代码生成java连接数据库的所需代码（超详细）

  1 import java.sql.Connection;
  2 import java.sql.DriverManager;
  3 import java.sql.PreparedStatement;
  4 import java.sql.ResultSet;
  5 import java.sql.SQLException;
  6 import java.sql.Statement;
  7 
  8 
  9 
 10 
 11 
 12 /*
 13  *连接数据库
 14  *加载驱动
 15  * 
 16  * */
 17 
 18 public class Jdbcutil {
 19     // 数据库url:jdbc:数据库名://本地ip:端口号/创建的数据库名字
 20     private static String url = "jdbc:mysql://127.0.0.1:3306/books";
 21     // 连接数据库用户名
 22     private static String user = "root"; 
 23     //连接数据库密码
 24     private static String password = "123456";
 25 
 26     // 创建连接method
 27     public static Connection getConnection() {
 28         Connection conn = null;
 29         if (conn == null) {
 30             //加载驱动
 31             try {
 32                 Class.forName("com.mysql.jdbc.Driver");
 33                 conn = DriverManager.getConnection(url, user, password);
 34             } catch (Exception e) {
 35                 e.printStackTrace();
 36             }
 37         }
 38         return conn;
 39     }
 40 
 41     //关闭连接
 42     public static void closeAll(Connection conn, Statement stmt, ResultSet rs) {
 43         if (rs != null) {
 44             try {
 45                 rs.close();
 46             } catch (Exception e) {
 47                 e.printStackTrace();
 48             }
 49         }
 50     
 51         if (stmt != null) {
 52             try {
 53                 stmt.close();
 54             } catch (Exception e) {
 55                 e.printStackTrace();
 56             }
 57         }
 58     
 59         if (conn != null) {
 60             try {
 61                 conn.close();
 62             } catch (Exception e) {
 63                 e.printStackTrace();
 64             }
 65         }
 66     }
 67 
 68 
 69     public static int executeUpdate(String sql, Object[] param) {
 70         Connection conn = getConnection();// 创建连接
 71         PreparedStatement pstmt = null;//sql语句预处理
 72         int num = 0;
 73         
 74         try {
 75             pstmt = conn.prepareStatement(sql);
 76             if (param != null) {
 77                 for (int i = 0; i < param.length; i++) {
 78                     pstmt.setObject(i + 1, param[i]); 
 79                 }
 80             }
 81             num = pstmt.executeUpdate();
 82         } catch (SQLException e) {
 83             e.printStackTrace();
 84         } finally {
 85             closeAll(conn, pstmt, null);
 86         }
 87         return num;
 88     }
 89 
 90 //对数据库做查询处理
 91 public static void main(String[]args) {
 92     
 93         try {
 94             Connection conn=getConnection();
 95             String sql="select * from book ";
 96             PreparedStatement p=conn.prepareStatement(sql);
 97             ResultSet rs=p.executeQuery();//返回的结果集
 98     
 99             while(rs.next()) {
100                 System.out.print(rs.getInt(1)+"\t");
101                 System.out.print(rs.getString(2)+"   \t");
102                 System.out.print(rs.getString(3)+"   \t");
103                 System.out.print(rs.getString(4)+"\t");
104                 System.out.println("\n");
105             }
106             
107             //关闭连接
108             closeAll(conn,p,rs);
109             System.out.println("关闭连接");
110         } catch (Exception e) {
111             // TODO Auto-generated catch block
112             e.printStackTrace();
113         }
114     }
115 }

/*截取代码片段，修改位置就是红色标记处*/
29         <!-- pojo mapper接口 mapper.xml -->
30         <!--通用代码生成器插件 -->
31         <!--mapper接口 -->
32         <!-- ../maker-assistant-service/src/test/java -->
33         <!-- 生成mapper的日志 -->
34         <plugin type="tk.mybatis.mapper.generator.TemplateFilePlugin">
35             <property name="targetProject"
36                 value="src/main/java" />
37             <property name="targetPackage"
38                 value="net.seehope.springboot.mapper" />
39             <property name="templatePath" value="generator/mapper.ftl" />
40             <property name="mapperSuffix" value="Mapper" />
41             <property name="fileName"
42                 value="${tableClass.shortClassName}${mapperSuffix}.java" />
43         </plugin>
44 
45