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
", content, name);
            content = String.format("%s　年龄：%s
", content, age);
            content = String.format("%s　身高：%scm
", content, height);
            content = String.format("%s　体重：%skg
", content, weight);
            content = String.format("%s　婚否：%s
", content, typeArray[bMarried==false?0:1]);
            content = String.format("%s　注册时间：%s
", 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：
"+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：
"+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>