @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(); } /** * 从手机中读取文件 *  * @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(); } /** * 把输入的内容存入到SD卡中 *  * @param filename * @param fileContent * @throws Exception */ public voID savetoSD(String filename,String fileContent) throws Exception { // 获取sd卡的路径 String path = Environment.getExternalStorageDirectory().getPath(); file file = new file(path,filename); BuffereDWriter buffereDWriter = new BuffereDWriter(new fileWriter(file)); buffereDWriter.write(fileContent); buffereDWriter.close(); } /** * 从sd卡中读取文件 *  * @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的代码如下：

<?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">请输入文件名</string> <string name="editVIEw_filename">filename</string> <string name="textVIEw_inputfileContent">请输入文件内容</string> <string name="editVIEw_fileContent">fileContent</string> <string name="button_savetoPhone">存到手机</string> <string name="button_savetoSD">存到SD卡</string> <string name="button_readFromPhone">读取手机</string> <string name="button_readFromSD">读取SD</string> <string name="editText_showResult">Here is the result of the reading</string> <string name="toast_missfilename">请输入文件名，文件名不可为空</string> <string name="toast_savetoPhone_success">存储到手机成功</string> <string name="toast_savetoPhone_fail">存储到手机失败啦......</string> <string name="toast_savetoSD_success">存储到SD成功</string> <string name="toast_savetoSD_fail">存储到SD失败啦......</string> <string name="toast_noSD">sd不存在或空间不足</string> <string name="toast_readFromPhone_fail">无法读取手机文件</string> <string name="toast_readFromSD_fail">无法读取SD文件</string></resources>

4.在AndroIDManifest.xml添加权限

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

5.项目部署在模拟器上：

进入程序后：

把文件存储到手机上并读取：

 

把文件存储到SD上并读取：

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持编程小技巧。

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