Spring JDBC RowMapper接口示例

广告位

JdbcTemplate类使用org.springframework.jdbc.core.RowMapper …

JdbcTemplate类使用org.springframework.jdbc.core.RowMapper <T>接口在每行的基础上映射ResultSet的行。该接口的实现执行将每行映射到结果对象的实际工作。如果抛出SQLExceptions将被调用的JdbcTemplate捕获和处理。

接口的声明

以下是org.springframework.jdbc.core.RowMapper<T>接口的声明 –

public interface RowMapper<T>  

用法

步骤1 – 使用配置的数据源创建一个JdbcTemplate对象。步骤2 – 创建一个实现RowMapper接口的StudentMapper对象。步骤3 – 使用JdbcTemplate对象方法在使用StudentMapper对象时进行数据库操作。

实例

以下示例将演示如何使用spring jdbc进行读取查询。使用StudentMapper对象将读取记录从student表映射到Student对象。

语法

String SQL = "select * from Student";  List <Student> students = jdbcTemplateObject.query(SQL,      new StudentMapper());  

在上面示例(语法)代码中 –

  • SQL – 选择查询语句来来读取学生记录信息。
  • jdbcTemplateObjectStudentJDBCTemplate对象从数据库中读取Student对象。
  • StudentMapperStudentMapper对象将学生记录映射到Student对象。

实例项目

要了解上述与Spring JDBC相关的概念,下面我们编写一个使用Mapper对象来读取查询并映射结果到Student对象。打开Eclipse IDE,并按照以下步骤创建一个Spring应用程序,这里创建一个名称为:RowMapper 的项目。

步骤说明

  1. 参考第一个Spring JDBC项目来创建一个Maven项目 –
  2. 更新bean配置并运行应用程序。

完整的项目结构如下所示 –

Spring JDBC RowMapper接口示例

以下是Maven配置文件:pom.xml的代码内容:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"      xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">      <modelVersion>4.0.0</modelVersion>      <groupId>com.yiibai</groupId>      <artifactId>RowMapper</artifactId>      <version>0.0.1-SNAPSHOT</version>      <packaging>jar</packaging>      <name>RowMapper</name>      <url>http://maven.apache.org</url>      <dependencies>          <dependency>              <groupId>junit</groupId>              <artifactId>junit</artifactId>              <version>3.8.1</version>              <scope>test</scope>          </dependency>          <dependency>              <groupId>mysql</groupId>              <artifactId>mysql-connector-java</artifactId>              <version>5.1.40</version>          </dependency>          <dependency>              <groupId>org.springframework</groupId>              <artifactId>spring-jdbc</artifactId>              <version>4.1.0.RELEASE</version>          </dependency>          <dependency>              <groupId>org.springframework</groupId>              <artifactId>spring-context</artifactId>              <version>4.1.4.RELEASE</version>          </dependency>      </dependencies>  </project>  

以下是数据访问对象接口文件:StudentDAO.java的内容:

package com.yiibai;    import java.util.List;  import javax.sql.DataSource;    public interface StudentDAO {      /**       * This is the method to be used to initialize database resources ie.       * connection.       */      public void setDataSource(DataSource ds);        /**       * This is the method to be used to list down all the records from the       * Student table.       */      public List<Student> listStudents();      public Student getStudent(Integer id);      public void create(String name, Integer age);  }  

以下是文件:Student.java的代码内容:

package com.yiibai;    public class Student {      private Integer age;      private String name;      private Integer id;        public void setAge(Integer age) {          this.age = age;      }        public Integer getAge() {          return age;      }        public void setName(String name) {          this.name = name;      }        public String getName() {          return name;      }        public void setId(Integer id) {          this.id = id;      }        public Integer getId() {          return id;      }  }  

以下是文件:StudentMapper.java的代码内容:

package com.yiibai;    import java.sql.ResultSet;  import java.sql.SQLException;  import org.springframework.jdbc.core.RowMapper;    public class StudentMapper implements RowMapper<Student> {      public Student mapRow(ResultSet rs, int rowNum) throws SQLException {          Student student = new Student();          student.setId(rs.getInt("id"));          student.setName(rs.getString("name"));          student.setAge(rs.getInt("age"));          return student;      }  }  

实现类StudentJDBCTemplate.java实现了定义的DAO接口 – StudentDAO.java,以下是文件:StudentJDBCTemplate.java的代码内容:

package com.yiibai;    import java.util.List;  import java.util.ArrayList;  import javax.sql.DataSource;    import org.springframework.dao.DataAccessException;  import org.springframework.jdbc.core.JdbcTemplate;  import org.springframework.jdbc.core.PreparedStatementSetter;  import org.springframework.jdbc.core.ResultSetExtractor;    import java.sql.PreparedStatement;  import java.sql.ResultSet;  import java.sql.SQLException;    public class StudentJDBCTemplate implements StudentDAO {      private DataSource dataSource;      private JdbcTemplate jdbcTemplateObject;        public void setDataSource(DataSource dataSource) {          this.dataSource = dataSource;          this.jdbcTemplateObject = new JdbcTemplate(dataSource);      }        public List<Student> listStudents() {          String SQL = "select * from Student";          List<Student> students = jdbcTemplateObject.query(SQL, new StudentMapper());          return students;      }        public void create(String name, Integer age) {          // TODO Auto-generated method stub          String insertQuery = "insert into student (name, age) values (?, ?)";            jdbcTemplateObject.update(insertQuery, name, age);          System.out.println("Created Record Name = " + name + " Age = " + age);          return;      }        public Student getStudent(final Integer id) {          final String SQL = "select * from Student where id = ? ";          List<Student> students = jdbcTemplateObject.query(SQL, new PreparedStatementSetter() {              public void setValues(PreparedStatement preparedStatement) throws SQLException {                  preparedStatement.setInt(1, id);              }          }, new StudentMapper());          return students.get(0);      }  }  

以下是文件:MainApp.java的代码内容:

package com.yiibai;    import java.util.ArrayList;  import java.util.List;    import org.springframework.context.ApplicationContext;  import org.springframework.context.support.ClassPathXmlApplicationContext;  import com.yiibai.StudentJDBCTemplate;    public class MainApp {      public static void main(String[] args) {          ApplicationContext context = new ClassPathXmlApplicationContext("application-beans.xml");            StudentJDBCTemplate studentJDBCTemplate = (StudentJDBCTemplate) context.getBean("studentJDBCTemplate");            System.out.println("------Records Creation--------");          studentJDBCTemplate.create("Maxsu", 21);          studentJDBCTemplate.create("Curry", 22);          studentJDBCTemplate.create("Suzend", 23);            System.out.println("------Listing Multiple Records--------");          List<Student> students = studentJDBCTemplate.listStudents();          for (Student record : students) {              System.out.print("ID : " + record.getId());              System.out.print(", Name : " + record.getName());              System.out.println(", Age : " + record.getAge());          }      }  }  

以下是文件:application-beans.xml的代码内容:

<?xml version="1.0" encoding="UTF-8"?>  <beans xmlns="http://www.springframework.org/schema/beans"      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"      xsi:schemaLocation="http://www.springframework.org/schema/beans      http://www.springframework.org/schema/beans/spring-beans-3.0.xsd ">        <!-- Initialization for data source -->      <bean id="dataSource"          class="org.springframework.jdbc.datasource.DriverManagerDataSource">          <property name="driverClassName" value="com.mysql.jdbc.Driver" />          <property name="url" value="jdbc:mysql://localhost:3306/test?characterEncoding=utf8&useSSL=true" />          <property name="username" value="root" />          <property name="password" value="123456" />      </bean>        <!-- Definition for studentJDBCTemplate bean -->      <bean id="studentJDBCTemplate" class="com.yiibai.StudentJDBCTemplate">          <property name="dataSource" ref="dataSource" />      </bean>    </beans>  

注意: application-beans.xml 文件的位置是:{workspace}/fistapp/src/main/java 目录,如果放置错了,程序可能会因为找不到此配置文件而出错。

完成创建源代码和bean和数据库连接信息的文件配置后,运行应用程序。这里先简单说明一下运行的步骤,在项目名称(RowMapper)上点击右键,在弹出的菜单中选择:【Run As】-> 【Maven test】

在运行测试成功后,应该会输出类似以下内容(含有 BUILD SUCCESS 的信息) 。接下来,点击类文件:MainApp.java 选择【Run As】->【Java Application】,如果应用程序一切正常,这将打印以下结果:

------Records Creation--------  Created Record Name = Maxsu Age = 21  Created Record Name = Curry Age = 22  Created Record Name = Suzend Age = 23  ------Listing Multiple Records--------  ID : 1, Name : Maxsu, Age : 21  ID : 2, Name : Curry, Age : 22  ID : 3, Name : Suzend, Age : 23  

贺, 贺朝

关于作者: 贺朝

为您推荐