JDBC从入门到熟练(二)
【摘要】
import java.sql.*;import java.util.List;//Dao工厂类public class DaoFactory { private static String driver="com.microsoft.sqlserver.jdbc.SQLServerDriver"; private static Str...
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import java.sql.*;
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import java.util.List;
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//Dao工厂类
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public class DaoFactory {
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private static String driver="com.microsoft.sqlserver.jdbc.SQLServerDriver";
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private static String url="jdbc:sqlserver://localhost:1433;DatabaseName=News";
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private static String sql="insert userInfo values('admin','admin',getdate())";
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private static String user="sa";
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private static String pwd="sa";
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//1.公共方法是获得数据库链接对象
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public static Connection getConnection(){
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Connection con=null;
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try {
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Class.forName(driver);//加,连
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con=DriverManager.getConnection(url,user,pwd);
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} catch (ClassNotFoundException e) {
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e.printStackTrace();
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} catch (SQLException e) {
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e.printStackTrace();
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}
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return con;//非void都需要return
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}
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//2.关闭所有方法;有3个参数!,省代码了!!!
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public static void closeAll(ResultSet rs,Statement stmt,Connection con){
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try {
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if(rs!=null){
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rs.close();
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}
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if(stmt!=null){
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stmt.close();
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}
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if(con!=null){
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con.close();
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}
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} catch (SQLException e) {
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e.printStackTrace();
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}
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}
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//3.setParams,用来设置预编译语句对象的?占位符的值;
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public void setParams(PreparedStatement pstmt,Object[]params){
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if(params==null){return; }//return:直接返回，啥也不做;
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try {
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for(int i=0;i<params.length;i++){
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pstmt.setObject(i+1,params[i]);
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}
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} catch (SQLException e) {//有异常,加上去
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e.printStackTrace();
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}
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}
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//4.做公共的更新方法，可以更新所有的基本sql语句;
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public int executeUpdate(String sql,Object[]params){
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//1.声明对象;是将来工作当中省内存;
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Connection con=null;
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PreparedStatement pstmt=null;
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int count=0; //增删改受影响的行数;
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try {
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con=this.getConnection();//调用本类的方法；
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pstmt=con.prepareStatement(sql);//建对象:预编译对象,?
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setParams(pstmt,params);//调用设置?的方法，已经写过了!!!
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count=pstmt.executeUpdate();//3.执行;
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} catch (SQLException e) {
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e.printStackTrace();
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}finally{
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this.closeAll(null, pstmt, con);
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}
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return count;
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}
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//5.执行查询方法;
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public static List executeQuery(String sql, Object[] params) {
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Connection con = null;
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PreparedStatement pstmt = null;
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ResultSet rs = null;
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int colCount = 0;
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ArrayList tableList=new ArrayList();//表集合
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try {
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con = getConnection();
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pstmt = con.prepareStatement(sql);
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setParams(pstmt, params);
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rs = pstmt.executeQuery();// 执行查询，结果给rs
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ResultSetMetaData rd = rs.getMetaData();// 获得元数据
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colCount = rd.getColumnCount();
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while (rs.next()) {
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ArrayList rowList = new ArrayList();//行集合
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for (int i = 1; i <= colCount; i++) {
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rowList.add(rs.getString(i));
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}
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tableList.add(rowList);
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}
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} catch (SQLException e) {
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e.printStackTrace();
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}finally{
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closeAll(rs,pstmt,con);
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}
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return tableList;
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}
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}
Connection con = null;
PreparedStatement pstmt = null;
ResultSet rs = null;
int colCount = 0;
ArrayList tableList=new ArrayList();//表集合
try {
con = getConnection();
pstmt = con.prepareStatement(sql);
setParams(pstmt, params);
rs = pstmt.executeQuery();// 执行查询，结果给rs
ResultSetMetaData rd = rs.getMetaData();// 获得元数据
colCount = rd.getColumnCount();
while (rs.next()) {
ArrayList rowList = new ArrayList();//行集合
for (int i = 1; i <= colCount; i++) {
rowList.add(rs.getString(i));
}
tableList.add(rowList);
}
} catch (SQLException e) {
e.printStackTrace();
}finally{
closeAll(rs,pstmt,con);
}
return tableList;
}
}
DAO接口
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import java.util.List;
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//针对UserInfo的增删改查接口;
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public interface UserInfoDAO {
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public int insertUserInfo(UserInfo user); //saveXXX
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public int updateUserInfo(UserInfo user);
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public int deleteUserInfo(UserInfo user);
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public List<UserInfo>queryUserInfo();//查询学生方法
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}
//实现类
在线课堂：https://edu.csdn.net/lecturer/1516
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import java.util.List;
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public class UserInfoDAOImpl extends DaoFactory implements UserInfoDAO {
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@Override
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public int deleteUserInfo(UserInfo user) {
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return 0;
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}
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/* (non-Javadoc)
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* @see 插入方法，重写
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*/
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@Override
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public int insertUserInfo(UserInfo user) {
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int result=0;
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String sql="";
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Object[]params=;
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result=super.executeUpdate(sql, params);
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return result;
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}
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@Override
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public List<UserInfo> queryUserInfo() {
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String sql="select * from userinfo";
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List list=DaoFactory.executeQuery(sql, null);
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return list;
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}
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@Override
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public int updateUserInfo(UserInfo user) {
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return 0;
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}
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}
List list=DaoFactory.executeQuery(sql, null);
return list;
}
@Override
public int updateUserInfo(UserInfo user) {
return 0;
}
}
测试类
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package nan;
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import java.util.List;
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public class Test {
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public static void main(String[] args) {
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UserInfoDAO udd=new UserInfoDAOImpl();
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List tableList=udd.queryUserInfo();
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for(int i=0;i<tableList.size();i++){
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List rowList=(List)tableList.get(i);
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//cann't from Object to List,必须强转
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for(int j=0;j<rowList.size();j++){
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System.out.print(rowList.get(j)+"\t");
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}
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System.out.println();//每行完毕后换行
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}
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}
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}
文章来源: aaaedu.blog.csdn.net，作者：tea_year，版权归原作者所有，如需转载，请联系作者。
原文链接：aaaedu.blog.csdn.net/article/details/52875860
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