android　写下文件到ＳＤ卡中去_Android

android　写入文件到ＳＤ卡中去

前面写了一篇Android对文件的基本读写操作，只是向手机自身的存储空间写入文件，但是手机自身的存储空间有限，这时就要考虑向SDCard中存入文件，比如视频，音频和大量的图片。在底层代码的实现上两者没有什么区别，不过想要往SDCard中写入和读取文件首选必须在AndroidManifest.xml 注册权限：

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<!-- 加入在SDCard中创建与删除文件的权限 -->
<uses -permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />
<!-- 加入在SDCard中写入数据的权限 -->
<uses -permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

FileActivity.java 程序主要实现类

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package net.androidla.file;
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import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
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import net.androidla.service.FileService;
import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
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public class FileActivity extends Activity {
????private EditText filenameTxt;
????private EditText fileContentTxt;
????private TextView result;
????private Button btnSave;
????private Button btnShow;
????@Override
????public void onCreate(Bundle savedInstanceState) {
????????super.onCreate(savedInstanceState);
????????setContentView(R.layout.main);
????????filenameTxt = (EditText) findViewById(R.id.filenameTxt);
????????fileContentTxt = (EditText) findViewById(R.id.fileContentTxt);
????????btnSave = (Button) findViewById(R.id.btnSave);
????????btnShow = (Button) findViewById(R.id.btnShow);
????????result = (TextView) findViewById(R.id.result);
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????????btnSave.setOnClickListener(listener);
????????btnShow.setOnClickListener(listener);
????}
????private View.OnClickListener listener = new OnClickListener() {
????????@Override
????????public void onClick(View v) {
????????????Button button = (Button) v;
????????????String filename = filenameTxt.getText().toString();
????????????File file = new File(Environment.getExternalStorageDirectory(), filename);
????????????Log.i("log", file.getAbsolutePath());
????????????switch (button.getId()) {
????????????case R.id.btnSave:
????????????????if (filename != null && !filename.equals("")) {
????????????????????try {
????????????????????????if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
????????????????????????????FileService.save(new FileOutputStream(file), fileContentTxt.getText().toString());
????????????????????????????Toast.makeText(FileActivity.this, R.string.success, Toast.LENGTH_SHORT).show();
????????????????????????} else {
????????????????????????????Toast.makeText(FileActivity.this, "sdcard不存在或有写保护", Toast.LENGTH_SHORT).show();
????????????????????????}
????????????????????} catch (Exception e) {
????????????????????????e.printStackTrace();
????????????????????}
????????????????} else {
????????????????????Toast.makeText(FileActivity.this, R.string.fail, Toast.LENGTH_SHORT).show();
????????????????}
????????????????break;
????????????case R.id.btnShow:
????????????????try {
????????????????????String resultTxt = FileService.read(new FileInputStream(file));
????????????????????result.setText(resultTxt);
????????????????} catch (Exception e) {
????????????????????Toast.makeText(FileActivity.this, "读取失败", Toast.LENGTH_SHORT).show();
????????????????????e.printStackTrace();
????????????????}
????????????????break;
????????????}
????????}
????};
}

android 写下文件到ＳＤ卡中去

android　写下文件到ＳＤ卡中去