jee、spring、spring mvc、mybatis 学习（六）

转载请申明出处：http://blog.csdn.net/qq5132834/article/details/52211902

在完成第五节spring、spring mvc配置文件的分离之后，这节里开始涉及数据库的连接了；连接数据库的方式方法有很多种，下面一一展示出来，在src类文件夹下新建包【com.zuk.database】。

1、JDBC数据库直连 ：新建一个【DB.java】类文件；

package com.zuk.database;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

/**
* @author 513283439@qq.com
* 采用数据JDBC数据库直连的方式
* */
public class DB {

public static Connection conn = null;

/**
* 建立数据库连接
* */
public static Connection getConnection(){

if(conn!=null){
return conn;
}else{
try {
//这里建立的是oracle数据连接
Class.forName("oracle.jdbc.OracleDriver") ;
String url = "jdbc:oracle:thin:@//10.2.12.14:1521/GGRDAT" ;
String username = "username" ;
String password = "password" ;

conn = DriverManager.getConnection(url , username , password ) ;

} catch (Exception e) {
e.printStackTrace();
}
return conn;
}
}

/**
* 关闭数据库连接
* */
public static void closeConnection(){
if(conn!=null){
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
conn = null;
}
}
}

2、采用【properties】文件的方式配置数据库链接信息，但是这种方式与上一种方式性质是一样，只是将数据库的驱动、url、用户、密码等信息存储在【properties】文件中。

在【src/sources】包中新建一个【jdbc.properties】文件，内容如下：

driver=oracle.jdbc.OracleDriver
url=jdbc:oracle:thin:@//10.2.12.14:1521/GGRDAT
user=username
password=password

再在【com.zuk.database】中新建一个【DatabaseProperties.java】类，内容如下。

注意：获取【jdbc.properties】文件的路径的方式。

如果在【WEB-INF】文件夹中的话，则用：

InputStream fis = context.getResourceAsStream("/WEB-INF/classes/jdbc.properties");

package com.zuk.database;

import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;

/**
* @author 513283439@qq.com
* 采用properties文件的方式建立JDBC数据库直连的方式
* */
public class DatabaseProperties {

public static Connection conn = null;

/**
* 建立数据库连接
* */
public static Connection getConnection(){

if(conn!=null){
return conn;
}

try {

Properties prop = new Properties();//属性集合对象
InputStream fis = DatabaseProperties.class.getClassLoader().getResourceAsStream("sources/jdbc.properties");
prop.load(fis);//将属性文件流装载到Properties对象中

String driver =  prop.getProperty("driver");
String url = prop.getProperty("url");
String user = prop.getProperty("user");
String password = prop.getProperty("password");

System.out.println(driver);
System.out.println(url);
System.out.println(user);
System.out.println(password);

Class.forName(driver);
conn = DriverManager.getConnection(url,user,password );

} catch (Exception e) {
e.printStackTrace();
}

return conn;
}

/**
* 关闭数据库连接
* */
public static void closeConnection(){
if(conn!=null){
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
conn = null;
}
}
}

3、采用【IoC】容器的方式建立数据链接，方式如下：

3.1新建一个java类【DatabaseJavaBean.java】内容如下：

package com.zuk.database;

import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.util.Properties;

public class DatabaseJavaBean {

private String driver = "driver";
private String url = "url";
private String user = "user";
private String password = "password";

public DatabaseJavaBean(){

}

public DatabaseJavaBean(String driver,String url,String user,String password){
this.driver = driver;
this.url = url;
this.user = user;
this.password = password;
}

public void setDriver(String driver) {
this.driver = driver;
}

public void setUrl(String url) {
this.url = url;
}

public void setUser(String user) {
this.user = user;
}

public void setPassword(String password) {
this.password = password;
}

public void showDataInfo(){
System.out.println(this.driver);
System.out.println(this.url);
System.out.println(this.user);
System.out.println(this.password);
}

public Connection getConnection(){

Connection conn = null;

try {
String driver =  this.driver;
String url = this.url;
String user = this.user;
String password = this.password;
Class.forName(driver);
conn = DriverManager.getConnection(url,user,password );

} catch (Exception e) {
e.printStackTrace();
}

return conn;
}

}

3.2:、在【src/sources】文件夹中新建一个xml文件【database-javabean.xml】，内容如下：

<?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" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd
">

<bean id="databaseJavaBean" class="com.zuk.database.DatabaseJavaBean">
<property name="driver" value="oracle.jdbc.OracleDriver" />
<property name="url" value="jdbc:oracle:thin:@//10.2.12.14:1521/GGRDAT" />
<property name="user" value="user" />
<property name="password" value="password" />
</bean>

</beans>

注意：bean的初始化采用【property】标签初始化，所以对于【com.zuk.database.DatabaseJavaBean.java】类的属性必须添加【set】方法。

3.3、将【database-javabean.xml】文件注入【IoC】的方式有两种，一种是手动注入；一种是自动注入；

手动注入：

/**
* 通过javabean的方式
* */
private Connection getConnection(){

//将其加入IOC容器中
ApplicationContext context = new ClassPathXmlApplicationContext("sources/database-javabean.xml");
DatabaseJavaBean javaBean = (DatabaseJavaBean) context.getBean("databaseJavaBean");
javaBean.showDataInfo();
return javaBean.getConnection();

}

自动注入：

在【web.xml】文件中添加，路径是【classpath:sources/database-javabean.xml】：

<!-- 加载spring配置文件 -->
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:sources/spring.xml,classpath:sources/database-javabean.xml</param-value>
</context-param>

然后采用【@Autowired】的方式使用

@Autowired
public DatabaseJavaBean databaseJavaBean;

4、综上所述，数据库连接的方式如下：

package com.zuk.services;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.stereotype.Component;

import com.zuk.database.DB;
import com.zuk.database.DatabaseJavaBean;
import com.zuk.database.DatabaseProperties;

/**
* @author 513283439@qq.com
* */
@Component
public class UserService {

@Autowired
public DatabaseJavaBean databaseJavaBean;

public final static String TAG = "com.zuk.services.UserService";

public UserService(){

}

public void showTag(){
System.out.println(TAG);
}

public boolean isExist(String usid1,String pawd1){

//Connection conn = DB.getConnection();
//Connection conn = DatabaseProperties.getConnection();
//Connection conn = this.getConnection();

Connection conn = this.databaseJavaBean.getConnection();//采用web.xml自动注入的方式

this.db(conn);

return true;
}

/**
* 通过javabean的方式
* */
private Connection getConnection(){

//将其加入IOC容器中
ApplicationContext context = new ClassPathXmlApplicationContext("sources/database-javabean.xml");
DatabaseJavaBean javaBean = (DatabaseJavaBean) context.getBean("databaseJavaBean");
javaBean.showDataInfo();
return javaBean.getConnection();

}

//直连
private void db(Connection conn){
try {
conn = DB.getConnection();
//conn = DatabaseProperties.getConnection();
String sql = "select t.usid,t.pawd,t.prnm from login t where t.usid = 'b180121'";
PreparedStatement pstm = conn.prepareStatement(sql);
ResultSet res = pstm.executeQuery();
while(res.next()){
String usid = res.getString("usid").trim();
String pawd = res.getString("pawd").trim();
String prnm = res.getString("prnm").trim();
System.out.println(usid+"/"+prnm);
}
if(pstm!=null){pstm.close();}
if(res!=null){res.close();}
} catch (Exception e) {
e.printStackTrace();
}finally{
try {
conn.close();
} catch (Exception e2) {e2.printStackTrace();}
}
}

}

5、上面的【database-javabean.xml】文件中数据库配置的方式，可以更进一不优化，直接关联【jdbc.properties】中的数据。具体怎么操作实现呢？如下：

5.1、在【spring.xml】文件中添加；

<!-- 引入属性文件 -->
<context:property-placeholder location="classpath:jdbc.properties" />

内容如下：

<?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" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd
">

<!-- 引入属性文件 -->
<context:property-placeholder location="classpath:jdbc.properties" />

<!-- service包(自动注入) -->
<context:component-scan base-package="com.zuk.services" />
<!-- 扫描com.zuk.services这个包里所以的service类，【务必在类上标注：@Component】，此时可以采用@Autowired实现自动注入这个包里面全部的对象     -->

</beans>

5.2、在【database-javabean.xml】中修改如下：

<?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" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd
">

<bean id="databaseJavaBean" class="com.zuk.database.DatabaseJavaBean">
<property name="driver" value="${driver}" />
<property name="url" value="${url}" />
<property name="user" value="${user}" />
<property name="password" value="${password}" />
</bean>

</beans>

6、源代码：http://download.csdn.net/detail/qq5132834/9605733