android – SQLite数据库“上下文”传递给适配器

25-03-09 11

如果您想了解android–SQLite数据库“上下文”传递给适配器的相关知识，那么本文是一篇不可错过的文章，我们将为您提供关于AndroidSQLite数据库中的表详解、androidSQLite数

如果您想了解android – SQLite数据库“上下文”传递给适配器的相关知识，那么本文是一篇不可错过的文章，我们将为您提供关于Android SQLite数据库中的表详解、android SQLite数据库使用实例、Android SQLite数据库升级方案、Android SQLite数据库已损坏的有价值的信息。

本文目录一览：

android – SQLite数据库“上下文”传递给适配器
Android SQLite数据库中的表详解
android SQLite数据库使用实例
Android SQLite数据库升级方案
Android SQLite数据库已损坏

android – SQLite数据库“上下文”传递给适配器

我已经跟着 this tutorial在我的Android应用程序中使用sqlite数据库.
由于我是一个初学者,我在理解“context”参数时遇到了问题.

我想从不扩展活动的类中调用适配器并插入/更新/删除记录,在此示例中代表上下文.

现在我不知道在适配器中作为上下文传递什么,因为我没有从活动调用适配器.

有人可以解释一下吗

解决方法

将ActivityName.this作为参数的类上下文传递给适配器类的构造函数 ActivityName是您在其中调用适配器的Activityclass的名称

Android SQLite数据库中的表详解

Android sqlite数据库

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";

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    ((Button)findViewById(R.id.btnQue)).setonClickListener(new OnClickListener() {

      @Override
      public 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_master
        String 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;

}

感谢阅读，希望能帮助到大家，谢谢大家对本站的支持！

android SQLite数据库使用实例

创建数据库帮助类DbHelper.java:

package com.example.db;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;

public class DbHelper extends SQLiteOpenHelper {

	public DbHelper(Context context, String name, CursorFactory factory,
			int version) {
		super(context, name, factory, version);
		// TODO Auto-generated constructor stub
	}

	@Override
	public void onCreate(SQLiteDatabase db) {

		db.execSQL("create table if not exists tb_people"+
				"(_id integer primary key autoincrement,"+
				"name varchar(20),"+
				"phone varchar(12),"+
				"mobile varchar(12),"+
				"email varchar(30))");
	}

	@Override
	public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
		// TODO Auto-generated method stub

	}

}

主布局文件：

ch9_sqlmain.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    <TextView android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="所有联系人:"
        android:textSize="15px"/>
    <LinearLayout android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content">
        <TextView android:layout_width="40px"
            android:layout_height="wrap_content"
            android:text="编号"/>
        <TextView android:layout_width="50px"
            android:layout_height="wrap_content"
            android:text="姓名"/>
        <TextView android:layout_width="80px"
            android:layout_height="wrap_content"
            android:text="电话"/>
        <TextView android:layout_width="80px"
            android:layout_height="wrap_content"
            android:text="手机"/>
        <TextView android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="电子信箱"/>
    </LinearLayout>
    <ListView android:layout_width="wrap_content"
        android:layout_height="fill_parent"
        android:id="@+id/list_people"/>

</LinearLayout>

编写ListView的Item显示布局文件ch9_peoplelist.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal" >
    <TextView android:id="@+id/id"
        android:layout_width="40px"
        android:layout_height="wrap_content"/>
    <TextView android:id="@+id/name"
        android:layout_width="50px"
        android:layout_height="wrap_content"/>
    <TextView android:id="@+id/phone"
        android:layout_width="80px"
        android:layout_height="wrap_content"/>
    <TextView android:id="@+id/mobile"
        android:layout_width="80px"
        android:layout_height="wrap_content"/>
    <TextView android:id="@+id/email"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"/>
    

</LinearLayout>

主活动类SqlMainActivity.java：

package com.example.ch9;

import com.example.baseexample.R;
import com.example.db.DbHelper;

import android.app.Activity;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView.AdapterContextMenuInfo;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
import android.widget.TextView;

public class SqlMainActivity extends Activity {
	private ListView list_people;
	private DbHelper dbhelper;
	private SQLiteDatabase db;
	
	public void onCreate(Bundle savedInstanceState){
		super.onCreate(savedInstanceState);
		setContentView(R.layout.ch9_sqlmain);
		
		list_people = (ListView)findViewById(R.id.list_people);
		
		dbhelper = new DbHelper(this, "Db_People", null, 1);
		
		db = dbhelper.getReadableDatabase();
		Cursor c = db.query("tb_people", new String[]{"_id","name","phone","mobile","email"}, null, null, null, null, null);
		SimpleCursorAdapter adapter = new SimpleCursorAdapter(this, R.layout.ch9_peoplelist, c, new String[]{"_id","name","phone","mobile","email"}, new int[]{R.id.id,R.id.name,R.id.phone,R.id.mobile,R.id.email});
		
		this.list_people.setAdapter(adapter);
		this.registerForContextMenu(list_people);
	}
	
	public boolean onCreateOptionsMenu(Menu menu){
		menu.add(Menu.NONE,Menu.FIRST+1,1,"添加").setIcon(android.R.drawable.ic_menu_add);
		menu.add(Menu.NONE,Menu.FIRST+1,2,"退出").setIcon(android.R.drawable.ic_menu_delete);
		return true;
	}
	
	public boolean onOptionsItemSelected(MenuItem item){
		switch(item.getItemId()){
		case Menu.FIRST+1:
			Intent intent = new Intent();
			intent.setClass(SqlMainActivity.this, AddPeopleActivity.class);
			startActivity(intent);
			break;
		case Menu.FIRST+2:finish();
			break;
		}
		return super.onOptionsItemSelected(item);
	}
	
	public void onCreateContextMenu(ContextMenu menu,View v,ContextMenuInfo menuInfo){
		menu.setHeaderIcon(R.drawable.ic_launcher);
		menu.add(0,3,0,"修改");
		menu.add(0, 4, 0, "删除");
	}
	
	public boolean onContextItemSelected(MenuItem item){
		AdapterContextMenuInfo menuInfo = (AdapterContextMenuInfo)item.getMenuInfo();
		switch(item.getItemId()){
		case 3:
			String name=((TextView)menuInfo.targetView.findViewById(R.id.name)).getText().toString();
			String phone=((TextView)menuInfo.targetView.findViewById(R.id.phone)).getText().toString();
			String mobile=((TextView)menuInfo.targetView.findViewById(R.id.mobile)).getText().toString();
			String email=((TextView)menuInfo.targetView.findViewById(R.id.email)).getText().toString();
			Intent intent = new Intent();
			intent.setClass(SqlMainActivity.this, AddPeopleActivity.class);
			Bundle bundle = new Bundle();
			bundle.putLong("id", menuInfo.id);
			bundle.putString("name", name);
			bundle.putString("phone", phone);
			bundle.putString("mobile", mobile);
			bundle.putString("email", email);
			intent.putExtras(bundle);
			startActivity(intent);
			break;
		case 4:
			dbhelper = new DbHelper(this,"Db_People",null,1);
			db = dbhelper.getWritableDatabase();
			db.delete("tb_people", "_id=?", new String[]{menuInfo.id+""});
			break;
		}
		
		return true;
	}
	
}

布局文件ch9_addpeople.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    <LinearLayout android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
        <TextView android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="用户名"
            android:layout_weight="2"/>
        <EditText android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:id="@+id/edt_name"
            android:layout_weight="1"/>
    </LinearLayout>
    <LinearLayout android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
        <TextView android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="联系电话"
            android:layout_weight="2"/>
        <EditText android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:id="@+id/edt_phone"
            android:layout_weight="1"/>
    </LinearLayout>
    <LinearLayout android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
        <TextView android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="手机"
            android:layout_weight="2"/>
        <EditText android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:id="@+id/edt_mobile"
            android:layout_weight="1"/>
    </LinearLayout>
    <LinearLayout android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
        <TextView android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="电子信箱"
            android:layout_weight="2"/>
        <EditText android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:id="@+id/edt_email"
            android:layout_weight="1"/>
    </LinearLayout>
    <LinearLayout android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
        <Button android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:id="@+id/bt_save"
            android:text="保存"
            android:layout_weight="1"/>
        <Button android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:id="@+id/bt_cancel"
            android:text="取消"
            android:layout_weight="1"/>
    </LinearLayout>

</LinearLayout>

创建活动AddPeopleActivity.java：

package com.example.ch9;

import com.example.baseexample.R;
import com.example.db.DbHelper;

import android.app.Activity;
import android.content.ContentValues;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class AddPeopleActivity extends Activity {
	private EditText edt_name;
	private EditText edt_phone;
	private EditText edt_mobile;
	private EditText edt_email;
	private Button bt_save;
	String name,phone,mobile,email;
	DbHelper dbhelper;
	SQLiteDatabase db;
	Bundle bundle;
	protected void onCreate(Bundle savedInstanceState){
		super.onCreate(savedInstanceState);
		setContentView(R.layout.ch9_addpeople);
		
		edt_name=(EditText)findViewById(R.id.edt_name);
		edt_phone=(EditText)findViewById(R.id.edt_phone);
		edt_mobile=(EditText)findViewById(R.id.edt_mobile);
		edt_email=(EditText)findViewById(R.id.edt_email);
		bt_save = (Button)findViewById(R.id.bt_save);
		
		bundle = this.getIntent().getExtras();
		if(bundle!=null){
			edt_name.setText(bundle.getString("name"));
			edt_phone.setText(bundle.getString("phone"));
			edt_mobile.setText(bundle.getString("mobile"));
			edt_email.setText(bundle.getString("email"));
		}
		
		bt_save.setOnClickListener(new Button.OnClickListener(){

			@Override
			public void onClick(View v) {
				name = edt_name.getText().toString();
				phone = edt_phone.getText().toString();
				mobile = edt_mobile.getText().toString();
				email = edt_email.getText().toString();
				
				ContentValues value = new ContentValues();
				value.put("name", name);
				value.put("phone", phone);
				value.put("mobile", mobile);
				value.put("email", email);
				
				DbHelper dbhelper = new DbHelper(AddPeopleActivity.this,"Db_People",null,1);
				SQLiteDatabase db = dbhelper.getWritableDatabase();
				long status;
				if(bundle!=null){
					status = db.update("tb_people", value, "_id=?", new String[]{bundle.getLong("id")+""});
				}else{
					status = db.insert("tb_people", null, value);
				}
				if(status!=-1){
					Toast.makeText(AddPeopleActivity.this, "保存成功", Toast.LENGTH_LONG).show();
				}else{
					Toast.makeText(AddPeopleActivity.this, "保存失败", Toast.LENGTH_LONG).show();
				}
			}
			
		});
	}
}

Android SQLite数据库升级方案

例如一个数据库表

19版本是2个字段
20版本是3个字段
21版本是4个字段

package com.yzc.atclient.service.db;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;

import com.allcam.atclient.app.ClientApplication;

public class DatabaseHelper extends SQLiteOpenHelper
{
private static final String DB_NAME = "allcam_db";

private static final int VERSION = 1;

private static volatile DatabaseHelper instance;

public DatabaseHelper(Context context)
{
this(context, DB_NAME, null, VERSION);
}

public DatabaseHelper(Context context, String name, CursorFactory factory, int version)
{
super(context, name, factory, version);
}

public static DatabaseHelper getInstance()
{
if (null == instance)
{
synchronized (DatabaseHelper.class)
{
if (null == instance)
{
instance = new DatabaseHelper(ClientApplication.getAppContext());
}
}
}
return instance;
}

@Override
public void onCreate(SQLiteDatabase db)
{
CardUserTable.createTable(db);
TaskStatusTable.createTable(db);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
//在这里组合case 判断升级
}
}

例如：


for (int j = oldVersion; j <= newVersion; j++) {

            switch (j) {

            case 2:

　　　　　　　　　　//创建临时表

                db.execSQL(TEMP_SQL_CREATE_TABLE_SUBSCRIBE);

　　　　　　　　　　//执行OnCreate方法，这个方法中放的是表的初始化操作工作，比如创建新表之类的

                onCreate(db);

　　　　　　　　　　//删除之前的表里面的那4条默认的数据

                for (int i = 0; i < arrWhereAct.length; i++) {

                    db.execSQL(DELETE_TEMP_SUBSCRIBE + arrWhereAct[i]);

                }

               //将临时表中的数据放入表A 

　　　　　　　　　Cursor cursor = db.rawQuery(INSERT_SUBSCRIBE, null);

                if (cursor.moveToFirst()) {

                    do {

                        db.execSQL(cursor.getString(cursor

                                .getColumnIndex("insertSQL")));

                    } while (cursor.moveToNext());

                }

                cursor.close();

　　　　　　　　　　//将临时表删除掉

                db.execSQL(DROP_TEMP_SUBSCRIBE);



                break;



            default:

                break;

            }

        }

Android SQLite数据库已损坏

此链接完全描述了我的问题： http://old.nabble.com/Android-database-corruption-td28044218.html#a28044218

现在大约有300人使用我的Android应用程序,每次使用此堆栈跟踪向服务器发送崩溃报告时：

android.database.sqlite.sqliteDatabaseCorruptException: database disk image is malformed
    at android.app.ActivityThread.performlaunchActivity(ActivityThread.java:2596)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2621)
    at android.app.ActivityThread.access$2200(ActivityThread.java:126)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1932)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:123)
    at android.app.ActivityThread.main(ActivityThread.java:4595)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:521)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
    at dalvik.system.NativeStart.main(Native Method) Caused by: android.database.sqlite.sqliteDatabaseCorruptException: database disk image is malformed
    at android.database.sqlite.sqliteQuery.native_fill_window(Native Method)
    at android.database.sqlite.sqliteQuery.fillWindow(sqliteQuery.java:75)
    at android.database.sqlite.sqliteCursor.fillWindow(sqliteCursor.java:295)
    at android.database.sqlite.sqliteCursor.getCount(sqliteCursor.java:276)
    at android.database.AbstractCursor.movetoPosition(AbstractCursor.java:171)
    at android.database.AbstractCursor.movetoFirst(AbstractCursor.java:248)

结果是应用程序崩溃并且数据库中的所有数据都丢失了.

需要注意的一点是,每次我读取或写入数据库时,我都会得到一个新的sqliteDatabase,并在完成后立即将其关闭.我这样做是为了防止这种腐败错误.

我还尝试使用单个静态对象同步所有数据库读取和写入,这似乎没有帮助.

这可能只是一个sqlite错误吗？

我在这里找到了与内置电子邮件应用程序类似的错误：http://code.google.com/p/android/issues/detail?id=5610.

这是我的代码：

public class keyvalueTableAdapter extends BaseTableAdapter {

    private String tableName;
    private String keyColumnName;
    private String valueColumnName;

    public keyvalueTableAdapter(Context context,String tableName,String keyColumnName,String valueColumnName) {
        super(context);
        this.tableName = tableName;
        this.keyColumnName = keyColumnName;
        this.valueColumnName = valueColumnName;
    }

    protected String getStringValue(int key) {
        Cursor cursor = null;
        sqliteDatabase db = null;
        String value;

        try {
            db = dbOpenHelper.getReadableDatabase();
            cursor = db.query(true,tableName,new String[] { valueColumnName },keyColumnName + "=" + key,null,null);

            if ((cursor.getCount() == 0) || !cursor.movetoFirst()) {
                value = null;
            } else {
                value = cursor.getString(0);
            }
        } finally {
            if (cursor != null) cursor.close();
            if (db != null) db.close();
            dbOpenHelper.close();
        }

        return value;
    }
}


public abstract class BaseTableAdapter {

    protected DbOpenHelper dbOpenHelper;

    public BaseTableAdapter(Context context) {
        this.dbOpenHelper = new DbOpenHelper(context,DatabaseSettings.DATABASE_NAME,DatabaseSettings.DATABASE_VERSION);
    }

}

解决方法

“the DB holds session information so
it’s not very feasible to do a backup.
The data changes by the minute”

您应该尝试使用SharedPreferences：它存储键值对(在后台,它使用文件).
存储值：

SharedPreferences sp=MyActivity.getSharedPreferences("Name",Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sp.edit();
editor.putString("key",value);
editor.putBoolean("another",true);
editor.commit();

检索数据：

sp.getString("key","Not found"); 
// "Not found" is the default value
// if sp does not contain the specified key
sp.getBoolean("another",false); 
// false is the default value
// if sp does not contain the specified key

有关更详细的说明,请参见getSharedPreferences和SharedPreferences.

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