个人看法:设计依赖查找的设计模式,是为了解耦.
- 单一类型依赖查找
- JNDI javax.naming.Context#lookup
- JavaBeans java.beans.beancontext.BeanContext
- 集合类型依赖查找
- java.beans.beancontext.BeanContext#getCurrentServiceSelectors
- 层析性依赖查找
Springboot中使用JNDI
JNDI即Java Naming and Directory Interface（JAVA命名和目录接口），那么java命名目的就是为了记录一些不方便记录的内容，就像人的名字或DNS中的域名与IP的关系。
两种模式
- Springboot Embedded Tomcat(嵌入Tomcat)使用JNDI
- Springboot WAR 使用JNDI
1. Springboot Embedded Tomcat(嵌入Tomcat)使用JNDI
- 启用默认禁用的JNDI命名。
- 构建一个ContextResource对象，然后添加到Context对象中
java:/comp/env/ 固定写法
JndiConfig.java
package com.rumenz;
import org.apache.catalina.Context;
import org.apache.catalina.startup.Tomcat;
import org.apache.tomcat.util.descriptor.web.ContextResource;
import org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory;
import org.springframework.boot.web.embedded.tomcat.TomcatWebServer;
import org.springframework.boot.web.servlet.server.ServletWebServerFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.jndi.JndiObjectFactoryBean;
import org.springframework.stereotype.Component;
import javax.naming.NamingException;
import javax.sql.DataSource;
@Component
public class JndiConfig {
@Bean
public ServletWebServerFactory servletContainer() {
TomcatServletWebServerFactory tomcatServletWebServerFactory = new TomcatServletWebServerFactory() {
@Override
protected TomcatWebServer getTomcatWebServer(Tomcat tomcat) {
tomcat.enableNaming(); //启用默认禁用的JNDI命名
return super.getTomcatWebServer(tomcat);
}
//数据库配置信息可以配置在文件中,数据库发生变动,只需修改配置文件,而不用修改代码.
@Override
protected void postProcessContext(Context context) {
ContextResource resource = new ContextResource();
resource.setName("jdbcMydb");
resource.setType(DataSource.class.getName());
resource.setProperty("driverClassName", "com.mysql.jdbc.Driver");
resource.setProperty("url", "jdbc:mysql://127.0.0.1:3306/test");
resource.setProperty("username", "root");
resource.setProperty("password","root1234");
context.getNamingResources().addResource(resource);
}
};
return tomcatServletWebServerFactory;
}
@Bean
public DataSource jndiDataSource() throws IllegalArgumentException,
NamingException {
JndiObjectFactoryBean bean = new JndiObjectFactoryBean(); // create JNDI data source
bean.setJndiName("java:/comp/env/jdbcMydb"); // jndiDataSource is name of JNDI data source
bean.setProxyInterface(DataSource.class);
bean.setLookupOnStartup(true);
bean.afterPropertiesSet();
return (DataSource) bean.getObject();
}
}
MysqlTest.java
package com.rumenz;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.ApplicationRunner;
import org.springframework.boot.CommandLineRunner;
import org.springframework.context.ApplicationContext;
import org.springframework.stereotype.Component;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
@Component
public class MysqlTest implements ApplicationRunner {
public static DataSource dataSource = null;
static {
Context context = null;
try {
context = new InitialContext();
} catch (NamingException e) {
e.printStackTrace();
}
//根据资源名称搜索
try {
dataSource = (DataSource)context.lookup("java:/comp/env/jdbcMydb");
} catch (NamingException e) {
e.printStackTrace();
}
System.out.println("static-----");
}
public void run(ApplicationArguments args) throws Exception {
System.out.println("run---------");
Statement stmt = null;
try {
Connection conn = dataSource.getConnection();
//查询
stmt = conn.createStatement();
String sql = "SELECT id,name FROM qq limit 1";
ResultSet rs = stmt.executeQuery(sql);
while(rs.next()){
int id = rs.getInt("id");
String name = rs.getString("name");
System.out.print("id: " + id);
System.out.println(", name: " + name);
}
rs.close();
stmt.close();
conn.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
源码:https://github.com/mifunc/springboot-jndi-Embedded-Tomcat
2.Springboot WAR 使用JNDI
打包成war包放到tomcat,需要修改tomcat/conf/context.xml和tomcat/conf/server.xml
tomcat/conf/context.xml
<ResourceLink name="jdbcMydb"
global="jdbcMydb"
auth="Container"
type="javax.sql.DataSource" />
tomcat/conf/server.xml
<Resource name="jdbcMydb"
global="jdbcMydb"
auth="Container"
type="javax.sql.DataSource"
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/test"
username="root"
password="root1234"
maxActive="100"
maxIdle="20"
minIdle="5"
maxWait="10000"/>
业务代码
JNDIController.java
package com.rumenz.controller;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import javax.sql.DataSource;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class JNDIController {
@Autowired
private DataSource dataSource;
@GetMapping("/test")
public String test() {
try {
Connection conn = dataSource.getConnection();
Statement stmt = conn.createStatement();
String sql = "SELECT id,name FROM qq limit 1";
ResultSet rs = stmt.executeQuery(sql);
while(rs.next()){
int id = rs.getInt("id");
String name = rs.getString("name");
System.out.print("id: " + id);
System.out.println(", name: " + name);
}
rs.close();
stmt.close();
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
return null;
}
}
源码:https://github.com/mifunc/Springboot-jndi-war-Tomcat
java.beans.beancontext.BeanContext(单一类型依赖查找/集合类型依赖查找)
- 单一类型依赖查找
- java.beans.beancontext.BeanContextServicesSupport#getService
- 集合类型依赖查找
- java.beans.beancontext.BeanContextServicesSupport#getCurrentServiceSelectors
层析性依赖查找
多个BeanContext相互为父子关系. 一个service的依赖有可能在多个BeanContext
image.png
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