如何在没有任何ORM（JPA / Hibernate）的Java数据库应用程序中管理数据库层？

Question

我愿意以后学习ORM。但现在我想使用纯SQL代码来管理我的Java Web应用程序的数据层，并且不希望任何类似ORM的框架。它的最佳方法或实践是什么？

Answer 1

建议尝试Spring-JDBC。它很容易启动和用户。见下面的例子。

Spring JDBC

来自documentation：

  

以下是获取关系中行数的简单查询：

不要忘记应该注射jdbcTemplate。

int rowCount = jdbcTemplate.queryForObject("select count(*) from t_actor", Integer.class);

jOOQ

来自documentation：

使用下面的SQL：

SELECT * FROM BOOK
   WHERE BOOK.PUBLISHED_IN = 2011
ORDER BY BOOK.TITLE

java jOOQ使用create.selectFrom(BOOK) .where(BOOK.PUBLISHED_IN.eq(2011)) .orderBy(BOOK.TITLE) ：

SQL

两者都很方便。但是关于 pure Spring JDBC的使用 - 我建议开始使用JDBC。

声明

如果你正在开始你的道路 - 强烈建议开始使用普通的public class Student { private String name; private int rollNo; Student(String name, int rollNo){ this.name = name; this.rollNo = rollNo; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getRollNo() { return rollNo; } public void setRollNo(int rollNo) { this.rollNo = rollNo; } } ，以便熟悉框架内部运行的样板代码。

DAO＆amp; DTO

DAO （数据访问对象）是一个通常具有 CRUD （创建，读取，更新，删除）操作的类 - 保存，阅读，更新，删除。

DTO （数据传输对象）只是一个包含数据的对象。它是一个带有实例变量和setter和getter的JavaBean。通常是传递给DAO的save方法的DTO。

实施例

<强> Student.java

public interface StudentDao {
   List<Student> getAllStudents();
   Student getStudent(int rollNo);
   void updateStudent(Student student);
   void deleteStudent(Student student);
}

<强> StudentDao.java

public class StudentDaoImpl implements StudentDao {
    //list is working as a database
   private static final List<Student> students;

   public StudentDaoImpl() {
      students = new ArrayList<Student>();
      students.add(new Student("Student 0", 0));
      students.add(new Student("Student 1", 1));        
   }

   @Override
   public void deleteStudent(Student student) {
      students.remove(student.getRollNo());
      System.out.println("Student: Roll No " + student.getRollNo() + ", deleted from database");
   }

   @Override
   public List<Student> getAllStudents() {
      return students;
   }

   @Override
   public Student getStudent(int rollNo) {
      return students.get(rollNo);
   }

   @Override
   public void updateStudent(Student student) {
      Student foundStudent = students.get(student.getRollNo())
      foundStudent.setName(student.getName());
      System.out.println("Student: Roll No " + student.getRollNo() + ", updated in the database");
   }
}

<强> StudentDaoImpl.java

public class DaoPatternDemo {
   public static void main(String[] args) {
      StudentDao studentDao = new StudentDaoImpl();

      for (Student student : studentDao.getAllStudents()) {
         System.out.println("Student: [RollNo : " + student.getRollNo() + ", Name : " + student.getName() + " ]");
      }

      Student student = studentDao.getAllStudents().get(0);
      student.setName("Michael"); // here student is our DTO because we are
                                  // passing it into our DAO
      studentDao.updateStudent(student);

      studentDao.getStudent(0);
      System.out.println("Student: [RollNo : " + student.getRollNo() + ", Name : " + student.getName() + " ]");      
   }
}

<强> DaoPatternDemo.java

<?php
require_once '../PHPWord.php';

// New Word Document
$PHPWord = new PHPWord();

// New portrait section
$section = $PHPWord->createSection();

// Add hyperlink elements
$section->addLink('http://www.google.com', 'Best search engine', array('color'=>'0000FF', 'underline'=>PHPWord_Style_Font::UNDERLINE_SINGLE));
$section->addTextBreak(2);
$PHPWord->addLinkStyle('myOwnLinkStyle', array('bold'=>true, 'color'=>'808000'));
$section->addLink('http://www.bing.com', null, 'myOwnLinkStyle');
$section->addLink('http://www.yahoo.com', null, 'myOwnLinkStyle');


// Save File
$objWriter = PHPWord_IOFactory::createWriter($PHPWord, 'Word2007');
$objWriter->save('Link.docx');
?>

要了解详情，请访问此resource。