Spring JDBC NamedParameterJdbcTemplate類示例

org.springframework.jdbc.core.NamedParameterJdbcTemplate類是一個具有基本JDBC操作的模板類，允許使用命名參數而不是傳統的’?‘佔位符。 這個類代表一個包裝的JdbcTemplate，在執行時完成從命名參數佔位符替換爲JDBC樣式’?‘ 佔位符。它還允許將值列表擴展到適當數量的佔位符。

使用到的 Student 表的結構如下 -

CREATE TABLE Student(
   ID   INT NOT NULL AUTO_INCREMENT,
   NAME VARCHAR(20) NOT NULL,
   AGE  INT NOT NULL,
   DESCRIPTION LONGTEXT DEFAULT NULL,
   PRIMARY KEY (ID)
);

類的聲明

以下是org.springframework.jdbc.core.NamedParameterJdbcTemplate接口的聲明 -

public class NamedParameterJdbcTemplate
   extends Object
      implements NamedParameterJdbcOperations

語法

MapSqlParameterSource in = new MapSqlParameterSource();
in.addValue("id", id);
in.addValue("description",  new SqlLobValue(description, new DefaultLobHandler()), Types.CLOB);

String SQL = "update Student set description = :description where id = :id";
NamedParameterJdbcTemplate jdbcTemplateObject = new NamedParameterJdbcTemplate(dataSource);
jdbcTemplateObject.update(SQL, in);

在上代碼中，

• in - SqlParameterSource對象將參數傳遞給更新查詢。
• SqlLobValue - 表示SQL BLOB/CLOB值參數的對象。
• jdbcTemplateObject - NamedParameterJdbcTemplate對象來更新數據庫中的Student對象。

實例項目

要了解上述與Spring JDBC相關的概念，下面我們編寫一個使用NamedParameterJdbcTemplate來更新Student對象。打開Eclipse IDE，並按照以下步驟創建一個Spring應用程序，這裏創建一個名稱爲：NamedParameterJdbcTemplate 的項目。

步驟說明

1. 參考第一個Spring JDBC項目來創建一個Maven項目 - http://www.yiibai.com/springjdbc/first\_application.html
2. 更新bean配置並運行應用程序。

完整的項目結構如下所示 -

以下是Maven配置文件：pom.xml的代碼內容：

<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>NamedParameterJdbcTemplate</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>
    <name>NamedParameterJdbcTemplate</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>

以下是數據訪問對象接口文件：StudentDAO.java的內容：

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();

    /**
     * This is the method to be used to update a record into the Student table.
     */
    public void updateDescription(Integer id, String description);

    public void create(String name, Integer age);

}

以下是文件：Student.java的代碼內容：

package com.yiibai;

public class Student {
    private Integer age;
    private String name;
    private Integer id;
    private String description;

    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;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }
}

以下是文件：StudentMapper.java的代碼內容：

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"));
        student.setDescription(rs.getString("description"));
        return student;
    }
}

實現類StudentJDBCTemplate.java實現了定義的DAO接口 - StudentDAO.java，以下是文件：StudentJDBCTemplate.java的代碼內容：

package com.yiibai;

import java.util.List;
import javax.sql.DataSource;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.namedparam.MapSqlParameterSource;
import org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate;
import org.springframework.jdbc.core.namedparam.SqlParameterSource;
import org.springframework.jdbc.core.simple.SimpleJdbcCall;
import org.springframework.jdbc.core.support.SqlLobValue;
import org.springframework.jdbc.support.lob.DefaultLobHandler;
import java.io.ByteArrayInputStream;
import java.sql.Types;

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, description) values (?, ?, NULL)";

        jdbcTemplateObject.update(insertQuery, name, age);
        System.out.println("Created Record Name = " + name + " Age = " + age);
        return;
    }

    public void updateDescription(Integer id, String description) {

        MapSqlParameterSource in = new MapSqlParameterSource();
        in.addValue("id", id);
        in.addValue("description", new SqlLobValue(description, new DefaultLobHandler()), Types.CLOB);

        String SQL = "update Student set description = :description where id = :id";
        NamedParameterJdbcTemplate jdbcTemplateObject = new NamedParameterJdbcTemplate(dataSource);
        jdbcTemplateObject.update(SQL, in);
        System.out.println("Updated Record with ID = " + id);
    }

}

以下是文件：MainApp.java的代碼內容：

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);

        // 更新描述
        studentJDBCTemplate.updateDescription(1, "This can be a very long text upto 4 GB of size.");
        studentJDBCTemplate.updateDescription(2, "隨便寫一下描述內容......易百教程(www.yiibai.com) - 專注於IT教程和實例");

        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());
            System.out.println(", Description : " + record.getDescription());
        }
    }
}

以下是文件：application-beans.xml的代碼內容：

<?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 目錄，如果放置錯了，程序可能會因爲找不到此配置文件而出錯。

完成創建源代碼和bean和數據庫連接信息的文件配置後，運行應用程序。這裏先簡單說明一下運行的步驟，在項目名稱(NamedParameterJdbcTemplate)上點擊右鍵，在彈出的菜單中選擇：【Run As】-> 【Maven test】

在運行測試成功後，應該會輸出類似以下內容(含有 BUILD SUCCESS 的信息) 。
接下來，點擊類文件：MainApp.java 選擇【Run As】->【Java Application】，如果應用程序一切正常，這將打印以下結果：

------Records Creation--------
Created Record Name = Maxsu Age = 21
Created Record Name = Curry Age = 22
Created Record Name = Suzend Age = 23
Updated Record with ID = 1
Updated Record with ID = 2
------Listing Multiple Records--------
ID : 1, Name : Maxsu, Age : 21
, Description : This can be a very long text upto 4 GB of size.
ID : 2, Name : Curry, Age : 22
, Description : 隨便寫一下描述內容......易百教程(www.yiibai.com) - 專注於IT教程和實例
ID : 3, Name : Suzend, Age : 23
, Description : null