Android持久化技术之文件的读取与写入实例详解

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  android:layout_width="fill_parent"  android:layout_height="fill_parent"  android:orientation="horizontal" >  <TextView    android:id="@+id/textView1"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="Account:" />  <EditText    android:id="@+id/editText1"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:ems="10" >  </EditText></LinearLayout>

package com.example.testfilestore;import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStreamReader;import java.io.OutputStreamWriter;import android.app.Activity;import android.content.Context;import android.os.Bundle;import android.text.TextUtils;import android.view.Menu;import android.widget.EditText;/** * 文件存储：写入与读取 * @author yy * */public class MainActivity extends Activity {  private EditText editText;  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    //获取editText对象    editText = (EditText) findViewById(R.id.editText1);    //首先加载上次输入的内容    String inputContent = readFromFile();    if(!TextUtils.isEmpty(inputContent)){      //如果上次输入的内容不为空，则加载进来      editText.setText(inputContent);      //设置光标位置，使之位于文本末尾，默认是在文本头部      editText.setSelection(inputContent.length());    }  }  /**   * 当活动销毁时，保存输入的内容   */  @Override  protected void onDestroy() {    super.onDestroy();    //获取输入的内容    String data = editText.getText().toString();    //写入文件    writeToFile(data);  }  /**   * 输入的内容写入文件   */  public void writeToFile(String data){    FileOutputStream fileOutputStream = null;    BufferedWriter bufferedWriter = null;    try {      //Context中的方法，用于存储数据      //第一个参数是文件名      //第二个参数是写入模式，表示覆盖写入，如果原来有内容，则会覆盖      fileOutputStream = openFileOutput("first",Context.MODE_PRIVATE);      bufferedWriter = new BufferedWriter(new OutputStreamWriter(fileOutputStream));      bufferedWriter.write(data);    } catch (FileNotFoundException e) {      e.printStackTrace();    } catch (IOException e) {      e.printStackTrace();    }finally{        //关闭流        try {          if(bufferedWriter!=null){            bufferedWriter.close();          }        } catch (IOException e) {          e.printStackTrace();        }    }  }  /**   * 从文件中读取数据   * @return   */  public String readFromFile(){    FileInputStream fileInputStream = null;    BufferedReader bufferedReader = null;    StringBuffer stringBuffer = new StringBuffer();    try {      fileInputStream = openFileInput("first");      bufferedReader = new BufferedReader(new InputStreamReader(fileInputStream));      String line = "";      while((line = bufferedReader.readLine())!=null){        stringBuffer.append(line);      }    } catch (FileNotFoundException e) {      e.printStackTrace();    } catch (IOException e) {      e.printStackTrace();    }finally{      //关闭流      try {        if (bufferedReader != null) {          bufferedReader.close();        }      } catch (IOException e) {        e.printStackTrace();      }    }    //返回    return stringBuffer.toString();  }  @Override  public boolean onCreateOptionsMenu(Menu menu) {    // Inflate the menu; this adds items to the action bar if it is present.    getMenuInflater().inflate(R.menu.main, menu);    return true;  }}