Android(安卓)数据存储（数据库、文件、参数）操作实例

1. 主界面

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:scrollbars="vertical" >    <LinearLayout        android:id="@+id/LinearLayout1"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="vertical"        tools:context=".MainActivity" >        <RadioGroup            android:id="@+id/radioClassName"            android:layout_width="wrap_content"            android:layout_height="wrap_content" >            <RadioButton                android:id="@+id/radio1"                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:text="@string/title_activity_preferences" />            <RadioButton                android:id="@+id/radio2"                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:text="@string/title_activity_file" />            <RadioButton                android:id="@+id/radio3"                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:checked="true"                android:text="@string/title_activity_data_base" />        </RadioGroup>        <Button            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:onClick="display"            android:text="@string/btn_display" />    </LinearLayout></ScrollView>

2. 参数存储实例

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:id="@+id/LinearLayout1"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical"    tools:context=".PreferencesActivity" >    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="horizontal" >        <TextView            android:layout_width="50dp"            android:layout_height="wrap_content"            android:text="@string/lblUsername" />        <EditText            android:id="@+id/txtUsername"            android:layout_width="match_parent"            android:layout_height="wrap_content" />    </LinearLayout>    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="horizontal" >        <TextView            android:layout_width="50dp"            android:layout_height="wrap_content"            android:text="@string/lblPassword" />        <EditText            android:id="@+id/txtPassword"            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:inputType="textPassword" />    </LinearLayout>    <Button        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="@string/btn_save"        android:onClick="save" /></LinearLayout>

文件存储路径：/data/data/<package_name>/shared_prefs/<filename>.xml
3. 文件存储实例

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:id="@+id/LinearLayout2"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical"    tools:context=".PreferencesActivity" >    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="horizontal" >        <TextView            android:layout_width="50dp"            android:layout_height="wrap_content"            android:text="@string/lblFilename" />        <EditText            android:id="@+id/txtFilename"            android:layout_width="0dip"            android:layout_height="wrap_content"            android:layout_weight="1" />        <Button            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:onClick="open"            android:text="@string/btn_open" />    </LinearLayout>    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="@string/lblFilecontent" />    <EditText        android:id="@+id/txtFilecontent"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:gravity="top"        android:inputType="textMultiLine"        android:lines="10" />    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="horizontal" >        <Button            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:onClick="save"            android:text="@string/btn_save" />        <Button            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:onClick="save2sdcard"            android:text="@string/btn_save2sdcard" />    </LinearLayout></LinearLayout>

package com.example.data;import android.app.Activity;import android.os.Bundle;import android.os.Environment;import android.view.View;import android.widget.EditText;import android.widget.Toast;import com.example.service.FileService;public class FileActivity extends Activity {private EditText filenameEditText, filecontentEditText;private FileService service;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_file);service = new FileService(this);filenameEditText = (EditText) findViewById(R.id.txtFilename);filecontentEditText = (EditText) findViewById(R.id.txtFilecontent);}public void save(View view) {String filename = filenameEditText.getText().toString();String content = filecontentEditText.getText().toString();try {service.save(filename, content);Toast.makeText(this, getString(R.string.save_success), Toast.LENGTH_LONG).show();} catch (Exception e) {Toast.makeText(this, getString(R.string.save_fail), Toast.LENGTH_LONG).show();e.printStackTrace();}}public void save2sdcard(View view) {String filename = filenameEditText.getText().toString();String content = filecontentEditText.getText().toString();try {if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {service.save2sdcard(filename, content);Toast.makeText(this, getString(R.string.save_success), Toast.LENGTH_LONG).show();}} catch (Exception e) {Toast.makeText(this, getString(R.string.save_fail), Toast.LENGTH_LONG).show();e.printStackTrace();}}public void open(View view) {String filename = filenameEditText.getText().toString();try {String content=service.open(filename);filecontentEditText.setText(content);Toast.makeText(this, getString(R.string.open_success), Toast.LENGTH_LONG).show();} catch (Exception e) {Toast.makeText(this, getString(R.string.open_fail), Toast.LENGTH_LONG).show();e.printStackTrace();}}}

package com.example.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 {private Context context;public FileService(Context content) {this.context = content;}///data/data/<package_name>/files/<filename>public void save(String filename, String content) throws Exception {FileOutputStream outputStream = context.openFileOutput(filename, Context.MODE_PRIVATE);outputStream.write(content.getBytes());outputStream.close();}//path: /Android/data/<package_name>/files/<filename>public void save2sdcard(String filename, String content) throws Exception {//Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);String path=Environment.getExternalStorageDirectory()+"/Android/data/com.example.data/files/";File file = new File(path, filename);new File(file.getParent()).mkdirs(); FileOutputStream outputStream = new FileOutputStream(file);outputStream.write(content.getBytes());outputStream.close();}public String open(String filename) throws Exception {FileInputStream inputStream = context.openFileInput(filename);ByteArrayOutputStream outputStream = new ByteArrayOutputStream();byte[] buffer = new byte[1024] ;int len = 0;while ((len = inputStream.read(buffer)) != -1) {outputStream.write(buffer, 0, len);}return new String(outputStream.toByteArray());}}

文件存储路径：
内部存储：/data/data/<package_name>/files/<filename>
SD卡存储：/Android/data/<package_name>/files/<filename>
4. 数据库存储实例

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:id="@+id/LinearLayout3"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical"    tools:context=".PreferencesActivity" >    <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/lblPhone" />        <EditText            android:id="@+id/txtPhone"            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:inputType="text" />    </LinearLayout>    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="horizontal" >        <Button            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:onClick="save"            android:text="@string/btn_save2db" />        <Button            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:onClick="list"            android:text="@string/btn_list" />    </LinearLayout></LinearLayout>

数据库文件存储路径：/data/data/<package_name>/databases/<databaseName>

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