制作数据库框架
一 利用前端条件组装sql与查询条件的集合
public void handle() throws Exception{
Map<String,String> requestMap = new HashMap();
String fromdate = requestMap.get("fromdate");
String todate = requestMap.get("todate");
String resultcode = requestMap.get("reultcode");
SimpleDateFormat yyyy1mm1dd = new SimpleDateFormat("yyyy-MM-dd");
List values = new ArrayList();
String sql="select d.* checkpaylog where 1=1 ";
if(!StringUtils.isBlank(fromdate)){
sql+=" and d.tdate>=? ";
values.add(yyyy1mm1dd.parse(fromdate));
}
if(!StringUtils.isBlank(todate)){
sql+=" and d.tdate<=? ";
values.add(yyyy1mm1dd.parse(todate));
}
if(!"-1".equals(resultcode)){
sql+=" and d.resultcode=? ";
values.add(resultcode);
}
Map classMap = getClassMap(Checkpaylog.class);
query(sql, values, classMap, Checkpaylog.class, 0, 30 );
}
二 getClassMap方法是通过反射获取结果类的字段与set方法与方法类型
public Map getClassMap(Class entiy){
Field[] declaredFields = entiy.getClass().getDeclaredFields();
Map map = new HashMap();
for (int i = 0; i <declaredFields.length ; i++) {
//设置是否可以访问，如果不设置将报错
declaredFields[i].setAccessible(true);
String type = declaredFields[i].getType().getName();
String name = declaredFields[i].getName();
String strT = name.substring(0, 1);
String strW = name.substring(1, name.length());
String method_set = "set" + strT.toUpperCase() + strW;
System.out.println("字段名称："+name);
System.out.println("类型："+type);
map.put(name.toLowerCase(),name);
map.put(name+"type",type);
map.put(name+"method",method_set);
}
return map;
}
三 query方法是组装sql并执行后解析结果集
public List query(String sql, List pvalues,Map classMap, Class entiy, int start, int limit)throws Exception{
ResourceBundle resource = ResourceBundle.getBundle("config");
String url = resource.getString("jdbc.url");
String user = resource.getString("jdbc.username");
String pwd = resource.getString("jdbc.password");
Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection(url, user, pwd);
List list = new ArrayList();
if (start == -1 && limit == -1) {
sql=sql;
}else{
sql = sql + "limit " + start+","+limit;
}
PreparedStatement query = null;
ResultSet set = null;
try {
query = con.prepareStatement(sql);
if (pvalues != null) {
for (int i = 0; i < pvalues.size(); i++) {
if (pvalues.get(i) instanceof String) {
query.setString(i+1, (String) pvalues.get(i));
} else if (pvalues.get(i) instanceof Date) {
query.setDate(i+1, new java.sql.Date( ((Date)pvalues.get(i)).getTime()));
} else if (pvalues.get(i) instanceof Timestamp) {
query.setTimestamp(i+1, (Timestamp) pvalues.get(i));
} else if (pvalues.get(i) instanceof Long) {
query.setLong(i+1, (Long) pvalues.get(i));
} else if (pvalues.get(i) instanceof Double) {
query.setDouble(i+1, (Double) pvalues.get(i));
} else {
query.setString(i+1, (String) pvalues.get(i));
}
}
}
set = query.executeQuery();
ResultSetMetaData metadata = set.getMetaData();
int columCount = metadata.getColumnCount();
Map map = null;
while (set.next()) {
map = new HashMap<String, Object>();
Class<? extends Class> entiyClass = entiy.getClass();
for (int i = 1; i <= columCount; i++) {
String key = metadata.getColumnLabel(i).toLowerCase();
String columName = (String) classMap.get(key);
if("".equals(columName)){
break;
}
Object value = set.getObject(i);
if(value==null ){
value =null;
}else if(value instanceof TIMESTAMP){
value = (Timestamp)((TIMESTAMP) value).toJdbc();
}else if (value instanceof java.sql.Date){
if(value.toString().length()>10){
value = set.getTimestamp(i);
}else{
value = set.getDate(i);
}
}else if(value instanceof java.math.BigDecimal){
if(value.toString().indexOf(".")!=-1){
value = String.valueOf(((java.math.BigDecimal) value).doubleValue());
}
}else if (value instanceof java.lang.Long){
value = Long.valueOf(String.valueOf(value));
} else {
value = value.toString();
}
String methodName = (String) classMap.get(key + "method");
Class<?> aClass = (Class<?>) classMap.get(key + "types");
Class instance = entiyClass.getConstructor().newInstance();
Method setGuid = instance.getDeclaredMethod(methodName, aClass);
setGuid.invoke(instance,value);
}
list.add(entiy);
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
if(set!=null){
try {
set.close();
} catch (SQLException e) {
}
}
if(query!=null){
try {
query.close();
} catch (SQLException e) {
}
}
}
return list;
}
四 如果结果集是左连接形成的集合,这时用map来接受结果的方法findMapsBySQL来替换query方法
public List findMapsBySQL(String sql, List pvalues, int start, int limit) throws Exception{
ResourceBundle resource = ResourceBundle.getBundle("config");
String url = resource.getString("jdbc.url");
String user = resource.getString("jdbc.username");
String pwd = resource.getString("jdbc.password");
Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection(url, user, pwd);
List list = new ArrayList();
if (start == -1 && limit == -1) {
sql=sql;
}else{
sql = sql + "limit " + start+","+limit;
}
PreparedStatement query = null;
ResultSet set = null;
try {
query = con.prepareStatement(sql);
if (pvalues != null) {
for (int i = 0; i < pvalues.size(); i++) {
if (pvalues.get(i) instanceof String) {
query.setString(i+1, (String) pvalues.get(i));
} else if (pvalues.get(i) instanceof Date) {
query.setDate(i+1, new java.sql.Date( ((Date)pvalues.get(i)).getTime()));
} else if (pvalues.get(i) instanceof Timestamp) {
query.setTimestamp(i+1, (Timestamp) pvalues.get(i));
} else if (pvalues.get(i) instanceof Long) {
query.setLong(i+1, (Long) pvalues.get(i));
} else if (pvalues.get(i) instanceof Double) {
query.setDouble(i+1, (Double) pvalues.get(i));
} else {
query.setString(i+1, (String) pvalues.get(i));
}
}
}
set = query.executeQuery();
ResultSetMetaData metadata = set.getMetaData();
int columCount = metadata.getColumnCount();
Map map = null;
while (set.next()) {
map = new HashMap<String, Object>();
for (int i = 1; i <= columCount; i++) {
Object value = set.getObject(i);
if(value==null ){
value =null;
}else if(value instanceof TIMESTAMP){
value = (Timestamp)((TIMESTAMP) value).toJdbc();
}else if (value instanceof java.sql.Date){
if(value.toString().length()>10){
value = set.getTimestamp(i);
}else{
value = set.getDate(i);
}
}else if(value instanceof java.math.BigDecimal){
if(value.toString().indexOf(".")!=-1){
value = String.valueOf(((java.math.BigDecimal) value).doubleValue());
}
}else {
value = value.toString();
}
String key = metadata.getColumnLabel(i).toLowerCase();
map.put(key, value);
}
list.add(map);
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
if(set!=null){
try {
set.close();
} catch (SQLException e) {
}
}
if(query!=null){
try {
query.close();
} catch (SQLException e) {
}
}
}
return list;
}