J2ee通用分页一
通用分页（一）
- util辅助文件
- DBHelper
- StringUtils
- EncodingFilter
- config.properties
- Dao包和Biz层
- Dao包文件
- baseDao含内部接口
- IBookDao接口
- BookDao类
- Biz层
- IBookBiz接口
- BookBiz类
- 总结
util辅助文件
DBHelper
我这里有乱码，但是不影响，要设置一下字符编码（utf-8）
package com.rong.book.utils;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
/**
* 鎻愪緵浜嗕竴缁勮幏寰楁垨鍏抽棴鏁版嵁搴撳璞＄殑鏂规硶
*
*/
public class DBHelper {
private static String driver;
private static String url;
private static String user;
private static String password;
static {// 闈欐�佸潡鎵ц涓�娆★紝鍔犺浇 椹卞姩涓�娆�
try {
InputStream is = DBHelper.class
.getResourceAsStream("config.properties");
Properties properties = new Properties();
properties.load(is);
driver = properties.getProperty("driver");
url = properties.getProperty("url");
user = properties.getProperty("user");
password = properties.getProperty("pwd");
Class.forName(driver);
} catch (Exception e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
/**
* 鑾峰緱鏁版嵁杩炴帴瀵硅薄
*
* @return
*/
public static Connection getConnection() {
try {
Connection conn = DriverManager.getConnection(url, user, password);
return conn;
} catch (SQLException e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
public static void close(ResultSet rs) {
if (null != rs) {
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
}
public static void close(Statement stmt) {
if (null != stmt) {
try {
stmt.close();
} catch (SQLException e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
}
public static void close(Connection conn) {
if (null != conn) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
}
public static void close(Connection conn, Statement stmt, ResultSet rs) {
close(rs);
close(stmt);
close(conn);
}
public static boolean isOracle() {
return "oracle.jdbc.driver.OracleDriver".equals(driver);
}
public static boolean isSQLServer() {
return "com.microsoft.sqlserver.jdbc.SQLServerDriver".equals(driver);
}
public static boolean isMysql() {
return "com.mysql.jdbc.Driver".equals(driver);
}
public static void main(String[] args) {
Connection conn = DBHelper.getConnection();
DBHelper.close(conn);
System.out.println("isOracle锛�" + isOracle());
System.out.println("isSQLServer锛�" + isSQLServer());
System.out.println("isMysql锛�" + isMysql());
System.out.println("鏁版嵁搴撹繛鎺�(鍏抽棴)鎴愬姛");
}
}
StringUtils
package com.rong.book.utils;
public class StringUtils {
// 绉佹湁鐨勬瀯閫犳柟娉曪紝淇濇姢姝ょ被涓嶈兘鍦ㄥ閮ㄥ疄渚嬪寲
private StringUtils() {
}
/**
* 濡傛灉瀛楃涓茬瓑浜巒ull鎴栧幓绌烘牸鍚庣瓑浜�""锛屽垯杩斿洖true锛屽惁鍒欒繑鍥瀎alse
*
* @param s
* @return
*/
public static boolean isBlank(String s) {
boolean b = false;
if (null == s || s.trim().equals("")) {
b = true;
}
return b;
}
/**
* 濡傛灉瀛楃涓蹭笉绛変簬null鎴栧幓绌烘牸鍚庝笉绛変簬""锛屽垯杩斿洖true锛屽惁鍒欒繑鍥瀎alse
*
* @param s
* @return
*/
public static boolean isNotBlank(String s) {
return !isBlank(s);
}
}
EncodingFilter
package com.rong.book.utils;
import java.io.IOException;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* 涓枃涔辩爜澶勭悊
*
*/
public class EncodingFilter implements Filter {
private String encoding = "UTF-8";// 榛樿瀛楃闆�
public EncodingFilter() {
super();
}
public void destroy() {
}
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
HttpServletRequest req = (HttpServletRequest) request;
HttpServletResponse res = (HttpServletResponse) response;
// 涓枃澶勭悊蹇呴』鏀惧埌 chain.doFilter(request, response)鏂规硶鍓嶉潰
res.setContentType("text/html;charset=" + this.encoding);
if (req.getMethod().equalsIgnoreCase("post")) {
req.setCharacterEncoding(this.encoding);
} else {
Map map = req.getParameterMap();// 淇濆瓨鎵�鏈夊弬鏁板悕=鍙傛暟鍊�(鏁扮粍)鐨凪ap闆嗗悎
Set set = map.keySet();// 鍙栧嚭鎵�鏈夊弬鏁板悕
Iterator it = set.iterator();
while (it.hasNext()) {
String name = (String) it.next();
String[] values = (String[]) map.get(name);// 鍙栧嚭鍙傛暟鍊糩娉細鍙傛暟鍊间负涓�涓暟缁刔
for (int i = 0; i < values.length; i++) {
values[i] = new String(values[i].getBytes("ISO-8859-1"),
this.encoding);
}
}
}
chain.doFilter(request, response);
}
public void init(FilterConfig filterConfig) throws ServletException {
String s = filterConfig.getInitParameter("encoding");// 璇诲彇web.xml鏂囦欢涓厤缃殑瀛楃闆�
if (null != s && !s.trim().equals("")) {
this.encoding = s.trim();
}
}
}
config.properties
用哪个数据库就把那个放出来，这里我用的是mysql,(注意改参数)
#oracle9i
#driver=oracle.jdbc.driver.OracleDriver
#url=jdbc:oracle:thin:@localhost:1521:orcl
#user=scott
#pwd=123
#sql2005
#driver=com.microsoft.sqlserver.jdbc.SQLServerDriver
#url=jdbc:sqlserver://localhost:1433;DatabaseName=test1
#user=sa
#pwd=123
#sql2000
#driver=com.microsoft.jdbc.sqlserver.SQLServerDriver
#url=jdbc:microsoft:sqlserver://localhost:1433;databaseName=unit6DB
#user=sa
#pwd=888888
#mysql
driver=com.mysql.jdbc.Driver
url=jdbc:mysql://47.100.191.44:3307/xiao?useUnicode=true&characterEncoding=UTF-8
user=root
pwd=123456
Dao包和Biz层
Dao包文件
baseDao含内部接口
最好用泛型
package com.rong.book.base;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
import com.rong.book.utils.DBHelper;
import com.rong.book.utils.PageBean;
public class BaseDao<K> {
/**
* 内部接口 专门用来遍历rs结果集
* @author Administrator
*
*/
public static interface CallBack<T> {
public List<T> forEachRs(ResultSet rs) throws SQLException;
}
public List<K> exectueQuery(String sql,PageBean pageBean,CallBack callBack) {
Connection con = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
con = DBHelper.getConnection();
//1.查询符合条件的总记录
if(null!=pageBean && pageBean.isPagination()) {
String countSql = this.getCountSql(sql);
ps = con.prepareStatement(countSql);
rs = ps.executeQuery();
if(rs.next()) {
Object obj = rs.getInt(1);
pageBean.setTotal(obj.toString());
}
DBHelper.close(null, ps, rs);
}
//2.查询符合条件的记录
if(null!=pageBean && pageBean.isPagination()) {
sql = this.pageSql(sql, pageBean);
}
ps = con.prepareStatement(sql);
rs = ps.executeQuery();
return callBack.forEachRs(rs);
} catch (Exception e) {
throw new RuntimeException(e);
}finally {
DBHelper.close(con, ps, rs);
}
}
/**
* 得到查询总记录的sql语句
* @param sql
* @return
*/
private String getCountSql(String sql) {
String countSql = "SELECT COUNT(*) FROM ("+ sql +")t1";
return countSql;
}
/**
* 得到分页的sql语句
* @param sql
* @param pageBean
* @return
*/
private String pageSql(String sql,PageBean pageBean) {
String pageSql = sql+" LIMIT "+pageBean.getStartIndex()+","+pageBean.getRows();
return pageSql;
}
}
IBookDao接口
package com.rong.book.dao;
import java.util.List;
import com.rong.book.entity.Book;
public interface IBookDao {
public void addBook(Book book);
public List<Book> listBook(Book book);
}
BookDao类
一定要继承basedao不然下面方法用不了内部接口，我因为这个错误也是耗挺长时间
package com.rong.book.dao;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import com.rong.book.base.BaseDao;
import com.rong.book.entity.Book;
import com.rong.book.utils.DBHelper;
import com.rong.book.utils.PageBean;
import com.rong.book.utils.StringUtils;
public class BookDao extends BaseDao<Book> implements IBookDao {
Connection con=null;
PreparedStatement ps=null;
ResultSet rs=null;
@Override
public void addBook(Book book) {
String sql="INSERT INTO book(bname,price)VALUES(?,?)";
try {
con=DBHelper.getConnection();
ps=con.prepareStatement(sql);
ps.setString(1, book.getBname());
ps.setFloat(2, book.getPrice());
ps.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
}finally {
DBHelper.close(con, ps, rs);
}
}
@Override
public List<Book> listBook(Book book) {
List<Book> ls=new ArrayList<Book>();
String sql="SELECT bid,bname,price FROM book WHERE 1=1";
if(StringUtils.isNotBlank(book.getBname())) {
sql += " AND bname LIKE '%"+book.getBname()+"%'";
}
try {
con=DBHelper.getConnection();
ps=con.prepareStatement(sql);
rs=ps.executeQuery();
Book b=null;
while(rs.next()) {
b=new Book();
b.setBid(rs.getInt(1));
b.setBname(rs.getString(2));
b.setPrice(rs.getFloat(3));
ls.add(b);
}
} catch (Exception e) {
e.printStackTrace();
}finally {
DBHelper.close(con, ps, rs);
}
return ls;
}
public List<Book> listBook1(Book book,PageBean pageBean) {
String sql = "SELECT bid,bname,price FROM book WHERE 1=1";
if(StringUtils.isNotBlank(book.getBname())) {
sql += " AND book_name LIKE '%"+book.getBname()+"%'";
}
return this.exectueQuery(sql, pageBean, new CallBack<Book>() {
@Override
public List<Book> forEachRs(ResultSet rs) throws SQLException {
List<Book> ls= new ArrayList<Book>();
Book b = null;
while(rs.next()) {
b = new Book();
b.setBid(rs.getInt("bid"));
b.setBname(rs.getString("bname"));
b.setPrice(rs.getFloat("price"));
ls.add(b);
}
return ls;
}
});
}
}
Biz层
biz层其实就是调用一下dao层其实差不多，在biz类里调用一下dao类
IBookBiz接口
package com.rong.book.biz;
import java.util.List;
import com.rong.book.entity.Book;
import com.rong.book.utils.PageBean;
public interface IBookBiz {
public void addBook(Book book);
public List<Book> listBook(Book book,PageBean pageBean);
}
BookBiz类
package com.rong.book.biz;
import java.util.List;
import com.rong.book.dao.BookDao;
import com.rong.book.dao.IBookDao;
import com.rong.book.entity.Book;
import com.rong.book.utils.PageBean;
public class BookBiz implements IBookBiz {
private IBookDao bookdao = new BookDao();
@Override
public void addBook(Book book) {
bookdao.addBook(book);
}
@Override
public List<Book> listBook(Book book,PageBean pageBean) {
return bookdao.listBook(book);
}
}
总结
这里是为后面的jsp页面做底层准备工作，所以出错了页面是没有数据甚至报错的，要注意细节