Java DBUtils-使用ResultSetHandler
我试图使用ResultSetHandler将学生列表传递给servlet,但出现以下错误Java DBUtils-使用ResultSetHandler,java,jsp,servlets,jdbc,Java,Jsp,Servlets,Jdbc,我试图使用ResultSetHandler将学生列表传递给servlet,但出现以下错误 java.lang.NumberFormatException: For input string: "id" at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48) 学生上课的方法是 public List<Student> list2() throws SQLExc
java.lang.NumberFormatException: For input string: "id"
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
学生上课的方法是
public List<Student> list2() throws SQLException {
Connection connection = null;
List<Student> studentList = null;
try {
Context initCtx = new InitialContext();
Context envCtx = (Context) initCtx.lookup("java:comp/env");
DataSource ds = (DataSource)
envCtx.lookup("jdbc/TestDB");
connection = ds.getConnection();
ResultSetHandler h = new ArrayListHandler();
QueryRunner run = new QueryRunner(ds);
String sql = "select student_id, student_name from tbl_student";
studentList = (List<Student>)run.query(sql, h);
}catch(SQLException sqle) {
sqle.printStackTrace();
}
catch(Exception e) {
e.printStackTrace();
}
finally {
DbUtils.closeQuietly(connection);
}
return studentList;
}
public List list2()引发SQLException{
连接=空;
List studentList=null;
试一试{
Context initCtx=new InitialContext();
Context-envCtx=(Context)initCtx.lookup(“java:comp/env”);
数据源ds=(数据源)
envCtx.lookup(“jdbc/TestDB”);
connection=ds.getConnection();
ResultSetHandler h=新的ArrayListHandler();
QueryRunner运行=新的QueryRunner(ds);
String sql=“从tbl\U学生中选择学生id、学生姓名”;
studentList=(List)run.query(sql,h);
}捕获(SQLException sqle){
printStackTrace();
}
捕获(例外e){
e、 printStackTrace();
}
最后{
DbUtils.closequilly(连接);
}
返回学生名单;
}
我不使用DButils的另一种方法工作得很好
public List<Student> list() throws SQLException {
Connection connection = null;
Statement statement = null;
ResultSet resultSet = null;
List<Student> studentList = new ArrayList<Student>();
try {
Context initCtx = new InitialContext();
Context envCtx = (Context) initCtx.lookup("java:comp/env");
DataSource ds = (DataSource)
envCtx.lookup("jdbc/TestDB");
connection = ds.getConnection();
statement = connection.createStatement();
resultSet = statement.executeQuery("select student_id, student_name from tbl_student");
while (resultSet.next()) {
Student student = new Student();
student.setId(resultSet.getInt("student_id"));
student.setName(resultSet.getString("student_name"));
studentList.add(student);
}
}catch(SQLException e) {
e.printStackTrace();
}
catch(Exception e) {
e.printStackTrace();
}
finally {
if (resultSet != null) try { resultSet.close(); } catch (SQLException logOrIgnore) {}
if (statement != null) try { statement.close(); } catch (SQLException logOrIgnore) {}
if (connection != null) try { connection.close(); } catch (SQLException logOrIgnore) {}
}
return studentList;
}
public List()引发SQLException{
连接=空;
Statement=null;
ResultSet ResultSet=null;
List studentList=new ArrayList();
试一试{
Context initCtx=new InitialContext();
Context-envCtx=(Context)initCtx.lookup(“java:comp/env”);
数据源ds=(数据源)
envCtx.lookup(“jdbc/TestDB”);
connection=ds.getConnection();
statement=connection.createStatement();
resultSet=statement.executeQuery(“从tbl_学生中选择学生id、学生姓名”);
while(resultSet.next()){
学生=新生();
student.setId(resultSet.getInt(“student_id”);
setName(resultSet.getString(“学生名”);
学生列表。添加(学生);
}
}捕获(SQLE异常){
e、 printStackTrace();
}
捕获(例外e){
e、 printStackTrace();
}
最后{
如果(resultSet!=null),请尝试{resultSet.close();}catch(SQLException logOrIgnore){}
如果(statement!=null),请尝试{statement.close();}catch(SQLException logOrIgnore){}
如果(connection!=null),请尝试{connection.close();}catch(SQLException logOrIgnore){}
}
返回学生名单;
}
如何解决此问题?我建议您使用BeanListHandler从结果集中获取所有行,并将它们转换为JavaBean列表,如下所示:
QueryRunner queryRunner = new QueryRunner(dataSource);
ResultSetHandler<List<Student>> resultSetHandler = new BeanListHandler<Student>(Student.class);
List<Student> studentList = queryRunner.query("SELECT student_id, student_name FROM tbl_student", resultSetHandler);
QueryRunner QueryRunner=newqueryrunner(数据源);
ResultSetHandler ResultSetHandler=新BeanListHandler(Student.class);
List studentList=queryRunner.query(“从tbl_student中选择学生id、学生姓名”,resultSetHandler);
如果列名与Bean的属性不匹配,请使用ColumntPropertyOverrides,这将非常适合解决此问题
public <T> List<T> queryBeanList(String sql, final Class<T> clazz,final Map<String, String> columnToPropertyOverrides) throws SQLException {
ResultSetHandler<List<T>> rsh = new ResultSetHandler<List<T>>(){
@Override
public List<T> handle(ResultSet rs) throws SQLException {
BeanProcessor bp = new BeanProcessor(columnToPropertyOverrides);
return bp.toBeanList(rs, clazz);
}
};
return query(sql, rsh);
}
公共列表queryBeanList(字符串sql、最终类clazz、最终映射列TopPropertyOverrides)抛出SQLException{
ResultSetThandler rsh=新的ResultSetThandler(){
@凌驾
公共列表句柄(ResultSet rs)引发SQLException{
BeanProcessor bp=新BeanProcessor(ColumntropertyOverrides);
返回bp.toBeanList(rs,clazz);
}
};
返回查询(sql、rsh);
}
您可以添加完整的堆栈跟踪吗?当您执行相同的查询时,从dbclient选择student\u id,student\u name from tbl\u student
返回什么?它是否在student_id列中返回值“id”?使用BeanHandler和ArrayListHandler有什么区别?BeanListHandler创建给定类的实例,并将给定列的值放入匹配属性中。因此,必须重命名列以匹配bean属性的名称。SQL应该是:从tbl\U学生中选择学生id、学生姓名,