Hibernate 開發實例全步驟

轉載：http://blog.chinaunix.net/uid-26284395-id-3048988.html

開發順序

1 下載並安裝Hibernate

2 Hibernate配置文件詳解配置與MySQL數據庫的鏈接與映射文件User.hbm.xml

3 生成映射文件User.hbm.xml

4 編寫持久化類User.java

5 編寫輔助類HibernateSessionFactory.java 負責取得和關閉Hibernate的Session對象

6 編寫DAO類UserDAO.java 編寫根據用戶名取得用戶對象的getUser()

7 編寫Service類UserService.java 編寫valid()函數調用UserDAO.java的getUser()函數執行函數驗證

1 下載並安裝Hibernate

下載hibernate-3.0.zip 將hibernate3.zip文件和lib下的所有文件都複製到新建的HibernateTest項目的lib子目錄下

MySQL數據庫的驅動文件複製到lib子目錄下

2 hibernate.cfg.xml配置文件

<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="myeclipse.connection.profile">
JDBC for MySQL
</property>
<property name="connection.url">
jdbc:mysql://localhost:3306/demo
</property>
<property name="connection.username">root</property>
<property name="connection.password">root</property>
<property name="connection.driver_class">
org.gjt.mm.mysql.Driver
</property>
<property name="dialect">
org.hibernate.dialect.MySQLDialect
</property>
<mapping resource="com/demo/hibernate/beans/User.hbm.xml" />
</session-factory>
</hibernate-configuration>

使用XML文件進行配置時指定Java類與數據庫表格的映射文件位置 XML配置文件的位置必須在CLASSPATH的設定中 Web程式的WEB-INF/classes中我們使用下面的方式讀入XML文件以配置Hibernate

SessionFactory sf = new Configuration().configure().buildSessionFactory();

Configuration表示Java類與數據庫表格映射的集合用於之後建立SessionFactory 之後Configuration就不再起作用了預設的XML文件名稱是hibernate.cfg.xml你也可以指定文件的名稱

壓縮包Hibernate-3.0.zip壓縮包的etc子目錄下提供默認的Hibernate配置文件hibernate.cfg.xml 我們要在HibernateTest中使用XML的配置文件因此請複製該文件到HibernateTest項目的src目錄下並添加MySQL的相關配置項這樣 HibernateTest就支持Hibernate了

3 編寫映射文件 User.hbm.xml

Hibernate映射文件包含了對象/關係映射所需的元數據元數據包含持久化類的聲明和屬性到數據庫的映射

映射文件是XML格式的文件它負責持久化類與數據庫表之間的映射其根目錄是hibernate-mapping 並通過屬性package指定類所在的包每一個表使用一個class定義那麼表示類的名稱 table表示關聯的表明通過property子元素來映射類的變量名與數據庫表字段名之間的映射關係

在這個HibernateTest項目中我們建立一個映射文件User.hbm.xml來映射到數據表user 映射的類名爲User 所在的包爲com.demo.hibernate.beans

<?xml version="1.0" encoding='UTF-8'?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >
<hibernate-mapping package="com.demo.hibernate.beans">
<class name="User" table="user">
<id name="id" column="ID" type="integer">
<generator class="native"/>
</id>
<property name="username" column="username" type="string" />
<property name="password" column="password" type="string" />
<property name="email" column="email" type="string" />
</class>
</hibernate-mapping>

4 編寫持久化類User.java

持久化類是指其實例需要被Hibernate持久化到數據庫中的類持久化通常是與模型中的實體域類一般都是一張數據表對應一個持久化類不能認爲所有的持久化類的實例都是持久的狀態一個實例的狀態也可能是瞬時的或脫管的。

在HibernateTest示例程序中包含了一個持久化類User.java 該類包含表User的4個字段對應的變量這些變量都申明爲private類型的

package com.demo.hibernate.beans;
public class User {
private java.lang.Integer id;
private java.lang.String username;
private java.lang.String password;
private java.lang.String email;
public java.lang.String getEmail() {
return email;
}
public void setEmail(java.lang.String email) {
this.email = email;
}
public java.lang.Integer getId() {
return id;
}
public void setId(java.lang.Integer id) {
this.id = id;
}
public java.lang.String getPassword() {
return password;
}
public void setPassword(java.lang.String password) {
this.password = password;
}
public java.lang.String getUsername() {
return username;
}
public void setUsername(java.lang.String username) {
this.username = username;
}
}

5 編寫輔助類 HibernateSessionFactory.java

Hibernate的Session 這是一個持久化管理器通過它從數據庫中存取User

首先我們要從SessionFactory中獲取一個Session

SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();

通過對configure()的調用來轉載hibernate.cfg.xml配置文件並初始化成一個Configuration實例在創建SessionFactory之前可以訪問Configuration來設置其他屬性

SessionFactory應該設置成單例模式這樣才能在程序中容易地訪問SessionFactory

程序代碼如下

package com.demo.hibernate.util;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.cfg.Configuration;
/**
* Configures and provides access to Hibernate sessions, tied to the
* current thread of execution. Follows the Thread Local Session
* pattern, see {@link http://hibernate.org/42.html}.
*/
public class HibernateSessionFactory {
/**
* Location of hibernate.cfg.xml file.
* NOTICE: Location should be on the classpath as Hibernate uses
* #resourceAsStream style lookup for its configuration file. That
* is place the config file in a Java package - the default location
* is the default Java package.
* Examples:
* CONFIG_FILE_LOCATION = "/hibernate.conf.xml".
* CONFIG_FILE_LOCATION = "/com/foo/bar/myhiberstuff.conf.xml".
*/
private static String CONFIG_FILE_LOCATION = "/hibernate.cfg.xml";
/** Holds a single instance of Session */
private static final ThreadLocal threadLocal = new ThreadLocal();
/** The single instance of hibernate configuration */
private static final Configuration cfg = new Configuration();
/** The single instance of hibernate SessionFactory */
private static org.hibernate.SessionFactory sessionFactory;
/**
* Returns the ThreadLocal Session instance. Lazy initialize
* the SessionFactory if needed.
*
* @return Session
* @throws HibernateException
*/
public static Session currentSession() throws HibernateException {
Session session = (Session) threadLocal.get();
if (session == null) {
if (sessionFactory == null) {
try {
cfg.configure(CONFIG_FILE_LOCATION);
sessionFactory = cfg.buildSessionFactory();
}
catch (Exception e) {
System.err.println("%%%% Error Creating SessionFactory %%%%");
e.printStackTrace();
}
}
session = sessionFactory.openSession();
threadLocal.set(session);
}
return session;
}
/**
* Close the single hibernate session instance.
*
* @throws HibernateException
*/
public static void closeSession() throws HibernateException {
Session session = (Session) threadLocal.get();
threadLocal.set(null);
if (session != null) {
session.close();
}
}
/**
* Default constructor.
*/
private HibernateSessionFactory() {
}
}

這個類不但在他的靜態初始器中使用了SessionFactory 還使用了了一個ThreadLocal變量來保存Session作爲當前工作線程

6 編寫DAO類UserDAO.java

所謂的DAO層就是數據訪問接口爲了基於Hibernate的開發中將業務層與數據層分開 DAO層只負責處理調用Hibernate API實現CRUD操作 Service層面向用戶負責調用DAO層的代碼這樣做的好處是數據層的代碼不用關心業務服務可以更好的實現移植

package com.demo.hibernate.dao;
import org.hibernate.HibernateException;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.Transaction;
import com.demo.hibernate.beans.User;
import com.demo.hibernate.util.HibernateSessionFactory;
public class UserDAO {
public User getUser(String username) throws HibernateException {
Session session = null;
Transaction tx = null;
User user = null;
try {
session = HibernateSessionFactory.currentSession();
tx = session.beginTransaction();
Query query = session.createQuery("from User where username=?");
query.setString(0, username.trim());
user = (User)query.uniqueResult();
query = null;
tx.commit ();
}catch(HibernateException e){
throw e;
}finally{
if (tx!=null) {
tx.rollback();
}
HibernateSessionFactory.closeSession();
}
return user;
}
}

該類實現了一個getUser()函數根據用戶名username查詢一個用戶對象在該函數中使用HibernateSessionFactory取得Session對象然後通過session執行事務創建查詢對象返回查詢的用戶對象，操作Session的代碼都是Hibernate提供的API

7 編寫Service類並運行

Service類即服務層就是面向用戶服務它定義的方法都是與實際的業務相關的

此例子中定義一個Service類UserService 他有一個函數valid() 根據用戶名和密碼來判斷用戶是否存在改函數調用DAO層的UserDAO類來取得一個用戶對象並比較該對象的密碼與輸入的密碼是否相等如果相等就返回true 否則返回false 然後編寫一個main()入口函數用戶調用valid()函數來執行業務的調用並輸出返回的結果

package com.demo.hibernate.service;
import com.demo.hibernate.beans.User;
import com.demo.hibernate.dao.UserDAO;
public class UserService {
public boolean valid(String username, String password) {
UserDAO test = new UserDAO();
User user = test.getUser("admin");
if(user.getPassword().equals(password)) {
return true;
} else {
return false;
}
}
public static void main(String[] args) {
UserService service = new UserService();
boolean login = service.valid("admin", "admin");
System.out.println("驗證結果："+login);
}
}

接下來運行 UserService.java 運行方式 Java應用程序即可運行main()函數

此處記住還要添加日誌屬性文件三個日誌屬性文件複製到Hibernate的src子目錄下即可

運行程序出現錯誤

Communication failure during handshake. Is there a server running on localhost:3306?

原因：

結果在Mysql.com的官方網站上看到這個解釋，是因爲新的Mysql的認證機制發生了一些變化造成的，解決方法如下

解決方法：

I'd to change the authentication method at the mysql server:
set password for @ = old_password('');

將紅色那部分在cmd-mysql登錄之後敲進去就解決了

假如你的用戶名密碼是root root 那麼紅色部分就是

set password for root@localhost=old_password('root');

最後正確運行的輸出信息

INFO - Hibernate 3.0.5
INFO - hibernate.properties not found
INFO - using CGLIB reflection optimizer
INFO - using JDK 1.4 java.sql.Timestamp handling
INFO - configuring from resource: /hibernate.cfg.xml
INFO - Configuration resource: /hibernate.cfg.xml
INFO - Mapping resource: com/demo/hibernate/beans/User.hbm.xml
INFO - Mapping class: com.demo.hibernate.beans.User -> user
INFO - Configured SessionFactory: null
INFO - processing extends queue
INFO - processing collection mappings
INFO - processing association property references
INFO - processing foreign key constraints
INFO - Using Hibernate built-in connection pool (not for production use!)
INFO - Hibernate connection pool size: 20
INFO - autocommit mode: false
INFO - using driver: org.gjt.mm.mysql.Driver at URL: jdbc:mysql://localhost:3306/demo
INFO - connection properties: {user=root, password=****}
INFO - RDBMS: MySQL, version: 5.5.17
INFO - JDBC driver: Mark Matthews' MySQL Driver, version: 2.0.4
INFO - Using dialect: org.hibernate.dialect.MySQLDialect
INFO - Using default transaction strategy (direct JDBC transactions)
INFO - No TransactionManagerLookup configured (in JTA environment, use of read-write or transactional second-level cache is not recommended)
INFO - Automatic flush during beforeCompletion(): disabled
INFO - Automatic session close at end of transaction: disabled
INFO - Scrollable result sets: enabled
INFO - JDBC3 getGeneratedKeys(): disabled
INFO - Connection release mode: null
INFO - Maximum outer join fetch depth: 2
INFO - Default batch fetch size: 1
INFO - Generate SQL with comments: disabled
INFO - Order SQL updates by primary key: disabled
INFO - Query translator: org.hibernate.hql.ast.ASTQueryTranslatorFactory
INFO - Using ASTQueryTranslatorFactory
INFO - Query language substitutions: {}
INFO - Second-level cache: enabled
INFO - Query cache: disabled
INFO - Cache provider: org.hibernate.cache.EhCacheProvider
INFO - Optimize cache for minimal puts: disabled
INFO - Structured second-level cache entries: disabled
INFO - Statistics: disabled
INFO - Deleted entity synthetic identifier rollback: disabled
INFO - Default entity-mode: pojo
INFO - building session factory
WARN - No configuration found. Configuring ehcache from ehcache-failsafe.xml found in the classpath: jar:file:/F:/eeeeeee/HibernateTest/WebRoot/WEB-INF/lib/ehcache-1.1.jar!/ehcache-failsafe.xml
INFO - Not binding factory to JNDI, no JNDI name configured
INFO - Checking 0 named queries
驗證結果：true

Hibernate 開發實例全步驟

Android商城項目

http編程、socket編程

Linux定時任務 Crontab命令詳解

HttpClient調用WebService（支持賬號密碼驗證）

MySQL中豎表和橫表之間的相互轉換

https://yachay.unat.edu.pe/blog/index.php?comment_area=format_blog&comment_component=blog&comment_co

linux以太網驅動總結