java代码重构汇总

String sql = "INSERT INTO t_student(name,age) VALUES(?,?)";
Connection conn = null;
Statement st = null;
try {
// 1.加载注册驱动
Class.forName("com.mysql.jdbc.Driver");
Class.forName("com.mysql.jdbc.Driver");
// 2.获取数据库连接
conn = DriverManager.getConnection("jdbc:mysql:///jdbcdemo", "root", "root");
// 3.创建语句对象
PreparedStatement ps = conn.prepareStatement(sql);
try {
if (st != null)
st.close();
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
if (conn != null)
conn.close();
} catch (SQLException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
}
}</span>
上述代码中功能没问题，但是代码重复的太多，因此我们可以进行抽取，把重复的代码放到一个工具类JDBCUtil2里
[java] view plain copy在CODE上查看代码片派生到我的代码片
}
@Override
public List<Student> list() {
List<Student> list = new ArrayList<>();
String sql = "SELECT * FROM t_student ";
ps.setObject(1, stu.getName());
ps.setObject(2, stu.getAge());
// 4.执行SQL语句
ps.executeUpdate();
// 5.释放资源
} catch (Exception e) {
e.printStackTrace();
} finally {
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
//释放资源
public static void close(ResultSet rs, Statement st, Connection conn) {
try {
if (rs != null)
try {
if (conn != null)
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
}
在实现类中直接调用工具类中的方法即可
[java] view plain copy在CODE上查看代码片派生到我的代码片
public class StudentDAOImpl2 implements IstudentDAO {
// 2.获取数据库连接
conn = DriverManager.getConnection("jdbc:mysql:///jdbcdemo", "root", "root");
// 3.创建语句对象
PreparedStatement ps = conn.prepareStatement(sql);
// 3.创建语句对象
ps = conn.prepareStatement(sql);
ps.setObject(1, id);
// 4.执行SQL语句
rs = ps.executeQuery();
if (rs.next()) {
String name = rs.getString("name");
int age = rs.getInt("age");
java代码重构
平时我们写的代码虽然满足了需求但往往不利于项目的开发与维护，以下面的JDBC代码为例
[java] view plain copy在CODE上查看代码片派生到我的代码片
<span style="font-size:18px;">//增加学生信息
@Override
public void save(Student stu) {
// 2.获取数据库连接
conn = DriverManager.getConnection("jdbc:mysql:///jdbcdemo", "root", "root");
// 3.创建语句对象
PreparedStatement ps = conn.prepareStatement(sql);
ps.setObject(1, id);
// 4.执行SQL语句
ps.executeUpdate();
// 5.释放资源
} catch (Exception e) {
e.printStackTrace();
} finally {
JDBCUtil2.close(null, ps, conn);
}
}
//修改学生信息
String sql = "SELECT * FROM t_student WHERE id=?";
Connection conn = null;
Statement st = null;
ResultSet rs = null;
PreparedStatement ps=null;
try {
conn=JDBCUtil2.getConnection();
// 4.执行SQL语句
ps.executeUpdate();
// 5.释放资源
} catch (Exception e) {
e.printStackTrace();
} finally {
JDBCUtil2.close(null, ps, conn);
}
}
@Override
public Student get(Long id) {
String sql = "DELETE FROM t_student WHERE id=?";
Connection conn = null;
PreparedStatement ps=null;
try {
conn=JDBCUtil2.getConnection();
// 3.创建语句对象
ps = conn.prepareStatement(sql);
ps.executeUpdate();
// 5.释放资源
} catch (Exception e) {
e.printStackTrace();
} finally {
JDBCUtil2.close(null, ps, conn);
}
}
//删除学生信息
@Override
public void delete(Long id) {
ps.setObject(1, stu.getName());
ps.setObject(2, stu.getAge());
ps.setObject(3, stu.getId());
// 4.执行SQL语句
ps.executeUpdate();
// 5.释放资源
} catch (Exception e) {
try {
conn=JDBCUtil2.getConnection();
// 3.创建语句对象
ps = conn.prepareStatement(sql);
ps.setObject(1, stu.getName());
ps.setObject(2, stu.getAge());
// 4.执行SQL语句
e.printStackTrace();
}
}
public static Connection getConnection() {
try {
// 2.获取数据库连接
return DriverManager.getConnection("jdbc:mysql:///jdbcdemo", "root", "root");
e.printStackTrace();
} finally {
try {
if (st != null)
st.close();
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
if (conn != null)
conn.close();
//增加学生信息
@Override
public void save(Student stu) {
String sql = "INSERT INTO t_student(name,age) VALUES(?,?)";