在Android项目开发中会经常使用到其内嵌的SQLite数据库，但是疲于Android本身的SQLiteOpenHelper的繁琐（也许个人从事过Web开发，惯用MySql的偏见），经过统一思想的 方式封装了该sqlite-helper.jar包，对于从Java Web方向转过来的人也许算是一种帮助吧！
1.新建实体类
package com.whl.helper.entity;import com.fasterxml.jackson.annotation.JsonIgnore;public class DownloadInfo { @JsonIgnore(value=true) private int id; private int threadId;// 下载器id private int startPos;// 开始点 private int endPos;// 结束点 private int completeSize;// 完成度 private String downloadUrl;// 下载器网络标识 private int finish;//下载完成（0：未完成，1：已完成） public DownloadInfo(){} public DownloadInfo(int threadId, int startPos, int endPos,int completeSize, String downloadUrl) { super(); this.threadId = threadId; this.startPos = startPos; this.endPos = endPos; this.completeSize = completeSize; this.downloadUrl = downloadUrl; } public int getId(){ return id; } public void setId(int id){ this.id = id; } public int getThreadId() { return threadId; } public void setThreadId(int threadId) { this.threadId = threadId; } public int getStartPos() { return startPos; } public void setStartPos(int startPos) { this.startPos = startPos; } public int getEndPos() { return endPos; } public void setEndPos(int endPos) { this.endPos = endPos; } public int getCompleteSize() { return completeSize; } public void setCompleteSize(int completeSize) { this.completeSize = completeSize; } public String getDownloadUrl() { return downloadUrl; } public void setDownloadUrl(String downloadUrl) { this.downloadUrl = downloadUrl; } public int getFinish() { return finish; } public void setFinish(int finish) { this.finish = finish; } @Override public String toString() { return "DownloadInfo [id=" + id + ", threadId=" + threadId + ", startPos=" + startPos + ", endPos=" + endPos + ", completeSize=" + completeSize + ", downloadUrl=" + downloadUrl + ", finish=" + finish + "]"; }}2.该实体类的Dao接口
package com.whl.helper.database.dao;import java.util.List;import com.whl.dao.common.BaseDao;import com.whl.dao.common.DaoException;import com.whl.helper.entity.DownloadInfo;public interface DownloadInfoDao extends BaseDao<DownloadInfo> { public Boolean isHasDownloadInfosWithDownloadUrl(String downloadUrl) throws DaoException; public List<DownloadInfo> findDownloadInfoListWithDownloadUrl(String downloadUrl) throws DaoException; public int deleteDownloadInfoWithDownloadUrl(String downloadUrl) throws DaoException; public int update(int completeSize,int threadId,String downloadUrl) throws DaoException; public DownloadInfo findDownloadInfoWithThreadIdAndDownloadUrl(int threadId, String downloadUrl) throws DaoException; public long findDownloadInfoSumCompleteSizeWithDownloadUrl(String downloadUrl) throws DaoException;}3.该实体类的Dao接口实现类
package com.whl.helper.database.dao.impl;import java.util.List;import android.content.Context;import android.database.Cursor;import com.whl.dao.common.DaoException;import com.whl.dao.impl.CreateBaseDaoImpl;import com.whl.helper.database.dao.DownloadInfoDao;import com.whl.helper.entity.DownloadInfo;import com.whl.utils.RowMapper;public class DownloadInfoDaoImpl extends CreateBaseDaoImpl<DownloadInfo> implements DownloadInfoDao { public DownloadInfoDaoImpl(Context context){ super.prepare(context, new RowMapper<DownloadInfo>() { @Override public DownloadInfo onRowMapper(Cursor cursor) { DownloadInfo downloadInfo = new DownloadInfo(); downloadInfo.setId(cursor.getInt(cursor.getColumnIndex("id"))); downloadInfo.setCompleteSize(cursor.getInt(cursor.getColumnIndex("completeSize"))); downloadInfo.setDownloadUrl(cursor.getString(cursor.getColumnIndex("downloadUrl"))); downloadInfo.setEndPos(cursor.getInt(cursor.getColumnIndex("endPos"))); downloadInfo.setStartPos(cursor.getInt(cursor.getColumnIndex("startPos"))); downloadInfo.setThreadId(cursor.getInt(cursor.getColumnIndex("threadId"))); downloadInfo.setFinish(cursor.getInt(cursor.getColumnIndex("finish"))); return downloadInfo; } }); } @Override public Boolean isHasDownloadInfosWithDownloadUrl(String downloadUrl) throws DaoException { String sql = "SELECT COUNT(*) AS size FROM downloadInfo WHERE downloadUrl = ?"; String[] values = {downloadUrl}; return super.countSqlResult(sql, values)==0?true:false; } @Override public List<DownloadInfo> findDownloadInfoListWithDownloadUrl(String downloadUrl) throws DaoException { String sql = "SELECT * FROM downloadInfo WHERE downloadUrl = ?"; String[] values = {downloadUrl}; //List<DownloadInfo> downloadInfoList = super.find(sql, values); return super.find(sql, values); } @Override public int deleteDownloadInfoWithDownloadUrl(String downloadUrl)throws DaoException { String sql = "DELETE FROM downloadInfo WHERE downloadUrl = ?"; String[] values = {downloadUrl}; return super.deleteUnique(sql, values); } @Override public int update(int completeSize,int threadId,String downloadUrl) throws DaoException { String sql = "UPDATE downloadInfo SET completeSize = ? WHERE threadId=? AND downloadUrl = ?"; String[] values = {String.valueOf(completeSize),String.valueOf(threadId),downloadUrl}; return super.batchExecute(sql, values); } @Override public DownloadInfo findDownloadInfoWithThreadIdAndDownloadUrl(int threadId, String downloadUrl) throws DaoException{ String sql = "SELECT * FROM downloadInfo WHERE threadId = ? AND downloadUrl = ?"; String[] values = {String.valueOf(threadId),downloadUrl}; return super.findUniqueResult(sql, values); } @Override public long findDownloadInfoSumCompleteSizeWithDownloadUrl(String downloadUrl) throws DaoException { long sumCompletedSize = 0; List<DownloadInfo> downloadInfoList = findDownloadInfoListWithDownloadUrl(downloadUrl); for (DownloadInfo downloadInfo : downloadInfoList) { sumCompletedSize+=downloadInfo.getCompleteSize(); } return sumCompletedSize; }}4.该实体类的Service类
package com.whl.helper.database.service;import java.util.List;import android.content.Context;import com.whl.dao.common.DaoException;import com.whl.helper.database.dao.DownloadInfoDao;import com.whl.helper.database.dao.impl.DownloadInfoDaoImpl;import com.whl.helper.entity.DownloadInfo;import com.whl.service.common.BaseService;public class DownloadInfoService extends BaseService<DownloadInfo> { private DownloadInfoDao downloadInfoDao; private static DownloadInfoService downloadInfoServiceInstance; private DownloadInfoService(Context context){ downloadInfoDao = new DownloadInfoDaoImpl(context); super.prepareBaseDao(downloadInfoDao); } public static DownloadInfoService getInstance(Context context){ if(downloadInfoServiceInstance==null){ downloadInfoServiceInstance = new DownloadInfoService(context); } return downloadInfoServiceInstance; } public Boolean isHasDownloadInfosWithDownloadUrl(String downloadUrl){ try { return downloadInfoDao.isHasDownloadInfosWithDownloadUrl(downloadUrl); } catch (DaoException e) { e.printStackTrace(); return false; } } public List<DownloadInfo> findDownloadInfoListWithDownloadUrl(String downloadUrl){ try { return downloadInfoDao.findDownloadInfoListWithDownloadUrl(downloadUrl); } catch (DaoException e) { e.printStackTrace(); return null; } } public int deleteDownloadInfoWithDownloadUrl(String downloadUrl){ try { return downloadInfoDao.deleteDownloadInfoWithDownloadUrl(downloadUrl); } catch (DaoException e) { e.printStackTrace(); return 0; } } public int update(int completeSize,int threadId,String downloadUrl){ try { return downloadInfoDao.update(completeSize,threadId, downloadUrl); } catch (DaoException e) { e.printStackTrace(); return 0; } } public DownloadInfo findDownloadInfoWithThreadIdAndDownloadUrl(int threadId, String downloadUrl){ try { return downloadInfoDao.findDownloadInfoWithThreadIdAndDownloadUrl(threadId, downloadUrl); } catch (DaoException e) { e.printStackTrace(); return null; } } public long findDownloadInfoSumCompleteSizeWithDownloadUrl(String downloadUrl){ try { return downloadInfoDao.findDownloadInfoSumCompleteSizeWithDownloadUrl(downloadUrl); } catch (DaoException e) { e.printStackTrace(); return 0; } }}当然，对于习惯写SQL语句的人来说这种方式很容易理解，jar中基本上已经封装好了常用的增删改查，特殊处理的地方也就是如上书写SQL语句并传递参数并调用响应的基本方法即可。
5.真正使用
做完上述基本工作以后接下来就是如何去使用，使用其实很简单，首先如果是新建的数据库就需要SQL语句：
/** * 初始化数据库 */ public void initDatabase(String[] sqlArray){ CreateDatabaseHelper createDatabaseHelper = CreateDatabaseHelper.getInstanceDatabaseHelper(getApplicationContext()); SQLiteDatabase database = createDatabaseHelper.getWritableDatabase(); database.beginTransaction(); for (String sql : sqlArray) { database.execSQL(sql); } database.setTransactionSuccessful(); database.endTransaction(); database.close(); }接着就是其他的一些操作只需获取响应实体类的Service对象：
public void testSqliteStatement(){ DownloadInfoService downloadInfoService = DownloadInfoService.getInstance(this); try { long startTime = System.currentTimeMillis(); DownloadInfo downloadInfo = downloadInfoService.get("2"); downloadInfoService.removeUnique(downloadInfo); long finishTime = System.currentTimeMillis(); Log.d(TAG, "testSqliteStatement:"+(finishTime-startTime)); } catch (DaoException e) { e.printStackTrace(); } /*List<DownloadInfo> downloadInfoList = new ArrayList<DownloadInfo>(); for(int i=0;i<2;i++){ DownloadInfo downloadInfo = new DownloadInfo(); downloadInfo.setCompleteSize(1000+i); downloadInfo.setDownloadUrl("www"+i); downloadInfo.setEndPos(2000+i); downloadInfo.setFinish(0+i); downloadInfo.setStartPos(0+i); downloadInfo.setThreadId(11+i); downloadInfoList.add(downloadInfo); } try { long startTime = System.currentTimeMillis(); for (DownloadInfo downloadInfo : downloadInfoList) { downloadInfoService.insert(downloadInfo); } long finishTime = System.currentTimeMillis(); Log.d(TAG, "testSqliteStatement:"+(finishTime-startTime)); } catch (DaoException e) { e.printStackTrace(); }*/ }这里需要说明的是实体类的属性名必须与数据库表中的字段名一样（虽然不区分大小写），实体名也与对应的数据表名一样（虽然不区分大小写），否则会报异常，这样的好处是方便明白意义。上述只是创建了一个数据表，该表的SQL语句如下：
CREATE TABLE IF NOT EXISTS downloadInfo(id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, threadId INTEGER, startPos INTEGER, endPos INTEGER, completeSize INTEGER,downloadUrl VARCHAR,finish INTEGER)