移动应用程序设计基础——数据库实践——简单日记本

谁借莪１个温暖的怀抱￠ 2023-10-01 13:19 104阅读 0赞

## **《移动应用程序设计基础》实验5 数据库实践——简单日记本** ##

### **实验名称：** ###

**实验5 数据库实践——简单日记本**

### **所使用的工具软件及环境：** ###

JDK1.8，Android Studio

### **一、实验目的：** ###

实验目的：

掌握安卓数据库的应用

### **二、实验内容：** ###

### 模拟一个日记本程序 ###

实现简单日记的新建、修 改、删除、查询功能。运行效果如下图。

![0adcbd21d8064267b4ecde320e160199.png][]

当点击右下方的添加按钮时如下图所示。

![30f45faf053049bfa727b3b4664d0d0e.png][]

当点击ListView的Item时，将显示日记的详细信息。

![c2e1357234a04d61922d92d5c33540ec.png][]

当点击ListView的右边的编辑图片按钮时，将进入编辑日记模式。

![a163ce8f196d49599baf4224e372bb64.png][]

当点击Toolbar中的值为“编辑”的TextView控件时，显示如下。

![cf22c57525d3491aa9717cdd8a224407.png][]

### 使用SQLiteExpert软件查看生成的数据库 ###

当使用Sqlite数据库时，Android系统对其存放的数据库文件位于/data/data/\[包名\]/databases/\*.db，如下图所示，在安装sdk目录下运行monitor.bat文件：

![03e0c34d58bd44fca480c2dd77399d0d.png][]

默认情况下，data目录是禁止非root用户访问的，这时，我们就需要root权限来查看。首先打开Android SDK下的platform-tools目录，然后按住Shift键并按下鼠标右键，点击“在此处打开命令窗口(W)”，如下图所示。

![a309e5fbe0954dcb9ffb1dabf6728fce.png][]

然后在命令窗口输入以下命令：

这时，我们就可以访问/data目录了，之后使用pull命令来复制文件。

<table> 
 <tbody> 
  <tr> 
   <td> 
    <div> 
     <p style="margin-left:0;text-align:justify;">adb pull /data/data/com.example.sqlitedemo/databases</p> 
     <p style="margin-left:0;text-align:justify;">/DiaryDB.db&nbsp; DiaryDB.db</p> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

默认情况下，文件将存放在D:\\WorkSpace\\ASSDK\\platform-tools目录中。

之后，打开SQLiteExpert软件（需网上下载），依次点击FileàOpen Database，选中刚刚导出的数据库文件：

![986faf01a8fa43f2bbaf7b427da26151.png][]

在左边的列表中，选中diary表，之后选择右上方的Data选项，就可以查看数据，选择旁边的Design选项可以查看表的结构。其下方的“加号”、“减号”、“对号”、“叉号”分别为插入一条数据、删除选中的数据、提交更改、撤销更改。

![d4139525b95d4d2288b9644770b41b06.png][]

#### 实验要求： ####

1.  完成实验内容所有代码；
2.  图文并重的方式叙述实现过程；
3.  展示运行结果。

#### 实验过程： ####

Android中封装了一个SQLiteOpenHelper抽象类，我们需要创建SQLiteOpenHelper的子类并覆写onCreate方法，在此方法中编写我们需要的SQL语句。使用契约类SQLiteContract来定义URI、表格和列名称的常数的容器，契约类允许我们跨同一软件包中的所有其他类使用相同的常数。

<table> 
 <tbody> 
  <tr> 
   <td> 
    <div> 
     <p style="margin-left:0;text-align:justify;">public final class SQLiteContract { </p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;&nbsp;&nbsp; //为了防止使用者不小心实例化类的构造方法，</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;&nbsp;&nbsp; //使构造函数私有化。</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;&nbsp;&nbsp; private SQLiteContract () {}</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;&nbsp;&nbsp; //此内部类定义日记表的内容</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;&nbsp;&nbsp; public static class DiaryEntry implements BaseColumns { </p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; public static final String TABLE_NAME = "diary";</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; public static final String COLUMN_NAME_TITLE = "title";</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; public static final String COLUMN_NAME_CONTENT = "content";</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;public static final String COLUMN_NAME_TIME = "time";</p> 
     <p style="margin-left:0;text-align:justify;">}</p> 
     <p style="margin-left:0;text-align:justify;">//其他表内容</p> 
     <p style="margin-left:0;text-align:justify;">}</p> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

继承SQLiteOpenHelper并覆写onCreate方法和onUpgrade方法，其中onUpgrade方法是一个设置数据库版本号的方法。需要我们注意的是，当我们实例化DBHelper 时（比如new DBHelper），onCreate方法只会执行一次，即数据库表只会创建一次。当数据库版本号增加时，系统将调用onUpgrade方法。我们可以将升级的SQL语句放在此方法内完成数据库的升级。

<table> 
 <tbody> 
  <tr> 
   <td> 
    <div> 
     <p style="margin-left:0;text-align:justify;">&nbsp; 1 public class DiaryDbHelper extends SQLiteOpenHelper { </p> 
     <p style="margin-left:0;text-align:justify;">&nbsp; 2&nbsp;&nbsp;&nbsp;&nbsp; public static final int DATABASE_VERSION = 1;</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp; 3&nbsp;&nbsp;&nbsp;&nbsp; public static final String DATABASE_NAME = "DiaryDB.db";</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp; 4&nbsp;&nbsp;&nbsp;&nbsp; public DiaryDbHelper(Context context) { </p> 
     <p style="margin-left:0;text-align:justify;">&nbsp; 5&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; super(context, DATABASE_NAME, null, DATABASE_VERSION);</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp; 6&nbsp;&nbsp;&nbsp;&nbsp; }</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp; 7&nbsp;&nbsp;&nbsp;&nbsp; @Override</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp; 8&nbsp;&nbsp;&nbsp;&nbsp; public void onCreate(SQLiteDatabase db) { </p> 
     <p style="margin-left:0;text-align:justify;">&nbsp; 9&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; db.execSQL(SQL_CREATE_ENTRIES);</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;10&nbsp;&nbsp;&nbsp;&nbsp; }</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;11&nbsp;&nbsp;&nbsp;&nbsp; @Override</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;12&nbsp;&nbsp;&nbsp;&nbsp; public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { </p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;13&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; db.execSQL(SQL_DELETE_ENTRIES);</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;14&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; onCreate(db);</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;15&nbsp;&nbsp;&nbsp;&nbsp; }</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;16 }</p> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

向数据库中插入一条数据时，可以使用ContentValues 对象传递至SQLiteDatabase对象的insert() 方法将数据插入数据库。

<table> 
 <tbody> 
  <tr> 
   <td> 
    <div> 
     <p style="margin-left:0;text-align:justify;">SQLiteDatabase db = dbHelper.getWritableDatabase();</p> 
     <p style="margin-left:0;text-align:justify;">//设置插入值</p> 
     <p style="margin-left:0;text-align:justify;">ContentValues values = new ContentValues();</p> 
     <p style="margin-left:0;text-align:justify;">values.put(SQLiteContract.DiaryEntry.COLUMN_NAME_TITLE, title);</p> 
     <p style="margin-left:0;text-align:justify;">values.put(SQLiteContract.DiaryEntry.COLUMN_NAME_CONTENT, content);</p> 
     <p style="margin-left:0;text-align:justify;">values.put(SQLiteContract.DiaryEntry.COLUMN_NAME_TIME, date);</p> 
     <p style="margin-left:0;text-align:justify;">//执行插入方法</p> 
     <p style="margin-left:0;text-align:justify;">long newRowId = db.insert(SQLiteContract.DiaryEntry.TABLE_NAME, null, values);</p> 
     <p style="margin-left:0;text-align:justify;">db.close();</p> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

可以使用query方法查询数据

<table> 
 <tbody> 
  <tr> 
   <td> 
    <div> 
     <p style="margin-left:0;text-align:justify;">SQLiteDatabase db = dbHelper.getReadableDatabase();</p> 
     <p style="margin-left:0;text-align:justify;">String[] projection = { </p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; SQLiteContract.DiaryEntry._ID,</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; SQLiteContract.DiaryEntry.COLUMN_NAME_TITLE,</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; SQLiteContract.DiaryEntry.COLUMN_NAME_CONTENT,</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; SQLiteContract.DiaryEntry.COLUMN_NAME_TIME</p> 
     <p style="margin-left:0;text-align:justify;">};</p> 
     <p style="margin-left:0;text-align:justify;">String selection = SQLiteContract.DiaryEntry._ID + " = ?";</p> 
     <p style="margin-left:0;text-align:justify;">String[] selectionArgs = { id };</p> 
     <p style="margin-left:0;text-align:justify;">String sortOrder =SQLiteContract.DiaryEntry.COLUMN_NAME_TIME + " DESC";</p> 
     <p style="margin-left:0;text-align:justify;">Cursor c = db.query(</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; SQLiteContract.DiaryEntry.TABLE_NAME,&nbsp;&nbsp;&nbsp;&nbsp;</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; projection, selection, selectionArgs, null, null, sortOrder</p> 
     <p style="margin-left:0;text-align:justify;">);</p> 
     <p style="margin-left:0;text-align:justify;">c.moveToFirst();</p> 
     <p style="margin-left:0;text-align:justify;">String title= c.getString(c.getColumnIndex(SQLiteContract.DiaryEntry.</p> 
     <p style="margin-left:0;text-align:justify;">COLUMN_NAME_TITLE))</p> 
     <p style="margin-left:0;text-align:justify;">c.close();</p> 
     <p style="margin-left:0;text-align:justify;">db.close();</p> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

更新数据可以使用update方法

<table> 
 <tbody> 
  <tr> 
   <td> 
    <div> 
     <p style="margin-left:0;text-align:justify;">SQLiteDatabase db = dbHelper.getWritableDatabase();</p> 
     <p style="margin-left:0;text-align:justify;">ContentValues values = new ContentValues();</p> 
     <p style="margin-left:0;text-align:justify;">values.put(SQLiteContract.DiaryEntry.COLUMN_NAME_TITLE, title);</p> 
     <p style="margin-left:0;text-align:justify;">String selection = SQLiteContract.DiaryEntry._ID + " = ?";</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; String[] selectionArgs = { id };</p> 
     <p style="margin-left:0;text-align:justify;">int count = db.update(</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; SQLiteContract.DiaryEntry.TABLE_NAME,</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; values,</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;selection,</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; selectionArgs);</p> 
     <p style="margin-left:0;text-align:justify;">db.close();</p> 
     <p style="margin-left:0;text-align:justify;">&nbsp;</p> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

删除数据可以使用delete方法

<table> 
 <tbody> 
  <tr> 
   <td> 
    <div> 
     <p style="margin-left:0;text-align:justify;">SQLiteDatabase db = dbHelper.getWritableDatabase();</p> 
     <p style="margin-left:0;text-align:justify;">String selection = SQLiteContract.DiaryEntry._ID + " = ?";</p> 
     <p style="margin-left:0;text-align:justify;">String[] selectionArgs = { id };</p> 
     <p style="margin-left:0;text-align:justify;">db.delete(SQLiteContract.DiaryEntry.TABLE_NAME, selection, selectionArgs);</p> 
     <p style="margin-left:0;text-align:justify;">db.close();</p> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

### **三、实验结果测试（****完整所有代码在资源下载压缩包中，文章结尾有资源下载链接）** ###

**4****个java****文件以及5****个布局文件**

![69f42e88dff14a5595c4e93ca5ea65a1.png][]

#### 部分主要代码：    ####

//MainActivity.java
    package com.example.mgh.diary;
    
    import android.annotation.SuppressLint;
    import android.app.Activity;
    import android.content.Intent;
    import android.database.Cursor;
    import android.database.sqlite.SQLiteDatabase;
    import android.graphics.Paint;
    import android.os.Bundle;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.AdapterView;
    import android.widget.BaseAdapter;
    import android.widget.Button;
    import android.widget.EditText;
    import android.widget.ImageView;
    import android.widget.ListView;
    import android.widget.TextView;
    
    import java.util.ArrayList;
    
    public class MainActivity extends Activity implements View.OnClickListener {
        public static ArrayList<info> info = new ArrayList<>();
        private ListView mlistview;
        public static SQLiteDatabase db;
        public Button buttonHide;
        public Button btn_search;
        public ImageView iv;
        private EditText editText;
        public Button look_button;
    
        public int a=0;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            init();
        }
    
        private void init() {
            info = new ArrayList<>();
            //editText = (EditText) findViewById(R.id.editText);
            btn_search = (Button) findViewById(R.id.btn_search);
            //buttonHide = (Button) findViewById(R.id.buttonHide);
            iv = (ImageView) findViewById(R.id.imageView);
            //buttonHide.setOnClickListener(this);
            btn_search.setOnClickListener(this);
            iv.setOnClickListener(this);
    
            //list监听
            mlistview = (ListView) findViewById(R.id.mlistview);
            db = new MyHelper(this).getWritableDatabase();
            Cursor cursor = db.query("diary", null, null,
                    null, null, null, null);
            if (cursor.moveToFirst()) {
                do {
    // 遍历Cursor对象，取出数据
                    info.add(new info(cursor.getString(cursor.getColumnIndex("name")),
                            cursor.getString(cursor.getColumnIndex("content")),
                                    cursor.getInt(cursor.getColumnIndex("_id"))));
                } while (cursor.moveToNext());
            }
    
            db.close();
            updateAdapter();
    
    
        }
    
        public void updateAdapter() {
            /*View vi=View.inflate(MainActivity.this,R.layout.for_list,null);
            look_button=(Button)vi.findViewById(R.id.look_Button);
            look_button.setOnClickListener(new View.OnClickListener(){
                @Override
                public void onClick(View v) {
                    Intent intent = new Intent(MainActivity.this, Show_diary.class);
                    db = new MyHelper(MainActivity.this).getWritableDatabase();
                    startActivity(intent);
                }
            });*/
            MyAdapter myAdapter = new MyAdapter();
            mlistview.setAdapter(myAdapter);
            mlistview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
    
                @Override
                public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
                    Intent intent = new Intent(MainActivity.this, Show_diary.class);
                    intent.putExtra("id", i);
                    db = new MyHelper(MainActivity.this).getWritableDatabase();
                    startActivity(intent);
    
                }
            });
        }
    
    
        @Override
        public void onClick(View view) {
            switch (view.getId()) {
                case R.id.imageView:
                    Intent intent = new Intent(this, Add_diary.class);
                    intent.putExtra("id", info.size());
                    startActivity(intent);
                    a=1;
                case R.id.btn_search:
                    if(a==0) {
                        btn_search.setText("取消");
                        look_button.setVisibility(View.VISIBLE);
                        a=1;
                    }
                    else {
                        btn_search.setText("编辑");
                        look_button.setVisibility(View.INVISIBLE);
                        a=0;
                    }
                    /*Intent intent2 = new Intent(this, Delete_diary.class);
                    intent2.putExtra("id", info.size());
                    startActivity(intent2);*/
                    /*info = new ArrayList<>();
    
                    buttonHide.setVisibility(View.VISIBLE);
                    db = new MyHelper(this).getWritableDatabase();
                    Cursor cursor = db.query("diary", new String[]{"_id,name,content"},
                            "name like ?", new String[]{"%"+editText.getText().toString()+"%"}, null, null,
                            null, null);
                    if (cursor.moveToFirst()) {
                        do {
    // 遍历Cursor对象，取出数据
                            info.add(new info(cursor.getString(cursor.getColumnIndex("name")),
                                    cursor.getString(cursor.getColumnIndex("content")),
                                    cursor.getInt(cursor.getColumnIndex("_id"))));
                        } while (cursor.moveToNext());
                    }
    
                    db.close();
                    updateAdapter();*/
                    break;
            }
        }
    
        class MyAdapter extends BaseAdapter {
    
            public MyAdapter() {
                super();
            }
    
            public int getCount() {
                return info.size();
            }
    
            @Override
            public Object getItem(int i) {
                return info.get(i).name;
            }
    
            @Override
            public long getItemId(int i) {
                return i;
            }
    
            @SuppressLint("WrongConstant")
            @Override
            public View getView(int i, View view, ViewGroup viewGroup) {
                ViewHolder viewholder;
                if (view == null) {
                    view = LayoutInflater.from(getApplicationContext()).inflate(R.layout.for_list, viewGroup, false);
                    viewholder = new ViewHolder();
                    viewholder.tv = (TextView) view.findViewById(R.id.name);
                } else {
                    viewholder = (ViewHolder) view.getTag();
                }
    
                //View vi=View.inflate(MainActivity.this, R.layout.for_list,null);
                look_button=(Button)view.findViewById(R.id.button3);
                //删除按钮不可见
                look_button.setVisibility(View.INVISIBLE);
                look_button.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        /*int id;
                        Intent intent = getIntent();
                        id = intent.getIntExtra("id", -1);
                        MainActivity.db.delete("diary", "_id=?", new String[]{String.valueOf(MainActivity.info.get(id).id)});
                        MainActivity.db.close();*/
                        /*SQLiteDatabase db = dbHelper.getWritableDatabase();
                        String selection = SQLiteContract.DiaryEntry._ID + " = ?";
                        String[] selectionArgs = { id };
                        db.delete(SQLiteContract.DiaryEntry.TABLE_NAME, selection, selectionArgs);
                        db.close();*/
    
                    }
                });
    
                viewholder.tv.setText(String.valueOf(i + 1) + ": " + info.get(i).name);
                viewholder.tv.getPaint().setFlags(Paint.UNDERLINE_TEXT_FLAG);
                return view;
            }
    
            class ViewHolder {
                TextView tv;
            }
    
    
        }
    
        class info {
            String name;
            String content;
            int id;
    
            public info(String name, String content, int id) {
                this.name = name;
                this.content = content;
                this.id = id;
            }
        }
    
    }

//Add_diary.java
    package com.example.mgh.diary;
    
    import android.app.Activity;
    import android.content.ContentValues;
    import android.content.Intent;
    import android.os.Bundle;
    import android.view.View;
    import android.widget.Button;
    import android.widget.EditText;
    import android.widget.Toast;
    
    import org.jetbrains.annotations.Nullable;
    
    public class Add_diary extends Activity {
        public int id;
        private EditText name;
        private EditText diary;
        private Button btn;
    
        @Override
        protected void onCreate(@Nullable Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.add_diary);
            name = (EditText) findViewById(R.id.diary_name);
            diary = (EditText) findViewById(R.id.diary);
            btn = (Button) findViewById(R.id.submit);
    
            Intent intent = getIntent();
            id = intent.getIntExtra("id", -1);
    
        }
    
        public void sub(View v) {
            ContentValues values = new ContentValues();
            values.put("name", name.getText().toString());
            values.put("content", diary.getText().toString());
            MainActivity.db = new MyHelper(this).getWritableDatabase();
    
            MainActivity.db.insert("diary", null, values);
            MainActivity.db.close();
    
            Toast.makeText(this, "日志保存成功", Toast.LENGTH_SHORT).show();
            Intent intent = new Intent(this, MainActivity.class);
            startActivity(intent);
        }
    
    
    }

//MyHelper.java
    package com.example.mgh.diary;
    
    import android.content.ContentValues;
    import android.content.Context;
    import android.database.sqlite.SQLiteDatabase;
    import android.database.sqlite.SQLiteOpenHelper;
    
    public class MyHelper extends SQLiteOpenHelper{
    
        public MyHelper(Context context){
            super(context,"dia.db",null,5);
        }
    
        @Override
        public void onCreate(SQLiteDatabase sqLiteDatabase) {
            sqLiteDatabase.execSQL("create table diary(_id integer primary key autoincrement," +
                    "name varchar(11),content varchar(1000))");
        }
    
        @Override
        public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
    
        }
    }

//Show_diary.java
    package com.example.mgh.diary;
    
    import android.app.Activity;
    import android.content.ContentValues;
    import android.content.Intent;
    import android.os.Bundle;
    import android.view.View;
    import android.widget.EditText;
    
    import org.jetbrains.annotations.Nullable;
    
    //import android.support.annotation.Nullable;
    
    public class Show_diary extends Activity {
        private EditText name;
        private EditText ed;
        int id;
    
        @Override
        protected void onCreate(@Nullable Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.show_diary);
    
            name = (EditText) findViewById(R.id.name);
            ed = (EditText) findViewById(R.id.content);
            Intent intent = getIntent();
            id = intent.getIntExtra("id", -1);
    
            name.setText(MainActivity.info.get(id).name);
            ed.setText(MainActivity.info.get(id).content);
        }
    
        public void backandchange(View v) {
    
            ContentValues values=new ContentValues();
            values.put("name",name.getText().toString());
            values.put("content",ed.getText().toString());
    
            MainActivity.db.update("diary", values,"_id=?", new String[]{String.valueOf(MainActivity.info.get(id).id)});
            MainActivity.db.close();
    
    
            Intent intent = new Intent(this, MainActivity.class);
            startActivity(intent);
    
        }
    
        public void del(View v) {
            MainActivity.db.delete("diary", "_id=?", new String[]{String.valueOf(MainActivity.info.get(id).id)});
            MainActivity.db.close();
    
            Intent intent = new Intent(this, MainActivity.class);
            startActivity(intent);
        }
    }

#### **实验结果截图：** ####

![5f1d9ea352bf4cc9ba16d329a9a62f7f.png][] ![034545ed6bc64945b6cb133f1f96afbf.png][]![411e837fa8974ddcae9b8679bfe7c5df.png][]

![689ffd3fc357403a82625f48bf9ed1a2.png][] ![347f7fc1385f4a948b9ce33b30126f42.png][]

#### **心得与体会：** ####

本次实验功能基本完成，学习到数据库的使用，通过查找资料以及学习，完成最后日记本的制作。通过本次实验，收获颇多，不仅复习了以前的知识，同时也学习到了新的知识，对今后的学习有了较大的帮助。

**注：本次实验结果与原实验要求有部分不相似，若要一样的实验结果请到如下链接博客中的代码进行修改！（该实验部分代码为网上资源修改）**

[https://blog.csdn.net/weixin\_48388330/article/details/122546221][https_blog.csdn.net_weixin_48388330_article_details_122546221]

**下载资源包链接：**

[https://download.csdn.net/download/weixin\_48388330/76307026][https_download.csdn.net_download_weixin_48388330_76307026]

**资源中的图片以及内容只适用与学习**

[0adcbd21d8064267b4ecde320e160199.png]: https://img-blog.csdnimg.cn/0adcbd21d8064267b4ecde320e160199.png
[30f45faf053049bfa727b3b4664d0d0e.png]: https://img-blog.csdnimg.cn/30f45faf053049bfa727b3b4664d0d0e.png
[c2e1357234a04d61922d92d5c33540ec.png]: https://img-blog.csdnimg.cn/c2e1357234a04d61922d92d5c33540ec.png
[a163ce8f196d49599baf4224e372bb64.png]: https://img-blog.csdnimg.cn/a163ce8f196d49599baf4224e372bb64.png
[cf22c57525d3491aa9717cdd8a224407.png]: https://img-blog.csdnimg.cn/cf22c57525d3491aa9717cdd8a224407.png
[03e0c34d58bd44fca480c2dd77399d0d.png]: https://img-blog.csdnimg.cn/03e0c34d58bd44fca480c2dd77399d0d.png
[a309e5fbe0954dcb9ffb1dabf6728fce.png]: https://img-blog.csdnimg.cn/a309e5fbe0954dcb9ffb1dabf6728fce.png
[986faf01a8fa43f2bbaf7b427da26151.png]: https://img-blog.csdnimg.cn/986faf01a8fa43f2bbaf7b427da26151.png
[d4139525b95d4d2288b9644770b41b06.png]: https://img-blog.csdnimg.cn/d4139525b95d4d2288b9644770b41b06.png
[69f42e88dff14a5595c4e93ca5ea65a1.png]: https://img-blog.csdnimg.cn/69f42e88dff14a5595c4e93ca5ea65a1.png
[5f1d9ea352bf4cc9ba16d329a9a62f7f.png]: https://img-blog.csdnimg.cn/5f1d9ea352bf4cc9ba16d329a9a62f7f.png
[034545ed6bc64945b6cb133f1f96afbf.png]: https://img-blog.csdnimg.cn/034545ed6bc64945b6cb133f1f96afbf.png
[411e837fa8974ddcae9b8679bfe7c5df.png]: https://img-blog.csdnimg.cn/411e837fa8974ddcae9b8679bfe7c5df.png
[689ffd3fc357403a82625f48bf9ed1a2.png]: https://img-blog.csdnimg.cn/689ffd3fc357403a82625f48bf9ed1a2.png
[347f7fc1385f4a948b9ce33b30126f42.png]: https://img-blog.csdnimg.cn/347f7fc1385f4a948b9ce33b30126f42.png
[https_blog.csdn.net_weixin_48388330_article_details_122546221]: https://blog.csdn.net/weixin_48388330/article/details/122546221
[https_download.csdn.net_download_weixin_48388330_76307026]: https://download.csdn.net/download/weixin_48388330/76307026