通用查询------------详细讲解通用 查询所有，模糊查询，分页查询集为一体，一个方法解决三个查询

package com.yinzi.utils;
/**
 * 分页工具类
 *
 */
public class PageBean {
  private int page = 1;// 页码
  private int rows = 10;// 页大小
  private int total = 0;// 总记录数
  private boolean pagination = true;// 是否分页
  public PageBean() {
    super();
  }
  public int getPage() {
    return page;
  }
  public void setPage(int page) {
    this.page = page;
  }
  public int getRows() {
    return rows;
  }
  public void setRows(int rows) {
    this.rows = rows;
  }
  public int getTotal() {
    return total;
  }
  public void setTotal(int total) {
    this.total = total;
  }
  public void setTotal(String total) {
    this.total = Integer.parseInt(total);
  }
  public boolean isPagination() {
    return pagination;
  }
  public void setPagination(boolean pagination) {
    this.pagination = pagination;
  }
  /**
   * 获得起始记录的下标
   * 
   * @return
   */
  public int getStartIndex() {
    return (this.page - 1) * this.rows;
  }
  @Override
  public String toString() {
    return "PageBean [page=" + page + ", rows=" + rows + ", total=" + total + ", pagination=" + pagination + "]";
  }
}

  /**
   * 带分页的模糊查询
   * @param c
   * @param sql
   * @param pagebean
   * @return
   * @throws Exception
   */
  public List<T> executeQuery(Class c ,String sql,PageBean pagebean) throws Exception{
    //创建集合保存数据
    List<T> list = new ArrayList<>();
    //获取连接
    Connection conn =null;
    //执行SQL语句
    PreparedStatement ps = null;
    //结果集对象
    ResultSet rs =null;
    //判断是否需要分页
    if(pagebean!=null && pagebean.isPagination()) {//如果需要分页，就拼接SQL语句
      String Countsql=getCountsql(sql);//获取总数量
      conn = DBAccess.getConnection();
      ps = conn.prepareStatement(Countsql);//执行改变后的SQL语句
      rs = ps.executeQuery();
      if(rs.next()) {
        pagebean.setTotal(rs.getObject("n").toString());
      }
      String pagesql=getPagesql(sql,pagebean);
      conn = DBAccess.getConnection();
      ps = conn.prepareStatement(pagesql);//执行改变后的SQL语句
      rs = ps.executeQuery();
    }else {//否则不需要，就按照原sql语句执行
      conn = DBAccess.getConnection();
      ps = conn.prepareStatement(sql);
      rs = ps.executeQuery();
    }
    //循环遍历数据
    while(rs.next()) {
      T t = (T) c.newInstance();
      //拿到所有的属性
      Field[] fields = c.getDeclaredFields();
      for (Field field : fields) {
        //打开访问权限
        field.setAccessible(true);
        field.set(t,rs.getObject(field.getName()));
      }
      list.add(t);
    }
    return list;
  }

package com.yinzi.dao;
import java.util.ArrayList;
/**
 * dao方法类
 * @author 86131
 *
 */
import java.util.List;
import org.junit.Test;
import com.yinzi.entity.Book;
import com.yinzi.utils.PageBean;
import com.yinzi.utils.StringUtils;
public class BookDao extends BaseDao<Book>{
  /**
   * 查询所有的方法
   * @param book
   * @param pagebean
   * @return list
   * @throws Exception
   */
  public List<Book> queryAll(Book book,PageBean pagebean) throws Exception{
    //sql语句
    //查询所有
    String sql="select * from t_mvc_book where 1=1 ";//必然会进来
    //根据name属性进行模糊查询
    String bname = book.getBname();//获取bname属性
    //判断（模糊查询）
    if(StringUtils.isNotBlank(bname)) {//如果字符串bname不为空就拼接在SQL语句
      sql+=" and bname like '%"+bname+"%'";
    }
    return super.executeQuery(Book.class, sql, pagebean);
  }
  //测试
  public static void main(String[] args) throws Exception {
    Book book=new Book();
    PageBean pagebean =new PageBean();
    List<Book> queryAll = new BookDao().queryAll(book, pagebean);
    for (Book book2 : queryAll) {
      System.out.println(book2);
    }
  }