Android Studio连接数据库实现增删改查
源代码如下:
DBUtil.java:
package dao; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import java.sql.PreparedStatement; public class DBUtil { public static String db_url = "jdbc:mysql://localhost:3306/test?useSSL=false&characterEncoding=UTF-8&serverTimezone=GMT"; public static String db_user = "root"; public static String db_pass = "root"; public static Connection getConn () { Connection conn = null; try { Class.forName("com.mysql.cj.jdbc.Driver"); conn = DriverManager.getConnection(db_url, db_user, db_pass); } catch (Exception e) { e.printStackTrace(); } return conn; } public static void close (Statement state, Connection conn) { if (state != null) { try { state.close(); } catch (SQLException e) { e.printStackTrace(); } } if (conn != null) { try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } } public static void close (ResultSet rs, Statement state, Connection conn) { if (rs != null) { try { rs.close(); } catch (SQLException e) { e.printStackTrace(); } } if (state != null) { try { state.close(); } catch (SQLException e) { e.printStackTrace(); } } if (conn != null) { try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } } }
Add.java:
package add; import java.sql.Connection; import java.sql.Statement; import dao.DBUtil; public class Add { public static boolean add(String table, AddService user ) { String sql = "insert into "+table+"(username,password)values('" + user.getUsername() + "','" + user.getPassword() + "')"; Connection conn = DBUtil.getConn(); Statement state = null; boolean f = false; int a = 0; try { state = conn.createStatement(); a = state.executeUpdate(sql); } catch (Exception e) { e.printStackTrace(); } finally { DBUtil.close(state, conn); } if (a > 0) { f = true; } return f; } }
AddService.java:
package add; public class AddService { String username; String password; public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public static void main(String args[]){ AddService user=new AddService(); user.setUsername("123"); user.setPassword("456"); Add test=new Add(); test.add("user1",user); } }
Delete.java:
package delete; import java.sql.Connection; import java.sql.Statement; import java.sql.SQLException; import dao.DBUtil; public class Delete { public boolean delete(String table,String username) { boolean c=false; Connection conn= DBUtil.getConn(); Statement state=null; String sql="delete from "+table+" where username="+username; try { state=conn.createStatement(); int num = state.executeUpdate(sql); if(num!=0) { c= true; } state.close(); conn.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } return c; } }
DeleteService.java:
package delete; public class DeleteService { String username; public void setUsername(String username) { this.username = username; } public String getUsername() { return username; } public static void main(String args[]){ DeleteService user=new DeleteService(); user.setUsername("123"); String username="'"+user.getUsername()+"'"; Delete test=new Delete(); test.delete("user1",username); } }
Change.java:
package change; import java.sql.Connection; import java.sql.SQLException; import java.sql.Statement; import dao.DBUtil; public class Change { public boolean change(String table,String lie,String lie0,String gai,String biao) { Connection conn=DBUtil.getConn(); Statement state=null; try { state=conn.createStatement(); String sql="update "+table+" set "+lie+"='"+gai+"' where "+lie0+"='"+biao+"'"; System.out.println(sql); state.executeUpdate(sql); state.close(); conn.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } return true; } }
ChangeService.java:
package change; public class ChangeService { String lie; String lie0; String gai; String biao; public String getBiao() { return biao; } public String getGai() { return gai; } public String getLie() { return lie; } public String getLie0() { return lie0; } public void setBiao(String biao) { this.biao = biao; } public void setGai(String gai) { this.gai = gai; } public void setLie(String lie) { this.lie = lie; } public void setLie0(String lie0) { this.lie0 = lie0; } public static void main(String args[]){ ChangeService user=new ChangeService(); user.setBiao("2"); user.setGai("xhj"); user.setLie0("username"); user.setLie("password"); Change test=new Change(); test.change("user1",user.getLie(),user.getLie0(),user.getGai(),user.getBiao()); } }
Select.java:
package select; import java.sql.Connection; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import dao.DBUtil; public class Select { public boolean select(String table) { boolean c; Connection conn=DBUtil.getConn(); Statement state=null; try { state=conn.createStatement(); String sql="select * from "+table; ResultSet rs=state.executeQuery(sql); while(rs.next()) { System.out.println(rs.getString(1)+" "+rs.getString(2)); } rs.close(); state.close(); conn.close(); } catch(Exception e) { } return true; } }
SelectService.java:
package select; public class SelectService { String table; public String getTable() { return table; } public void setTable(String table) { this.table = table; } public static void main(String[] args) { SelectService user=new SelectService(); user.setTable("user1"); Select test=new Select(); test.select(user.getTable()); } }
数据库表名:user1