package db.com;
import java.util.Properties;
import java.io.*;public class Env extends Properties{
private static Env instance;
public static Env getInstance(){
if(instance!=null){
return instance;
}else{
makeInstance();
return instance;
}
}
private static synchronized void makeInstance(){
if(instance==null){
instance=new Env();
}
}
private Env(){
InputStream is=getClass().getResourceAsStream("/ddb.properties");
try {
load(is);
} catch (IOException e) {
System.err.println("错误:没有读取属性文件,"+"请确认是否存在");
}
}
}==========================================================================================================
package db.com;import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;public class ConnectionManager {
public static synchronized Connection getConnection(){
String driverClassName=Env.getInstance().getProperty("driver");
String url=Env.getInstance().getProperty("url");
String user=Env.getInstance().getProperty("user");
String password=Env.getInstance().getProperty("password");
Connection con=null;
try {
Class.forName(driverClassName);
con=DriverManager.getConnection(url,user,password);
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return con;
}
}
===================================================================================================
package db.com;public class test { /**
* @param args
*/
public static void main(String[] args){
ConnectionManager.getConnection();
System.out.println("con.getConn()");
}
}
======================================================================================
Exception in thread "main" java.lang.NullPointerException
at java.util.Properties$LineReader.readLine(Properties.java:418)
at java.util.Properties.load0(Properties.java:337)
at java.util.Properties.load(Properties.java:325)
at db.com.Env.<init>(Env.java:23)
at db.com.Env.makeInstance(Env.java:17)
at db.com.Env.getInstance(Env.java:11)
at db.com.ConnectionManager.getConnection(ConnectionManager.java:9)
at db.com.test.main(test.java:9)
晕死了
import java.util.Properties;
import java.io.*;public class Env extends Properties{
private static Env instance;
public static Env getInstance(){
if(instance!=null){
return instance;
}else{
makeInstance();
return instance;
}
}
private static synchronized void makeInstance(){
if(instance==null){
instance=new Env();
}
}
private Env(){
InputStream is=getClass().getResourceAsStream("/ddb.properties");
try {
load(is);
} catch (IOException e) {
System.err.println("错误:没有读取属性文件,"+"请确认是否存在");
}
}
}==========================================================================================================
package db.com;import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;public class ConnectionManager {
public static synchronized Connection getConnection(){
String driverClassName=Env.getInstance().getProperty("driver");
String url=Env.getInstance().getProperty("url");
String user=Env.getInstance().getProperty("user");
String password=Env.getInstance().getProperty("password");
Connection con=null;
try {
Class.forName(driverClassName);
con=DriverManager.getConnection(url,user,password);
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return con;
}
}
===================================================================================================
package db.com;public class test { /**
* @param args
*/
public static void main(String[] args){
ConnectionManager.getConnection();
System.out.println("con.getConn()");
}
}
======================================================================================
Exception in thread "main" java.lang.NullPointerException
at java.util.Properties$LineReader.readLine(Properties.java:418)
at java.util.Properties.load0(Properties.java:337)
at java.util.Properties.load(Properties.java:325)
at db.com.Env.<init>(Env.java:23)
at db.com.Env.makeInstance(Env.java:17)
at db.com.Env.getInstance(Env.java:11)
at db.com.ConnectionManager.getConnection(ConnectionManager.java:9)
at db.com.test.main(test.java:9)
晕死了
注意要将ddb.properties文件和Env.java文件放一个目录下
这个文件路径 仔细确认一下吧