SQLiteDatebase--- android数据库操作出现错误了
06-08 21:39:20.053: E/PhonePolicy(4043): Could not preload class for phone policy: com.android.internal.policy.impl.PhoneWindow$ContextMenuCallback
06-08 21:39:32.253: W/dalvikvm(4043): threadid=1: thread exiting with uncaught exception (group=0x40a851f8)
06-08 21:39:32.263: E/AndroidRuntime(4043): FATAL EXCEPTION: main
06-08 21:39:32.263: E/AndroidRuntime(4043): android.database.sqlite.SQLiteException: Can't downgrade database from version 2 to 1
06-08 21:39:32.263: E/AndroidRuntime(4043): at android.database.sqlite.SQLiteOpenHelper.onDowngrade(SQLiteOpenHelper.java:307)
06-08 21:39:32.263: E/AndroidRuntime(4043): at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:168)
06-08 21:39:32.263: E/AndroidRuntime(4043): at com.example.android_sqliterdemo.MainActivity$UpdateListener.onClick(MainActivity.java:111)
06-08 21:39:32.263: E/AndroidRuntime(4043): at android.view.View.performClick(View.java:3511)
06-08 21:39:32.263: E/AndroidRuntime(4043): at android.view.View$PerformClick.run(View.java:14110)
06-08 21:39:32.263: E/AndroidRuntime(4043): at android.os.Handler.handleCallback(Handler.java:605)
06-08 21:39:32.263: E/AndroidRuntime(4043): at android.os.Handler.dispatchMessage(Handler.java:92)
06-08 21:39:32.263: E/AndroidRuntime(4043): at android.os.Looper.loop(Looper.java:137)
06-08 21:39:32.263: E/AndroidRuntime(4043): at android.app.ActivityThread.main(ActivityThread.java:4424)
06-08 21:39:32.263: E/AndroidRuntime(4043): at java.lang.reflect.Method.invokeNative(Native Method)
06-08 21:39:32.263: E/AndroidRuntime(4043): at java.lang.reflect.Method.invoke(Method.java:511)
06-08 21:39:32.263: E/AndroidRuntime(4043): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
06-08 21:39:32.263: E/AndroidRuntime(4043): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
06-08 21:39:32.263: E/AndroidRuntime(4043): at dalvik.system.NativeStart.main(Native Method)
06-08 21:40:58.283: E/PhonePolicy(4099): Could not preload class for phone policy: com.android.internal.policy.impl.PhoneWindow$ContextMenuCallback
06-08 21:40:59.603: E/SQLiteOpenHelper(4099): Couldn't open test_m_db1 for writing (will try read-only):
06-08 21:40:59.603: E/SQLiteOpenHelper(4099): android.database.sqlite.SQLiteException: Can't downgrade database from version 2 to 1
06-08 21:40:59.603: E/SQLiteOpenHelper(4099): at android.database.sqlite.SQLiteOpenHelper.onDowngrade(SQLiteOpenHelper.java:307)
06-08 21:40:59.603: E/SQLiteOpenHelper(4099): at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:168)
06-08 21:40:59.603: E/SQLiteOpenHelper(4099): at android.database.sqlite.SQLiteOpenHelper.getReadableDatabase(SQLiteOpenHelper.java:231)
06-08 21:40:59.603: E/SQLiteOpenHelper(4099): at com.example.android_sqliterdemo.MainActivity$QueryListener.onClick(MainActivity.java:133)
06-08 21:40:59.603: E/SQLiteOpenHelper(4099): at android.view.View.performClick(View.java:3511)
06-08 21:40:59.603: E/SQLiteOpenHelper(4099): at android.view.View$PerformClick.run(View.java:14110)
06-08 21:40:59.603: E/SQLiteOpenHelper(4099): at android.os.Handler.handleCallback(Handler.java:605)
06-08 21:40:59.603: E/SQLiteOpenHelper(4099): at android.os.Handler.dispatchMessage(Handler.java:92)
06-08 21:40:59.603: E/SQLiteOpenHelper(4099): at android.os.Looper.loop(Looper.java:137)
06-08 21:40:59.603: E/SQLiteOpenHelper(4099): at android.app.ActivityThread.main(ActivityThread.java:4424)
06-08 21:40:59.603: E/SQLiteOpenHelper(4099): at java.lang.reflect.Method.invokeNative(Native Method)
06-08 21:40:59.603: E/SQLiteOpenHelper(4099): at java.lang.reflect.Method.invoke(Method.java:511)
06-08 21:40:59.603: E/SQLiteOpenHelper(4099): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
06-08 21:40:59.603: E/SQLiteOpenHelper(4099): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
06-08 21:40:59.603: E/SQLiteOpenHelper(4099): at dalvik.system.NativeStart.main(Native Method)
06-08 21:40:59.613: W/dalvikvm(4099): threadid=1: thread exiting with uncaught exception (group=0x40a851f8)
06-08 21:40:59.613: E/AndroidRuntime(4099): FATAL EXCEPTION: main
06-08 21:40:59.613: E/AndroidRuntime(4099): android.database.sqlite.SQLiteException: Can't upgrade read-only database from version 2 to 1: /data/data/com.example.android_sqliterdemo/databases/test_m_db1
06-08 21:40:59.613: E/AndroidRuntime(4099): at android.database.sqlite.SQLiteOpenHelper.getReadableDatabase(SQLiteOpenHelper.java:244)
06-08 21:40:59.613: E/AndroidRuntime(4099): at com.example.android_sqliterdemo.MainActivity$QueryListener.onClick(MainActivity.java:133)
06-08 21:40:59.613: E/AndroidRuntime(4099): at android.view.View.performClick(View.java:3511)
06-08 21:40:59.613: E/AndroidRuntime(4099): at android.view.View$PerformClick.run(View.java:14110)
06-08 21:40:59.613: E/AndroidRuntime(4099): at android.os.Handler.handleCallback(Handler.java:605)
06-08 21:40:59.613: E/AndroidRuntime(4099): at android.os.Handler.dispatchMessage(Handler.java:92)
06-08 21:40:59.613: E/AndroidRuntime(4099): at android.os.Looper.loop(Looper.java:137)
06-08 21:40:59.613: E/AndroidRuntime(4099): at android.app.ActivityThread.main(ActivityThread.java:4424)
06-08 21:40:59.613: E/AndroidRuntime(4099): at java.lang.reflect.Method.invokeNative(Native Method)
06-08 21:40:59.613: E/AndroidRuntime(4099): at java.lang.reflect.Method.invoke(Method.java:511)
06-08 21:40:59.613: E/AndroidRuntime(4099): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
06-08 21:40:59.613: E/AndroidRuntime(4099): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
06-08 21:40:59.613: E/AndroidRuntime(4099): at dalvik.system.NativeStart.main(Native Method)
下面是源代码，希望高手们能帮助我检查一下：
Activity中的代码：
package com.example.android_sqliterdemo;
import com.sql.db.DatabaseHelper;
import android.os.Bundle;
import android.app.Activity;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
public class MainActivity extends Activity {
// 声明各个组件
private Button createdb;
private Button updatedb;
private Button insert;
private Button update;
private Button query;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
getPart();
getListener();
}
// 通过ID获得各个组件
public void getPart() {
this.createdb = (Button) findViewById(R.id.createdb);
this.updatedb = (Button) findViewById(R.id.updatedb);
this.insert = (Button) findViewById(R.id.insert);
this.update = (Button) findViewById(R.id.update);
this.query = (Button) findViewById(R.id.query);
}
// 为控件绑定监听事件
public void getListener() {
this.createdb.setOnClickListener(new CreatebdListener());
this.updatedb.setOnClickListener(new UpdateBDListener());
this.insert.setOnClickListener(new InsertListener());
this.update.setOnClickListener(new UpdateListener());
this.query.setOnClickListener(new QueryListener());
}
// 创建各个按钮的监听事件
// 创建数据库
public class CreatebdListener implements OnClickListener {
@Override
public void onClick(View v) {
// 实例化DatabaseHelper对象
DatabaseHelper dbHelper = new DatabaseHelper(MainActivity.this,
"test_m_db1");
// 获得SQLiteDatabase对象
SQLiteDatabase db = dbHelper.getReadableDatabase();
}
}
// 更新数据库
public class UpdateBDListener implements OnClickListener {
@Override
public void onClick(View v) {
// 实例化DatabaseHelper对象
DatabaseHelper db = new DatabaseHelper(MainActivity.this,
"test_m_db1", 2);
// 得到SQLiteDatabase对象
SQLiteDatabase database = db.getReadableDatabase();
}
}
// 插入数据
public class InsertListener implements OnClickListener {
@Override
public void onClick(View v) {
// 生成ContentValues对象
ContentValues values = new ContentValues();
// 将该对象中应该插入的键值对，其中间是列名，值是希望插入这一列中值
values.put("id", 1);
values.put("name", "zhangsan");
DatabaseHelper dbHelper = new DatabaseHelper(MainActivity.this,
"test_m_db1",2);
// 通过writer方式获得数据库
SQLiteDatabase db = dbHelper.getWritableDatabase();
// 向数据库中插入数据 表格名称、是否为空、插入的值
db.insert("users", null, values);
}
}
// 修改数据库中的表格
public class UpdateListener implements OnClickListener {
@Override
public void onClick(View v) {
// 获得ContetValues对象
ContentValues values = new ContentValues();
// 向values中添加键值对
values.put("name", "李四");
// 实例化DatabaseHelper对象
DatabaseHelper dbHelper = new DatabaseHelper(MainActivity.this,
"test_m_db1");
// 使用writer方法获得数据库
SQLiteDatabase db = dbHelper.getWritableDatabase();
// 修改数据库中表格中数据
// 1.要更新的表格的名称
// 2.是一个ContentValues对象
// 3.where语句 ？是占位符
// 占位符处得值
db.update("users", values, "id=?", new String[] { "1" });
}
}
// 查询数据库中表格的数据
public class QueryListener implements OnClickListener {
@Override
public void onClick(View v) {
// 实例化DatabaseHelper对象
DatabaseHelper dbHelper = new DatabaseHelper(MainActivity.this,
"test_m_db1");
// 使用reader的方法获得SQLiteDatabse数据库
SQLiteDatabase db = dbHelper.getReadableDatabase();
//执行查寻操作
Cursor cursor=db.query("users", new String[]{"id" , "name"},"id=?",new String[]{"1"}, null, null, null);
while(cursor.moveToNext()){
String name=cursor.getString(cursor.getColumnIndex("name"));
System.out.println("query---->"+name);
}
}
}
}
SQLiteDataBaseHelper子类代码“
package com.sql.db;
import android.content.Context;
import android.database.DatabaseErrorHandler;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
/**
* 这是一个操作数据库的助手类，
* 功能：继承到了父类的构造方法和onCreate，onUpgrade方法
* 继承父类中getReadableDatabase和getWritableDatabase中操作
* @author Administrator
*
*/
public class DatabaseHelper extends SQLiteOpenHelper {
private static final int VERSION=1;
//在SQLiteOpenHelper的子类中，必须包含的构造方法，作用：
//1.context:activity 2.name 数据库的名称 3.cursorFactory：不知道
//4.version：数据库的版本，正数且递增
public DatabaseHelper(Context context, String name, CursorFactory factory,
int version) {
super(context, name, factory, version);
}
public DatabaseHelper(Context context, String name, CursorFactory factory,
int version, DatabaseErrorHandler errorHandler) {
super(context, name, factory, version, errorHandler);
// TODO Auto-generated constructor stub
}
// 自定义两个参数的构造函数
public DatabaseHelper(Context context, String name) {
this(context, name, VERSION);
}
public DatabaseHelper(Context context, String name, int version) {
this(context, name, null, version);
}
public DatabaseHelper(Context context, String name, CursorFactory factory) {
this(context, name, null, VERSION);
}
// 该函数是在第一次创建数据库的时候才能用到这个方法
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
System.out.println("create a Database");
db.execSQL("create table users(id int,name varchar(20))");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
// 更新数据库，增删改的方法都得调用这个函数
System.out.println("update a Database");
}
}