假想用配置Sql语句的方式来完毕一个处理逻辑，而且映射到一个Url，这样当请求这个url的时候，运行前面配置的sql。

以下的一段详细配置，比如 当请求pagerlistdept.do的时候，会传入參数Offset，并调用handler运行里面配置的SQL语句。

dept_sql_mapping.xml

     
     
     	
      		
       
        			select d.id_f,d.name_f,count(e.id_f) emp_count from dept_t d left join emp_t e 			on d.id_f=e.dept_id_f group by d.id_f limit #offset#,6		
       		
       
        			select count(*) from dept_t		
       	
      	
      		
       
        			select d.id_f,d.name_f,count(e.id_f) emp_count from dept_t d left join emp_t e 			on d.id_f=e.dept_id_f group by d.id_f limit 0,6		
       		
       
        			select count(*) from dept_t		
       	
      	
      		
       
        			select * from dept_t		
       	
      	
      		
       
        			select id_f,name_f from dept_t where id_f=#did#		
       	
      	
      		
       
        			insert into dept_t(name_f) values('#name#')		
       		
       			
        		
       	
      	
      		
       			
        
         delete from dept_t where id_f=#did#
        		
       	
      	
      		
       
        			update dept_t set name_f='#name#' where id_f=#did#		
       	
      
     

以下看看怎么实现。。。

首先。在classpath以下定义一个总的配置文件，临时命名为sqlparser.xml，定义好默认的handler和数据库连接信息(db.properties)

创建总的控制器，用一个Servlet来完毕。

主要用于载入配置信息，拦截请求并解析

/** * Dispacher servlet for sqlparser * You should configure this servlet as normal servlet int web.xml * and set 
     
      1
      to make  * it starts with web container * @author john.liu * */public class SqlParserServlet extends HttpServlet {	private static final long serialVersionUID = 1L;		protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {		try {			request.setCharacterEncoding("UTF-8");			request.removeAttribute("VALIDATION_ERRORS");			request.getSession().removeAttribute("ERRORS");		} catch (UnsupportedEncodingException e) {			e.printStackTrace();		}		RequestParser rp = new RequestParser(request,response);		rp.parse();	}	@Override	public void init(ServletConfig config) throws ServletException {		long st = System.currentTimeMillis();		ConfigurationParser.loadConfiguration();		long ed = System.currentTimeMillis();		System.out.println("load configurations in "+(ed-st)+" ms.");	}}

载入配置信息由RequestParser完毕，这里面主要是依据请求的uri获取到处理的handler和sql语句，运行并分发视图.

/** * Class for parsing request * This is almost heart of sqlparser,which parses request,executes sql,dispatches result,returns error. * @author john.liu * */public class RequestParser {	private HttpServletRequest request;	private HttpServletResponse response;	private String request_do;	/**	 * 404 request target	 */	private String success = "404error.do";	/**	 * error request target 	 */	private String fail = "error.do";	/**	 * specify type='json' to make an ajax request 	 */	private String type; 	/**	 * by default ,redirect is false	 */	private boolean redirect = false;	private SqlBean[] sql_array;	private SqlBean[] tran_sql_array;	private HashMap
     
       parameters;	private SqlHandler default_sql_handler;			public RequestParser(HttpServletRequest request,HttpServletResponse response){		this.request = request;		this.response = response;		init();	}	/**	 * initiate some variables by request	 */	private void init(){		String uri = request.getRequestURI();		String context = request.getContextPath();		this.request_do = uri.substring(uri.indexOf(context)+context.length()+1);		if(request_do.indexOf("?
     

")!=-1) this.request_do = request_do.substring(0, request_do.indexOf("?")); HashMap url_map = ConfigurationParser.sqlMap.get(request_do); if(url_map == null) { this.request_do = "404error.do"; } boolean isError = handleErrorRequest(); if(isError) return; type = url_map.get("TYPE")!=null?

(String)url_map.get("TYPE"):null; success = url_map.get("SUCCESS")!=null?(String)url_map.get("SUCCESS"):success; fail = url_map.get("FAIL")!=null?(String)url_map.get("FAIL"):fail; redirect = url_map.get("REDIRECT")!=null?Boolean.valueOf((String)url_map.get("REDIRECT")):false; sql_array = url_map.get("SQL_ARRAY")!=null?(SqlBean[])url_map.get("SQL_ARRAY"):null; tran_sql_array = url_map.get("TRAN_SQL_ARRAY")!=null?

(SqlBean[])url_map.get("TRAN_SQL_ARRAY"):null; parameters = url_map.get("VALIDATE_PARAM")!=null?

(HashMap<String,String>)url_map.get("VALIDATE_PARAM"):null; String handler_class = url_map.get("SQL_HANDLER")!=null?url_map.get("SQL_HANDLER").toString():null; initHandlerClass(handler_class); //initiate handler class } private void initHandlerClass(String handler_class) { try { long st = System.currentTimeMillis(); if(default_sql_handler != null && default_sql_handler.getClass().getCanonicalName().equals(handler_class)){ //dont initialize the same handler return; } if(handler_class!=null){ Class<SqlHandler> clazz = (Class<SqlHandler>)Class.forName(handler_class); default_sql_handler = clazz.newInstance(); }else if(ConfigurationParser.default_sql_handler_class!=null){ Class<SqlHandler> clazz = (Class<SqlHandler>)Class.forName(ConfigurationParser.default_sql_handler_class); default_sql_handler = clazz.newInstance(); }else{ default_sql_handler = new SimpleSqlHandler(ConfigurationParser.db_config_file); } long ed = System.currentTimeMillis(); System.out.println("["+new SimpleDateFormat("yyyy/MM/dd HH:mm:ss").format(new Date())+"]"+default_sql_handler.toString()+" cost: "+(ed-st)+" ms"); } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (InstantiationException e) { e.printStackTrace(); } catch (IllegalAccessException e) { e.printStackTrace(); } } /** * pasrse request */ public void parse() { if(default_sql_handler==null) return; if(default_sql_handler.getConnection()==null) default_sql_handler.openConnection(); if(ConfigurationParser.sqlMap.get(success)!=null){ redirect = true; //redirect to another request in the url-map } List<String> errors = ReuqestParameterValidator.doValidate(request,parameters); //do validation if(errors.size()>0){ try { //validate error if(type!=null&&(type.equals("json")||type.equals("xml"))){ PrintWriter pw = response.getWriter(); pw.write("false"); pw.close(); }else{ request.setAttribute("VALIDATION_ERRORS", errors); request.getRequestDispatcher(fail).forward(request, response); } } catch (Exception e) { e.printStackTrace(); } }else{ //no error with validation,dispatch result distrubuteResult(); } } /** * handle errors * @return */ private boolean handleErrorRequest() { if(!request_do.equals("error.do")&&!request_do.equals("404error.do")) return false; String url = ""; if(request_do.equals("error.do")){ url = "/WEB-INF/classes/web/error.jsp"; }else if(request_do.equals("404error.do")){ url = "/WEB-INF/classes/web/404.jsp"; } try { request.getRequestDispatcher(url).forward(request, response); } catch (Exception e) { e.printStackTrace(); } return true; } /** * dispatche result */ private void distrubuteResult() { try{ response.setCharacterEncoding("UTF-8"); default_sql_handler.getErrors().clear(); HashMap<String,Object> resultMap = getSqlResult(); if(type!=null&&(type.equals("json"))){ PrintWriter pw = response.getWriter(); JSONObject jo = JSONObject.fromObject(resultMap); pw.write(jo.toString()); pw.close(); }else{ if(default_sql_handler.getErrors().size()>0){ //sql execute error request.getSession().setAttribute("ERRORS", default_sql_handler.getErrors()); //response.sendRedirect(request.getContextPath()+""+fail); response.sendRedirect(request.getContextPath()+"/"+fail); }else{ if(redirect){ response.sendRedirect(request.getContextPath()+"/"+success); }else{ request.getRequestDispatcher(success).forward(request, response); } } } } catch (Exception e) { e.printStackTrace(); } finally{ default_sql_handler.closeConnection(); //close current connection } } /** * execute sql, and return result map * @return result map * @throws SQLException */ private HashMap<String,Object> getSqlResult() throws SQLException { HashMap<String,Object> resultMap = new HashMap<String, Object>(0); if(sql_array!=null){ for(SqlBean sql:sql_array){ Object res = executeSql(sql); if(type!=null&&(type.equals("json"))){ resultMap.put(sql.getResult(), res); } } } if(tran_sql_array!=null){ if(default_sql_handler.getConnection()==null) default_sql_handler.openConnection(); default_sql_handler.getConnection().setAutoCommit(false); for(SqlBean tran_sql:tran_sql_array){ Object res = executeSql(tran_sql); if(type!=null&&(type.equals("json"))){ resultMap.put(tran_sql.getResult(), res); } } default_sql_handler.getConnection().commit(); } return resultMap; } /** * execute single sql * @param sqlbean * @return mixed type object probably are int,object[] or list<object[]> * @throws SQLException */ private Object executeSql(SqlBean sqlbean) throws SQLException{ String sql = sqlbean.getSql(); sql = setSqlParameters(sql); //set parameter String result = sqlbean.getResult(); String type = sqlbean.getType(); String[] variables = sqlbean.getVariables(); Object res = null; if("update".equals(type)){ int rows = 0; try { rows = default_sql_handler.update(sql); } catch (SQLException e) { default_sql_handler.rollback(); System.err.println("[sql execute error]"+sql); default_sql_handler.setError("[sql execute error]"); } res = rows; }else if("query".equals(type)){ if(result==null) return null; res = default_sql_handler.query(sql); }else if("find".equals(type)){ if(result==null) return null; res = default_sql_handler.find(sql); }else if("count".equals(type)){ if(result==null) return 0; res = default_sql_handler.count(sql); } HttpSession session = request.getSession(); if(result != null){ if(redirect){ session.setAttribute(result, res); }else{ request.setAttribute(result, res); } } if(variables != null){ for(String var:variables){ if(redirect){ session.setAttribute(var, request.getParameter(var)); }else{ request.setAttribute(var, request.getParameter(var)); } } } return res; } private String setSqlParameters(String sql){ Pattern p = Pattern.compile("#(\\w|\\d)+#"); Matcher m = p.matcher(sql); while(m.find()){ String g = m.group(); String param = g.replace("#", ""); sql = sql.replace(g, escapeString(request.getParameter(param))); } return sql; } private static String escapeString(String str){ if(str==null) return "null"; return str.replace("\'", "\\'").replace("\"", "\\\"").replaceAll("\\s+or\\s+", " ｏｒ "); }

SimpleSqlHandler类定义增改删查之类的方法

package org.sqlparser.handler.impl;import java.io.IOException;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.util.ArrayList;import java.util.List;import java.util.Properties;import org.sqlparser.handler.SqlHandler;/** * 
Simple implementation of sql handler
 * 
This class defined the simplest jdbc operations,which are query,count,find,update
 * 
You can make your owner sql handler by implementing interface SqlHandler
 * 
The best way is defining a default sql handler by implementing interface SqlHandler , *  and implementing all methods.Then if needed, you can define other handlers by  *  extending the default sql handler you defined before, and override one or more methods  *  according to your detail logic.And these handlers can be sepecified in 'handler' attribute  *  of sql-mapping to make this sql-mapping request handled by your owner sql handler.
 * @author john.liu * */public class SimpleSqlHandler implements SqlHandler {	private String configFile = "db.properties";	/**	 * Connection	 */	private Connection conn;	/**	 * PreparedStatement	 */	private PreparedStatement pstmt;	/**	 * Database driver class	 * 
It is suggested that u make this property configured in a file 	 * and configure 'database-config-file' attribute in sqlparser.xml
	 */	private static String db_driver;	/**	 * Database connection url	 * 
It is suggested that u make this property configured in a file 	 * and configure 'database-config-file' attribute in sqlparser.xml
	 */	private static String db_url;	/**	 * Database user name	 * 
It is suggested that u make this property configured in a file 	 * and configure 'database-config-file' attribute in sqlparser.xml
	 */	private static String db_user;	/**	 * database connect password	 * 
It is suggested that u make this property configured in a file 	 * and configure 'database-config-file' attribute in sqlparser.xml
	 */	private static String db_password;	/**	 * Default constructor method	 */	public SimpleSqlHandler(){		init();	}	/**	 * Constructor method	 * 
Initiate an instance by specified database configure file	 * @param config_file	 */	public SimpleSqlHandler(String config_file){		if(config_file != null && !"".equals(configFile)) {			this.configFile = config_file;		}		init();	}	/**	 * Load database configure file	 * @param config_file database configure file	 */	private void init() {				Properties props = new Properties();		try {			props.load(this.getClass().getClassLoader().getResourceAsStream(this.configFile));			db_driver = props.getProperty("db_driver");			db_url = props.getProperty("db_url");			db_user = props.getProperty("db_user");			db_password = props.getProperty("db_password");		} catch (IOException e) {			e.printStackTrace();			setError("can not load database config file");		}	}	/**	 * Open a new connection if connection is null	 */	@Override	public void openConnection(){		if(conn != null) return;		try {			Class.forName(db_driver);			conn = DriverManager.getConnection(db_url,db_user,db_password);		} catch (ClassNotFoundException e) {			e.printStackTrace();		} catch (SQLException e) {			e.printStackTrace();		}	}	/**	 * Close connection if connection is not null	 */	@Override	public void closeConnection() {		if(conn!=null){			try {				conn.close();			} catch (SQLException e) {				e.printStackTrace();			}		}	}	/**	 * Get a connection 	 */	@Override	public Connection getConnection() {		return this.conn;	}	/**	 * Execute update	 */	@Override	public int update(String sql) throws SQLException{		openConnection();		pstmt = conn.prepareStatement(sql);		return pstmt.executeUpdate();	}	/**	 * Execute select, return result set row number	 */	@Override	public int count(String sql) {		try {			openConnection();			pstmt = conn.prepareStatement(sql);			ResultSet rs = pstmt.executeQuery();			if(rs.next()){				return rs.getInt(1);			}		} catch (SQLException e) {			e.printStackTrace();		}		return 0;	}	/**	 * Execute select, return one row data 	 */	@Override	public Object[] find(String sql) {		try {			openConnection();			pstmt = conn.prepareStatement(sql);			ResultSet rs = pstmt.executeQuery();			int cols = rs.getMetaData().getColumnCount();			Object[] row = new Object[cols];			if(rs.next()){				for(int loop=0; loop
      
       Use row index and column index to retrieve items in data list
      
	 */	@Override	public List
     
       query(String sql) {		try {			openConnection();			pstmt = conn.prepareStatement(sql);			ResultSet rs = pstmt.executeQuery();			int cols = rs.getMetaData().getColumnCount();			ArrayList
      
        list = new ArrayList
       
        (0);			while(rs.next()){				Object[] row = new Object[cols];				for(int loop=0; loop
        
         You can put some 
         
           tags in 
          
            to make these sql executed * within a transaction,either of these sql 's failure will cause this method 's invoke
           
 */ @Override public void rollback() { try { if(!conn.getAutoCommit()) conn.rollback(); } catch (SQLException e) { e.printStackTrace(); } } /** * Put an error to error list */ @Override public void setError(String error) { errors.add(error); } /** * Get error list return by this handler instance */ @Override public ArrayList
           
             getErrors() { return errors; }}