如何新建一个类调用以下这个类并操纵数据库import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;public class MyBean {
private String url = "jdbc:mysql://localhost:3306/zcjdb";
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
public MyBean() {
System.out.println("开始初始化 ");
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection(url,"root","123456");
System.out.println("初始化完成");
} catch (Exception e) {
System.out.println("初始化错误 ");
e.printStackTrace();
}
}
public ArrayList SelectBySQL(String SQLString) throws SQLException {
java.util.ArrayList myList=new java.util.ArrayList ();
try {
//conn = DriverManager.getConnection(url);
System.out.println("conn");
String QueryString = "SELECT * FROM testtab " + SQLString;
System.out.println(QueryString);
ps = conn.prepareStatement(QueryString);
rs = ps.executeQuery();
while (rs.next()) {
String row[]=new String[3];
row[0] = rs.getString("id");
row[1] = rs.getString("name");
row[2] = rs.getString("description");
myList.add(row);
}
} catch (SQLException e) {
System.out.println("Exception appear in Select");
e.printStackTrace();
throw e;
} finally {
try {
rs.close();
ps.close();
//conn.close();
} catch (Exception e) {
e.printStackTrace();
}
}
return myList;
}
public String InsertBySQL(String SQLString) {
System.out.println("Entering InsertBySQL()");
String judgement = null;
try{
//conn = DriverManager.getConnection("url", "root","123456");
String QueryString=SQLString;
ps=conn.prepareStatement(QueryString);
ps.executeUpdate();
System.out.println("InsertString is "+QueryString);
}catch(SQLException e){
System.out.println("Exception appear in InsertBySQL()"+e);
e.printStackTrace();
return judgement = "repeat";
}
finally{
try {
ps.close();
//conn.close();
} catch (Exception e) {
e.printStackTrace();
}
}
System.out.println("Leaving InsertBySQL()");
return judgement = "success";
}
public String UpdateBySQL(String SQLString) {
System.out.println("Entering UserManDaoImpl.UpdateBySQL()");
String judgement = null;
try{
//conn = DriverManager.getConnection("url", "root","123456");
String QueryString=SQLString;
ps=conn.prepareStatement(QueryString);
ps.executeUpdate();
System.out.println("UpdateString is "+QueryString);
}catch(Exception e){
System.out.println("Exception appear in UserManDaoImpl.UpdateBySQL()"+e);
e.printStackTrace();
return judgement = "repeat";
}
finally{
try {
ps.close();
//conn.close();
} catch (Exception e) {
e.printStackTrace();
}
}
System.out.println("Leaving UserManDaoImpl.UpdateBySQL()");
return judgement = "success";
}
public String DeleteBySQL(String SQLString) {
System.out.println("Entering DeleteBySQL()");
String judgement = null;
try{
String QueryString=SQLString;
ps=conn.prepareStatement(QueryString);
int count=ps.executeUpdate();
if(count==0){
return judgement = "repeat";
}
}
catch(SQLException e){
System.out.println("Exception appear in UserManDaoImpl.DeleteBySQL()"+e);
e.printStackTrace();
return judgement = "repeat";
}
finally{
try{
ps.close();
//conn.close();
}
catch(Exception e){
}
}
System.out.println("Leaving UserManDaoImpl.DeleteBySQL()");
return judgement = "success";
}
public void close(){
try {
conn.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}}
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;public class MyBean {
private String url = "jdbc:mysql://localhost:3306/zcjdb";
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
public MyBean() {
System.out.println("开始初始化 ");
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection(url,"root","123456");
System.out.println("初始化完成");
} catch (Exception e) {
System.out.println("初始化错误 ");
e.printStackTrace();
}
}
public ArrayList SelectBySQL(String SQLString) throws SQLException {
java.util.ArrayList myList=new java.util.ArrayList ();
try {
//conn = DriverManager.getConnection(url);
System.out.println("conn");
String QueryString = "SELECT * FROM testtab " + SQLString;
System.out.println(QueryString);
ps = conn.prepareStatement(QueryString);
rs = ps.executeQuery();
while (rs.next()) {
String row[]=new String[3];
row[0] = rs.getString("id");
row[1] = rs.getString("name");
row[2] = rs.getString("description");
myList.add(row);
}
} catch (SQLException e) {
System.out.println("Exception appear in Select");
e.printStackTrace();
throw e;
} finally {
try {
rs.close();
ps.close();
//conn.close();
} catch (Exception e) {
e.printStackTrace();
}
}
return myList;
}
public String InsertBySQL(String SQLString) {
System.out.println("Entering InsertBySQL()");
String judgement = null;
try{
//conn = DriverManager.getConnection("url", "root","123456");
String QueryString=SQLString;
ps=conn.prepareStatement(QueryString);
ps.executeUpdate();
System.out.println("InsertString is "+QueryString);
}catch(SQLException e){
System.out.println("Exception appear in InsertBySQL()"+e);
e.printStackTrace();
return judgement = "repeat";
}
finally{
try {
ps.close();
//conn.close();
} catch (Exception e) {
e.printStackTrace();
}
}
System.out.println("Leaving InsertBySQL()");
return judgement = "success";
}
public String UpdateBySQL(String SQLString) {
System.out.println("Entering UserManDaoImpl.UpdateBySQL()");
String judgement = null;
try{
//conn = DriverManager.getConnection("url", "root","123456");
String QueryString=SQLString;
ps=conn.prepareStatement(QueryString);
ps.executeUpdate();
System.out.println("UpdateString is "+QueryString);
}catch(Exception e){
System.out.println("Exception appear in UserManDaoImpl.UpdateBySQL()"+e);
e.printStackTrace();
return judgement = "repeat";
}
finally{
try {
ps.close();
//conn.close();
} catch (Exception e) {
e.printStackTrace();
}
}
System.out.println("Leaving UserManDaoImpl.UpdateBySQL()");
return judgement = "success";
}
public String DeleteBySQL(String SQLString) {
System.out.println("Entering DeleteBySQL()");
String judgement = null;
try{
String QueryString=SQLString;
ps=conn.prepareStatement(QueryString);
int count=ps.executeUpdate();
if(count==0){
return judgement = "repeat";
}
}
catch(SQLException e){
System.out.println("Exception appear in UserManDaoImpl.DeleteBySQL()"+e);
e.printStackTrace();
return judgement = "repeat";
}
finally{
try{
ps.close();
//conn.close();
}
catch(Exception e){
}
}
System.out.println("Leaving UserManDaoImpl.DeleteBySQL()");
return judgement = "success";
}
public void close(){
try {
conn.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}}
表 user
字段有 id name
方法都写好了就是不会用
如何新建一个类调用以下这个类并操纵数据库import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;public class MyBean {
private String url = "jdbc:mysql://localhost:3306/zcjdb";
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;public MyBean() {
System.out.println("开始初始化 ");
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection(url,"root","123456");
System.out.println("初始化完成");
} catch (Exception e) {
System.out.println("初始化错误 ");
e.printStackTrace();
}
}public ArrayList SelectBySQL(String SQLString) throws SQLException {
java.util.ArrayList myList=new java.util.ArrayList ();
try {
//conn = DriverManager.getConnection(url);
System.out.println("conn");
String QueryString = "SELECT * FROM testtab " + SQLString;
System.out.println(QueryString);
ps = conn.prepareStatement(QueryString);
rs = ps.executeQuery();
while (rs.next()) {
String row[]=new String[3];
row[0] = rs.getString("id");
row[1] = rs.getString("name");
row[2] = rs.getString("description");
myList.add(row);
}
} catch (SQLException e) {
System.out.println("Exception appear in Select");
e.printStackTrace();
throw e;
} finally {
try {
rs.close();
ps.close();
//conn.close();
} catch (Exception e) {
e.printStackTrace();
}
}return myList;
}
public String InsertBySQL(String SQLString) {
System.out.println("Entering InsertBySQL()");
String judgement = null;
try{
//conn = DriverManager.getConnection("url", "root","123456");
String QueryString=SQLString;
ps=conn.prepareStatement(QueryString);
ps.executeUpdate();
System.out.println("InsertString is "+QueryString);
}catch(SQLException e){
System.out.println("Exception appear in InsertBySQL()"+e);
e.printStackTrace();
return judgement = "repeat";
}
finally{
try {
ps.close();
//conn.close();
} catch (Exception e) {
e.printStackTrace();
}
}
System.out.println("Leaving InsertBySQL()");
return judgement = "success";
}public String UpdateBySQL(String SQLString) {
System.out.println("Entering UserManDaoImpl.UpdateBySQL()");
String judgement = null;
try{
//conn = DriverManager.getConnection("url", "root","123456");
String QueryString=SQLString;
ps=conn.prepareStatement(QueryString);
ps.executeUpdate();
System.out.println("UpdateString is "+QueryString);
}catch(Exception e){
System.out.println("Exception appear in UserManDaoImpl.UpdateBySQL()"+e);
e.printStackTrace();
return judgement = "repeat";
}
finally{
try {
ps.close();
//conn.close();
} catch (Exception e) {
e.printStackTrace();
}
}
System.out.println("Leaving UserManDaoImpl.UpdateBySQL()");
return judgement = "success";
}public String DeleteBySQL(String SQLString) {
System.out.println("Entering DeleteBySQL()");
String judgement = null;
try{
String QueryString=SQLString;
ps=conn.prepareStatement(QueryString);
int count=ps.executeUpdate();
if(count==0){
return judgement = "repeat";
}
}
catch(SQLException e){
System.out.println("Exception appear in UserManDaoImpl.DeleteBySQL()"+e);
e.printStackTrace();
return judgement = "repeat";
}
finally{
try{
ps.close();
//conn.close();
}
catch(Exception e){
}
}
System.out.println("Leaving UserManDaoImpl.DeleteBySQL()");
return judgement = "success";
} public void close(){
try {
conn.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
这些写的很冗余。直到MVC 吗 把驱动和需要带调用的单独放。//conn = DriverManager.getConnection(url); 你都注视掉了 我怀疑能练到数据库库不?????