SQLite数据库存储
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一、运行效果图
二、核心代码
MainActivity.java
package com.example.databasetest;import android.app.Activity;import android.content.ContentValues;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.os.Bundle;import android.util.Log;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;public class MainActivity extends Activity {private MyDatabaseHelper dbHelper;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);dbHelper = new MyDatabaseHelper(this, "BookStore.db", null, 2);Button createDatabase = (Button) findViewById(R.id.create_database);createDatabase.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {dbHelper.getWritableDatabase();}});Button addData = (Button) findViewById(R.id.add_data);addData.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {SQLiteDatabase db = dbHelper.getWritableDatabase();ContentValues values = new ContentValues();// 开始组装第一条数据values.put("name", "The Da Vinci Code");values.put("author", "Dan Brown");values.put("pages", 454);values.put("price", 16.96);db.insert("Book", null, values); // 插入第一条数据values.clear();// 开始组装第二条数据values.put("name", "The Lost Symbol");values.put("author", "Dan Brown");values.put("pages", 510);values.put("price", 19.95);db.insert("Book", null, values); // 插入第二条数据}});Button updateData = (Button) findViewById(R.id.update_data);updateData.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {SQLiteDatabase db = dbHelper.getWritableDatabase();ContentValues values = new ContentValues();values.put("price", 10.99);db.update("Book", values, "name = ?", new String[] { "The Da Vinci Code" });}});Button deleteButton = (Button) findViewById(R.id.delete_data);deleteButton.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {SQLiteDatabase db = dbHelper.getWritableDatabase();db.delete("Book", "pages > ?", new String[] { "500" });}});Button queryButton = (Button) findViewById(R.id.query_data);queryButton.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {SQLiteDatabase db = dbHelper.getWritableDatabase();// 查询Book表中所有的数据Cursor cursor = db.query("Book", null, null, null, null, null, null);if (cursor.moveToFirst()) {do {// 遍历Cursor对象,取出数据并打印String name = cursor.getString(cursor. getColumnIndex("name"));String author = cursor.getString(cursor. getColumnIndex("author"));int pages = cursor.getInt(cursor.getColumnIndex ("pages"));double price = cursor.getDouble(cursor. getColumnIndex("price"));Log.d("MainActivity", "book name is " + name);Log.d("MainActivity", "book author is " + author);Log.d("MainActivity", "book pages is " + pages);Log.d("MainActivity", "book price is " + price);} while (cursor.moveToNext());}cursor.close();}});} @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.main, menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { // Handle action bar item clicks here. The action bar will // automatically handle clicks on the Home/Up button, so long // as you specify a parent activity in AndroidManifest.xml. int id = item.getItemId(); if (id == R.id.action_settings) { return true; } return super.onOptionsItemSelected(item); }}
MyDatabaseHelper.java
package com.example.databasetest;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteDatabase.CursorFactory;import android.database.sqlite.SQLiteOpenHelper;import android.widget.Toast;public class MyDatabaseHelper extends SQLiteOpenHelper {public static final String CREATE_BOOK = "create table book ("+ "id integer primary key autoincrement, " + "author text, "+ "price real, " + "pages integer, " + "name text)";public static final String CREATE_CATEGORY = "create table Category ("+ "id integer primary key autoincrement, "+ "category_name text, "+ "category_code integer)";private Context mContext;public MyDatabaseHelper(Context context, String name, CursorFactory factory, int version) {super(context, name, factory, version);mContext = context;}@Overridepublic void onCreate(SQLiteDatabase db) {db.execSQL(CREATE_BOOK);Toast.makeText(mContext, "Create succeeded", Toast.LENGTH_SHORT).show();}@Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {db.execSQL("drop table if exists Book");db.execSQL("drop table if exists Category");onCreate(db);}}
activity_main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" > <Button android:id="@+id/create_database" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="Create database" /> <Button android:id="@+id/add_data" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="Add data" /> <Button android:id="@+id/update_data" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="Update data" /> <Button android:id="@+id/delete_data" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="Delete data" /> <Button android:id="@+id/query_data" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="Query data" /></LinearLayout>
三、运行中遇到的问题
对方法的调用不熟悉,不知道该用什么方法,不知道传递什么参数,编写中出现很多错误。
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