Dao层和Param层代码示例
时间: 2023-06-01 13:01:42 浏览: 59
对于Dao层和Param层代码示例,具体实现方式会根据具体业务需求和技术选型而有所不同。以下是一些常见的示例代码:
1. 使用JDBC技术实现Dao层和Param层
Dao层代码示例:
```java
public class UserDaoImpl implements UserDao {
private Connection conn;
private PreparedStatement ps;
public UserDaoImpl(Connection conn) {
this.conn = conn;
}
@Override
public User getUserById(int id) {
User user = null;
try {
String sql = "select * from user where id=?";
ps = conn.prepareStatement(sql);
ps.setInt(1, id);
ResultSet rs = ps.executeQuery();
if (rs.next()) {
user = new User();
user.setId(rs.getInt("id"));
user.setName(rs.getString("name"));
user.setAge(rs.getInt("age"));
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
close();
}
return user;
}
private void close() {
try {
if (ps != null) {
ps.close();
}
if (conn != null) {
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}
```
Param层代码示例:
```java
public class GetUserByIdParam implements Param {
private int id;
public GetUserByIdParam(int id) {
this.id = id;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
}
```
2. 使用MyBatis技术实现Dao层和Param层
Dao层代码示例:
```java
public interface UserDao {
User getUserById(int id);
}
```
```xml
<!-- UserDao.xml -->
<mapper namespace="com.example.dao.UserDao">
<select id="getUserById" parameterType="com.example.param.GetUserByIdParam" resultType="com.example.model.User">
select * from user where id=#{id}
</select>
</mapper>
```
Param层代码示例:
```java
public class GetUserByIdParam {
private int id;
public GetUserByIdParam(int id) {
this.id = id;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
}
```
以上是一些常见的Dao层和Param层代码示例,具体实现方式可以根据具体业务需求和技术选型进行调整。
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