1 package com.yxfyg.crud; 2  3 import java.sql.Connection; 4 import java.sql.ResultSet; 5 import java.sql.SQLException; 6 import java.sql.Statement; 7  8 import org.junit.jupiter.api.Test; 9  10 import com.yxfyg.util.JDBCUtil; 11  12 public class TestCrud { 13  14  @Test 15 public void testQuery() { 16 Connection conn = null; 17 Statement st = null; 18 ResultSet rs = null; 19 try { 20 conn = JDBCUtil.getConn(); 21 st = conn.createStatement(); 22 String sql = "select * from student"; 23 rs = st.executeQuery(sql); 24 while(rs.next()) { 25 int sno = rs.getInt("sno"); 26 String sname = rs.getString("sname"); 27 String sex = rs.getString("ssex"); 28 int sage = rs.getInt("sage"); 29 String sdept = rs.getString("sdept"); 30 System.out.println("sno="+ sno +",sname="+ sname +",sex="+ sex +",age="+ sage +",sdept=" + sdept); 31  } 32 } catch (SQLException e) { 33  e.printStackTrace(); 34 } finally { 35  JDBCUtil.release(rs, st, conn); 36  } 37  } 38  39  @Test 40 public void testInsert() { 41 Connection conn = null; 42 Statement st = null; 43 try { 44 conn = JDBCUtil.getConn(); 45 st = conn.createStatement(); 46 String sql = "insert into student values(null,‘刘文‘,‘男‘,20,‘MA‘)"; 47 //返回修改的行数 48 int result = st.executeUpdate(sql); 49 if(result > 0) { 50 System.out.println("添加成功"); 51 }else { 52 System.out.println("添加失败"); 53  } 54 } catch (SQLException e) { 55  e.printStackTrace(); 56 } finally { 57  JDBCUtil.release(st, conn); 58  } 59  } 60  61  @Test 62 public void testUpdate() { 63 Connection conn = null; 64 Statement st = null; 65 try { 66 conn = JDBCUtil.getConn(); 67 st = conn.createStatement(); 68 String sql = "update student set sname = ‘测试‘ where sno = 5"; 69 //返回修改的行数 70 int result = st.executeUpdate(sql); 71 if(result > 0) { 72 System.out.println("更新成功"); 73 }else { 74 System.out.println("更新失败"); 75  } 76 } catch (SQLException e) { 77  e.printStackTrace(); 78 } finally { 79  JDBCUtil.release(st, conn); 80  } 81  } 82  83  @Test 84 public void testDelete() { 85 Connection conn = null; 86 Statement st = null; 87 try { 88 conn = JDBCUtil.getConn(); 89 st = conn.createStatement(); 90 String sql = "delete from student where sno = 5"; 91 //返回修改的行数 92 int result = st.executeUpdate(sql); 93 if(result > 0) { 94 System.out.println("删除成功"); 95 }else { 96 System.out.println("删除失败"); 97  } 98 } catch (SQLException e) { 99  e.printStackTrace();100 } finally {101  JDBCUtil.release(st, conn);102  }103  }104 }

 1 package com.yxfyg.util; 2  3 import java.io.FileInputStream; 4 import java.io.IOException; 5 import java.io.InputStream; 6 import java.sql.Connection; 7 import java.sql.DriverManager; 8 import java.sql.ResultSet; 9 import java.sql.SQLException;10 import java.sql.Statement;11 import java.util.Properties;12 13 public class JDBCUtil {14 15 static String url = null;16 static String driverClass = null;17 18 static {19 try {20 //1.创建一个属性配置对象21 Properties properties = new Properties();22 //2.使用类加载器去读取src底下的资源文件23 InputStream is = JDBCUtil.class.getClassLoader().getResourceAsStream("jdbc.properties");24 //若使用下面这种，properties文件要位于工程根目录25 //InputStream is = new FileInputStream("jdbc.properties");26 //3.导入输入流27  properties.load(is);28 //4.读取属性29 driverClass = properties.getProperty("driverClass");30 url = properties.getProperty("url");31 } catch (IOException e) {32  e.printStackTrace();33  }34  }35 36 public static void release(ResultSet rs,Statement st,Connection conn) {37  closeRs(rs);38  closeSt(st);39  closeConn(conn);40  }41 42 public static void release(Statement st,Connection conn) {43  closeSt(st);44  closeConn(conn);45  }46 47 public static Connection getConn() {48 Connection conn = null;49 try {50  Class.forName(driverClass);51 conn = DriverManager.getConnection(url);52 } catch (Exception e) {53  e.printStackTrace();54  }55 return conn;56  }57 58 private static void closeRs(ResultSet rs) {59 try {60 if(rs != null) {61  rs.close();62  }63 }catch(SQLException e) {64  e.printStackTrace();65 }finally {66 rs = null;67  }68  }69 70 private static void closeSt(Statement st) {71 try {72 if(st != null) {73  st.close();74  }75 }catch(SQLException e) {76  e.printStackTrace();77 }finally {78 st = null;79  }80  }81 82 private static void closeConn(Connection conn) {83 try {84 if(conn != null) {85  conn.close();86  }87 }catch(SQLException e) {88  e.printStackTrace();89 }finally {90 conn = null;91  }92  }93 }

url=jdbc:mysql://localhost/mydb?user=root&password=rootdriverClass=com.mysql.jdbc.Driver