Android 开发笔记___SD卡文件操作
package com.example.alimjan.hello_world.Utils; import android.graphics.Bitmap;
import android.graphics.BitmapFactory; import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FilenameFilter;
import java.util.ArrayList;
import java.util.Locale; public class FileUtil { public static void saveText(String path, String txt) {
try {
FileOutputStream fos = new FileOutputStream(path);
fos.write(txt.getBytes());
fos.close();
} catch (Exception e) {
e.printStackTrace();
}
} public static String openText(String path) {
String readStr = "";
try {
FileInputStream fis = new FileInputStream(path);
byte[] b = new byte[fis.available()];
fis.read(b);
readStr = new String(b);
fis.close();
} catch (Exception e) {
e.printStackTrace();
}
return readStr;
} public static void saveImage(String path, Bitmap bitmap) {
try {
BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(path));
bitmap.compress(Bitmap.CompressFormat.JPEG, 80, bos);
bos.flush();
bos.close();
} catch (Exception e) {
e.printStackTrace();
}
} public static Bitmap openImage(String path) {
Bitmap bitmap = null;
try {
BufferedInputStream bis = new BufferedInputStream(new FileInputStream(path));
bitmap = BitmapFactory.decodeStream(bis);
bis.close();
} catch (Exception e) {
e.printStackTrace();
}
return bitmap;
} public static ArrayList<File> getFileList(String path, String[] extendArray) {
ArrayList<File> displayedContent = new ArrayList<File>();
File[] files = null;
File directory = new File(path);
if (extendArray != null && extendArray.length>0) {
FilenameFilter fileFilter = getTypeFilter(extendArray);
files = directory.listFiles(fileFilter);
} else {
files = directory.listFiles();
} if (files != null) {
for (File f : files) {
if (!f.isDirectory() && !f.isHidden()) {
displayedContent.add(f);
}
}
}
return displayedContent;
} public static FilenameFilter getTypeFilter(String[] extendArray) {
final ArrayList<String> fileExtensions = new ArrayList<String>();
for (int i=0; i<extendArray.length; i++) {
fileExtensions.add(extendArray[i]);
}
FilenameFilter fileNameFilter = new FilenameFilter() {
@Override
public boolean accept(File directory, String fileName) {
boolean matched = false;
File f = new File(String.format("%s/%s",
directory.getAbsolutePath(), fileName));
matched = f.isDirectory();
if (!matched) {
for (String s : fileExtensions) {
s = String.format(".{0,}\\%s$", s);
s = s.toUpperCase(Locale.getDefault());
fileName = fileName.toUpperCase(Locale.getDefault());
matched = fileName.matches(s);
if (matched) {
break;
}
}
}
return matched;
}
};
return fileNameFilter;
} }
write
package com.example.alimjan.hello_world; /**
* Created by alimjan on 7/5/2017.
*/ import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.AdapterView.OnItemSelectedListener; import com.example.alimjan.hello_world.Utils.DateUtil;
import com.example.alimjan.hello_world.Utils.FileUtil; public class class_4_3_2 extends AppCompatActivity implements OnClickListener { private EditText et_name;
private EditText et_age;
private EditText et_height;
private EditText et_weight;
private boolean bMarried = false; private String mPath;
private TextView tv_path; @Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.code_4_3_2);
et_name = (EditText) findViewById(R.id.et_name);
et_age = (EditText) findViewById(R.id.et_age);
et_height = (EditText) findViewById(R.id.et_height);
et_weight = (EditText) findViewById(R.id.et_weight);
tv_path = (TextView) findViewById(R.id.tv_path);
findViewById(R.id.btn_save).setOnClickListener(this); ArrayAdapter<String> typeAdapter = new ArrayAdapter<String>(this,
R.layout.item_select, typeArray);
typeAdapter.setDropDownViewResource(R.layout.item_dropdown);
Spinner sp_married = (Spinner) findViewById(R.id.sp_married);
sp_married.setPrompt("请选择婚姻状况");
sp_married.setAdapter(typeAdapter);
sp_married.setSelection(0);
sp_married.setOnItemSelectedListener(new TypeSelectedListener()); mPath = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS) + "/";
} private String[] typeArray = {"未婚", "已婚"};
class TypeSelectedListener implements OnItemSelectedListener {
public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
bMarried = (arg2==0)?false:true;
} public void onNothingSelected(AdapterView<?> arg0) {
}
} @Override
public void onClick(View v) {
if (v.getId() == R.id.btn_save) {
String name = et_name.getText().toString();
String age = et_age.getText().toString();
String height = et_height.getText().toString();
String weight = et_weight.getText().toString();
if (name==null || name.length()<=0) {
showToast("请先填写姓名");
return;
}
if (age==null || age.length()<=0) {
showToast("请先填写年龄");
return;
}
if (height==null || height.length()<=0) {
showToast("请先填写身高");
return;
}
if (weight==null || weight.length()<=0) {
showToast("请先填写体重");
return;
} String content = "";
content = String.format("%s 姓名：%s\n", content, name);
content = String.format("%s 年龄：%s\n", content, age);
content = String.format("%s 身高：%scm\n", content, height);
content = String.format("%s 体重：%skg\n", content, weight);
content = String.format("%s 婚否：%s\n", content, typeArray[bMarried==false?0:1]);
content = String.format("%s 注册时间：%s\n", content, DateUtil.getCurDateStr("yyyy-MM-dd HH:mm:ss"));
if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED) == true) {
String file_path = mPath + DateUtil.getCurDateStr("") + ".txt";
FileUtil.saveText(file_path, content);
tv_path.setText("用户注册信息文件的保存路径为：\n"+file_path);
showToast("数据已写入SD卡文件");
} else {
showToast("未发现已挂载的SD卡，请检查");
}
}
} private void showToast(String desc) {
Toast.makeText(this, desc, Toast.LENGTH_SHORT).show();
} public static void startHome(Context mcontext){
Intent intent = new Intent(mcontext,class_4_3_2.class);
mcontext.startActivity(intent);
} }
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:focusable="true"
android:focusableInTouchMode="true"
android:orientation="vertical"
android:padding="10dp" > <RelativeLayout
android:layout_width="match_parent"
android:layout_height="50dp" > <TextView
android:id="@+id/tv_name"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_alignParentLeft="true"
android:gravity="center"
android:text="姓名："
android:textColor="@color/black"
android:textSize="17sp" /> <EditText
android:id="@+id/et_name"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginBottom="5dp"
android:layout_marginTop="5dp"
android:layout_toRightOf="@+id/tv_name"
android:background="@drawable/editext_selector"
android:gravity="left|center"
android:hint="请输入姓名"
android:inputType="text"
android:maxLength="12"
android:textColor="@color/black"
android:textColorHint="@color/grey"
android:textCursorDrawable="@drawable/text_cursor"
android:textSize="17sp" />
</RelativeLayout> <RelativeLayout
android:layout_width="match_parent"
android:layout_height="50dp" > <TextView
android:id="@+id/tv_age"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_alignParentLeft="true"
android:gravity="center"
android:text="年龄："
android:textColor="@color/black"
android:textSize="17sp" /> <EditText
android:id="@+id/et_age"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginBottom="5dp"
android:layout_marginTop="5dp"
android:layout_toRightOf="@+id/tv_age"
android:background="@drawable/editext_selector"
android:gravity="left|center"
android:hint="请输入年龄"
android:inputType="number"
android:maxLength="2"
android:textColor="@color/black"
android:textColorHint="@color/grey"
android:textCursorDrawable="@drawable/text_cursor"
android:textSize="17sp" />
</RelativeLayout> <RelativeLayout
android:layout_width="match_parent"
android:layout_height="50dp" > <TextView
android:id="@+id/tv_height"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_alignParentLeft="true"
android:gravity="center"
android:text="身高："
android:textColor="@color/black"
android:textSize="17sp" /> <EditText
android:id="@+id/et_height"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginBottom="5dp"
android:layout_marginTop="5dp"
android:layout_toRightOf="@+id/tv_height"
android:background="@drawable/editext_selector"
android:gravity="left|center"
android:hint="请输入身高"
android:inputType="number"
android:maxLength="3"
android:textColor="@color/black"
android:textColorHint="@color/grey"
android:textCursorDrawable="@drawable/text_cursor"
android:textSize="17sp" />
</RelativeLayout> <RelativeLayout
android:layout_width="match_parent"
android:layout_height="50dp" > <TextView
android:id="@+id/tv_weight"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_alignParentLeft="true"
android:gravity="center"
android:text="体重："
android:textColor="@color/black"
android:textSize="17sp" /> <EditText
android:id="@+id/et_weight"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginBottom="5dp"
android:layout_marginTop="5dp"
android:layout_toRightOf="@+id/tv_weight"
android:background="@drawable/editext_selector"
android:gravity="left|center"
android:hint="请输入体重"
android:inputType="numberDecimal"
android:maxLength="5"
android:textColor="@color/black"
android:textColorHint="@color/grey"
android:textCursorDrawable="@drawable/text_cursor"
android:textSize="17sp" />
</RelativeLayout> <RelativeLayout
android:layout_width="match_parent"
android:layout_height="50dp" > <TextView
android:id="@+id/tv_married"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_alignParentLeft="true"
android:gravity="center"
android:text="婚否："
android:textColor="@color/black"
android:textSize="17sp" /> <Spinner
android:id="@+id/sp_married"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_toRightOf="@+id/tv_married"
android:gravity="left|center"
android:spinnerMode="dialog" />
</RelativeLayout> <Button
android:id="@+id/btn_save"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="保存文本到SD卡"
android:textColor="@color/black"
android:textSize="20sp" /> <TextView
android:id="@+id/tv_path"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:textColor="@color/black"
android:textSize="17sp" /> </LinearLayout>
read
package com.example.alimjan.hello_world; import java.io.File;
import java.util.ArrayList; /**
* Created by alimjan on 7/5/2017.
*/ import com.example.alimjan.hello_world.Utils.FileUtil; import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.AdapterView.OnItemSelectedListener; public class class_4_3_2_1 extends AppCompatActivity implements OnClickListener { private final static String TAG = "TextReadActivity";
private TextView tv_text;
private Spinner sp_file;
private String mPath; @Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.code_4_3_2_1);
tv_text = (TextView) findViewById(R.id.tv_text);
sp_file = (Spinner) findViewById(R.id.sp_file);
findViewById(R.id.btn_delete).setOnClickListener(this);
mPath = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS) + "/";
if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED) == true) {
refreshSpinner();
} else {
showToast("未发现已挂载的SD卡，请检查");
}
} private void refreshSpinner() {
ArrayList<File> fileAlllist = FileUtil.getFileList(mPath, new String[]{".txt"});
if (fileAlllist.size() > 0) {
fileArray = new String[fileAlllist.size()];
for (int i=0; i<fileAlllist.size(); i++) {
fileArray[i] = fileAlllist.get(i).getName();
}
ArrayAdapter<String> typeAdapter = new ArrayAdapter<String>(this,
R.layout.item_select, fileArray);
typeAdapter.setDropDownViewResource(R.layout.item_dropdown);
sp_file.setPrompt("请选择文本文件");
sp_file.setAdapter(typeAdapter);
sp_file.setSelection(0);
sp_file.setOnItemSelectedListener(new FileSelectedListener());
} else {
fileArray = null;
fileArray = new String[1];
fileArray[0] = "";
ArrayAdapter<String> typeAdapter = new ArrayAdapter<String>(this,
R.layout.item_select, fileArray);
sp_file.setPrompt(null);
sp_file.setAdapter(typeAdapter);
sp_file.setOnItemSelectedListener(null);
tv_text.setText("");
}
} private String[] fileArray;
class FileSelectedListener implements OnItemSelectedListener {
public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
String file_path = mPath + fileArray[arg2];
String content = FileUtil.openText(file_path);
tv_text.setText("文件内容如下：\n"+content);
} public void onNothingSelected(AdapterView<?> arg0) {
}
} @Override
public void onClick(View v) {
if (v.getId() == R.id.btn_delete) {
for (int i=0; i<fileArray.length; i++) {
String file_path = mPath + fileArray[i];
File f = new File(file_path);
boolean result = f.delete();
if (result != true) {
Log.d(TAG, "file_path="+file_path+", delete failed");
}
}
refreshSpinner();
showToast("已删除临时目录下的所有文本文件");
}
} private void showToast(String desc) {
Toast.makeText(this, desc, Toast.LENGTH_SHORT).show();
} public static void startHome(Context mcontext){
Intent intent = new Intent(mcontext,class_4_3_2_1.class);
mcontext.startActivity(intent);
} }
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:focusable="true"
android:focusableInTouchMode="true"
android:orientation="vertical"
android:padding="10dp" > <Button
android:id="@+id/btn_delete"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="删除所有文本文件"
android:textColor="@color/black"
android:textSize="20sp" /> <RelativeLayout
android:layout_width="match_parent"
android:layout_height="50dp" > <TextView
android:id="@+id/tv_file"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_alignParentLeft="true"
android:gravity="center"
android:text="文件名："
android:textColor="@color/black"
android:textSize="17sp" /> <Spinner
android:id="@+id/sp_file"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_toRightOf="@+id/tv_file"
android:gravity="left|center"
android:spinnerMode="dialog" />
</RelativeLayout> <TextView
android:id="@+id/tv_text"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textColor="@color/black"
android:textSize="17sp" /> </LinearLayout>
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