android-实例1-数据库sqlite（依赖sqlite）
1.将事先准备好的数据库模板放在model的资源文件夹中
2 权限
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
3.依赖
4.先键一个类MySQLiteHelper.java
功能：
识别系统路径下是否存在SQLite数据库 （/data/user/0/com.example.testa/databases/data.db）
如果没有，将工程下 文件夹res-raw-data.db复制到系统该路径。
import android.content.Context; import android.database.sqlite.SQLiteDatabase; import android.util.Log; import com.rx.mytest1.R; import java.io.File; import java.io.FileOutputStream; import java.io.InputStream; public class MySQLiteHelper { static String TAG = "MySQLiteHelper"; private Context context; static String fileName = "data.db"; //=========================================== public static SQLiteDatabase getDatabase(Context context){ String TAG = context.getClass().getName(); try{ //String path0 = context.getApplicationContext().getFilesDir().getAbsolutePath(); File filePath = context.getDatabasePath(fileName); //data/user/0/com.example.testa/databases/data.db if(!filePath.exists()){ Log.e(TAG, "getDatabase: 从raw中复制文件到 " + filePath.toString()); try{ InputStream is = context.getResources().openRawResource(R.raw.data); FileOutputStream fos = new FileOutputStream(filePath); byte[] buffer = new byte[8192]; int count = 0; while ((count= is.read(buffer)) > 0){ fos.write(buffer, 0,count); } fos.close(); is.close(); }catch (Exception e){ Log.e(TAG, "getDatabase错误1: "+ e) ; } } else{ Log.e(TAG, "getDatabase: 数据库已存在"); } SQLiteDatabase mysql = SQLiteDatabase.openOrCreateDatabase(filePath,null); return mysql; }catch (Exception e){ Log.e(TAG, "getDatabase错误1: "+ e) ; e.printStackTrace(); } return null; } }5. 新建工具类 SQliteManager_Curve.java
public class SQliteManager_Curve { protected String tabel_name = "YZK_2603_curve_list"; String TAG = getClass().getName(); Context context; 方法1 方法1 。。。。。略 }5.1 插入数据 （SQliteManager_Curve.java类中的方法）
insertData();
public void insertData(BeanYZKCurve bean) { SQLiteDatabase db = MySQLiteHelper.getDatabase(context); ContentValues values = contentValuesLoadData(bean); db.insert(tabel_name, null, values);//执行插入操作 } private ContentValues contentValuesLoadData(BeanYZKCurve bean){ ContentValues values = new ContentValues(); values.put("curveId", bean.getCurveId()); values.put("productId", bean.getProductId()); values.put("productName", bean.getProductName()); values.put("agrochemicaleId", bean.getAgrochemicaleId()); values.put("agrochemicaleName",bean.getAgrochemicaleName()); values.put("agrochemicaleNo", bean.getAgrochemicaleNo()); values.put("matrix", bean.getMatrix()); values.put("diluent", bean.getDiluent()); values.put("cardType", bean.getCardType()); values.put("algorithm", bean.getAlgorithm()); //节省空间 略 return values; }5.2 读数据 （SQliteManager_Curve.java类中的方法）
read()；
public ArrayList<BeanYZKCurve> read(String str){ //单条件模糊查询（多列查询）（如 str=”H” “name”列 或 “type”列 或 “fristPY”列 // 中有 “h”相关字的都将查询出来，（如h hh h1）） Cursor cursor; ArrayList<BeanYZKCurve> listBeans = new ArrayList<>(); SQLiteDatabase db = MySQLiteHelper.getDatabase(context); //--------------------------------------- String[] columns = null; //String selection ="company_name like '%"+ str+"%'"+ " or first_letter like '%"+ str+"%'"; String selection = null; String[] selectionArgs = null; cursor=db.query(tabel_name, columns, selection, selectionArgs, null, null, null); //--------------------------------------- while (cursor.moveToNext()){ listBeans.add(BeanSetData(cursor)); } if(cursor!=null)cursor.close(); //--------------------------------------- return listBeans; } private BeanYZKCurve BeanSetData(Cursor c){ BeanYZKCurve bean = new BeanYZKCurve(); //int id = c.getInt(c.getColumnIndex("id")); //bean.set_id(String.valueOf(id)); bean.setCurveId(c.getInt(c.getColumnIndex("curveId"))); bean.setProductId(c.getInt(c.getColumnIndex("productId"))); bean.setProductName(c.getString(c.getColumnIndex("productName"))); bean.setAgrochemicaleId(c.getInt(c.getColumnIndex("agrochemicaleId"))); bean.setAgrochemicaleName(c.getString(c.getColumnIndex("agrochemicaleName"))); bean.setAgrochemicaleNo(c.getInt(c.getColumnIndex("agrochemicaleNo"))); bean.setMatrix(c.getInt(c.getColumnIndex("matrix"))); bean.setDiluent(c.getInt(c.getColumnIndex("diluent"))); bean.setCardType(c.getInt(c.getColumnIndex("cardType"))); bean.setAlgorithm(c.getInt(c.getColumnIndex("algorithm"))); //略 return bean; }5.3 删除表单，而不是清除表单内容 （SQliteManager_Curve.java类中的方法）
public void delectSheet(){ try{ SQLiteDatabase db = MySQLiteHelper.getDatabase(context); db.execSQL("DELETE FROM " + tabel_name); Log.e(TAG, "delectSheet: 删除表单ok" ); }catch (Exception e){ Log.e(TAG, "delectSheet: 删除表单错误" ); } }5.4 清空表单内容，而不是删除表单 （SQliteManager_Curve.java类中的方法）
public void clearSheet(){ try{ SQLiteDatabase db = MySQLiteHelper.getDatabase(context); db.execSQL("DELETE FROM " + tabel_name); db.beginTransaction(); try { db.delete(tabel_name, null, null); db.setTransactionSuccessful(); } finally { db.endTransaction(); } db.execSQL("VACUUM"); }catch (Exception e){ Log.e(TAG, "清空-错误" ); } }5.5 获取表单-总数量（SQliteManager_Curve.java类中的方法）
public int getCount(){ try{ SQLiteDatabase db = MySQLiteHelper.getDatabase(context); // 查询所有数据 Cursor cursor = db.rawQuery("SELECT * FROM " + tabel_name, null); int count = cursor.getCount(); // 直接获取Cursor中的记录数 cursor.close(); db.close(); Log.e("TAG","getCount()数量: "+ count); return count; }catch (Exception e){ Log.e("TAG","getCount()错误:"); return -1; }