前言
以前写PHP的时候,内置了print_r()
和var_dump()
两个函数用于打印输出任意类型的数据内部结构,现在做Android的开发,发现并没有这种类似的函数,对于数据库的查看很不方便,于是就写了一下查看数据库表的方法代码。
代码实现
import java.util.Arrays;
import android.app.Activity;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;public class SecondActivity extends Activity {public static final String TAG = "Debug Info";@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);((Button)findViewById(R.id.btnQue)).setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {MyDatabaseHelper dbhelper = new MyDatabaseHelper(SecondActivity.this, "BookStore.db", null, 1);SQLiteDatabase db = dbhelper.getWritableDatabase();//核心区//读取系统表 sqlite_masterString sql = "select * from sqlite_master";Cursor cursor = db.rawQuery(sql, null);//打印表的所有列名Log.i(TAG, Arrays.toString(cursor.getColumnNames()));//打印当前数据库中的所有表if (cursor.moveToFirst()) {do {String str = "";for (String item : cursor.getColumnNames()) {str += item + ": " + cursor.getString(cursor.getColumnIndex(item)) + "\n";}Log.i(TAG, str);} while (cursor.moveToNext());}}});}}
功能扩展
查看表是否存在
public Boolean tableIsExist(SQLiteDatabase db, String tableName){boolean result = false;Cursor cursor = null;if(tableName == null){return result;}String sql = "select count(*) from sqlite_master where type ='table' and name ='"+tableName.trim()+"'";cursor = db.rawQuery(sql, null);if(cursor.moveToNext()){if(cursor.getInt(0) > 0){result = true;}}return result;
}
查看数据库中有哪些表
public ArrayList<String> tablesInDB(SQLiteDatabase db){ArrayList<String> list = new ArrayList<String>();String sql = "select name from sqlite_master where type='table'";Cursor cursor = db.rawQuery(sql, null);if (cursor.moveToFirst()) {do {list.add(cursor.getString(0));} while (cursor.moveToNext());}return list;}
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