public class MainActivity extends AppCompatActivity {
EditText name,tel,address,et,updatename;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
name=(EditText)findViewById(R.id.name);
tel=(EditText)findViewById(R.id.tel);
address=(EditText)findViewById(R.id.address);
et=(EditText)findViewById(R.id.et);
updatename=(EditText)findViewById(R.id.updateName);
}
//copy sqllite檔案到手機方法一
//將database檔案放在raw下
public void copy(View view) {
//要取得專案中的resources，就要用getResources()，回傳Resources物件
//要抓raw中的資料，要用openRawResource，回傳InputStream物件，再用一個InputStream變數接住
InputStream is=getResources().openRawResource(R.raw.student);
try {
//new一個FileOutputStream物件(FileOutputStream是OutputStream的子類別)
//輸出串流有很多種，網路資料串流，文字資料串流...
OutputStream os=new FileOutputStream(getFilesDir()+ File.separator+"student.sqlite");
//從inputStream讀，從OutputStream寫出去
int i=0;
//每讀一個byte進來就寫一個byte，當i=-1時讀不到就結束
while(i!=-1){
i=is.read();
os.write(i);
}
is.close();
os.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
//copy sqlite檔案到手機方法二
//用java nio2的path(java7以後才有)，用path或Files的method來做
public void copy2(View view) {
//因為path和Files要用api26以上測試，所以不能用android device monitor看檔案是否建立
//要用File+log來看
File f = new File(getFilesDir() + File.separator + "student2.sqlite");
//boolean exists ()
//Tests whether the file or directory denoted by this abstract pathname exists.
// return:true if and only if the file or directory denoted by this abstract pathname exists; false otherwise
//先偵測檔案是否存在，不存在才覆蓋檔案過去
if(!f.exists()){
InputStream is = getResources().openRawResource(R.raw.student);
//uri抓file的格式是file:///tmp/android.txt，而getFilesDir().getAbsolutePath()取出來前面會有一個斜線，所以file:後面只要兩條斜線
//create():URI create (String str)
//Creates a URI by parsing the given string.
URI uri = URI.create("file://" + getFilesDir().getAbsolutePath() + File.separator + "student2.sqlite");
//Path get (URI uri)
//Converts the given URI to a Path object.
Path p = Paths.get(uri);
try {
//long copy (InputStream in, Path target,CopyOption... options)
//Copies all bytes from an input stream to a file.
//CopyOption: options specifying how the copy should be done
//三個參數是inputStream,paht,常數
//StandardCopyOption:Defines the standard copy options.
//REPLACE_EXISTING:Replace an existing file if it exists.
Files.copy(is, p, StandardCopyOption.REPLACE_EXISTING);
} catch (IOException e) {
e.printStackTrace();
}
}
Log.d("FILE", String.valueOf(f.exists()));
}
//讀取sqlLite檔
public void clickRead(View view) {
String path = getFilesDir().getAbsolutePath() + File.separator + "student2.sqlite"; //這邊是讀取student2.sqlite
//宣告db是在抓資料庫student2的資料
SQLiteDatabase db = SQLiteDatabase.openDatabase(path, null, 0);
//Cusor:This interface provides random read-write access to the result set returned by a database query.
//執行sql時，可以直接用execSQL，下SQL指令，或是用query，sqlLite內建的方法
//Query the given URL, returning a Cursor over the result set.有七個參數，後面五個可以用null，前兩個分別為table name，用字串陣列存的欄位名稱
//注意欄位名稱不可以和sql指令重複ex:add不可用
//宣告c是在抓資料庫裡一筆一筆的資料，cursor是代表指向第幾筆資料
Cursor c = db.query("phone", new String[] {"id", "name", "tel", "addr"}, null, null, null, null, null);
//因為cursor沒有設定的話會指向第一筆資料的上面空白出，所以設定移動到第一筆資料
c.moveToFirst();
//Log.d("COUNT", "NUMBER"+c.getCount());
StringBuilder sb=new StringBuilder();
do{
sb.append(String.valueOf(c.getInt(0)));
sb.append(":");
//Log.d("DB", String.valueOf(c.getInt(0)));//用log print id
for(int i=1;i<4;i++){
sb.append(c.getString(i)+",");
//Log.d("DB", c.getString(i)); //getString(i)取得第i筆的欄位資料
}
sb.append("\n");
et.setText(sb.toString());
//Log.d("DB", c.getString(1));
//moveToNext():Move the cursor to the next row.
}while (c.moveToNext());
}
//新增SQL lite資料
public void clicknew(View view) {
String path = getFilesDir().getAbsolutePath() + File.separator + "student2.sqlite";
SQLiteDatabase db = SQLiteDatabase.openDatabase(path, null, 0);
//ContentValues:This class is used to store a set of values that the ContentResolver can process.
//ContentValues也是map的概念，put()兩個參數，key和value，key就是欄位名稱
ContentValues cv = new ContentValues();
cv.put("name",name.getText().toString());
cv.put("tel",tel.getText().toString());
cv.put("addr",address.getText().toString());
//long insert (String table, String nullColumnHack, ContentValues values)=>因為插入的內容必須是一個ContentValues，所以前面要先把ContentValues建好
//Convenience method for inserting a row into the database.
db.insert("phone", null, cv);
db.close();
}
//刪除table欄位資料
public void delete(View view) {
String path = getFilesDir().getAbsolutePath() + File.separator + "student2.sqlite";
SQLiteDatabase db = SQLiteDatabase.openDatabase(path, null, SQLiteDatabase.OPEN_READWRITE);
/*delete
int delete (String table,String whereClause, String[] whereArgs)
Convenience method for deleting rows in the database.
參數說明：
1.table name
2.要如何篩選資料,寫法:id=? 代表要把id都是?的資料都找出來，同時對應到下個參數為指定數值的資料
=>如果有兩個不同欄位寫法為id=? and tel=? ，同時陣列的參數就要變成new String[] {"2","2"}，指定不同欄位的第幾筆資料
=>如果同一個欄位要刪除多筆資料寫法範例：id IN (?,?,?)
3.這個參數是陣列型態*/
//注意三四個參數絕對不能NULL，否則會把所有的資料全部刪除
db.delete("phone", "id IN (?,?)", new String[] {"2","5"}); //這邊刪除第二和第五筆資料
db.close();
}
//更新table欄位資料
public void update(View view) {
String path = getFilesDir().getAbsolutePath() + File.separator + "student2.sqlite";
SQLiteDatabase db = SQLiteDatabase.openDatabase(path, null, SQLiteDatabase.OPEN_READWRITE);
ContentValues cv = new ContentValues();
cv.put("name", updatename.getText().toString());
//int update (String table, ContentValues values, String whereClause, String[] whereArgs)
//Convenience method for updating rows in the database.
//參數說明：1.資料表名稱 2.要更新的資料
//注意三四個參數絕對不能NULL，否則會把所有的資料全部更新
db.update("phone", cv, "id=?", new String[] {"1"}); //這邊更新第一筆資料的name欄位
db.close();
}
}
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