後端開發基礎-Spring框架學習-002——基礎概念
阿新 • • 發佈：2018-12-11
自動裝配(瞭解)
. 預設情況下，容器是禁止自動裝配的。 . 如果要自動裝配，必須設定autowire為以下三個值： byName:查詢id等於屬性名稱的bean，然後呼叫 set方法完成注入。 注： 有無參構造器。 有set方法。 如果找不到對應的bean,注入null。 byType:查詢與屬性型別一致的bean,然後呼叫 set方法完成注入。 注： 有無參構造器。 有set方法。 如果找不到對應的bean,注入null。 如果找到多個，會出錯。 constructor:查詢與屬性型別一致的bean,然後呼叫 構造器完成注入。 注： 有對應的構造器。 如果找不到對應的bean,注入null。 . 自動裝配儘量少用，如果要用，可以使用byName。
注入基本型別的值
使用value屬性來注入。
注入集合型別的值
將集合型別當做一個bean來配置
spring表示式
用來讀取bean的屬性值，語法上類似於el表示式。
案例演示：
工程案例目錄結構
spring環境搭建必備jar：
pom.xml：
<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.study</groupId> <artifactId>springcase-day02</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>war</packaging> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.12</version> </dependency> <dependency> <groupId>javax</groupId> <artifactId>javaee-api</artifactId> <version>6.0</version> </dependency> </dependencies> </project>
Restaurant.java
package ioc.auto; public class Restaurant { private Waiter wt; public Restaurant() { System.out.println("Restaurant無參構造器..."); } public Waiter getWt() { return wt; } public void setWt(Waiter wt) { System.out.println("Restaurant的set方法..."); this.wt = wt; } @Override public String toString() { return "Restaurant [wt=" + wt + "]"; } }
Restaurant2.java
package ioc.auto;
public class Restaurant2 {
private Waiter wt;
public Restaurant2() {
System.out.println("Restaurant2的無參構造器...");
}
public Restaurant2(Waiter wt) {
System.out.println("Restaurant2的帶參構造器...");
this.wt = wt;
}
@Override
public String toString() {
return "Restaurant2 [wt=" + wt + "]";
}
}
Waiter.java
package ioc.auto;
public class Waiter {
public Waiter(){
System.out.println("Waiter的無參構造器...");
}
/*public static Waiter getInstance(){
System.out.println("靜態工廠方式");
return new Waiter();
}*/
}
ExampleBean.java
package ioc.basic;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
public class ExampleBean {
private String name;
private int age;
private List<String> cities;
private Set<String> interest;
private Map<String,Double> scores;
private Properties db;
public ExampleBean() {
System.out.println("ExampleBean的無參構造器...");
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public List<String> getCities() {
return cities;
}
public void setCities(List<String> cities) {
this.cities = cities;
}
public Set<String> getInterest() {
return interest;
}
public void setInterest(Set<String> interest) {
this.interest = interest;
}
public Map<String, Double> getScores() {
return scores;
}
public void setScores(Map<String, Double> scores) {
this.scores = scores;
}
public Properties getDb() {
return db;
}
public void setDb(Properties db) {
this.db = db;
}
@Override
public String toString() {
return "ExampleBean [name=" + name + ", age=" + age + ", cities=" + cities + ", interest=" + interest
+ ", scores=" + scores + ", db=" + db + "]";
}
}
SomeBean.java
package ioc.basic;
public class SomeBean {
private String name;
private String city;
private double score;
private String pageSize;
public SomeBean() {
System.out.println("SomeBean的無參構造器...");
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public double getScore() {
return score;
}
public void setScore(double score) {
this.score = score;
}
public String getPageSize() {
return pageSize;
}
public void setPageSize(String pageSize) {
this.pageSize = pageSize;
}
@Override
public String toString() {
return "SomeBean [name=" + name + ", city=" + city + ", score=" + score + ", pageSize=" + pageSize + "]";
}
}
app2.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:context="http://www.springframework.org/schema/context"
xmlns:jdbc="http://www.springframework.org/schema/jdbc"
xmlns:jee="http://www.springframework.org/schema/jee"
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:util="http://www.springframework.org/schema/util"
xmlns:jpa="http://www.springframework.org/schema/data/jpa"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd
http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.2.xsd
http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.2.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd
http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa-1.3.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.2.xsd">
<bean id="eb1" class="ioc.basic.ExampleBean">
<property name="name" value="黛玉"/>
<property name="age" value="16"/>
<property name="cities">
<list>
<value>北京</value>
<value>武漢</value>
<value>岳陽</value>
<value>岳陽</value>
</list>
</property>
<property name="interest">
<set>
<value>釣魚</value>
<value>做飯</value>
<value>看電視</value>
<value>看電視</value>
</set>
</property>
<property name="scores">
<map>
<entry key="english" value="59.5"/>
<entry key="math" value="80"/>
</map>
</property>
<property name="db">
<props>
<prop key="username">Tom</prop>
<prop key="password">tiger</prop>
</props>
</property>
</bean>
<!--
將集合型別當做一個bean來配置，這樣，
集合型別的值就可以重用。
-->
<util:list id="citiesBean">
<value>長沙</value>
<value>南昌</value>
<value>重慶</value>
</util:list>
<util:set id="interestBean">
<value>釣魚</value>
<value>做飯</value>
<value>看電視</value>
</util:set>
<util:map id="scoresBean">
<entry key="english" value="59.5"/>
<entry key="math" value="80"/>
</util:map>
<util:properties id="dbBean" >
<prop key="username">Tom</prop>
<prop key="password">tiger</prop>
</util:properties>
<bean id="eb2" class="ioc.basic.ExampleBean">
<property name="cities" ref="citiesBean"/>
<property name="interest"
ref="interestBean"/>
<property name="scores" ref="scoresBean"/>
<property name="db" ref="dbBean"/>
</bean>
<!--
讀取location屬性指定位置的檔案的內容，
並將內容存放到Properties物件裡面。
-->
<util:properties id="jdbc"
location="classpath:config.properties"/>
<bean id="sb1" class="ioc.basic.SomeBean">
<!-- 讀取id為eb1的bean的name屬性值 -->
<property name="name" value="#{eb1.name}"/>
<!-- 讀取id為eb1的bean的cities屬性值(
該屬性是一個List,讀取下標為１的元素的值)。 -->
<property name="city"
value="#{eb1.cities[1]}"/>
<!-- 讀取id為eb1的bean的scores屬性值(
該屬性是一個Map,讀取的key為english的值) -->
<!-- <property name="score"
value="#{eb1.scores.english}"/> -->
<property name="score" value="#{eb1.scores.math}"/>
<!-- 讀取id為jdbc的bean的pageSize屬性值(
該屬性是一個Properties，讀取key為pageSize的值) -->
<property name="pageSize"
value="#{jdbc.pageSize}"/>
</bean>
</beans>config.properties
pageSize=10
TestCase.java
package test;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import ioc.auto.Restaurant2;
import ioc.basic.ExampleBean;
import ioc.basic.SomeBean;
public class TestCase {
@Test
//自動裝配
public void test1(){
ApplicationContext ac = new ClassPathXmlApplicationContext("app.xml");
Restaurant2 rest = ac.getBean("rest3",Restaurant2.class);
System.out.println(rest);
}
@Test
//測試基本型別值的注入，集合型別值的注入
public void test2(){
ApplicationContext ac = new ClassPathXmlApplicationContext("app2.xml");
ExampleBean eb= ac.getBean("eb2", ExampleBean.class);
System.out.println(eb);
}
@Test
//測試spring表示式
public void test3(){
ApplicationContext ac = new ClassPathXmlApplicationContext("app2.xml");
SomeBean sb1 = ac.getBean("sb1", SomeBean.class);
System.out.println(sb1);
}
}
依次執行test1，test2，test3,後臺執行結果：
A.
B.
C.
