Java 常用工具類
阿新 • • 發佈：2018-11-03
- PageBaen 分頁工具類
package com.strurts.utli; import java.util.Map; import javax.servlet.http.HttpServletRequest; public class PageBean { private int page = 1;// 頁碼 private int rows = 2;// 行數/頁大小 private int total = 0;// 總記錄數 private boolean pagination = true;// 預設分頁 private String url;// 上一次請求的地址 private Map<String, String[]> parameterMap;// 上一次請求的所有引數 public PageBean() { super(); } /** * 對分頁bean進行初始化 * * @param request */ public void setRequest(HttpServletRequest request) { // 公共引數 this.setPage(request.getParameter("page")); this.setRows(request.getParameter("rows")); this.setPagination(request.getParameter("pagination")); // 請求地址和請求引數 this.setUrl(request.getContextPath() + request.getServletPath()); this.setParameterMap(request.getParameterMap()); } public String getUrl() { return url; } public void setUrl(String url) { this.url = url; } public Map<String, String[]> getParameterMap() { return parameterMap; } public void setParameterMap(Map<String, String[]> parameterMap) { this.parameterMap = parameterMap; } public int getPage() { return page; } public void setPage(int page) { this.page = page; } public void setPage(String page) { if (null != page && !"".equals(page.trim())) { this.page = Integer.parseInt(page); } } public int getRows() { return rows; } public void setRows(int rows) { this.rows = rows; } public void setRows(String rows) { if (null != rows && !"".equals(rows.trim())) { this.rows = Integer.parseInt(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; } public void setPagination(String pagination) { if ("false".equals(pagination)) { this.pagination = false; } } /** * 下一頁 * * @return */ public int getNextPage() { int nextPage = page + 1; if (nextPage > this.getMaxPage()) { nextPage = this.getMaxPage(); } return nextPage; } /** * 上一頁 * * @return */ public int getPreviousPage() { int previousPage = page - 1; if (previousPage < 1) { previousPage = 1; } return previousPage; } /** * 最大頁碼 * * @return */ public int getMaxPage() { return total % rows == 0 ? total / rows : total / rows + 1; } /** * 起始記錄的下標 * * @return */ public int getStartIndex() { return (page - 1) * rows; } @Override public String toString() { return "PageBean [page=" + page + ", rows=" + rows + ", total=" + total + ", pagination=" + pagination + "]"; } }
- StringUtils 判斷字串是否為空的類
package com.hibernateSql.util; public class StringUtils { // 私有的構造方法，保護此類不能在外部例項化 private StringUtils() { } /** * 如果字串等於null或去空格後等於""，則返回true，否則返回false * * @param s * @return */ public static boolean isBlank(String s) { boolean b = false; if (null == s || s.trim().equals("")) { b = true; } return b; } /** * 如果字串不等於null或去空格後不等於""，則返回true，否則返回false * * @param s * @return */ public static boolean isNotBlank(String s) { return !isBlank(s); } }
- Hibernate 查詢通用BaseDao
package com.hibernateSql.dao; import java.util.Collection; import java.util.List; import java.util.Map; import org.hibernate.Session; import org.hibernate.query.Query; import com.hibernateSql.util.PageBean; /** * jdbc： * executeQuery(pagebean,sql,clz) * sql: select * from book where book_name '%?%' * select * from book where book_name '%xx%' * * 分頁：1.sql-->countSql-->total-->pagebaen * 2.sql-->pagesql-->result * 3.處理結果集 * * hibername * 分頁： * 1.hql-->countHql-->total-->pagebaen * 2.Hql-->pageHql-->result * * @author Administrator * */ public class BaseDao { /** * 如果有帶引數， * 命名引數 ：賦值 * * @param query * @param hql */ public void setParameters(Query<?> query,Map<String, Object> map) { if(map == null || map.size()==0) { return ; } else { //建立map的檢視 Object values=null; for (Map.Entry<String, Object> entry : map.entrySet()) { values=entry.getValue(); //判斷它的資料型別 if(values instanceof Collection) { query.setParameterList(entry.getKey(), (Collection) values); } else if(values instanceof Object[]) { query.setParameterList(entry.getKey(), (Object[]) values); } else { query.setParameter(entry.getKey(), values); } } } } /** * 拼接Hqlcount語句 */ public String getcountHql(String hql) { int index = hql.toUpperCase().indexOf("FROM"); return "select count(*) "+ hql.substring(index); } /** * */ public List<?> executeQuery(String hql,Map<String, Object> map,PageBean pageBean,Session session){ //判斷它是否分頁 if(pageBean != null && pageBean.isPagination()) { //如果分頁 String countHql = getcountHql(hql); //查詢出總頁數 Query<?> query = session.createQuery(countHql); //給這個countHql中的命名引數賦值 setParameters(query, map); String total = query.getSingleResult().toString(); //放入pageBeau pageBean.setTotal(total); //開始查詢資料 Query<?> pageQuery = session.createQuery(hql); //給命名引數賦值 this.setParameters(pageQuery, map); //設定分頁 pageQuery.setFirstResult(pageBean.getStartIndex()); pageQuery.setMaxResults(pageBean.getRows()); return pageQuery.list(); } else { //不分頁的時候 Query<?> query = session.createQuery(hql); //給引數賦值 setParameters(query, map); return query.list(); } } }
- 獲取Map , 根據傳遞過來到key獲取裡面到值
package com.strurts.utli;
import java.util.Arrays;
import java.util.Map;
public class JsonUtil {
/**
* 獲取Map , 根據傳遞過來到key獲取裡面到值
* @param map
* @param key
* @return
*/
public static String getParamMapVal(Map<String, String[]> map,String key) {
if(map!=null&&map.size()>0) {
String[] vals = map.get(key);
if(vals!=null&&vals.length>0) {
String val = Arrays.toString(vals);
return val.substring(1, val.length()-1);
}
}
return "";
}
}
- BaseDao 利用oop思想進行增強的一個通用查詢分頁類
package com.zking.util;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
/**
* 利用oop思想進行增強的一個通用查詢分頁類
* @author Administrator
*
* @param <T>
*/
public class BaseDao<T> {
/**
* 沿用的思想類似於ajax
* success：function{
* }
* @author Administrator
*
*/
public abstract class CallBack{
public abstract List<T> forEach(ResultSet rst,Connection con) throws SQLException, InstantiationException, IllegalAccessException;
}
/**
*
* @param sql
* @param pageBean
* @param callBack
* @return
* @throws SQLException
* @throws InstantiationException
* @throws IllegalAccessException
*/
public List<T> executeQuery(String sql, PageBean pageBean,CallBack callBack) throws SQLException, InstantiationException, IllegalAccessException {
Connection con = DBAccess.getConnection();
if(pageBean.isPagination()) {
String countSql = getCountSql(sql);
PreparedStatement pst = con.prepareStatement(countSql);
ResultSet rst = pst.executeQuery();
if(rst.next()) {
pageBean.setTotal(rst.getObject(1).toString());
}
}
String pageSql = getPageSql(sql,pageBean);
PreparedStatement pst = con.prepareStatement(pageSql);
ResultSet rst = pst.executeQuery();
return callBack.forEach(rst, con);
}
/**
* 拼裝分頁的sql語句
* @param sql
* @param PageBean
* @return
*/
private String getPageSql(String sql, PageBean pageBean) {
int page = pageBean.getPage();
int rows = pageBean.getRows();
int startIndex = (page - 1) * rows;
return pageBean.isPagination() ? (sql + " limit "+ startIndex +"," + rows) : sql;
}
/**
* 獲取符合記錄數的sql語句
* @param sql
* @return
*/
private String getCountSql(String sql) {
return "select count(*) from ("+ sql +") t;";
}
}
- EntityBaseDao 利用反射對通用分頁查詢進行二次增強
package com.zking.util;
import java.lang.reflect.Field;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
/**
* 利用反射對通用分頁查詢進行二次增強
* @author Administrator
*
* @param <T>
*/
public class EntityBaseDao<T> extends BaseDao<T> {
public List<T> executeQuery(String sql, PageBean pageBean, Class<T> clz) throws SQLException, InstantiationException, IllegalAccessException{
return super.executeQuery(sql, pageBean, new CallBack() {
@Override
public List<T> forEach(ResultSet rst,Connection con) throws SQLException, InstantiationException, IllegalAccessException {
List<T> list = new ArrayList<>();
while(rst.next()) {
// 1、例項化一個具體的類物件出來
// 2、給具體的哪一個類物件賦值（用於頁面展示）
// 3、要通過類物件的屬性從ResultSet拿到資料
// 4、把裝有資料的實體類新增給list
// list.add(new Book(rst.getInt("bid"), rst.getString("bname"), rst.getFloat("price")));
T t = (T) clz.newInstance();
Field[] declaredFields = clz.getDeclaredFields();
for (Field field : declaredFields) {
field.setAccessible(true);
field.set(t, rst.getObject(field.getName()));
}
list.add(t);
}
return list;
}
});
}
/**
* 通用的增刪改方法
* @param sql 增刪改的sql語句
* @param attrs 要個sql語句的那個表字段進行賦值，需要呼叫方傳遞過來
* @param t 具體要給哪個物件進行增刪改操作
* @return
* @throws SQLException
* @throws InstantiationException
* @throws IllegalAccessException
* @throws SecurityException
* @throws NoSuchFieldException
*/
public int executeUpdate(String sql, String[] attrs, T t) throws SQLException, InstantiationException, IllegalAccessException, NoSuchFieldException, SecurityException{
Connection con = DBAccess.getConnection();
PreparedStatement pst = con.prepareStatement(sql);
// 給sql語句預定義物件賦值
for (int i = 0; i < attrs.length; i++) {
Field attrField = t.getClass().getDeclaredField(attrs[i]);
attrField.setAccessible(true);
int j = i+1;
pst.setObject(j, attrField.get(t));
}
return pst.executeUpdate();
}
}
- JsonBaseDao json格式的通用查詢
package com.zking.util;
import java.lang.reflect.Field;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* json格式的通用查詢
* @author Administrator
*
*/
public class JsonBaseDao extends BaseDao<Map<String, Object>>{
public List<Map<String, Object>> executeQuery(String sql, PageBean pageBean)
throws SQLException, InstantiationException, IllegalAccessException {
return super.executeQuery(sql, pageBean, new CallBack() {
@Override
public List<Map<String, Object>> forEach(ResultSet rst,Connection con)
throws SQLException, InstantiationException, IllegalAccessException {
List<Map<String, Object>> list=new ArrayList<>();
ResultSetMetaData md=rst.getMetaData();
int columnCount = md.getColumnCount();
Map<String, Object> map=null;
while(rst.next()) {
map=new HashMap<>();
for (int i = 1; i <=columnCount; i++) {
map.put(md.getColumnName(i), rst.getObject(i));
}
list.add(map);
}
con.close();
return list;
}
});
}
/**
* 通用增刪改
*/
public int executeUpdate(String sql, String[] keys,Map<String, String[]> map) throws SQLException, InstantiationException, IllegalAccessException, NoSuchFieldException, SecurityException{
Connection con = DBAccess.getConnection();
PreparedStatement pst = con.prepareStatement(sql);
// 給sql語句預定義物件賦值
for (int i = 0; i < keys.length; i++) {
pst.setObject(i+1, JsonUtil.getParamMapVal(map,keys[i]));
}
return pst.executeUpdate();
}
}