Java Database Access Summary

1. JDBC Access method

DBHelper class Access database, DAO class write data access, view class to apply, a beginner instance book management system.

package util;import Java.sql.connection;import Java.sql.drivermanager;public class DBHelper {private static Connection conn;private static final String dburl= "Jdbc:mysql://localhost:3306/db_book?    Useunicode=true&characterencoding=utf-8 ";    private static final String dbuser= "root";    private static final String dbpass= "root";        private static final String driver= "Com.mysql.jdbc.Driver";    static {try {Class.forName (DRIVER)} catch (ClassNotFoundException e) {//TODO auto-generated catch block E.printstacktrace ();} } private DBHelper () {} public static Connection getconnection () throws Exception {if (c    Onn==null) {conn=drivermanager.getconnection (Dburl, DBuser, Dbpass);        }return Conn;    public static void Closeconn () throws Exception {if (conn!=null) {conn.close (); }    }}

Package Dao;import java.sql.connection;import java.sql.preparedstatement;import java.sql.resultset;import util. Strutil;import model. Book;public class Bookdao {public int addbook (Connection Conn,book bk) throws exception{string sql= ' insert into T_book val UEs (null,?,?,?,?,?,?) "; PreparedStatement psmt=conn.preparestatement (SQL);p smt.setstring (1, Bk.getbookname ());p smt.setstring (2, Bk.getauthor ());p smt.setstring (3, Bk.getsex ());p smt.setstring (4, Bk.getpublisher ());p smt.setstring (5, Bk.getbookdes ());p Smt.setint (6, Bk.getbooktypeid ()); return psmt.executeupdate (); public int Delbook (Connection Conn,book bk) throws exception{string sql= "Delete from T_book where id = '" +bk.getid () + "'";P Reparedstatement psmt=conn.preparestatement (SQL); return psmt.executeupdate ();} public int bookmodify (Connection Con,book bk) throws exception{string sql= "update t_booktype set booktypename=?, Booktypedes=? where id=? "; PreparedStatement pstmt=con.preparestatement (SQL);p stmt.setstring (1, Bk.getbookname ());p Stmt.setstrING (2, bk.getbookdes ());p Stmt.setint (3, Bk.getid ()); return pstmt.executeupdate (); Public ResultSet Booklist (Connection con,book book) throws Exception{stringbuffer sb=new stringbuffer ("Select T_book.id , T_book.bookname,t_book.author,t_book.sex,t_book.publisher,t_book.bookdes,t_booktype.booktypename from T_book,t_ BookType WHERE t_book.booktypeid=t_booktype.id "), if (Strutil.isnotempty (Book.getbookname ())) {Sb.append (" and BookName like '% ' +book.getbookname () + "% '");} if (Strutil.isnotempty (Book.getauthor ())) {Sb.append ("and author like '%" +book.getauthor () + "% '");} if (Strutil.isnotempty (Book.getsex ())) {sb.append ("and sex = '" +book.getsex () + "'");} if (Book.getbooktypeid ()!=-1) {sb.append ("and Booktypeid =" +book.getbooktypeid ());} PreparedStatement pstmt=con.preparestatement (sb.tostring ()); return Pstmt.executequery ();} Public ResultSet Booklistall (Connection con,book book) throws Exception{stringbuffer sb=new stringbuffer ("Select T_ Book.id,t_book.bookname,t_book.author,t_book.sex,t_book.publisher,t_boOk.bookdes,t_booktype.booktypename from T_book,t_booktype WHERE t_book.booktypeid=t_booktype.id "); PreparedStatement pstmt=con.preparestatement (sb.tostring ()); return Pstmt.executequery ();} public boolean Getbookbybooktypeid (Connection con,string booktypeid) throws exception{string sql= "select * from T_book where booktypeid=? "; PreparedStatement pstmt=con.preparestatement (SQL);p stmt.setstring (1, Booktypeid); ResultSet rs=pstmt.executequery (); return Rs.next ();}}

2, still is the JDBC method, the DAO class uses the simple template method practiced hand the instance source code management system

Package Dao;import Java.sql.connection;import Java.sql.preparedstatement;import java.sql.resultset;import Java.util.arraylist;import java.util.list;import util. Dbhelper;interface Rowmapimpl {abstract Object Rowmap (ResultSet rs) throws Exception;abstract list<object> Rowmaplist (ResultSet rs) throws Exception;} public class Basedao implements Rowmapimpl {public Object query (String sql, object[] args, Rowmapimpl Rowmapimpl) throws Ex ception {Connection conn = null; PreparedStatement PS = null; ResultSet rs = Null;conn = Dbhelper.getconnection ();p s = conn.preparestatement (sql); for (int i = 0; i < args.length; i+ +) Ps.setobject (i + 1, args[i]); rs = Ps.executequery (); Object obj = Null;if (Rs.next ()) {obj = Rowmapimpl.rowmap (rs);} return obj;} Public list<object> querylist (String sql, object[] Args,rowmapimpl Rowmapimpl) throws Exception {Connection conn = n Ull PreparedStatement PS = null; ResultSet rs = null; list<object> list = Null;conn = Dbhelper.getconnection ();p s = conn.prepArestatement (SQL); for (int i = 0; i < args.length; i++) Ps.setobject (i + 1, args[i]); rs = Ps.executequery (); list = new A Rraylist<object> (); list = Rowmapimpl.rowmaplist (RS); return list;} public int operate (String sql, object[] args) throws Exception {Connection conn = null; PreparedStatement PS = Null;conn = Dbhelper.getconnection ();p s = conn.preparestatement (sql); for (int i = 0; i < Args.le Ngth; i++) Ps.setobject (i + 1, args[i]); return ps.executeupdate ();} @Overridepublic Object Rowmap (ResultSet rs) throws Exception {//TODO auto-generated method Stubreturn null;} @Overridepublic list<object> rowmaplist (ResultSet rs) throws Exception {//TODO auto-generated method Stubreturn nu ll;}}

Package Dao;import Java.sql.resultset;import Java.util.list;import model. Content;public class Contentdao {private Basedao template = new Basedao ();p ublic int Addtree (Content cont) throws Exceptio n {String sql = "INSERT into t_content values (?,?,?)"; O bject[] args = new object[] {Cont.getnodeid (), Cont.getcontent (), Cont.getupdatetime ()};return template.operate (SQL, args);} public int deltree (Content cont) throws Exception {String sql = "Delete from t_content where nodeid=?"; O bject[] args = new object[] {Cont.getnodeid ()};return template.operate (sql, args);} public int Updatetree (Content cont) throws Exception {String sql = "Update t_content set nodeid=?, content=?" Updatetime=? "; object[] args = new object[] {Cont.getnodeid (), Cont.getcontent (), Cont.getupdatetime ()};return template.operate (sql , args);} Public Content Findtree (string NodeId) throws Exception {String sql = "SELECT * from T_content where nodeid=?"; O bject[] args = new object[] {NodeId};object cont = template.query (SQL,args, new Rowmapimpl () {public Object Rowmap (ResultSet rs) throws Exception {Content cont = new content (); Cont.setnodeid (R S.getint ("NodeId")), Cont.setcontent (rs.getstring ("Content")), Cont.setupdatetime (rs.getstring ("UpdateTime")); Return cont;} @Overridepublic list<object> rowmaplist (ResultSet rs) throws Exception {//TODO auto-generated method stub return null;}}); Return (Content) cont;}}

3, MyBatis Access is the XML file configuration is more annoying, comfortable to use. Instance test.

Package Util;import Java.io.ioexception;import Java.io.reader;import org.apache.ibatis.io.resources;import Org.apache.ibatis.session.sqlsessionfactory;import Org.apache.ibatis.session.sqlsessionfactorybuilder;public Class DBHelper {private static sqlsessionfactory sessionfactory;private static Reader reader;private dbhelper () {}static {String resource = "util/config.xml";//load MyBatis configuration file (It also loads the associated mapping file) try {reader = Resources.getresourceasreader ( Resource);} catch (IOException e) {//TODO auto-generated catch block E.printstacktrace ();}} public static Sqlsessionfactory Getsessionfactory () throws exception{//build sqlsession factory sessionfactory = new Sqlsessionfactorybuilder (). build (reader); return sessionfactory;}}

<?xml Version= "1.0" encoding= "UTF-8"? ><! DOCTYPE Mapper Public "-//mybatis.org//dtd mapper 3.0//en" "Http://mybatis.org/dtd/mybatis-3-mapper.dtd" > < Mapper Namespace= "DAO. Userdao "> <select id=" getUser "parametertype=" int "resulttype=" User ">select * from T_user where id=#{id}</ Select><select id= "Getalluser" resulttype= "User" >select * from T_user</select><delete id= " DeleteUser "parametertype=" int ">delete from T_user where id=#{id}</delete><update id=" UpdateUser " Parametertype= "User" >update T_user set Username=#{username}, Password=#{password} where id=#{id}</update> <insert id= "Insertuser" parametertype= "User" >insert into T_user (Username,password) VALUES (#{username},#{ password}) </insert></mapper> 

Package Dao;import Java.util.list;import model. User;public interface Userdao {public User getUser (int i);p ublic list<user> getalluser ();p ublic int Insertuser ( User u);p ublic int UpdateUser (user u);p ublic int deleteuser (int i);}

public static void Main (string[] args) throws Exception {    sqlsession session=dbhelper.getsessionfactory (). Opensession (true);    Userdao Userdao=session.getmapper (Userdao.class); User User=userdao.getuser (1); System.out.println (User.getusername ());}

Java Database Access Summary