java中连接数据库的BaseDao
两种basedao的写法：
方式一：
public class BaseDao {
private final String driver="com.microsoft.sqlserver.jdbc.SQLServerDriver";
private final String url= "jdbc:sqlserver://localhost:1433;databaseName=MyJava";
private final String username = "root";
private final String pwd = "root";
private Connection connection;
private PreparedStatement ps;
protected ResultSet rs;
public void getConnection(){
try {
//加载驱动
Class.forName(driver);
// 创建连接对象
connection = DriverManager.getConnection( url, username,pwd);
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block e.printStackTrace();
}
return connection;
}
//释放资源（注意：三个关闭要分别用try-catch补获，防止释放资源的时候其中一个没能关闭成功）
public void closeAll(){
try {
if (rs != null){
rs.close();
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace(); }
}
}
try {
if (ps != null){
ps.close();
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace(); }
}
try {
if (connection != null){
connection.close();
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace(); }
}
//查询方式一
public void executeQuery(String sql , Object[] params){
try {
getConnection();
ps = connection.prepareStatement(sql);
if(params!= null){
for (int i = 0; i < params.length; i++) {
ps.setObject(i+1, params[i]);
}
}
rs = ps.executeQuery();
} catch (SQLException e) { /
/ TODO Auto-generated catch block
e.printStackTrace();
}
}
//查询方式二
public void executeQuery1(String sql , Object... params){
try {
getConnection();
ps = connection.prepareStatement(sql);
if(params!= null){
for (int i = 0; i < params.length; i++) {
ps.setObject(i+1, params[i]);
}
}
rs = ps.executeQuery();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
//增删改方式一(数组的形式)
public int executeUpdate(String sql , Object[] params){
int result = -1;
try {
getConnection();
ps = connection.prepareStatement(sql);
if(params!= null){
for (int i = 0; i < params.length; i++) {
ps.setObject(i+1, params[i]);
}
}
result= ps.executeUpdate();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
this.closeAll();//关闭所有资源
}
return result;
}
//增删改方式二
public int executeUpdate1(String sql , Object... params){
int result = -1;
try {
getConnection();
ps = connection.prepareStatement(sql);
if(params!= null){
for (int i = 0; i < params.length; i++) {
ps.setObject(i+1, params[i]);
}
}
result= ps.executeUpdate();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
this.closeAll();//关闭所有资源
}
return result;
}
}
//方式二
public class BaseDao1 {
private final String DRIVER="com.microsoft.sqlserver.jdbc.SQLServerDriver";
private final String URL= "jdbc:sqlserver://localhost:1433;databaseName=MyJava";
private final String USERNAME = "sa";
private final String PWD = "sa";
protected Connection connection;
protected PreparedStatement ps;
public Connection getConnection(){
try {
Class.forName(DRIVER);
// 2在网络中查找数据库，创建连接对象
connection = DriverManager.getConnection( URL, USERNAME,PWD);
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace(); }
return connection;
}
public void closeAll(ResultSet rs, PreparedStatement ps, Connection conn ){
try {
// 释放资源 if (rs != null)
rs.close();
if (ps != null)
ps.close();
if (conn != null)
conn.close();
} catch (SQLException e) { // TODO Auto-generated catch block
e.printStackTrace();
}
}
public ResultSet executeQuery(String sql , Object[] params){
ResultSet rs = null;
try {
getConnection();
ps = connection.prepareStatement(sql);
if(params!= null){
for (int i = 0; i < params.length; i++) {
ps.setObject(i+1, params[i]);
}
}
rs = ps.executeQuery();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace(); } return rs;
}
public int executeUpdate1(String sql , Object... params){
int result = -1;
try {
getConnection();
ps = connection.prepareStatement(sql);
if(params!= null){
for (int i = 0; i < params.length; i++) {
ps.setObject(i+1, params[i]);
}
}
result= ps.executeUpdate();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
this.closeAll(null,ps,connection);
}
return result;
}
}
