JAVA WEB新进展-白红宇

JAVA WEB新进展

阅读量：4961 次

发布时间：2019-06-12

本文共 5771 字，大约阅读时间需要 19 分钟。

哈哈，终于搞来页面来了，丑是丑，但是好的进展。

高手的思路，自己用库建连接池，确实利害。

最关键的一个HELPER代码：

package org.smart4j.chapter2.helper;import java.io.BufferedReader;import java.io.InputStream;import java.io.InputStreamReader;import java.sql.Connection;import java.sql.DriverManager;import java.sql.SQLException;import java.util.ArrayList;import java.util.List;import java.util.Map;import java.util.Properties;import org.apache.commons.dbcp2.BasicDataSource;import org.apache.commons.dbutils.handlers.BeanHandler;import org.apache.commons.dbutils.handlers.MapListHandler;import org.apache.log4j.helpers.ThreadLocalMap;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.apache.commons.dbutils.QueryRunner;import org.apache.commons.dbutils.handlers.BeanListHandler;import org.smart4j.chapter2.util.CollectionUtil;import org.smart4j.chapter2.util.PropsUtil;/** * Created by sahara on 2016/3/16. */public final class DatabaseHelper {    private static final Logger LOGGER = LoggerFactory.getLogger((DatabaseHelper.class));    private static final ThreadLocal
     
       CONNECTION_HOLDER ;    private static final QueryRunner QUERY_RUNNER;    private static final BasicDataSource DATA_SOURCE;    static  {        CONNECTION_HOLDER = new ThreadLocal
      
       ();        QUERY_RUNNER = new QueryRunner();        Properties conf = PropsUtil.loadProps("config.properties");        String driver = conf.getProperty("jdbc.driver");        String url = conf.getProperty("jdbc.url");        String username = conf.getProperty("jdbc.username");        String password = conf.getProperty("jdbc.password");        DATA_SOURCE = new BasicDataSource();        DATA_SOURCE.setDriverClassName(driver);        DATA_SOURCE.setUrl(url);        DATA_SOURCE.setUsername(username);        DATA_SOURCE.setPassword(password);    }    public static Connection getConnection() {        Connection conn = CONNECTION_HOLDER.get();        if (conn == null) {            try {                conn = DATA_SOURCE.getConnection();            }catch (SQLException e) {                LOGGER.error("get connection failure", e);                throw new RuntimeException(e);            }finally {                CONNECTION_HOLDER.set(conn);            }        }        return conn;    }    public static 
       
         List
        
          queryEntityList(Class
         
           entityClass, String sql, Object...params) {        List
          
            entityList; try { Connection conn = getConnection(); entityList = QUERY_RUNNER.query(conn, sql, new BeanListHandler
           
            (entityClass), params); } catch (SQLException e) { LOGGER.error("query entity list failure", e); throw new RuntimeException(e); } return entityList; } public static 
            
              T queryEntity(Class
             
               entityClass, String sql, Object...params) { T entity; try { Connection conn = getConnection(); entity = QUERY_RUNNER.query(conn, sql, new BeanHandler
              
               (entityClass), params); } catch (SQLException e) { LOGGER.error("query entity failure", e); throw new RuntimeException(e); } return entity; } public static List
               
                
                 > executeQuery(String sql, Object...params) { List
                 
                  
                   > result; try { Connection conn = getConnection(); result = QUERY_RUNNER.query(conn, sql, new MapListHandler(), params); } catch (Exception e) { LOGGER.error("execute query failure", e); throw new RuntimeException(e); } return result; } public static int executeUpdate(String sql, Object...params) { int rows = 0; try { Connection conn = getConnection(); rows = QUERY_RUNNER.update(conn, sql, params); } catch (SQLException e) { LOGGER.error("execute update failure", e); throw new RuntimeException(e); } return rows; } public static 
                   
                     boolean insertEntity(Class
                    
                      entityClass, Map
                     
                       fieldMap) { if (CollectionUtil.isEmpty(fieldMap)) { LOGGER.error("can not insert entity: fieldMap is empty"); return false; } String sql = "INSERT INTO " + getTableName(entityClass); StringBuilder columns = new StringBuilder("("); StringBuilder values = new StringBuilder("("); for (String fieldName : fieldMap.keySet()) { columns.append(fieldName).append(", "); values.append("?, "); } columns.replace(columns.lastIndexOf(", "), columns.length(), ")"); values.replace(values.lastIndexOf(", "), values.length(), ")"); sql += columns + " VALUES " + values; Object[] params = fieldMap.values().toArray(); return executeUpdate(sql, params) == 1; } public static 
                      
                        boolean updateEntity(Class
                       
                         entityClass, long id, Map
                        
                          fieldMap) { if (CollectionUtil.isEmpty(fieldMap)) { LOGGER.error("can not update entity: fieldMap is empty"); return false; } String sql = "UPDATE " + getTableName(entityClass) + " SET "; StringBuilder columns = new StringBuilder(); for (String fieldName : fieldMap.keySet()) { columns.append(fieldName).append("=?, "); } sql += columns.substring(0, columns.lastIndexOf(", ")) + " WHERE id=?"; List