第一步，改写AndroidManifest.xml,给手机的Scard卡授权
<!--添加Scard卡读写授权 --><uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
然后加单元测试instrumentation
<instrumentationandroid:name="android.test.InstrumentationTestRunner"android:targetPackage="com.example.androidsdcard" ></instrumentation>
并且在application下加 <uses-library android:name="android.test.runner"/>
<applicationandroid:allowBackup="true"android:icon="@drawable/ic_launcher"android:label="@string/app_name"android:theme="@style/AppTheme" ><uses-library android:name="android.test.runner"/><activityandroid:name=".MainActivity"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>
第二步，编写文件读写的类FileStream
package com.example.androidsdcard;import java.io.ByteArrayOutputStream;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.OutputStream;import android.content.Context;import android.os.Environment;public class FileStream {private Context context;public FileStream(Context context) {this.context = context;}public FileStream() {}
//读取sd卡的文件内容public String readFile(String filename){FileInputStream inputStream=null;//字符缓冲流ByteArrayOutputStream outputStream=new ByteArrayOutputStream();
// 通过Environment获得sd卡的路径File file=new File(Environment.getExternalStorageDirectory(),filename);//判断sdcard是否存在if(Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())){try {inputStream=new FileInputStream(file);int len=0;
//创建字节数组byte[]data=new byte[2048];
//按字节数组的大小进行读取while((len=inputStream.read(data))!=-1){outputStream.write(data, 0, len); }} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{if(inputStream!=null){try {inputStream.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}return new String(outputStream.toByteArray());}public boolean savaFile(String filename, String content) {boolean flag = false;FileOutputStream outputStream = null;File file = new File(Environment.getExternalStorageDirectory(),filename);if (Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())) {try {outputStream = new FileOutputStream(file);outputStream.write(content.getBytes());flag = true;} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();} finally {if (outputStream != null) {try {outputStream.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}return flag;}}
第三部，编写测试类进行单元测试，进行文件的读写
1 package com.example.androidsdcard; 2 3 import android.content.Context; 4 import android.test.AndroidTestCase; 5 import android.util.Log; 6 7 public class MyTest extends AndroidTestCase { 8private final String TAG="MyTest"; 9public MyTest(){10 11}12public void saveFile(){//测试文件写入13 Context context=getContext();14 FileStream fileStream=new FileStream(context);15 boolean flag=fileStream.savaFile("hello.txt","你好吗？");16 Log.i(TAG,"--->"+flag);17 18}19public void readFile(){//测试文件内容读取20 Context context=getContext();21 FileStream fileStream=new FileStream(context);22 String filename="hello.txt";23 String flag=fileStream.readFile(filename);24 Log.i(TAG,"--->"+flag);25 26}27 28 }
