java csv 注入

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mob64ca14061c9e 2024-09-10 15:12:06

文章标签 java csv 注入 Spring spring java xml 文章分类 Java 后端开发

关于Spring的属性注入一共有两种方式，分别为XML方式与注解方式，其中XML方式又分为Set注入与构造方法注入，注解方式分为java注解与Spring注解。根据需要新建java project，项目结构与源代码如下：（可以通过本文结尾提供的链接下载

Students.java

package com.spr.vo;

public class Students {
	
	private String sid;
	private String sname;
	private int sage;
	public String getSid() {
		return sid;
	}
	public void setSid(String sid) {
		this.sid = sid;
	}
	public String getSname() {
		return sname;
	}
	public void setSname(String sname) {
		this.sname = sname;
	}
	public int getSage() {
		return sage;
	}
	public void setSage(int sage) {
		this.sage = sage;
	}
	
}

StudentsDAO.java

package com.spr.dao;

import com.spr.vo.Students;

public interface StudentsDAO {
	public boolean saveStudents(Students s);
}

StudentsDAOImpl.java

package com.spr.dao;

import com.spr.vo.Students;

public class StudentsDAOImpl implements StudentsDAO{

	@Override
	public boolean saveStudents(Students students) {
		// TODO Auto-generated method stub
		
		//在此模拟数据存入数据库
		if(students != null){
			System.out.println("学号："+students.getSid());
			System.out.println("姓名："+students.getSname());
			System.out.println("年龄："+students.getSage());
			System.out.println("数据保存成功！");
			return true;
		}
		else{
			return false;
		}
		
	}

}

StudentsService.java

package com.spr.service;

public interface StudentsService {
	public boolean saveStudents();
}

StudentsServiceImpl.java

package com.spr.service;


import com.spr.dao.StudentsDAO;
import com.spr.vo.Students;


public class StudentsServiceImpl implements StudentsService{


	private StudentsDAO studentsDAO;
	private Students students;
	
	@Override
	//保存学生（调用DAO层方法）
	public boolean saveStudents() {
		// TODO Auto-generated method stub
		
		if(studentsDAO.saveStudents(students)){
			return true;
		}
		else{
			return false;
		}
		
	}


}

TestSaveStudents.java

package com.spr.test;

public class TestSaveStudents {
	public static void main(String[] args){
		//稍后完善
	}
}

其中，在StudentsServiceImpl.java中，仅仅拥有studentsDAO与students两个属性，但是并没有对其实例化，如果直接引用，在运行程序时会抛出空指针异常，所有我们要用Spring为其注入。

一、Set属性注入：

首先在StudentsServiceImpl.java中生成属性的set/get方法，代码修改后为：

StudentsServiceImpl.java

package com.spr.service;

import com.spr.dao.StudentsDAO;
import com.spr.vo.Students;

public class StudentsServiceImpl implements StudentsService{

	private StudentsDAO studentsDAO;
	private Students students;
	
	public StudentsServiceImpl(){
		
	}
	public StudentsServiceImpl(StudentsDAO studentsDAO){
		this.studentsDAO = studentsDAO;
	}
	
	
	@Override
	//保存学生（调用DAO层方法）
	public boolean saveStudents() {
		// TODO Auto-generated method stub
		
		if(studentsDAO.saveStudents(students)){
			return true;
		}
		else{
			return false;
		}
		
	}
	//生成的Set/get方法
	public StudentsDAO getStudentsDAO() {
		return studentsDAO;
	}
	public void setStudentsDAO(StudentsDAO studentsDAO) {
		this.studentsDAO = studentsDAO;
	}
	public Students getStudents() {
		return students;
	}
	public void setStudents(Students students) {
		this.students = students;
	}
	
}

编写applicationContext.xml文件：

applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans
	xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:p="http://www.springframework.org/schema/p"
	xsi:schemaLocation="http://www.springframework.org/schema/beans 
						http://www.springframework.org/schema/beans/spring-beans-3.1.xsd">

	<bean name="students" class="com.spr.vo.Students"></bean>
	<bean name="studentsDAO" class="com.spr.dao.StudentsDAOImpl"></bean>
	<bean name="studentsService" class="com.spr.service.StudentsServiceImpl">
		<!-- 1、Setter属性注入 -->
		<!-- <property name="属性名称" ref="bean引用名称"></property> -->
	    <property name="studentsDAO" ref="studentsDAO"></property>
		<property name="students" ref="students"></property>
		<!-- 2、构造方法注入 -->
		<!-- <constructor-arg ref="studentsDAO"></constructor-arg> -->
	</bean>
	
</beans>

修改TestSaveStudents.java

package com.spr.test;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.spr.service.StudentsServiceImpl;
import com.spr.vo.Students;

public class TestSaveStudents {
	public static void main(String[] args){
		//稍后完善
		
		ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
		
		Students s = (Students) ctx.getBean("students");
		s.setSid("L003");
		s.setSname("张三");
		s.setSage(20);
		
		StudentsServiceImpl serviceImpl = (StudentsServiceImpl) ctx.getBean("studentsService");
		
		if(serviceImpl.saveStudents()){
			System.out.println("操作成功");
		}
		else{
			System.out.println("操作失败");
		}
		
	}
}

运行后的结果：

二、构造方法注入：

首先要在需要注入属性的类中实现一个含有属性参数的构造方法（注意要保留没有参数的构造方法）：

StudentsServiceImpl.java

package com.spr.service;

import com.spr.dao.StudentsDAO;
import com.spr.vo.Students;

public class StudentsServiceImpl implements StudentsService{

	private StudentsDAO studentsDAO;
	private Students students;
	
	//保留不含参数的构造方法
	public StudentsServiceImpl(){
		
	}
	//含有属性参数的构造方法
	public StudentsServiceImpl(StudentsDAO studentsDAO,Students students){
		this.studentsDAO = studentsDAO;
		this.students = students;
	}
	
	
	@Override
	//保存学生（调用DAO层方法）
	public boolean saveStudents() {
		// TODO Auto-generated method stub
		
		if(studentsDAO.saveStudents(students)){
			return true;
		}
		else{
			return false;
		}
		
	}
	
}

之后配置applicationContext.xml文件：

applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans
	xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:p="http://www.springframework.org/schema/p"
	xsi:schemaLocation="http://www.springframework.org/schema/beans 
						http://www.springframework.org/schema/beans/spring-beans-3.1.xsd">

	<bean name="students" class="com.spr.vo.Students"></bean>
	<bean name="studentsDAO" class="com.spr.dao.StudentsDAOImpl"></bean>
	<bean name="studentsService" class="com.spr.service.StudentsServiceImpl">
		<!-- 1、Setter属性注入 -->
		<!-- <property name="属性名称" ref="bean引用名称"></property> -->
	    <!-- <property name="studentsDAO" ref="studentsDAO"></property> -->
		<!-- <property name="students" ref="students"></property> -->
		<!-- 2、构造方法注入 -->
		<!-- <constructor-arg ref="bean引用名称" index="属性索引"></constructor-arg> -->
		<constructor-arg ref="studentsDAO" index="0"></constructor-arg>
		<constructor-arg ref="students" index="1"></constructor-arg>
	</bean>
	
</beans>

运行结果与set注入方式一样。

相对于xml文件的注入方法，annotation方法注入就十分的方便。

首先先修改applicationContext.xml文件，加入下面代码：

xmlns:context="http://www.springframework.org/schema/context" 

	http://www.springframework.org/schema/context   
	http://www.springframework.org/schema/context/spring-context-2.5.xsd

    <context:annotation-config/>

修改后的applicationContext.xml文件如下：

<?xml version="1.0" encoding="UTF-8"?>
<beans
	xmlns:context="http://www.springframework.org/schema/context"
	xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:p="http://www.springframework.org/schema/p"
	xsi:schemaLocation="http://www.springframework.org/schema/beans 
						http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
						http://www.springframework.org/schema/context   
						http://www.springframework.org/schema/context/spring-context-2.5.xsd">
	
	<context:annotation-config/>
						
	<bean name="students" class="com.spr.vo.Students"></bean>
	<bean name="studentsDAO" class="com.spr.dao.StudentsDAOImpl"></bean>
	<bean name="studentsService" class="com.spr.service.StudentsServiceImpl">
		<!-- 1、Setter属性注入 -->
		<!-- <property name="属性名称" ref="bean引用名称"></property> -->
	    <!-- <property name="studentsDAO" ref="studentsDAO"></property> -->
		<!-- <property name="students" ref="students"></property> -->
		<!-- 2、构造方法注入 -->
		<!-- <constructor-arg ref="bean引用名称" index="属性索引"></constructor-arg> -->
		<!-- <constructor-arg ref="studentsDAO" index="0"></constructor-arg> -->
		<!-- <constructor-arg ref="students" index="1"></constructor-arg> -->
	</bean>
	
</beans>

在StudentsServiceImpl.java加入java注解

StudentsServiceImpl.java

package com.spr.service;

import javax.annotation.Resource;

import com.spr.dao.StudentsDAO;
import com.spr.vo.Students;

public class StudentsServiceImpl implements StudentsService{
	
	@Resource(name="studentsDAO")
	private StudentsDAO studentsDAO;
	@Resource(name="students")
	private Students students;

	@Override
	//保存学生（调用DAO层方法）
	public boolean saveStudents() {
		// TODO Auto-generated method stub
		
		if(studentsDAO.saveStudents(students)){
			return true;
		}
		else{
			return false;
		}
		
	}
	
}

运行TestSaveStudents.java，运行效果一样。

四、Spring注解注入

Spring注解注入与java注解注入的applicationContext.xml配置一样只不过是在注解上有所不同，如下：

StudentsServiceImpl.java

package com.spr.service;

import javax.annotation.Resource;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;

import com.spr.dao.StudentsDAO;
import com.spr.vo.Students;

public class StudentsServiceImpl implements StudentsService{
	
	@Autowired
	@Qualifier("studentsDAO")
	private StudentsDAO studentsDAO;
	@Autowired
	@Qualifier("students")
	private Students students;

	@Override
	//保存学生（调用DAO层方法）
	public boolean saveStudents() {
		// TODO Auto-generated method stub
		
		if(studentsDAO.saveStudents(students)){
			return true;
		}
		else{
			return false;
		}
		
	}
	
}

但是运行效果是一样的

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