diff --git a/src/main/java/RowMapper.java b/src/main/java/RowMapper.java
deleted file mode 100644
index 2a53630..0000000
--- a/src/main/java/RowMapper.java
+++ /dev/null
@@ -1,6 +0,0 @@
-import java.sql.ResultSet;
-import java.sql.SQLException;
-
-public interface RowMapper<T> {
-    public abstract T mapRow(ResultSet rs, int index) throws SQLException;
-}
diff --git a/src/main/java/SqliteClient.java b/src/main/java/SqliteClient.java
index 408ac79..ffd4d6f 100644
--- a/src/main/java/SqliteClient.java
+++ b/src/main/java/SqliteClient.java
@@ -19,7 +19,7 @@ public class SqliteClient {
     private Statement statement;
     private ResultSet resultSet;
     private String dbFilePath;
-    private List<Class> obList = new ArrayList<>();
+    private Map<String, Class> classMap = new HashMap<>();
 
     /**
      * 构造函数
@@ -31,10 +31,13 @@ public class SqliteClient {
      */
     public SqliteClient(File dbFile, List<Class> classList) throws ClassNotFoundException, SQLException {
         this.dbFilePath = dbFile.getAbsolutePath();
-        this.obList.addAll(classList);
+        for (Class aClass : classList) {
+            classMap.put(aClass.getName(), aClass);
+        }
         if (!dbFile.exists()) {
             connection = getConnection();
-            for (Class object : obList) {
+            for (String key : classMap.keySet()) {
+                Class object = classMap.get(key);
                 StringBuffer sql = new StringBuffer();
                 String name = object.getSimpleName();
 
@@ -54,139 +57,192 @@ public class SqliteClient {
 
                 sql.replace(sql.length() - 1, sql.length(), "");
                 sql.append(")");
-                System.out.println(sql.toString());
+                System.out.println("SQL ==> " + sql.toString());
                 execute(sql.toString());
             }
         }
     }
 
-    public <T> void insert(T t) throws SQLException, ClassNotFoundException {
+    public <T> void insert(Class<T> poClass, T po) throws SQLException, ClassNotFoundException {
         try {
-            for (Class aClass : obList) {
-                if (t.getClass() == aClass) {
-                    StringBuffer sql = new StringBuffer();
-                    String tableName = aClass.getSimpleName();
-                    sql.append("INSERT INTO ");
-                    sql.append(tableName.toUpperCase());
-                    sql.append("(");
-
-                    Map<String, Object> keyValues = new HashMap<>();
-                    for (Field f : aClass.getDeclaredFields()) {
-                        if (f.isAnnotationPresent(Varchar.class)) {
-                            try {
-                                f.setAccessible(true);
-                                keyValues.put(f.getName().toUpperCase(), f.get(t));
-                            } catch (IllegalAccessException e) {
-                                e.printStackTrace();
-                            }
-                        }
+            Class aClass = classMap.get(poClass.getName());
+            if (aClass == null) {
+                System.err.println(poClass.getName() + " not found.");
+            } else {
+                StringBuffer sql = new StringBuffer();
+                sql.append("INSERT INTO ");
+                sql.append(aClass.getSimpleName().toUpperCase());
+                sql.append("(");
+
+                //获取字段列表
+                List<Field> fs = new ArrayList<>();
+                for (Field f : poClass.getDeclaredFields()) {
+                    if (f.isAnnotationPresent(Varchar.class)) {
+                        f.setAccessible(true);
+                        fs.add(f);
                     }
+                }
 
-                    StringBuffer fieldsSql = new StringBuffer();
-                    StringBuffer valueSql = new StringBuffer();
+                StringBuffer fieldsSql = new StringBuffer();
+                StringBuffer valueSql = new StringBuffer();
 
-                    List<String> argsList = new ArrayList<>();
-                    for (String key : keyValues.keySet()) {
-                        fieldsSql.append(key.toUpperCase());
-                        fieldsSql.append(",");
+                for (int i = 0; i < fs.size(); i++) {
+                    Field f = fs.get(i);
+                    fieldsSql.append(f.getName().toUpperCase());
 
-                        Object value = keyValues.get(key);
-                        if (value instanceof String) {
-                            valueSql.append("'");
-                            valueSql.append(value);
-                            valueSql.append("'");
-                        } else {
-                            valueSql.append(value);
-                        }
-                        valueSql.append(",");
-                    }
-                    String[] args = new String[argsList.size()];
-                    argsList.toArray(args);
-
-                    if (",".equals(fieldsSql.substring(fieldsSql.length() - 1, fieldsSql.length()))) {
-                        fieldsSql.replace(fieldsSql.length() - 1, fieldsSql.length(), "");
+                    Object value = f.get(po);
+                    if (value instanceof String) {
+                        valueSql.append("'");
+                        valueSql.append(value);
+                        valueSql.append("'");
+                    } else {
+                        valueSql.append(value);
                     }
-                    if (",".equals(valueSql.substring(valueSql.length() - 1, valueSql.length()))) {
-                        valueSql.replace(valueSql.length() - 1, valueSql.length(), "");
+                    if (i != fs.size() - 1) {
+                        fieldsSql.append(",");
+                        valueSql.append(",");
                     }
-                    sql.append(fieldsSql);
-                    sql.append(") VALUES (");
-                    sql.append(valueSql);
-                    sql.append(")");
-                    System.out.println(sql.toString());
-                    executeUpdate(sql.toString());
                 }
+
+                sql.append(fieldsSql);
+                sql.append(") VALUES (");
+                sql.append(valueSql);
+                sql.append(")");
+                System.out.println("SQL ==> " + sql.toString());
+                executeUpdate(sql.toString());
             }
+        } catch (IllegalAccessException e) {
+            e.printStackTrace();
         } finally {
             destroyed();
         }
     }
 
-    public <T> int delete(T t, String... wheres) throws SQLException, ClassNotFoundException {
-        for (Class aClass : obList) {
-            if (t.getClass() == aClass) {
+    public <T> int delete(Class<T> poClass, String... wheres) throws SQLException, ClassNotFoundException {
+        try {
+            Class aClass = classMap.get(poClass.getName());
+            if (aClass == null) {
+                System.err.println(poClass.getName() + " not found.");
+            } else {
                 StringBuffer sql = new StringBuffer();
-                sql.append("delete from ");
-                sql.append(aClass.getSimpleName());
+                sql.append("DELETE FROM ");
+                sql.append(aClass.getSimpleName().toUpperCase());
 
                 if (wheres.length > 0) {
-                    sql.append(" where");
+                    sql.append(" WHERE");
                     for (int i = 0; i < wheres.length; i++) {
                         String where = wheres[i];
                         sql.append(where);
-                        sql.append(i != wheres.length ? " and " : "");
+                        sql.append(i != wheres.length ? " AND " : "");
                     }
                 }
                 return executeUpdate(sql.toString());
             }
+        } finally {
+            destroyed();
         }
         return 0;
     }
 
-    public <T> int update(T t, String... wheres) throws SQLException, ClassNotFoundException {
-        ArrayList<T> list = new ArrayList<>();
-        for (Class aClass : obList) {
-            if (t.getClass() == aClass) {
+    public <T> int update(Class<T> poClass, T po, String... wheres) throws SQLException, ClassNotFoundException {
+        try {
+            Class aClass = classMap.get(poClass.getName());
+            if (aClass == null) {
+                System.err.println(poClass.getName() + " not found.");
+            } else {
                 StringBuffer sql = new StringBuffer();
-                sql.append("update set ");
-                sql.append(aClass.getSimpleName());
+                sql.append("UPDATE ");
+                sql.append(aClass.getSimpleName().toUpperCase());
+                sql.append(" SET ");
+
+                //获取字段列表
+                List<Field> fs = new ArrayList<>();
+                for (Field f : poClass.getDeclaredFields()) {
+                    if (f.isAnnotationPresent(Varchar.class)) {
+                        f.setAccessible(true);
+                        fs.add(f);
+                    }
+                }
+                for (int i = 0; i < fs.size(); i++) {
+                    Field f = fs.get(i);
+                    sql.append(f.getName());
+                    sql.append(" = ");
+
+                    Object value = f.get(po);
+                    if (value instanceof String) {
+                        sql.append("'");
+                        sql.append(value);
+                        sql.append("'");
+                    } else {
+                        sql.append(value);
+                    }
+                    if (i != fs.size() - 1) {
+                        sql.append(",");
+                    }
+                }
 
                 if (wheres.length > 0) {
-                    sql.append(" where");
+                    sql.append(" WHERE");
                     for (int i = 0; i < wheres.length; i++) {
                         String where = wheres[i];
                         sql.append(where);
-                        sql.append(i != wheres.length ? " and " : "");
+                        sql.append(i != wheres.length ? " AND " : "");
                     }
                 }
 
-                System.out.println(sql.toString());
+                System.out.println("SQL ==> " + sql.toString());
                 return executeUpdate(sql.toString());
             }
+        } catch (IllegalAccessException e) {
+            e.printStackTrace();
+        } finally {
+            destroyed();
         }
         return 0;
     }
 
-    public <T> List<T> select(T t, String... wheres) throws SQLException, ClassNotFoundException {
+    public <T> List<T> select(Class<T> poClass, String... wheres) throws SQLException, ClassNotFoundException {
         ArrayList<T> list = new ArrayList<>();
-        for (Class aClass : obList) {
-            if (t.getClass() == aClass) {
+        try {
+            Class aClass = classMap.get(poClass.getName());
+            if (aClass == null) {
+                System.err.println(poClass.getName() + " not found.");
+            } else {
                 StringBuffer sql = new StringBuffer();
-                sql.append("select * from ");
-                sql.append(aClass.getSimpleName());
+                sql.append("SELECT ");
+
+                //获取字段列表
+                List<Field> fs = new ArrayList<>();
+                for (Field f : poClass.getDeclaredFields()) {
+                    if (f.isAnnotationPresent(Varchar.class)) {
+                        fs.add(f);
+                    }
+                }
+                for (int i = 0; i < fs.size(); i++) {
+                    Field f = fs.get(i);
+                    sql.append(f.getName().toUpperCase());
+                    if (i != fs.size() - 1) {
+                        sql.append(",");
+                    }
+                }
+
+                sql.append(" FROM ");
+                sql.append(aClass.getSimpleName().toUpperCase());
 
                 if (wheres.length > 0) {
-                    sql.append(" where");
+                    sql.append(" WHERE");
                     for (int i = 0; i < wheres.length; i++) {
                         String where = wheres[i];
                         sql.append(where);
-                        sql.append(i != wheres.length ? " and " : "");
+                        sql.append(i != wheres.length ? " AND " : "");
                     }
                 }
 
-                System.out.println(sql.toString());
-                list.addAll(executeQuery(sql.toString(),t));
+                System.out.println("SQL ==> " + sql.toString());
+                list.addAll(executeQuery(sql.toString(), poClass));
             }
+        } finally {
+            destroyed();
         }
         return list;
     }
@@ -194,31 +250,31 @@ public class SqliteClient {
     /**
      * 执行select查询，返回结果列表
      *
-     * @param sql sql select 语句
-     * @param t   结果集的行数据处理类对象
+     * @param sql     sql select 语句
+     * @param poClass 结果集的行数据处理类对象
      * @return
      * @throws SQLException
      * @throws ClassNotFoundException
      */
-    public <T> List<T> executeQuery(String sql, T t) throws SQLException, ClassNotFoundException {
+    public <T> List<T> executeQuery(String sql, Class<T> poClass) throws SQLException, ClassNotFoundException {
         List<T> rsList = new ArrayList<T>();
         try {
             resultSet = getStatement().executeQuery(sql);
-            //2、获取字段列表
+            //获取字段列表
             List<Field> fs = new ArrayList<>();
-            for (Field f : t.getClass().getDeclaredFields()) {
+            for (Field f : poClass.getDeclaredFields()) {
                 if (f.isAnnotationPresent(Varchar.class)) {
+                    f.setAccessible(true);
                     fs.add(f);
                 }
             }
             while (resultSet.next()) {
                 try {
-                    T o = (T) t.getClass().newInstance();
+                    T o = poClass.newInstance();
                     for (int i = 0; i < fs.size(); i++) {
-                        Field field = fs.get(i);
-                        field.setAccessible(true);
-                        String string = resultSet.getString(field.getName());
-                        field.set(o, string);
+                        Field f = fs.get(i);
+                        String string = resultSet.getString(f.getName());
+                        f.set(o, string);
                     }
                     rsList.add(o);
                 } catch (InstantiationException e) {
@@ -249,7 +305,7 @@ public class SqliteClient {
     }
 
     /**
-     * 执行多个sql更新语句
+     * 执行sql更新语句
      *
      * @param sqls
      * @throws SQLException
@@ -282,6 +338,9 @@ public class SqliteClient {
         return connection;
     }
 
+    /**
+     * 获取数据库Statement对象
+     */
     private Statement getStatement() throws SQLException, ClassNotFoundException {
         if (null == statement) {
             statement = getConnection().createStatement();
diff --git a/src/main/java/SqliteTest.java b/src/main/java/SqliteTest.java
deleted file mode 100644
index f90e911..0000000
--- a/src/main/java/SqliteTest.java
+++ /dev/null
@@ -1,30 +0,0 @@
-import entity.User;
-
-import java.io.File;
-import java.sql.*;
-import java.util.ArrayList;
-import java.util.List;
-
-
-public class SqliteTest {
-    public static void main(String[] args) {
-        try {
-            List<Class> arrayList = new ArrayList();
-            arrayList.add(User.class);
-            SqliteClient h = new SqliteClient(new File("D:\\test.db"),arrayList);
-
-            User user = new User();
-            user.setName("wangbing");
-            user.setPassword(null);
-            h.insert(user);
-
-            List<User> select = h.select(user);
-            System.out.println("");
-
-        } catch (ClassNotFoundException e) {
-            e.printStackTrace();
-        } catch (SQLException e) {
-            e.printStackTrace();
-        }
-    }
-}
\ No newline at end of file
diff --git a/src/test/java/SqliteTest.java b/src/test/java/SqliteTest.java
new file mode 100644
index 0000000..d810959
--- /dev/null
+++ b/src/test/java/SqliteTest.java
@@ -0,0 +1,42 @@
+import entity.User;
+
+import java.io.File;
+import java.sql.*;
+import java.util.ArrayList;
+import java.util.List;
+
+
+public class SqliteTest {
+    public static void main(String[] args) {
+        try {
+            List<Class> arrayList = new ArrayList();
+            arrayList.add(User.class);
+            SqliteClient h = new SqliteClient(new File("D:\\test.db"),arrayList);
+
+            System.out.println("测试 insert");
+            User user = new User();
+            user.setName("wangbingwangbingwangbingwangbingwangbingwangbingwangbingwangbingwangbingwangbingwangbingwangbingwangbingwangbingwangbingwangbingwangbingwangbingwangbingwangbingwangbingwangbingwangbingwangbing");
+            user.setPassword("test");
+            h.insert(User.class, user);
+
+            System.out.println("测试 select");
+            List<User> select = h.select(User.class);
+            System.out.println(select.size());
+
+//            System.out.println("测试 update");
+//            user.setName("==");
+//            user.setPassword("==");
+//            int update = h.update(User.class, user);
+//            System.out.println(select.size());
+
+//            System.out.println("测试 delete");
+//            int delete = h.delete(User.class);
+//            System.out.println(delete);
+
+        } catch (ClassNotFoundException e) {
+            e.printStackTrace();
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+    }
+}
\ No newline at end of file