java模板动态sql语句_Jdbc模板，实现动态⽣成
1.[代码]简单ORMapping
import flect.Field;
import flect.Method;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;
import org.ddang.util.DbUtil;
/**
* 规定：
* 1.数据表名 “tb_” + “对象名”
* 2.数据库字段顺序与对应实体属性顺序⼀致(不是必须的，但是ID必须是第⼀个属性)
* 功能：通过反射实现CRUD
* 使⽤：继承该类，调⽤对应⽅法，传⼊对象类型
DbUtil.为⾃定义操作数据库⼯具类
* @author Administrator
*
*/
public class JdbcTemplate {
public final static String TABLE_PREFIX = "tb_";
private String tableName = "";
private Field[] fields;
private List getFields(Object obj) {
Class c = Class();
// 获得类名
String className = Class().getSimpleName();
// 类名 + 前缀 = 表名
tableName = TABLE_PREFIX + LowerCase();
// 获得所有的属性
fields = c.getDeclaredFields();
Method[] method = c.getMethods();
List list = new ArrayList();
for (int j = 0; j < fields.length; j++) {
String m = "get" + fields[j].getName().toUpperCase().charAt(0) + fields[j].getName().substring(1);
for (int i = 0; i < method.length; i++) {
if (method[i].getName().endsWith(m)) {
// method[i].invoke("", null);
try {
list.add(method[i].invoke(obj, null));
System.out.println("---------"
+ method[i].invoke(obj, null));
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
}
}
return list;
}
private String getInsertSQL(Object obj) {
// 拼SQL语句
StringBuffer sql = new StringBuffer();
sql.append("INSERT INTO ");
sql.append("`" + tableName + "`");
sql.append(" (");
for (int i = 0; i < fields.length; i++) {
sql.append("`" + fields[i].getName() + "`");
if (i < fields.length - 1) {
sql.append(",");
}
}
sql.append(") ");
sql.append(" VALUES(");
for (int i = 0; i < fields.length; i++) {
sql.append("?");
if (i < fields.length - 1) {
sql.append(",");
}
}
sql.append(") ");
String();
}
private String getUpdateSQL(Object obj) { // 拼SQL语句
StringBuffer sql = new StringBuffer(); sql.append("UPDATE ");
sql.append("`" + tableName + "` ");
sql.append(" SET ");
for (int i = 1; i < fields.length; i++) {
sql.append("`" + fields[i].getName() + "`"); sql.append("=?");
if (i < fields.length - 1) {
sql.append(",");
}
}
sql.append(" WHERE ");
sql.append(fields[0].getName());
sql.append("=?");
String();
}
private String getSelectSQL(Object obj) { // 拼SQL语句
StringBuffer sql = new StringBuffer(); sql.append("SELECT * FROM ");
sql.append("`" + tableName + "` ");
String();
}
private String getDeleteSQL(Object obj) {
// 拼SQL语句
StringBuffer sql = new StringBuffer();
sql.append("DELETE FROM ");
sql.append("`" + tableName + "` ");
sql.append(" WHERE ");
sql.append(fields[0].getName());
sql.append("=?");
String();
}
public boolean save(Object obj) throws Exception {
// 获取obj的属性的值
List list = getFields(obj);
// 获取sql
String sql = getInsertSQL(obj);
System.out.println(sql);
// 通过DbUtil//连接数据库
Connection conn = Conn(); PreparedStatement ps = conn.prepareStatement(sql); for (int i = 1; i <= list.size(); i++) {
ps.setObject(i, (i-1));
}
boolean flag = ps.executeUpdate() > 0 ? true : false; DbUtil.close(conn);
return flag;
}
public boolean update(Object obj) throws Exception { // 获取obj的属性的值
List list = getFields(obj);
// 获取sql
String sql = getUpdateSQL(obj);
// 通过DbUtil
Connection conn = Conn(); PreparedStatement ps = conn.prepareStatement(sql); for (int i = 1; i < list.size(); i++) {
ps.setObject(i, (i));
}
ps.setInt(list.size(), (Integer) (0));
boolean flag = ps.executeUpdate() > 0 ? true : false;
DbUtil.close(conn);
return flag;
}
public List select(Object obj) throws Exception {
return select(obj,null,null);
}
public List select(Object obj,String fieldName,Object fieldValue) throws Exception { // 获取obj的属性的值
List lists = getFields(obj);
// 获取sql
String sql = getSelectSQL(obj);
if(fieldName != null)
sql += " WHERE `"+ fieldName +"` =?";
// 通过DbUtil
System.out.println("SQL:"+sql);
Connection conn = Conn();
PreparedStatement ps = conn.prepareStatement(sql);
if(fieldName != null)
ps.setObject(1, fieldValue);
ResultSet rs = ps.executeQuery();
Class c = Class();
Method[] method = c.getMethods();
List list = new ArrayList();
while (rs.next()) {
Object o = c.newInstance();
// 获得所有的属性
for (int j = 0; j < fields.length; j++) {
String m = "set" + fields[j].getName().toUpperCase().charAt(0)
+ fields[j].getName().substring(1);
for (int i = 0; i < method.length; i++) {
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