給JFinal添加 Sqlite 數據庫支持

Sqlite 的單文件便攜性、高性能在開發中方便性無與倫比，即便部署在中小型應用中也勝任有餘。

在JFinal中添加對 Sqlite 的支持 Step by Step：

一、點擊 http://www.xerial.org/maven/repository/artifact/org/xerial/sqlite-jdbc/3.7.2/sqlite-jdbc-3.7.2.jar 下載 sqlite JDBC驅動，並將其放入 Jfinal_app/WEB-INF/lib ；

二、下載一個Sqlite的數據庫管理工具，推薦 Navicate Premium，在此下載：http://www.navicat.com/en/products/navicat_premium/premium_overview.html ；或者你也能夠到 Sqlite 官網下載Sqlite Shell ，當前版本是 3.7.13: http://www.sqlite.org/sqlite-shell-win32-x86-3071300.zip ；

三、使用數據庫管理工具建立一個數據庫，存放路徑爲 Jfinal_app/WEB-INF/data.db ；建立必要的表，插入測試記錄，等等；

四、在 a_little_config.txt （或你本身的配置文件） 中設置：

jdbcUrl = jdbc:sqlite:D:/webs/Jfinal_app/WEB-INF/data.db 
user = 
password = 
devMode = true

五、新建一個類 Sqlite3Dialect.java ：（注：也能夠等待JFinal 1.1.1版Jar將增長此類）

package com.jfinal.plugin.activerecord.dialect;

import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import com.jfinal.plugin.activerecord.ActiveRecordException;
import com.jfinal.plugin.activerecord.Record;
import com.jfinal.plugin.activerecord.TableInfo;

/**
 * Sqlite3Dialect. Try to use Sqlite3 SQL dialect with ActiveRecordPlugin.
 * <p>
 * A clever person solves a problem. A wise person avoids it.
 */
public class Sqlite3SqlDialect implements IDialect {
	
	public String forTableInfoBuilderDoBuildTableInfo(String tableName) {
		return "select * from " + tableName + " where 1 = 2";
	}
	
	public void forModelSave(TableInfo tableInfo, Map<String, Object> attrs, StringBuilder sql, List<Object> paras) {
		sql.append("insert into ").append(tableInfo.getTableName()).append("(");
		StringBuilder temp = new StringBuilder(") values(");
		for (Entry<String, Object> e: attrs.entrySet()) {
			String colName = e.getKey();
			if (tableInfo.hasColumnLabel(colName)) {
				if (paras.size() > 0) {
					sql.append(", ");
					temp.append(", ");
				}
				sql.append(colName);
				temp.append("?");
				paras.add(e.getValue());
			}
		}
		sql.append(temp.toString()).append(")");
	}
	
	public String forModelDeleteById(TableInfo tInfo) {
		String pKey = tInfo.getPrimaryKey();
		StringBuilder sql = new StringBuilder(45);
		sql.append("delete from ");
		sql.append(tInfo.getTableName());
		sql.append(" where ").append(pKey).append(" = ?");
		return sql.toString();
	}
	
	public void forModelUpdate(TableInfo tableInfo, Map<String, Object> attrs, Set<String> modifyFlag, String pKey, Object id, StringBuilder sql, List<Object> paras) {
		sql.append("update ").append(tableInfo.getTableName()).append(" set ");
		for (Entry<String, Object> e : attrs.entrySet()) {
			String colName = e.getKey();
			if (!pKey.equalsIgnoreCase(colName) && modifyFlag.contains(colName) && tableInfo.hasColumnLabel(colName)) {
				if (paras.size() > 0)
					sql.append(", ");
				sql.append(colName).append(" = ? ");
				paras.add(e.getValue());
			}
		}
		sql.append(" where ").append(pKey).append(" = ?");
		paras.add(id);
	}
	
	public String forModelFindById(TableInfo tInfo, String columns) {
		StringBuilder sql = new StringBuilder("select ");
		if (columns.trim().equals("*")) {
			sql.append(columns);
		}
		else {
			String[] columnsArray = columns.split(",");
			for (int i=0; i<columnsArray.length; i++) {
				if (i > 0)
					sql.append(", ");
				sql.append(columnsArray[i].trim());
			}
		}
		sql.append(" from ");
		sql.append(tInfo.getTableName());
		sql.append(" where ").append(tInfo.getPrimaryKey()).append(" = ?");
		return sql.toString();
	}
	
	public String forDbFindById(String tableName, String primaryKey, String columns) {
		StringBuilder sql = new StringBuilder("select ");
		if (columns.trim().equals("*")) {
			sql.append(columns);
		}
		else {
			String[] columnsArray = columns.split(",");
			for (int i=0; i<columnsArray.length; i++) {
				if (i > 0)
					sql.append(", ");
				sql.append(columnsArray[i].trim());
			}
		}
		sql.append(" from ");
		sql.append(tableName.trim());
		sql.append(" where ").append(primaryKey).append(" = ?");
		return sql.toString();
	}
	
	public String forDbDeleteById(String tableName, String primaryKey) {
		StringBuilder sql = new StringBuilder("delete from ");
		sql.append(tableName.trim());
		sql.append(" where ").append(primaryKey).append(" = ?");
		return sql.toString();
	}
	
	public void forDbSave(StringBuilder sql, List<Object> paras, String tableName, Record record) {
		sql.append("insert into ");
		sql.append(tableName.trim()).append("(");
		StringBuilder temp = new StringBuilder();
		temp.append(") values(");
		
		for (Entry<String, Object> e: record.getColumns().entrySet()) {
			if (paras.size() > 0) {
				sql.append(", ");
				temp.append(", ");
			}
			sql.append(e.getKey());
			temp.append("?");
			paras.add(e.getValue());
		}
		sql.append(temp.toString()).append(")");
	}
	
	public void forDbUpdate(String tableName, String primaryKey, Object id, Record record, StringBuilder sql, List<Object> paras) {
		sql.append("update ").append(tableName.trim()).append(" set ");
		for (Entry<String, Object> e: record.getColumns().entrySet()) {
			String colName = e.getKey();
			if (!primaryKey.equalsIgnoreCase(colName)) {
				if (paras.size() > 0) {
					sql.append(", ");
				}
				sql.append(colName).append(" = ? ");
				paras.add(e.getValue());
			}
		}
		sql.append(" where ").append(primaryKey).append(" = ?");
		paras.add(id);
	}
	
	public void forPaginate(StringBuilder sql, int pageNumber, int pageSize, String select, String sqlExceptSelect) {
		int offset = pageSize * (pageNumber - 1);
		sql.append(select).append(" ");
		sql.append(sqlExceptSelect);
		sql.append(" limit ").append(offset).append(", ").append(pageSize);	// limit can use one or two '?' to pass paras
	}
}

六、在DemoConfig.java （或你本身的 Config 類）中：

1) 引入Sqlite3Dialect類： 

import com.jfinal.plugin.activerecord.dialect.Sqlite3Dialect;

public void configPlugin(Plugins me) {
		// 配置C3p0數據庫鏈接池插件
		C3p0Plugin c3p0Plugin = new C3p0Plugin(getProperty("jdbcUrl"), getProperty("user"), getProperty("password"));
                c3p0Plugin.setDriverClass("org.sqlite.JDBC"); //指定驅動程序
                me.add(c3p0Plugin);	
		// 配置ActiveRecord插件
		ActiveRecordPlugin arp = new ActiveRecordPlugin(c3p0Plugin);
		me.add(arp);
                arp.setDialect(new Sqlite3Dialect());  //指定 Dialect
                arp.addMapping("blog", Blog.class);	// 映射blog 表到 Blog模型
	}

七、至此大功告成！啓動，服務器，在瀏覽器中查看效果吧！