解决mybatis使用char类型字段查询oracle数据库时结果返回null问题

select * from data where data.name=#{name}

select * from data where trim(data.name)=#{name}

create table t_user(
    user_name char(5)
);
insert into t_user (user_name)values('sgl');

conn=getConnection();
ps=conn.prepareStatement("select * from t_user where user_name=?");
ps.setString(1,"sgl");
ResultSet rs = ps.executeQuery();

conn=getConnection();
ps=conn.prepareStatement("select * from t_user where user_name=?");
ps.setString(1,"sgl "); -- 增加两个空格不足5位长度
ResultSet rs = ps.executeQuery();

conn=getConnection();
ps=conn.prepareStatement("select * from t_user where trim(user_name)=?"); -- 先对数据库中user_name进行去空格，然后再比较
ps.setString(1,"sgl");
ResultSet rs = ps.executeQuery();

<select id="selectByName" resultType="com.entity.Data" parameterType="java.lang.String">
 select * from data where data.name=#{name}
</select>

public static void main(String[] args) {
  ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
  DataService d = (DataService) ctx.getBean("dataServiceImpl");

  Data data = d.selectByName("sgl");
  System.out.println(data);
}

package com.songguoliang.url;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import java.util.ResourceBundle;
/**
 * 纯jdbc连接数据类
 * @author sgl
 *
 */
public class PureJdbcDao {
  private static ResourceBundle bundle = ResourceBundle.getBundle("jdbc");
  private static int reCount = 0;
  /**
   * 获取连接
   * @return
   */
  private static Connection getConnection(){
    Connection conn=null;
    try {
      Class.forName(bundle.getString("driverClassName"));
      conn = DriverManager.getConnection(bundle.getString("url") ,
          bundle.getString("username") , bundle.getString("password"));
    } catch (ClassNotFoundException e) {
      e.printStackTrace();
    } catch (SQLException e) {
      e.printStackTrace();
    }finally{
      if(null==conn&&reCount<5){
        try {
          Thread.sleep(10000);
        } catch (InterruptedException e) {
          e.printStackTrace();
        }
        reCount++;
        System.out.println("数据库第"+reCount+"次重连");
        conn = getConnection();
      }
    }
    return conn;
  }
  /**
   * 查询数据
   * @param sql
   * @return
   */
  public static List<String[]>query(String sql){
    List<String[]>result=new ArrayList<String[]>();
    Connection conn=null;
    Statement stmt=null;
    try {
      //System.out.println("[PureJdbcDao]查询语句：" + sql);
      conn=getConnection();
      stmt = conn.createStatement();
      ResultSet rs = stmt.executeQuery(sql);
      ResultSetMetaData rsMeta = rs.getMetaData();
      while(rs.next()){
        int columnNum=rsMeta.getColumnCount();
        String []field=new String[columnNum];
        String fieldValue=null;
        for(int i=1;i<=columnNum;i++){
          fieldValue=rs.getString(i);
          if(fieldValue==null){
            fieldValue="";
          }
          field[i-1]=fieldValue;
        }
        result.add(field);
      }
    } catch (SQLException e) {
      e.printStackTrace();
    }finally{
      try {
        if(stmt!=null){
          stmt.close();
        }
        if(conn!=null){
          conn.close();
        }
      } catch (SQLException e) {
        e.printStackTrace();
      }
    }
    return result;
  }
  public static List<String[]>query(String sql,List<String>params){
    List<String[]>result=new ArrayList<String[]>();
    Connection conn=null;
    PreparedStatement ps=null;
    try {
      conn=getConnection();
      ps=conn.prepareStatement(sql);
      for(int i=0;i<params.size();i++){
        ps.setString(i+1,params.get(i));
      }
      ResultSet rs = ps.executeQuery();
      ResultSetMetaData rsMeta = rs.getMetaData();
      while(rs.next()){
        int columnNum=rsMeta.getColumnCount();
        String []field=new String[columnNum];
        String fieldValue=null;
        for(int i=1;i<=columnNum;i++){
          fieldValue=rs.getString(i);
          if(fieldValue==null){
            fieldValue="";
          }
          field[i-1]=fieldValue;
        }
        result.add(field);
      }
    } catch (SQLException e) {
      e.printStackTrace();
    }finally{
      try {
        if(ps!=null){
          ps.close();
        }
        if(conn!=null){
          conn.close();
        }
      } catch (SQLException e) {
        e.printStackTrace();
      }
    }
    return result;
  }
  /**
   * 执行sql语句
   * @param sql
   */
  public static void execute(String sql){
    Connection conn=null;
    Statement stmt=null;
    try {
      //System.out.println("[PureJdbcDao]sql语句：" + sql);
      conn = getConnection();
      conn.setAutoCommit(false);
      stmt = conn.createStatement();
      stmt.execute(sql);
      conn.commit();
    } catch (SQLException e) {
      try {
        conn.rollback();
      } catch (SQLException e1) {
        e1.printStackTrace();
      }
      e.printStackTrace();
    }finally{
      try {
        if(stmt!=null){
          stmt.close();
        }
        if(conn!=null){
          conn.close();
        }
      } catch (SQLException e) {
        e.printStackTrace();
      }
    }
  }
}

package com.songguoliang;
import java.util.Arrays;
import java.util.List;
import com.songguoliang.url.PureJdbcDao;
public class Test {
  public static void main(String[] args) {
    //List<String[]>list=PureJdbcDao.query("select * from t_user where user_name=?",Arrays.asList("sgl")); // 查询到条数：0
    //List<String[]>list=PureJdbcDao.query("select * from t_user where user_name=?",Arrays.asList("sgl ")); //查询到条数：1
    List<String[]>list=PureJdbcDao.query("select * from t_user where trim(user_name)=?",Arrays.asList("sgl")); //查询到条数：1
    System.out.println("查询到条数："+list.size());
  }
}