static{
try {
//发布使用
//Context context = new InitialContext(); //创建一个上下文件对象
//dataSource = (DataSource) context.lookup("java:comp/env/jdbc/jspJNDI");
//开发中测试使用
Properties props = new Properties();
props.load(DbHelper.class.getClassLoader().getResourceAsStream("db.properties"));
dataSource = BasicDataSourceFactory.createDataSource(props);
} catch (Exception e) {
e.printStackTrace();
}
}

//获取数据库连接对象
public static Connection getConn(){
Connection con = null;
if (dataSource != null){
try {
con = dataSource.getConnection(); //在数据源中取到一个连接
} catch (SQLException e) {
e.printStackTrace();
}
}
return con;
}

public static void closeAll(ResultSet rs,Statement stmt,Connection conn ){
//关闭结果集对象
if(null!=rs){
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
//关闭语句对象
if(null!=stmt){
try {
stmt.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
//关闭数据库连接对象
if(null!=conn){
try {
conn.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

public static void closeAll(ResultSet rs,PreparedStatement pstmt,Connection conn ){
//关闭结果集对象
if(null!=rs){
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
//关闭语句对象
if(null!=pstmt){
try {
pstmt.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
//关闭数据库连接对象
if(null!=conn){
try {
conn.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

/**

*@param pstmt 预编译对象

* @param params 传入的设置值的集合

* @throws SQLException
*/
private static void setParams(PreparedStatement pstmt,Object...params) throws SQLException{
if(null!=params&&params.length>0){
for(int i=0;i<params.length;i++){
if(params[i] instanceof Date){
//params存储值的顺序与 ?的顺序一样
pstmt.setTimestamp(i+1, new Timestamp(((Date)params[i]).getTime()));
}else{
pstmt.setObject(i+1, params[i]);//params存储值的顺序与 ?的顺序一样
}

}
}
}

/**
* 增删改
* @param sql
* @param params
* @return
* @throws SQLException
*/
public static int doUpdate(String sql,Object...params) {
Connection conn =null;
PreparedStatement pstmt =null;
int result =-1;

try {
conn=getConn();
pstmt=conn.prepareStatement(sql);
setParams(pstmt, params);
result =pstmt.executeUpdate();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally {
closeAll(null, pstmt, conn);
}
return result;
}

public static int doUpdate(List<String> sqls, Object[]...params) throws SQLException{
Connection conn =null;
PreparedStatement pstmt =null;
int result =-1;
try {
conn = getConn();
conn.setAutoCommit(false);
if(null!= sqls && sqls.size()>0){
// 循环sql语句
for(int i=0;i<sqls.size();i++){
String sql=sqls.get(i);
pstmt =conn.prepareStatement(sql);
// 给当前sql语句设置
setParams(pstmt, params[i]);
result +=pstmt.executeUpdate();
}
}
// 提交事物
conn.commit();
} catch (Exception e) {
e.printStackTrace();
// 回滚事物
result=0;
conn.rollback();
} finally {
// 回复现场
conn.setAutoCommit(true);
closeAll(null, pstmt, conn);
}
return result;
}

public static int updateImg(String sql,int id ,File file) throws FileNotFoundException{
FileInputStream in = new FileInputStream(file);
Connection conn =null;
PreparedStatement pstmt =null;
int result = 0;
try {
pstmt = conn.prepareStatement(sql);
pstmt.setBinaryStream(1, in,(int)file.length());
pstmt.setInt(2, id);
result = pstmt.executeUpdate();
} catch (SQLException e) {

} finally {
closeAll(null, pstmt, conn);
}

return result;
} 

6、查询操作  

/**
* 查询多条记录
* @param sql
* @param params
* @return
* @throws SQLException
*/
public static List<Map<String , Object>> findMultiObject(String sql,Object...params) throws SQLException{
List<Map<String , Object>> list =new ArrayList<Map<String ,Object>>();
Connection conn =null;
PreparedStatement pstmt =null;
ResultSet rs =null;
Map<String, Object> map =null;
try {
conn =getConn();
pstmt =conn.prepareStatement(sql);
setParams(pstmt, params);
rs =pstmt.executeQuery();
List<String > columnNames =getAllColumnNames(rs);//获取结果中的所有列表
while(rs.next()){
map = new HashMap<String,Object>();
for(String cn:columnNames){//循环列名，将列表作用map的键，根据列表获取到每个列的值
map.put(cn, rs.getObject(cn));
}
list.add(map);
}
} finally {
closeAll(rs, pstmt, conn);
}

return list;
}

/**
* 查询单条记录 select * from 表名 where id = 1
* @param sql
* @param params
* @return
* @throws SQLException
*/
public static Map<String,Object> findSingleObject(String sql, Object...params) throws SQLException{
Connection conn = null;
PreparedStatement pstmt = null;
ResultSet rs = null;
Map<String,Object> map = null;
try {
conn = getConn();
pstmt = conn.prepareStatement(sql);
setParams(pstmt, params);
rs = pstmt.executeQuery();
List<String> columnNames = getAllColumnNames(rs); //获取结果集中的所有列表
while(rs.next()){
map = new HashMap<String,Object>();
for(String cn: columnNames){ //循环列名，将列表作用Map的键，根据列表获取到每个列的值
map.put(cn, rs.getObject(cn));
}
}
}finally{
closeAll(rs, pstmt, conn);
}
return map;
}

8、操作结果操作
/**
* 根据结果集对象获取所有的列名 存在一个list集合中 jdbc2.0取元数据
* @param rs
* @return
* @throws SQLException
*/
private static List<String> getAllColumnNames(ResultSet rs ) throws SQLException{
List<String> columnNames =new ArrayList<String>();
if(null !=rs){
for(int i=0 ;i<rs.getMetaData().getColumnCount();i++){
columnNames.add(rs.getMetaData().getColumnName(i+1));
}
}
return columnNames;
}

public static<T> T get(Class<T> clazz, String sql, Object...params) throws SQLException {
return mapping2Obj(clazz, findSingleObject(sql, params));
}

public static <T> List<T> list(Class<T> clazz, String sql, Object...params) throws SQLException {
List<Map<String , Object>> results = findMultiObject(sql, params);
List<T> ts = null;
if (results != null) {
ts = new ArrayList<T>();
for (Map<String, Object> result : results) {
ts.add(mapping2Obj(clazz, result));
}
}
return ts;
}

private static <T> T mapping2Obj(Class<T> clazz, Map<String,Object> temps){
T t = null;
try {
t = clazz.newInstance();
} catch (InstantiationException | IllegalAccessException e) {
e.printStackTrace();
}
Method[] ms = clazz.getDeclaredMethods(); //取到所有的方法
for (Method m : ms) {
String mn = m.getName(); //取到方法名
if(mn.startsWith("set")){
String pt = m.getParameterTypes()[0].getName(); //取到set方法的参数类型
Object obj = temps.get(mn.replace("set", "").toUpperCase()); //取到set方法对应数据库字段的值
try {
if(obj != null){
if (pt.endsWith("int") || pt.endsWith("Integer")) {
m.invoke(t, ((BigDecimal)obj).intValue());
} else if (pt.endsWith("double") || pt.endsWith("Double")) {
m.invoke(t, ((BigDecimal)obj).doubleValue());
} else if (pt.endsWith("java.util.Date")) {
m.invoke(t, (Timestamp)obj); //11g
//m.invoke(t, new Date(((java.sql.Date)obj).getTime())); //10g
} else {
if(obj.getClass().getName().endsWith("CLOB")){
obj = clobToString((CLOB)obj);
}
m.invoke(t, obj);
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
return t;
}

public static String clobToString(Clob clob) {
String reString = "";
Reader is = null;
try {
is = clob.getCharacterStream();
} catch (SQLException e) {
e.printStackTrace();
}
// 得到流
BufferedReader br = new BufferedReader(is);
String s = null;
try {
s = br.readLine();
} catch (IOException e) {
e.printStackTrace();
}
StringBuffer sb = new StringBuffer();
while (s != null) {
//执行循环将字符串全部取出付值给StringBuffer由StringBuffer转成STRING
sb.append(s);
try {
s = br.readLine();
} catch (IOException e) {
e.printStackTrace();
}
}
reString = sb.toString();
return reString;
}
}