所有业务逻辑类皆可调用该类
package com.parddu.
dao;
import
java.lang.reflect.InvocationTargetException;
import
java.lang.reflect.Method;
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;
/**
* 通用
DAO类
* @author parddu
* @version Sep 29, 2010 10:16:23 AM
*/
public class Common
DAO {
/**
* 修改数据
* @param sql sql语句
* @param param 参数列表
* @return 修改记录行数
*/
public int update
(String sql,List param
){
int row = -1;
Connection conn = null;
PreparedStatement update = null;
try {
conn = DButil.getConn
();
update = conn.prepareStatement
(sql
);
this.setParam
(update, param
);
row = update.executeUpdate
();
}
catch
(Exception e
) {
throw new RuntimeException
(e.getMessage
());
}
finally{
DButil.closeConn
(update, conn
);
}
return row;
}
/**
* 查询数据
* @param sql sql语句
* @param param 参数
* @return 结果集HashMap<列名,值
对象>
*/
public List<HashMap> query
(String sql,List param
) {
List<HashMap> list = new ArrayList<HashMap>
();
Connection conn = null;
PreparedStatement query = null;
ResultSet rs = null;
try {
conn = DButil.getConn
();
query = conn.prepareStatement
(sql
);
this.setParam
(query, param
);
rs = query.executeQuery
();
if
(rs!=null
){
//取得所有的列名
ResultSetMetaData rsmd = rs.getMetaData
();
int columnCount = rsmd.getColumnCount
();
String[] columnNameArray = new String[columnCount];
for
(int i=0;i<columnCount;i++
){
columnNameArray[i] = rsmd.getColumnName
(i+1
);
}
//读取结果
while
(rs.next
()){
HashMap<String,Object> hm = new HashMap<String,Object>
();
for
(String cn : columnNameArray
){
hm.put
(cn, rs.getObject
(cn
));
}
list.add
(hm
);
}
}
}
catch
(Exception e
) {
throw new RuntimeException
(e.getMessage
());
}
finally{
DButil.closeConn
(rs,query, conn
);
}
return list;
}
/**
* 查询数据
* @param sql sql语句
* @param param 参数
* @return 结果集List<实体
对象>
*/
public List query
(String sql,List param,Class cla
){
List list = new ArrayList
();
Connection conn = null;
PreparedStatement query = null;
ResultSet rs = null;
try {
conn = DButil.getConn
();
query = conn.prepareStatement
(sql
);
this.setParam
(query, param
);
rs = query.executeQuery
();
if
(rs!=null
){
//取得所有的列名
ResultSetMetaData rsmd = rs.getMetaData
();
int columnCount = rsmd.getColumnCount
();
String[] columnNameArray = new String[columnCount];
for
(int i=0;i<columnCount;i++
){
columnNameArray[i] = rsmd.getColumnName
(i+1
);
}
//得到所有列和方法匹配的项
List<PropertyMthod> mList = new ArrayList<PropertyMthod>
();
for
(String columnName : columnNameArray
){
Method m = this.getMethod
(cla,columnName
);
if
(m!=null
){
PropertyMthod pm = new PropertyMthod
(m,columnName
);
mList.add
(pm
);
}
}
//读取结果
while
(rs.next
()){
Object o = cla.newInstance
();
for
(PropertyMthod pm : mList
){
this.invokeSetMethod
(o, pm.getMethod
(), rs, pm.getColumn
());
}
list.add
(o
);
}
}
}
catch
(Exception e
) {
throw new RuntimeException
(e.getMessage
());
}
finally{
DButil.closeConn
(rs,query, conn
);
}
return list;
}
/**
* 调用目标
对象的set方法
* @param o 目标
对象
* @param m set方法
* @param rs 结果集
* @param columnName 列名
* @throws SecurityException
* @throws NoSuchMethodException
* @throws IllegalArgumentException
* @throws IllegalAccessException
* @throws InvocationTargetException
*/
private void invokeSetMethod
(Object o,Method m,ResultSet rs,String columnName
)
throws SecurityException, NoSuchMethodException,
IllegalArgumentException, IllegalAccessException,
InvocationTargetException{
String paramType = m.getParameterTypes
()[0].getName
();
paramType = paramType.substring
(paramType.lastIndexOf
("."
)+1
);
/*****特殊类型处理******/
if
("Integer".equals
(paramType
)){
paramType = "Int";
}
String strName = "get" + this.firstUpper
(paramType
);
Method rsMethod = rs.getClass
().getDeclaredMethod
(strName, String.class
);
m.invoke
(o, rsMethod.invoke
(rs, columnName
));
}
/**
* 匹配指定列名的set方法
* @param o
* @param column
* @return
* @throws NoSuchMethodException
* @throws SecurityException
*/
private Method getMethod
(Class o,String column
)
throws SecurityException, NoSuchMethodException{
Method m = null;
List<String> strList = new ArrayList<String>
();
/********set方法转换设置***********/
strList.add
(column
);
//去掉下划线stu_name--->stuName
strList.add
(this.delLine
(column,"_"
));
boolean flage = false;
Method[] mlist = o.getDeclaredMethods
();
for
(Method tempm : mlist
){
for
(String s:strList
){
String name = "set"+this.firstUpper
(s
);
if
(tempm.getName
().equals
(name
)){
m=tempm;
flage = true;
break;
}
}
if
(flage
){
break;
}
}
if
(!flage
){
System.out.println
("查询列名" + column +
"在实体中无方法名匹配，值将不会被设置！"
);
}
return m;
}
/**
* 删除列分割符
* @return
*/
private String delLine
(String str,String fg
){
String result = str;
if
(str.indexOf
(fg
)!=-1
){
result = str.substring
(0,str.indexOf
(fg
))+
this.firstUpper
(str.substring
(str.indexOf
(fg
)+1
));
result = delLine
(result,fg
);
}
return result;
}
/**
* 将给定字符串首字母修改为小写
* @param str 字符串
* @return 转换后的字符串
*/
private String firstUpper
(String str
){
return
(str.charAt
(0
)+""
).toUpperCase
()+str.substring
(1
);
}
/**
* 设置参数
* @param ps 预编译
对象
* @param param 参数集合
* @throws SQLException
*/
private void setParam
(PreparedStatement ps,List param
) throws SQLException{
if
(param!=null&¶m;.size
()>0
){
for
(int i=0;i<param.size
();i++
){
ps.setObject
(i+1, param.get
(i
));
}
}
}
}
DAO模式在Java中用于分离数据访问逻辑与业务逻辑，提高代码可维护性和可测试性。通过创建DAO接口和实现类，模拟数据存储并集成到业务逻辑中，如UserService，实现了数据操作的解耦。
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