org.apache.commons.dbcp.DelegatingPreparedStatement无法转换为com.mysql.jdbc.PreparedStatement

Question

我正在尝试使用预准备语句查询数据库，但是出现错误： org.apache.commons.dbcp.DelegatingPreparedStatement不能转换为com.mysql.jdbc.PreparedStatement。

进口

import org.springframework.beans.factory.annotation.Autowired; 
import org.springframework.dao.DataAccessException; 
import org.springframework.jdbc.core.PreparedStatementCreator; 
import org.springframework.jdbc.core.ResultSetExtractor; 
import org.springframework.jdbc.core.simple.ParameterizedRowMapper; 
import org.springframework.jdbc.core.support.JdbcDaoSupport; 
import org.springframework.jdbc.support.GeneratedKeyHolder; 
import org.springframework.jdbc.support.KeyHolder; 
import org.springframework.stereotype.Repository; 


import com.mysql.jdbc.PreparedStatement; 
import com.mysql.jdbc.Statement; 

JDBC

public List<Crime> getCrimeList(Crime crime) { 
     String where_clause = ""; 

     final List<Object> args = new ArrayList<Object>(); 
     final StringBuilder whereClause = new StringBuilder(); 


     if (crime.getCrimeDate()!= null){ 
      whereClause.append(" and crime.crimeDate = ?"); 
      args.add(crime.getCrimeDate()); 

     } 

     if(crime.getCrimeDetails() != null){ 
      whereClause.append(" and crime.crimeDetails = ?"); 
      args.add(crime.getCrimeDetails()); 

     } 

     .............. 

     logger.debug("In getCrimeList()"); 
     final String sql = "select crime.*, "+ 
        "criminalSocialSecurityNumber,criminal.fName as criminalFName,criminal.lName as criminalLName,"+ 
        "criminal.photo as criminalPhoto,criminal.dob as criminalDob,victimSocialSecurityNumber,"+ 
        "victim.fName as victimFName,victim.lName as victimLName,victim.photo as victimPhoto, victim.dob as victimDob "+ 
        "from tblcrimes crime "+ 
        "left join tblcriminalcrime on crime.crimeRecNo = tblcriminalcrime.crimeRecNo "+ 
        "left join tblvictimcrime on crime.crimeRecNo = tblvictimcrime.crimeRecNo "+ 
        "inner join tblcitizens criminal on criminal.socialSecurityNumber = tblcriminalcrime.criminalSocialSecurityNumber "+ 
        "inner join tblcitizens victim on victim.socialSecurityNumber = tblvictimcrime.victimSocialSecurityNumber "; 

     logger.debug("Executing getCrimeList String "+sql); 



     List<Crime> crimeList = getJdbcTemplate().query(new PreparedStatementCreator(){ 

     public java.sql.PreparedStatement createPreparedStatement(
       java.sql.Connection connection) throws SQLException { 

      PreparedStatement ps =(PreparedStatement) connection.prepareStatement(sql + whereClause); 
      int i = 1; 
      for (Object arg : args) { 
       ps.setObject(i, arg); 
       i++; 
      } 

      return ps; 
     } 
     }, new CrimeMapper());  



     return crimeList; 

    } 

错误

HTTP Status 500 - Request processing failed; nested exception is java.lang.ClassCastException: org.apache.commons.dbcp.DelegatingPreparedStatement cannot be cast to com.mysql.jdbc.PreparedStatement 

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.ClassCastException: org.apache.commons.dbcp.DelegatingPreparedStatement cannot be cast to com.mysql.jdbc.PreparedStatement 

org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:894) 
    org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:789) 
    javax.servlet.http.HttpServlet.service(HttpServlet.java:647) 
    javax.servlet.http.HttpServlet.service(HttpServlet.java:728) 

root cause 

java.lang.ClassCastException: org.apache.commons.dbcp.DelegatingPreparedStatement cannot be cast to com.mysql.jdbc.PreparedStatement 
    com.crimetrack.jdbc.JdbcCrimeDAO$2.createPreparedStatement(JdbcCrimeDAO.java:372) 
    org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:581) 
    org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:637) 
    org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:662) 
    com.crimetrack.jdbc.JdbcCrimeDAO.getCrimeList(JdbcCrimeDAO.java:367) 
    com.crimetrack.service.CrimeManager.getCrimesList(CrimeManager.java:24) 
    com.crimetrack.web.CrimeRegistrationController.handelCrimeList(CrimeRegistrationController.java:229) 
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) 
    sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) 
    java.lang.reflect.Method.invoke(Unknown Source) 
    org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:213) 
    org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:126) 
    org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:96) 
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:617) 
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:578) 
    org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80) 
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923) 
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852) 
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882) 
    org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:789) 
    javax.servlet.http.HttpServlet.service(HttpServlet.java:647) 
    javax.servlet.http.HttpServlet.service(HttpServlet.java:728) 

Answer 1

在行：

PreparedStatement ps =(PreparedStatement) connection.prepareStatement(sql + whereClause); 

Are you sure PreparedStatement is java.sql.PreparedStatement？

不确定为什么您需要投射从connection.prepareStatement()返回的对象。此方法返回java.sql.PreparedStatement类型的对象。如果您正确导入课程，请检查您的导入声明。