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同步思想：
先介绍客户端为最新数据的数据同步问题，这种机制常常应用在云笔记，随手记类似的app。
这里我建了一个listview，对listview上item的增删改，来代替实际项目中的情况。
1.对listview 和本地数据表datatable表(使用id作为数据唯一表示)映射，实现增删改。
2.每次将对本地数据表的操作记录在operation表中，在表中记录该操作的时间戳。
3.将operation 表中内容封装成json数据发送给服务器（从服务器获取上次同步时间戳，只提交在这次更新以后的操作）。
4.服务器更新完成，返回success,表示同步成功，在时候可以清空operation表
MainActivity.java
package com.example.sqllitcache;
import java.text.SimpleDateFormat;
import java.util.Date;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.ContentValues;
import android.content.DialogInterface;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.AdapterView.OnItemLongClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.ListView;
import android.widget.Toast;
public class MainActivity extends Activity {
ListView lv;
Button submit;
EditText et;
SQLiteDatabase dbwrite ;
Dbhelper dbhelper;
ArrayAdapter <String> adapter;
ImageButton upload;
Cursor c;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
lv=(ListView) findViewById(R.id.listView1);
submit=(Button) findViewById(R.id.button1);
upload=(ImageButton) findViewById(R.id.imageButton1);
et=(EditText) findViewById(R.id.autoCompleteTextView1);
adapter=new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1);
lv.setAdapter(adapter);
dbhelper=new Dbhelper(this);
dbwrite=dbhelper.getWritableDatabase();
getData();
//点击提交
submit.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
String newData=et.getText().toString();
addData(newData);
}
});
//点击了同步
upload.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
getOp();
}
});
//长按列表项，修改数据
lv.setOnItemLongClickListener(new OnItemLongClickListener() {
@Override
public boolean onItemLongClick(AdapterView<?> arg0, View arg1,
final int position, long arg3) {
// TODO Auto-generated method stub
new AlertDialog.Builder(MainActivity.this).setPositiveButton("我确定修改",new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
updateData(position);
}
}).show();
return false;
}
});
//短按列表项删除数据
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> arg0, View arg1, int position,
long arg3) {
// TODO Auto-generated method stub
Toast.makeText(MainActivity.this, position+"", 0).show();
deleteData(position);
}
});
}
//添加数据的执行函数，添加到本地数据库，并提示更新listtview
void addData(String newData)
{
//添加到本地数据库
ContentValues content=new ContentValues();
String putdata=et.getText().toString();
content.put("data", putdata);
dbwrite.insert("datatable",null, content);
//下面将操作保存到operation表
getData();
c.moveToLast();
int id=c.getInt(c.getColumnIndex("_id"));
ContentValues content2=new ContentValues();
content2.put("data", putdata);
content2.put("op", 0);
content2.put("dataid",id );
long time=System.currentTimeMillis();
SimpleDateFormat sdf=new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
Date date=new Date(time);
String formattime=sdf.format(date);
content2.put("timestamp", formattime);
dbwrite.insert("operation", null, content2);
}
//删除一条数据
void deleteData(int position)
{
c.moveToPosition(position);
int id=c.getInt(c.getColumnIndex("_id"));
dbwrite.delete("datatable", "_id=?", new String[]{id+""} );
getData();
//记录到operation表
ContentValues content2=new ContentValues();
content2.put("data", "");
content2.put("op", 1);
content2.put("dataid",id );
long time=System.currentTimeMillis();
SimpleDateFormat sdf=new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
Date date=new Date(time);
String formattime=sdf.format(date);
content2.put("timestamp", formattime);
dbwrite.insert("operation", null, content2);
}
//修改一条数据
void updateData(int position)
{
c.moveToPosition(position);
ContentValues cv=new ContentValues();
cv.put("data", "changed");
int id=c.getInt(c.getColumnIndex("_id"));
dbwrite.update("datatable", cv, "_id=?", new String [] {id+""});
getData();
ContentValues content2=new ContentValues();
content2.put("data", "changed");
content2.put("op", 2);
content2.put("dataid",id );
long time=System.currentTimeMillis();
SimpleDateFormat sdf=new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
Date date=new Date(time);
String formattime=sdf.format(date);
content2.put("timestamp", formattime);
dbwrite.insert("operation", null, content2);
}
//获取数据
void getData()
{
c= dbwrite.query("datatable", null, null, null, null, null, null);
adapter.clear();
//读取本地数据库
while(c.moveToNext())
{
String data=c.getString(c.getColumnIndex("data"));
int id=c.getInt(c.getColumnIndex("_id"));
adapter.add(data+":"+id);
System.out.println(data+": "+id);
}
adapter.notifyDataSetChanged();
}
//从日志表获得操作记录
void getOp()
{
c= dbwrite.query("operation", null, null, null, null, null, null);
while(c.moveToNext())
{
String data=c.getString(c.getColumnIndex("data"));
int id=c.getInt(c.getColumnIndex("dataid"));
int op=c.getInt(c.getColumnIndex("op"));
String timestamp=c.getString(c.getColumnIndex("timestamp"));
Toast.makeText(MainActivity.this, id+": "+op+" "+timestamp, 0).show();
System.out.println(id+": "+op+" "+timestamp);
}
dbwrite.delete("operation", "1", null);
}
}
package com.example.sqllitcache;
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 ) {
super(context, "mydb",null, 1);
// TODO Auto-generated constructor stub
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
db.execSQL("CREATE TABLE datatable ("+
"_id INTEGER PRIMARY KEY AUTOINCREMENT,"+
"data String DEFAULT \"\")" );
//创建一个操作表作为日志，dataid为数据项id,opt=0,1,2,3为对数据的增删改查
db.execSQL("CREATE TABLE operation ("+
"_id INTEGER PRIMARY KEY AUTOINCREMENT,"+
"dataid INTEGER ,"+
"op INTEGER,"+
"data String DEFAULT \"\","+
"timestamp String"+")");
}
@Override
public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
// TODO Auto-generated method stub
}
}
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原文地址：http://blog.csdn.net/davidluo001/article/details/42527799
