Android 学习笔记7---数据存储与访问

文件
SharedPreferences
SQLite数据库
内容提供者（Content provider）(对外共享数据使用)
网络

本文讲讲文件的例子，其余后续讲解。

例子采用MVC模式

1业务bean（junit test） 2设计界面（美工）这两项工作可以同步进行

3设计activity

android 内部类为了性能，尽量少用类，合理。

例子

运行后截图

Android 学习笔记7---数据存储与访问_第1张图片

目录结构：

Android 学习笔记7---数据存储与访问_第2张图片

代码:

DataActivity.javapackage com.leo.file;import java.io.FileNotFoundException;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import android.app.Activity;import android.content.Context;import android.os.Bundle;import android.util.Log;import android.view.View;import android.widget.Button;import android.widget.EditText;import android.widget.TextView;import android.widget.Toast;import com.leo.service.FileService;public class DataActivity extends Activity {private static final String TAG = "DataActivity";    private EditText filenameText;    private EditText contentText;    private TextView resultView;        @Override     public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        filenameText = (EditText)this.findViewById(R.id.filename);        contentText = (EditText)this.findViewById(R.id.content);        resultView = (TextView)this.findViewById(R.id.result);        Button button = (Button)this.findViewById(R.id.button);        Button showButton = (Button)this.findViewById(R.id.showButton);                button.setOnClickListener(listner);        showButton.setOnClickListener(listner);    }        private View.OnClickListener listner = new View.OnClickListener() {public void onClick(View v) {Button button = (Button)v;String filename = filenameText.getText().toString();switch (button.getId()){case R.id.button:int resId = R.string.success;String content = contentText.getText().toString();try {OutputStream outStream = DataActivity.this.openFileOutput(filename, Context.MODE_WORLD_READABLE + Context.MODE_WORLD_WRITEABLE);FileService.save(outStream, content);} catch (IOException e) {Log.e(TAG, e.toString());resId = R.string.error;}Toast.makeText(DataActivity.this, resId, Toast.LENGTH_LONG).show();break;case R.id.showButton:try {InputStream inStream = DataActivity.this.openFileInput(filename);String text = FileService.read(inStream);resultView.setText(text);} catch (IOException e) {Log.e(TAG, e.toString());Toast.makeText(DataActivity.this, "read error", Toast.LENGTH_LONG).show();}break;}}};}

FileServiceTest.javapackage com.leo.file;import java.io.InputStream;import java.io.OutputStream;import android.content.Context;import android.test.AndroidTestCase;import android.util.Log;import com.leo.service.FileService;public class FileServiceTest extends AndroidTestCase {private static final String TAG = "FileServiceTest";public void testSave() throws Exception {OutputStream outStream = this.getContext().openFileOutput("leo.txt", Context.MODE_PRIVATE);FileService.save(outStream, "leo");}public void testread() throws Exception {InputStream inStream = this.getContext().openFileInput("leo.txt");String content = FileService.read(inStream);Log.i(TAG, content);}}

FileService.javapackage com.leo.service;import java.io.ByteArrayOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;public class FileService {/** * 保存数据 * @param outStream * @param content * @throws IOException */public static void save (OutputStream outStream, String content) throws IOException {outStream.write(content.getBytes());outStream.close();}/** * 读取数据 * @param inStream * @return * @throws IOException */public static String read (InputStream inStream) throws IOException {ByteArrayOutputStream outStream = new ByteArrayOutputStream();byte[] buffer = new byte[1024];int len = -1;while( (len = inStream.read(buffer)) != -1 ) {outStream.write(buffer, 0, len);}byte[] data =  outStream.toByteArray();outStream.close();inStream.close();return new String (data);}}

strings.xml<?xml version="1.0" encoding="utf-8"?><resources>    <string name="hello">Hello World, DataActivity!</string>    <string name="app_name">数据保存</string>    <string name="filename">文件名称</string>    <string name="content">文件内容</string>    <string name="save">保存</string>     <string name="show">显示文件内容</string>    <string name="error">保存失败</string>    <string name="success">保存成功</string></resources>

AndroidManifest.xml<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"      package="com.leo.file"      android:versionCode="1"      android:versionName="1.0">    <uses-sdk android:minSdkVersion="8" />    <application android:icon="@drawable/icon" android:label="@string/app_name">   <uses-library android:name="android.test.runner" />        <activity android:name=".DataActivity"                  android:label="@string/app_name">            <intent-filter>                <action android:name="android.intent.action.MAIN" />                <category android:name="android.intent.category.LAUNCHER" />            </intent-filter>        </activity>    </application>    <instrumentation android:name="android.test.InstrumentationTestRunner"  android:targetPackage="com.leo.file" android:label="Tests for My App" /></manifest>

附件： http://files.cnblogs.com/khldragon/File.zip

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