String[] colNames = new String[count];
for(int i = 1; i < colNames.length;i++){
colNames[i-1] = rsmd.getColumnName(i);
}
List
// 5.处理结果
while (rs.next()) {// 按行来遍历,将每一行添加到map中，list中最后存放的是表
Map
for(inti = 1;i<= colNames.length;i++){
data.put(colNames[i-1],rs.getObject(i));
}
datas.add(data);
}
return datas;
} finally {
JdbcUtils.free(rs, ps, conn);
}
}
}
11. 对象与关系的映射（利用反射）
[java]
public class ORMTest {
/**
* @param args
* @throwsInvocationTargetException
* @throwsIllegalAccessException
* @throws SQLException
* @throwsIllegalArgumentException
* @throws InstantiationException
*/
public static void main(String[] args) throws IllegalArgumentException,
SQLException, IllegalAccessException,InvocationTargetException,
InstantiationException {
User user = (User) getObject(
"select idas Id ,name as Name, birthday as Birthday,money as Money from user whereid=2",
User.class);
System.out.println(user);
}
static ObjectgetObject(String sql, Class clazz) throws SQLException,
IllegalArgumentException, IllegalAccessException,
InvocationTargetException, InstantiationException {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
conn = JdbcUtils.getConnection();
ps = conn.prepareStatement(sql);
rs = ps.executeQuery();
// 得到结果集的列数
int count = rsmd.getColumnCount();
String[] colNames = new String[count];
for (int i = 1; i <= colNames.length; i++) {
colNames[i - 1] = rsmd.getColumnLabel(i);
}
Object object = null;
Method[] ms = clazz.getMethods();
// 5.处理结果
if (rs.next()) {// 按行来遍历,将每一行添加到map中，list中最后存放的是表
object = clazz.newInstance();
for (int i = 0; i < colNames.length; i++) {
String colName = colNames[i];
String methodName = "set" + colName;
// System.out.println(methodName);
for (Method m : ms) {
if (methodName.equals(m.getName())) {
m.invoke(object, rs.getObject(colName));
}
}
}
}
return object;
} finally {
JdbcUtils.free(rs, ps, conn);
}
}
}
12. 创建数据库连接池，先创建多个连接，将连接一次放在List的尾部，用的时候从List的头部取出连接，使用连接；用完释放连接的时候是将连接返回到连接池的尾部，供后边的用户使用。达到连接重复使用的目地。
[java]
/**
*
* 创建数据库连接池
*/
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.LinkedList;
public class MyDataSource {
private static String url = "jdbc:mysql://localhost:3306/jdbc";
private static String user = "root";
private static String password = "mysql";
private LinkedList
public MyDataSource(){
for(int i = 0; i<5;i++){
try {
this.conn