Android Sqlite的使用（多线程优化）

package com.db;

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

/**
* Created by c9736 on 2016/6/26.
*/
public class DBHelper extends SQLiteOpenHelper{
private static final String DB_NAME="download.db";
private static final int VERSION=1;
private static final String SQI_CREATE="create table thread_info(_id integer primary key autoincrement,thread_id integer,url text,start " +
"integer,end integer,finished integer);";
private static final String SQL_DROP="drop table if exists thread_info";
public DBHelper(Context context) {
super(context, DB_NAME, null, VERSION);
}

@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(SQI_CREATE);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

db.execSQL(SQL_DROP);
db.execSQL(SQI_CREATE);
}
}
/**
* 获得类的对象
*/
public static DBHelper getInstance(Context context){
if(dbHelper==null){
dbHelper=new DBHelper(context);    //永远只会被实例化一次
}
return dbHelper;
}

package com.db;
import com.entities.ThreadInfo;

import java.util.List;

/**
* 数据访问接口
* Created by c9736 on 2016/6/26.
*/
public interface ThreadDao {
/**
插入线程信息
*/
public void insertThread(ThreadInfo threadInfo);
/**
删除线程
*/
public void deleteThread(String url,int Thread_id);

/**
* 更新线程
*/

public void updateThread(String url,int thread_id,int finished);
/**
查询文件线程信息
*/
public List<ThreadInfo> getThreads(String url);

/**
*线程是否存在
*/
public  boolean isExists(String url ,int thread_id);

}

package com.db;

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.util.Log;

import com.entities.ThreadInfo;

import java.util.ArrayList;
import java.util.List;

/**
* 数据访问接口的实现
* Created by c9736 on 2016/6/26.
*/
public class ThreadDaoImp1 implements ThreadDao {
private DBHelper dbHelper=null;
public ThreadDaoImp1(Context context){
dbHelper=DBHelper.getInstance(context);
}
@Override
public synchronized  void  insertThread(ThreadInfo threadInfo) {//多线程优化，任何时刻不能有多个线程进行插入操作，防止死锁发送

SQLiteDatabase db=dbHelper.getWritableDatabase();//获取可写的数据库
db.execSQL("insert into thread_info(thread_id,url,start,end,finished)values(?,?,?,?,?)",new Object[]{threadInfo.getId()
,threadInfo.getUrl(), threadInfo.getStart()
,threadInfo.getEnd(),threadInfo.getFinished()});
db.close();

}

@Override
public synchronized void deleteThread(String url) {

SQLiteDatabase db=dbHelper.getWritableDatabase();//获取可写的数据库
db.execSQL("delete from thread_info where url=?",new Object[]{url});
db.close();
}

@Override
public synchronized void updateThread(String url, int thread_id, int finished) {
SQLiteDatabase db=dbHelper.getWritableDatabase();//获取可写的数据库
db.execSQL("update  thread_info set finished=? where url=? and thread_id=?",new Object[]{finished,url,thread_id});
db.close();
}

@Override
public List<ThreadInfo> getThreads(String url) {
SQLiteDatabase db=dbHelper.getReadableDatabase();
List<ThreadInfo> threadInfoList=new ArrayList<ThreadInfo>();
Cursor cursor=db.rawQuery("select * from thread_info where url=?",new String[]{url});
while (cursor.moveToNext()){
ThreadInfo threadInfo=new ThreadInfo();
threadInfo.setId(cursor.getInt(cursor.getColumnIndex("thread_id")));
threadInfo.setUrl(cursor.getString(cursor.getColumnIndex("url")));
threadInfo.setStart(cursor.getInt(cursor.getColumnIndex("start")));
threadInfo.setEnd(cursor.getInt(cursor.getColumnIndex("end")));
threadInfo.setFinished(cursor.getInt(cursor.getColumnIndex("finished")));

Log.i("test", "thread_info_Query" + threadInfo.toString());
threadInfoList.add(threadInfo);
}
db.close();

return threadInfoList;
}

@Override
public boolean isExists(String url,int thread_id) {
be5b
SQLiteDatabase db=dbHelper.getReadableDatabase();

Cursor cursor=db.rawQuery("select * from thread_info where url=? and thread_id=?",new String[]{url,thread_id+""});
boolean exists=cursor.moveToNext();
db.close();

return false;
}
}

package com.entities;

/**
* 线程信息
* Created by c9736 on 2016/6/25.
*/
public class ThreadInfo {
private int id;
private String url;
private int start;
private int end;
private int finished;

public ThreadInfo(int id, int finished, String url, int start, int end) {
this.id = id;
this.finished = finished;
this.url = url;
this.start = start;
this.end = end;
}

@Override
public String toString() {
return "ThreadInfo{" +
"id=" + id +
", url='" + url + '\'' +
", start=" + start +
", end=" + end +
", finished=" + finished +
'}';
}

public ThreadInfo() {
super();
}

public int getId() {
return id;
}

public void setId(int id) {
this.id = id;
}

public String getUrl() {
return url;
}

public void setUrl(String url) {
this.url = url;
}

public int getStart() {
return start;
}

public void setStart(int start) {
this.start = start;
}

public int getEnd() {
return end;
}

public void setEnd(int end) {
this.end = end;
}

public int getFinished() {
return finished;
}

public void setFinished(int finished) {
this.finished = finished;
}
}