对象持久化操作
package mliwng.persistent;
import java.sql.Connection;import java.sql.DriverManager;
import javax.sql.DataSource;
public class ConnectionManager {
public static ThreadLocal local = new ThreadLocal(); private static DataSource dataSource; private static final String DRIVER = "com.mysql.jdbc.Driver"; private static final String URL = "jdbc:mysql://localhost:3306/test"; private static final String UID = "root"; private static final String PWD = "mliwng"; public static void openConnection() { Connection conn = (Connection)local.get(); try { if(conn == null) { Class.forName(DRIVER); conn = DriverManager.getConnection(URL,UID,PWD); local.set(conn); } }catch(Exception e) { e.printStackTrace(); } } public static void closeConnection() { Connection conn = (Connection)local.get(); try { if(conn != null) { conn.close(); } }catch(Exception e) { e.printStackTrace(); }finally { local.set(null); } }
public static DataSource getDataSource() { return dataSource; }
public static void setDataSource(DataSource dataSource) { ConnectionManager.dataSource = dataSource; }}
package mliwng.persistent;
import java.lang.reflect.Field;import java.sql.Connection;import java.sql.PreparedStatement;
public class PreparedStatementManager {
public static PreparedStatement getSelectPstmt(Class c) { PreparedStatement pstmt = null; String sql = SqlManager.createSelect(c); if(ConnectionManager.local.get()== null) { System.out.println("local == null"); } try { pstmt = ((Connection)ConnectionManager.local.get()).prepareStatement(sql); }catch(Exception e) { e.printStackTrace(); } return pstmt; } public static PreparedStatement getSelectByKeyPstmt(Class c,String key,Object object) { PreparedStatement pstmt = null; String sql = SqlManager.createSelectById(c, key); try { pstmt = ((Connection)ConnectionManager.local.get()).prepareStatement(sql); pstmt.setObject(1, object); }catch(Exception e) { e.printStackTrace(); } return pstmt; }
public static PreparedStatement getInsertPstmt(Object object) { PreparedStatement pstmt = null; String sql = SqlManager.createInsert(object); try { pstmt = ((Connection)ConnectionManager.local.get()).prepareStatement(sql); setParameter(pstmt,object); }catch(Exception e) { e.printStackTrace(); } return pstmt; } public static PreparedStatement getUpdatePstmt(Object object,String key) { PreparedStatement pstmt = null; String sql = SqlManager.createUpdate(object, key); try { pstmt = ((Connection)ConnectionManager.local.get()).prepareStatement(sql); int j = setParameter(pstmt,object); Field field = object.getClass().getDeclaredField(key); field.setAccessible(true); System.out.println(j); pstmt.setObject(j+1, field.get(object)); }catch(Exception e) { e.printStackTrace(); } return pstmt; } public static PreparedStatement getDeletePstmt(Class c,String key,Object object) { PreparedStatement pstmt = null; String sql = SqlManager.createDelete(c,key); try { pstmt = ((Connection)ConnectionManager.local.get()).prepareStatement(sql); pstmt.setObject(1,object); }catch(Exception e) { e.printStackTrace(); } return pstmt; }
private static int setParameter(PreparedStatement pstmt,Object object) { Class c = object.getClass(); Field[] fields = c.getDeclaredFields(); int j = 0; for(int i = 0;i<fields.length;i++) { if(!isNull(fields[i],object)) { j ++; try { pstmt.setObject(j, fields[i].get(object)); }catch(Exception e) { e.printStackTrace(); } } } return j; } private static boolean isNull(Field field,Object obj) { boolean flag = true; field.setAccessible(true); try { if(field.get(obj) == null) { flag = true; }else { flag = false; } }catch(Exception e) { e.printStackTrace(); } return flag; }}
package mliwng.persistent;
import java.lang.reflect.Field;import java.sql.Connection;import java.sql.ResultSet;import java.util.ArrayList;import java.util.List;
public class SessionManager {
private Connection conn; public SessionManager() { conn = (Connection)ConnectionManager.local.get(); } public List loadAll(Class c) throws Exception { ResultSet rs = PreparedStatementManager.getSelectPstmt(c).executeQuery(); return this.getList(rs, c); } public List loadByKey(Class c,String key,Object object) throws Exception { ResultSet rs = PreparedStatementManager.getSelectByKeyPstmt(c, key,object).executeQuery(); return this.getList(rs, c); } public int save(Object object,String key) throws Exception { int i = 0; i = PreparedStatementManager.getInsertPstmt(object).executeUpdate(); return i; } public int updateByKey(Object object,String key) throws Exception { int i = 0; i = PreparedStatementManager.getUpdatePstmt(object, key).executeUpdate(); return i; } public int deleteByKey(Class c,String key,Object arg) throws Exception { int i = 0; i = PreparedStatementManager.getDeletePstmt(c,key,arg).executeUpdate(); return i; } private List getList(ResultSet rs,Class c) throws Exception { List list = new ArrayList(); Object object = null; Field[] fields = c.getDeclaredFields(); while(rs.next()) { object = c.newInstance(); for(int i = 0;i<fields.length;i++) { fields[i].setAccessible(true); fields[i].set(object, rs.getObject(fields[i].getName())); } list.add(object); } return list; }}
package mliwng.persistent;
import java.lang.reflect.Field;
public class SqlManager {
public static String createSelect(Class c) { StringBuffer buffer = new StringBuffer("SELECT * FROM "); buffer.append(c.getSimpleName()); return buffer.toString(); } public static String createSelectById(Class c , String key) { String sql = createSelect(c); StringBuffer buffer = new StringBuffer(sql); buffer.append(" WHERE "); buffer.append(key); buffer.append(" = ?"); return buffer.toString(); } public static String createUpdate(Object obj,String key) { Field[] fields = obj.getClass().getDeclaredFields(); StringBuffer buffer = new StringBuffer("UPDATE "); buffer.append(obj.getClass().getSimpleName()); buffer.append(" SET "); for(int i = 0;i < fields.length;i ++) { if(!isNull(fields[i],obj)) { buffer.append(fields[i].getName()); buffer.append( " = ? ,"); } } buffer = buffer.deleteCharAt(buffer.length() - 1); buffer.append(" WHERE "); buffer.append(key); buffer.append(" = ?"); System.out.println(buffer.toString()); return buffer.toString(); } public static String createInsert(Object obj) { StringBuffer buffer = new StringBuffer("INSERT INTO "); buffer.append(obj.getClass().getSimpleName()); buffer.append("("); Field[] fields = obj.getClass().getDeclaredFields(); StringBuffer bufferValue = new StringBuffer(); for(int i = 0;i < fields.length;i ++) { if(!isNull(fields[i],obj)) { buffer.append(fields[i].getName()); buffer.append(","); bufferValue.append("?,"); } } buffer = buffer.deleteCharAt(buffer.length() - 1); buffer.append(")"); bufferValue = bufferValue.deleteCharAt(bufferValue.length() - 1); buffer.append(" VALUES("); buffer.append(bufferValue); buffer.append(")"); return buffer.toString(); } private static boolean isNull(Field field,Object obj) { boolean flag = true; field.setAccessible(true); try { if(field.get(obj) == null) { flag = true; }else { flag = false; } }catch(Exception e) { e.printStackTrace(); } return flag; } public static String createDelete(Class c,String key) { StringBuffer buffer = new StringBuffer("DELETE FROM "); buffer.append(c.getSimpleName()); buffer.append(" WHERE "); buffer.append(key); buffer.append(" = ?"); return buffer.toString(); } }
package mliwng.persistent;
import java.sql.Connection;
public class TransactionManager { public static void beginTransaction() { Connection conn = (Connection)ConnectionManager.local.get(); try { conn.setAutoCommit(false); }catch(Exception e) { e.printStackTrace(); } } public static void commit() { Connection conn = (Connection)ConnectionManager.local.get(); try { conn.commit(); }catch(Exception e) { e.printStackTrace(); } } public static void rollback() { Connection conn = (Connection)ConnectionManager.local.get(); try { conn.rollback(); }catch(Exception e) { e.printStackTrace(); } }}
这个是测试用的package test;
public class User{ private Integer id; private String userName; private String userPassword; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getUserName() { return userName; } public void setUserName(String userName) { this.userName = userName; } public String getUserPassword() { return userPassword; } public void setUserPassword(String userPassword) { this.userPassword = userPassword; }}
package test;
import java.sql.Connection;import java.sql.ResultSet;import java.sql.Statement;import java.util.List;
import mliwng.persistent.ConnectionManager;import mliwng.persistent.SessionManager;import mliwng.persistent.TransactionManager;
public class UserDao{
public List list() throws Exception { return new SessionManager().loadAll(User.class); } public void insert(User user) throws Exception { new SessionManager().save(user, "id"); } public void update(User user) throws Exception { new SessionManager().updateByKey(user, "id"); } public void delete(int id) throws Exception { new SessionManager().deleteByKey(User.class,"id",id); } public List select() throws Exception { return new SessionManager().loadByKey(User.class, "userName","mliwng"); }
public static void main(String[] args) { UserDao dao = new UserDao(); User user = new User(); user.setUserName("11111"); user.setId(1); User user1 = new User(); user1.setUserName("cccc"); user1.setUserPassword("cccc"); User user2 = new User(); user2.setUserName("bbbb"); user2.setUserPassword("bbb"); ConnectionManager.openConnection(); //打开连接 TransactionManager.beginTransaction(); //开启事务 try { dao.insert(user2); //调用UserDao.insert()方法保存User2对象 TransactionManager.commit(); 提交事务 }catch(Exception e) { e.printStackTrace(); TransactionManager.rollback(); //出错时回滚 }finally { ConnectionManager.closeConnection(); } }}
