我用的spring配置的c3po数据源
然后自己写了一个jdbc基础类，
然后通过加载spring配置文件来获得配置源，是注入的方式来实现的
可是在实际用的时候提示错误
代码：
spring配置文件：
<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"
destroy-method="close">
<property name="driverClass">
<value>${jdbc.driverClassName}</value>
</property>
<property name="jdbcUrl">
<value>${jdbc.url}</value>
</property>
<property name="user">
<value>${jdbc.username}</value>
</property>
<property name="password">
<value>${jdbc.password}</value>
</property>
<!--连接池中保留的最小连接数。 -->
<property name="minPoolSize">
<value>5</value>
</property>
<!--连接池中保留的最大连接数。Default: 15 -->
<property name="maxPoolSize">
<value>30</value>
</property>
<!--初始化时获取的连接数，取值应在minPoolSize与maxPoolSize之间。Default: 3 -->
<property name="initialPoolSize">
<value>10</value>
</property>
<!--最大空闲时间,60秒内未使用则连接被丢弃。若为0则永不丢弃。Default: 0 -->
<property name="maxIdleTime">
<value>60</value>
</property>
<!--当连接池中的连接耗尽的时候c3p0一次同时获取的连接数。Default: 3 -->
<property name="acquireIncrement">
<value>5</value>
</property>
<!--JDBC的标准参数，用以控制数据源内加载的PreparedStatements数量。但由于预缓存的statements 属于单个connection而不是整个连接池。所以设置这个参数需要考虑到多方面的因素。
如果maxStatements与maxStatementsPerConnection均为0，则缓存被关闭。Default: 0 -->
<property name="maxStatements">
<value>0</value>
</property>
<!--每60秒检查所有连接池中的空闲连接。Default: 0 -->
<property name="idleConnectionTestPeriod">
<value>60</value>
</property>
<!--定义在从数据库获取新连接失败后重复尝试的次数。Default: 30 -->
<property name="acquireRetryAttempts">
<value>30</value>
</property>
<!--获取连接失败将会引起所有等待连接池来获取连接的线程抛出异常。但是数据源仍有效 保留，并在下次调用getConnection()的时候继续尝试获取连接。如果设为true，那么在尝试
获取连接失败后该数据源将申明已断开并永久关闭。Default: false -->
<property name="breakAfterAcquireFailure">
<value>true</value>
</property>
<!--因性能消耗大请只在需要的时候使用它。如果设为true那么在每个connection提交的 时候都将校验其有效性。建议使用idleConnectionTestPeriod或automaticTestTable
等方法来提升连接测试的性能。Default: false -->
<property name="testConnectionOnCheckout">
<value>false</value>
</property>
</bean>
jdbc基础类：
package com.tpy.util;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ResourceBundle;
import javax.sql.DataSource;
import org.springframework.beans.factory.annotation.Autowired;
import com.tpy.strategy.Strategy;
public class MysqlStrategy implements Strategy {
//三大核心接口
private Connection conn = null;
private PreparedStatement pstmt = null;
private ResultSet rs = null;
@Autowired
private DataSource dataSource;
//四个方法
//method1: 创建数据库的连接
public Connection getConnDB(){
try {
conn = dataSource.getConnection();
} catch (SQLException e) {
e.printStackTrace();
}
return conn;
}
//method2：关闭数据库的方法
public void closeConn(){
if(rs!=null){
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(pstmt!=null){
try {
pstmt.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if(conn!=null){
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
//method3: 专门用于发送增删改语句的方法
public int execOther(PreparedStatement pstmt){
try {
int affectedRows = pstmt.executeUpdate();
return affectedRows;
} catch (SQLException e) {
e.printStackTrace();
return -1;
}
}
//method4: 专门用于发送查询语句
public ResultSet execQuery(PreparedStatement pstmt){
try {
rs = pstmt.executeQuery();
return rs;
} catch (SQLException e) {
e.printStackTrace();
return null;
}
}
}
Connection 报错：
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.tpy.dao.UserDao com.tpy.service.implement.UserServiceImpl.userDao; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userDao' defined in file [D:\Users\admin\workspace\java_maven\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\maven-springmvc-springjdbc\WEB-INF\classes\com\tpy\dao\implement\UserDaoImpl.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.tpy.dao.implement.UserDaoImpl]: Constructor threw exception; nested exception is java.lang.NullPointerException
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:561)
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:331)
... 22 more
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userDao' defined in file [D:\Users\admin\workspace\java_maven\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\maven-springmvc-springjdbc\WEB-INF\classes\com\tpy\dao\implement\UserDaoImpl.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.tpy.dao.implement.UserDaoImpl]: Constructor threw exception; nested exception is java.lang.NullPointerException
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1093)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1038)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:504)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:303)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:299)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1127)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1051)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:949)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:533)
... 24 more
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.tpy.dao.implement.UserDaoImpl]: Constructor threw exception; nested exception is java.lang.NullPointerException
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:163)
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:89)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1086)
... 35 more
Caused by: java.lang.NullPointerException
at com.tpy.util.MysqlStrategy.getConnDB(MysqlStrategy.java:56)
at com.tpy.util.ClientContext.getConnDB(ClientContext.java:19)
at com.tpy.util.BaseDAO.<init>(BaseDAO.java:50)
at com.tpy.util.BaseDAO.<init>(BaseDAO.java:63)
at com.tpy.dao.implement.UserDaoImpl.<init>(UserDaoImpl.java:44)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:147)
... 37 more
这里是一部分报错信息
大神们帮忙看看
------解决思路----------------------
日志不全，貌似你的DataSource没有注入成功呀