JAVA版的SqlHelper【自学jdbc3个晚上的总结】

      自学了3个晚上的jdbc，感觉还比较陌生，比如事务，并发那块还没有去学习，这里就简单山寨了个java班的SqlHelper

大家看了代码后，尽管血喷。

      jdbc操作流程：

      1、下载相关数据库的jdbc驱动，放在硬盘某个目录中

      2、配置classpath环境变量，把下载的jdbc驱动里面的jar路径添加到classpath中

      3、在代码中调用Class.forName方法加载驱动，参数为jar里面的类全名称

      4、调用DriverManager.getConnection方法，参数为连接字符串

      5、创建各种Statement，执行sql

      个人感觉，jdbc好麻烦，呵呵，相对于C#而言，比如：操作流程、批量sql操作、参数化sql操作等等，都很麻烦。

      

     

  1 package lbc;
  2 
  3 import java.sql.Connection;
  4 import java.sql.DriverManager;
  5 import java.sql.PreparedStatement;
  6 import java.sql.ResultSet;
  7 import java.sql.ResultSetMetaData;
  8 import java.sql.SQLException;
  9 import java.sql.Statement;
 10 import java.util.ArrayList;
 11 import java.util.HashMap;
 12 import java.util.List;
 13 import java.util.Map;
 14 
 15 public final class SqlHelper {
 16         
 17     private SqlHelper() {
 18         
 19     }
 20     
 21     static {
 22         //加载驱动
 23         try {
 24             Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
 25         } catch (ClassNotFoundException e) {
 26             e.printStackTrace();
 27             throw new RuntimeException(e);
 28         }
 29     }
 30     
 31     private static Connection getConnection(String connectionString) throws SQLException {
 32         Connection connection = DriverManager.getConnection(connectionString);
 33         return connection;
 34     }
 35     
 36     private static void close(Connection connection,Statement statement) {
 37         try {
 38             if(connection != null){
 39                 connection.close();
 40             }
 41             if (statement != null) {
 42                 statement.close();
 43             }
 44         } catch (Exception e) {
 45             e.printStackTrace();
 46         }
 47     }
 48     
 49     private static void close(ResultSet rs){
 50         try {
 51             if (rs != null) {
 52                 rs.close();
 53             }
 54         } catch (Exception e) {
 55             e.printStackTrace();
 56         }
 57     }
 58     
 59     private static List<Map<String, Object>> convert(ResultSet rs) throws SQLException {
 60         List<Map<String, Object>> list = new ArrayList<>();
 61         if(rs != null && !rs.isClosed()){
 62             ResultSetMetaData meta = rs.getMetaData();
 63             int colCount=meta.getColumnCount();
 64             while (rs.next()) {
 65                 Map<String, Object> map = new HashMap<String, Object>();
 66                 for(int i=1;i<=colCount;i++){
 67                     String key = meta.getColumnName(i);
 68                     Object value = rs.getObject(i);
 69                     map.put(key, value);
 70                 }
 71                 list.add(map);
 72                 
 73             }
 74         }
 75         return list;
 76     }
 77     
 78     private static void AttachParameters(PreparedStatement statement,Object ...values) throws Exception {
 79         if (values != null) {
 80             for (int i = 0; i < values.length; i++) {
 81                 statement.setObject(i + 1, values[i]);
 82             }
 83         }
 84     }
 85 
 86     public static int ExecuteNonQuery(String sql,String connectionString,Object ...parameterValues) throws SQLException,Exception {
 87         Connection connection = null;
 88         PreparedStatement statement = null;
 89         int result = 0;
 90         try {
 91             connection = getConnection(connectionString);
 92             statement = connection.prepareStatement(sql);
 93             AttachParameters(statement, parameterValues);
 94             result = statement.executeUpdate();
 95             statement.clearParameters();
 96         } 
 97         finally {
 98             close(connection, statement);
 99         }
100         return result;
101     }
102       
103     public static Object ExecuteScalar(String sql,String connectionString,Object ...parameterValues) throws Exception {
104         ResultSet rs = null;
105         Object value = null;
106         try {
107             rs = ExecuteResultSet(sql,connectionString,parameterValues);
108             if(rs != null){
109                 rs.next();
110                 value = rs.getObject(1);
111             }
112         } 
113         finally {
114             close(rs);
115         }
116         
117         return value;
118     }
119 
120     public static ResultSet ExecuteResultSet(String sql,String connectionString,Object ...parameterValues) throws Exception {
121         Connection connection = null;
122         PreparedStatement statement = null;
123         ResultSet rs = null;
124         try {
125             connection = getConnection(connectionString);
126             statement = connection.prepareStatement(sql);
127             AttachParameters(statement, parameterValues);
128             rs = statement.executeQuery();
129             statement.clearParameters();
130         } 
131         catch (Exception e) {
132             close(connection,statement);
133             throw e;
134         }  
135         return rs;
136     }
137     
138     public static List<Map<String, Object>> ExecuteList(String sql,String connectionString,Object ...parameterValues) throws Exception {
139         ResultSet rs = null;
140         List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
141         try {
142             rs = ExecuteResultSet(sql, connectionString,parameterValues);
143             list = convert(rs);
144         } 
145         finally {
146             close(rs);
147         }
148         return list;
149     }
150 
151     
152 }